Tema: Mejoras para GA16, Que opinan

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  1. #1
    Avatar de SUPERMODTR1
    No Disponible
    Fecha de ingreso Aug 2010
    Mensajes 949

    Mejoras para GA16, Que opinan

    Que opinan de este articulo que me encontre navegando, se podran dar esos numeros hablan hasta de 42 hp mas pero una perdida de 0.4 seg en 1/4 de milla.... Sera posible??

    Bueno aqui ire poniendo mejoras que se podrian hacer a ese "pequeño" motor tan potenciable, parapoder mejorar su rendimiento, todo esto se ha hecho por gente de USA y comprobados.

    Empezamos con el Timing (encendido).



    Un "pequeño" truco para mejorar un poco el rendimiento del GA16DE es tocar el encendido. Normalmente de fabrica salen con 10 grados o incluso se han visto salir tan bajo como 5-6 grados. Se puede tocar el encendido SIN NINGUN PROBLEMA el encendido hasta los 15 grados, yo diria que con gasolina del 95 sin plomo (osea la mas normal), no habria problemas. Esto se ha probado en dyno y la ganancia ha sido bastante "curiosa" en un GA16DE totalmente de serie, se consiguio 5 CV a las ruedas (diria que sobre los 8-10 CV al embrague) en medios y 2-3 CV en altas.

    Colectores.

    De serie:



    Los colectores de serie esta designado para reducir potencia. El catalizador esta nada casi a la salida de los colectores y cada tubo primario va a dos cilindros. Claramente esto es mas por emisiones , no por potencia.



    El interior de los colectores de serie son un "2 en 1 " , dos cilindros va con una sola pipa. no se aprecia casi nada en la foto pero si os fijais mirar la reduccion que lleva en el interior. No sirve para nada si estas pensando en preparar tu Ga16de.

    Mejorados:



    Los colectores de Hotshot estan fabricados de acero templado de gran espesor revestido de material ceramico para una larga duraccion de estos y como se ve , cadatubo va a cada cilindro.

    Los colectores son probablemente el "BOOm" en la lista de mejoras para este motor. Actualmente el mejor colector hecho para el GA16DE es el fabricado por HOTSHOT.



    Hace falta que diga algo mas acerca de estos colectores? :

    Este da sobre 6-8 CV a las ruedas (mas de 10-15CV al embrague) de pico de potencia y sober 9-10 CV a las ruedas sobre los 5.500 RPM. Esto esta muy bien para un pequeño motor.

    Sistema de Escape

    Quizas sea la pieza mas popular cuando se piensa en mejorar el rendimiendo de un motor.

    El sistema de escape del GA16DE es muy restrictivo , fue designado para un minimo sonido en vez de un mejor flujo de salida de gases. La mayoria de coches consiguen sobre 2-3 CV solo cambiando el silencioso final por uno menos restrictivo.

    Este tema lo voy a terminar casi aqui puesto que en el articulo para mejorar la linea de escape, se hizo artesanalmente asi que , para que os hagais una idea, poniendo una linea de escape, si piensas en mantenerlo atmosferico, no seria recomendable sobrepasar sobre las 2" (aunque esto depende de la preparacion pero no creo que tengais que ir a mayor diametro.) y si es turbo pues una de 2.5 - 3 " seria lo ideal (personalmente recomiendo una linea de 2.5 hasta los 300CV , si se supera esos 300cv ya iria a las 3").

    Con una linea se podria conseguir de 7 - 10CV.

    Admision Directa.

    Lo mas barato (lo pondria entre comillas) que da un poquito mas de potencia , es el truco (no en todos los coches, pero yo por ejemplo, hice esto a mi VTI y consegui una mejora considerable). de quitar las partes bajas de todo el sistema de la caja del filtro de aire, y tapando (no en todos los casos diria yo) el filtro por la parte inferior, esto se consiguio una mejora de 1.5 CV en el banco de potencia. Nada mal solo quitando plasticos y peso .

    Hay dos tipos de Admision, el CAI (cold air intake) y el bolt on filter ( vamos en pocas palabras seria el kit de admision tipico que se le pone a los coches tuning . , ese que se le quita la caja y se le pone un filtro conico ).

    Aqui resumo un poco comentando que las ganancias con el CAI de Hotshot fueron sobre los 5CV sobre las 4.500 RPM y de 3 CV en altas.

    Este seria un CAI



    Las ganancias con el bolt on filter fue sobre 1-1.5CV

    Algo asi seria el tipo "bolt on filter"




    [img]ECUs[/img]

    Aqui solo se hablara de las ECUs de JWT (Jim Wolf Technology , yo diria que de los mejores en preparaciones de NIssan en la actualidad).

    Estas ecus mejoran significantemente con una mejor respuesta en la aceleracion haciendo que el coche (o motor) se sienta mas agil sobre todo en WOT (estos signica WIDE OPEN THROTTLE, osea con pedal a fondo por asi decirlo). Estas ECUS se inclinan por un A/F ratio en WOT con un optimizado 12.6 : 1 normalmente. El corte se aumenta a las 7.300 RPM de 6.900 .

    Esta ECu añade unos "bonitos" 10CV (a las ruedas, recordar que son diferentes al embrague que son los que se dan casi siempre) en medios y 3CV en altas. ADemas de una mejora de combustible (economia) , un combustible del 95 y con un timing de 8-10 grados es recomdable.

    Esta ecu es reprogramable para ir con alta compresion o turbo , de hecho, por ejemplo si quieres correr con una compresion de 11:1 ,esta ecu es escencial para ir con gasolina normal (o pump gas, que esto significa de 95-98 , porque hay otro tipo ce combustible que se llama Racing gas o algo asi que esto si que supera los 100 octanos).

    Poleas aligeradas de Unorthodox Racing

    Despues de ver en la pagina web de Unorthodox Racing, Ordenador (los tios que hicieron este articulo) sus poleas para hacer pruebas en el banco de potencia. Despues de hacer pruebas, se consiguieron sobre 2 - 4 CV y el motor se sentia mas "ligero" revolucionandose y fue mayor cuando se quito el Aire acondicionado.

    Conclusion , hubo ganancias poniendo estas poleas.

    Muchos opinan lo contrario,pero despues de leer esto bueno, dicen que los motores nissan salen INternamente balanceados sin contar con el volante o polea del cigueñal (? pensaba que se balanceaban todos iguales pero ya veo que no) como motores ford o chevys..



    Arbol de levas.

    ACtulamente las levas de JWT (prototype) son las que hoy por hoy, se podria decir que son las mejores. Segun unas pruebas que se hicieron con estas, no se perdieron bajos y donde se consiguieron 7 HP .. La potencia empezo a partir de las 5.000 RPm.. a las 7.300 RPM.. donde las levas producian sobre 42 HP mas que las de serie. ( )

    Estas levas hacen un ralenti ligeramente "lento" pero van como loco hasta las 7.300 RPM con ninguna sensacion de perdida de potencia. Las levas quitaron 0.4 seg en el 1/4 de milla..

    Para mejores resultados, una ecu tambien de JWT seria imprescindible. La ecu tambien optimiza el punto VTC (en el caso de que los motores que lo llevasen). Esto, con escape, colectores,ecu,poleas (hasta ahora).. seria bastante rapido en comparacion con algun motor honda como un D16 ..

    Culata

    Desafortunadamente la culata del GA16DE es bastante pesima. Los conductos de escape son pequeños y diseñados para un aceptable potencia en bajs en vez de altos. De hecho, se hicieron mediciones de flujo con un aparatito (flow bench , no se como se diria en castellano ) ,el flujo del escape a la admision es que fluye el 60% del flujo de la admision, sobre el 80% seria aceptable asi que lo ideal para mejorar la culata seria trabajar en los conductos de escape para intentar al menos conseguir ese 80%. Comparando los conductos como otros motors 1.6 como el D16 de honda o el 4AG son aun mas pequeños.Pero no todo es malo, puesto que cuando se quito la culata, el GA16DE cuenta con unos buenos cilindros, dejando las valvulas un poco mas "separadas" ademas de que cuenta con suficiente area para una mayor resistencia a la detonacion (turbo? mmm ) . A ea "area" o espacio se le llama quench area, que esto ayuda a crear turbulencia cuando el piston sube al punto muerto superior haciendo que se queme mejor la combustion y menos probabilidades de detonacion. El area haber si me explico,es la distancia que han entre el punto mas alto del piston con la culata. (incuida la junta claro).

    Aqui unos pequeños pasos si quereis empezar a portear vuestra culata.

    El primer paso se traza con una junta puesta, marcando por el contorno de esta en la culata para ver lo que le "sobra" a los cnoductos.



    Despues empezamos a portear los conductos segun las marcas que se hicieron con la junta.



    Luego con los dedos, mientras cortamos, paramos para comprobar el cortorno que se hace todos por igual.



    Despues de usar la fresa metalica o de carburo , usaremos un cartucho "abrasivo"



    Aqui una foto del trabajo final.



    Volvemos a coger la fresa de carburo o metalica diria yo, y repasamos los asientos de valvulas ..



    aqui ya terminado.



    El objetivo de un buen porteo es incrementar lo mejor posible el flujo manteniendo el volumen tan bajo posible para conseguir una buena velocidad de flujo. Unos conductos agrandados tienen baja velocidad en bajas rpm .

    Luego otro tipo de trabajo en culata es el "valve job" que consiste en dar angulos a los asientos de valvulas, pueden ser de 3 o mas angulos que se le podrian dar. Lo que se consigue con esto es que el flujo pase por la valvula lo mas "recto" posible ,especialmente cuando estas abren y cierran.

    Aqui un ejemplo del trabajo de "valve job" que se le ha dado.



    Aqui una comparacion de una valvula normal con una que se le ha dado 30 grados.



    Comentan que de los mejores que portean sob DPR (Dan Paramore Racing), JWT y B.C. Gerolomy.

    ---------- Post added at 05:35 PM ---------- Previous post was at 05:34 PM ----------

    Tomado de: http://primerasclub.creatuforo.com/v...m=primerasclub
  2. #2
    Avatar de EstebanVenon
    TR Master
    Fecha de ingreso Dec 2007
    Ubicación A mas de 100kph :plop
    Edad 34
    Mensajes 10.538


    estos son los temas!!!!
    -------------------------------------------------------------------------
    [email protected]


  3. #3
    Avatar de JWeis
    Conocedor
    Fecha de ingreso Sep 2009
    Mensajes 4.825
    Muy buen aporte...!


    Ya ve, con unas cuantas cosillas se les saca unos 20 rucos a ese bichillo....


    Haber los que tienen esos motores que cuenten sus experiencias
  4. #4
    Avatar de CHUS
    Modificado
    Fecha de ingreso Feb 2006
    Ubicación CCSS
    Mensajes 1.315
    Yo si creo q el ga16DE se le puede sacar mucho potencial, solo q hot shot, JWT estamos hablando de muchos $$ que se podrían invertir en otro motor con mas grande q pueda dar mas con menos $$.
    Pero para algun fiebre del ga16 esas mod y algun controlador para sacarle provecho al VTC debe dar bonitos números..
  5. #5
    Avatar de EstebanVenon
    TR Master
    Fecha de ingreso Dec 2007
    Ubicación A mas de 100kph :plop
    Edad 34
    Mensajes 10.538
    hay cosas interesantes una vez el hermano de un gurú nissan me decia q con el header mas bien hay perdida... y son personas q solo ven esos motores... claro todo es prueba y error
  6. #6
    Avatar de -RoadRunner-
    Banned
    Fecha de ingreso Apr 2011
    Edad 40
    Mensajes 2.173
    Mae esa guia es viejiiiiiissssssssssssssssssssima. hay una mejor Valde tiene una copia, fue la que yo use para armar mi GA16DE, es la biblia de Mike Kojima

    ---------- Post added at 05:25 PM ---------- Previous post was at 05:22 PM ----------

    Engine Modifications

    By Mike Kojima

    Photography:
    Michael Young
    Mike Kojima

    Updated 08/09/01

    Return to Kojima's Garage
    Contents:

    * Timing
    * Synthetic Oils and Lubricants
    * Headers
    * Exhaust Systems
    * Air Intakes
    * ECUs
    * Unorthodox Racing Underdrive Pulleys
    * Cam Shafts
    * Headwork
    * Pistons
    * Crank, Rods, Bearings, Machining, Balancing, Coatings, Manifolds, etc.
    * Extrude Honing
    * Big Bore Throttle Bodies and MAFs
    * Spark Plugs and Ignition Systems
    * What if I have a B15?

    GA16DE Dyno Chart
    GA16DE Dyno Chart (incremental)
    Click for full-size
    Microsoft Excel version
    GA16DE Dyno Chart
    GA16DE Dyno Chart (totals)
    Click for full-size
    Microsoft Excel version

    Due to popular request, I have compiled a guideline list of sorts relating to my, experiences with various aftermarket performance parts for the GA16DE engine. This info can hopefully be a good reference source for newbies and can help to eliminate a lot of repeat posts on the Sentra mailing list. As a note, I am not an expert on the GA16DE motor as of yet and this information is just the start of what will be a long journey in figuring out what makes the GA16DE and its younger brother the QG18DE tick.

    GA16DE with all the bolt-ons

    A GA16DE with all of the bolt ons is a force to be reckoned with. Although it is weaker than a Honda D16 in stock form, the GA16DE responds to modifications much better. A modded GA has much better torque and bottom end power than the D16 and a well tuned one is faster than a D motor Civic with equivalent mods because of this. The often ignored GA16DE Nissan motor is also more powerful than a Miata motor and probably any of the other non heavy hitter compacts. Only the B series Honda motors and the Mighty SR20, both modded can humble the sleeper GA when it is tweaked up a little!

    Don't be so eager to tear that sucker out to drop in an SR20DE just yet.

    However everything done will be back up by dyno data, solid fact, not the butt dyno opinion of the unqualified that is common on the net.

    As everywhere, screwing with your car can be illegal and dangerous, check with you local and federal emissions laws and proceed at your own risk. We assume no responsibility for your actions. Please don’t use your newfound power to street race. Usually the victims of street racing are the innocent bystanders. Be safe and BE careful.

    Timing

    Checking ignition timing

    Motivational Mike checks the timing on his 200SX SE. Timing is a very effective no cost mod, check the gains on the dyno chart above.

    Here is the all time cheapest hop up that anyone can do. Typically most GA16DEs have the timing set to 10 degrees or less from the factory. I have seen as low as 5-6 degrees on a brand new factory fresh car. You can safely run up to 15 degrees on premium gas on the GA16DEs. This has been proven by recent dyno testing on a stock car to give up to 5 more hp at the wheels in the midrange and 2-3 at top end. Remember if you have your timing turned up this high you MUST use 92 octane fuel. Do not exceed 10 degrees of advance if you have a JWT ECU.

    Don’t tolerate any detonation though. Detonation will kill your engine quicker than lard and coconut oil will kill you! If you have the JWT ECU, set the timing at 8-10 degrees. On the dyno I have not seen any difference between 8 and 10 degrees with a JWT ECU although bottom end snap might feel a little better. Be sure to disconnect the TPS when adjusting the timing.

    [Information on adjusting timing.]

    Synthetic Oils and Lubricants

    Synthetic engine oil

    Synthetic oil is a good cheap mod. It can be good for up to a couple of hp, plus gives the motor much greater protection. If you drive hard or race, it can be cheap insurance. Synthetic oil should still be changed every 3000 miles. Motul and Mobil One are among the best you can get. Most high level pro racing teams use Mobil One and Nismo uses Motul.

    This is a good non-envasive hop up part. I am going two open a whole can of worms here but as far as I know, Mobil 1 is the only synthetic oil to get for your engine. Not only is it the cheapest but it works the best. There is a lot of industry insider information on oil and Mobil 1 has been tested by many OEM manufacturers and found to come out on top. I don’t want to start a big thing about it and cannot divulge my information's secret sources, but trust me on this one. Granted my test data did not include Valvoline, Castrol or Havoline Synthetic but it did include ALL of the famous synthetics who will remain nameless on the record. In fact, one oil that is highly regarded by list members that is sold as a direct marketed product is in fact nothing but rebottled Mobil 1 for twice the price.

    Recently, my buddies at Cosworth report that Royal Purple seems to have good bearing life in the XD Indy engine but for the most part Cosworth uses Mobil One as factory fill. I have had personal good luck with Motul but have no scientific test to prove that it is super good. Adam Saruwatari tells me that Motul has cut his engine wear by 3 fold. Nismo uses Motul in their Group C LeMans car as well as the GT390R. Their testing showed that Motul was excellent.

    Although not an engine hop up part, gear oil can affect your power by reducing frictional losses. For gear oil I do not recommend the popular Redline MTL. Its thin body does not protect well and Nissan transmissions are not the strongest in stock form. Nissan Motorsports has had good luck with regular Redline Shock Proof gear oil. Personally I like Motul gear oil. It seems to shift nearly as well as MTL and better than Mobil 1. It has a heavier body so it should have better shock protection for the gears than MTL. Granted this is not based on any scientific evidence, just observations and common sense. JUN reports excellent results with NEO RHD. The Hyper Yellow Civic was breaking it’s tranny every 5-7 passes. When JUN switched to RHD gear oil, the transmissions lasted up to 20 passes.

    Redline Water Wetter

    As a non oil related note, Redline Water Wetter is legitimate and really has a reduction of water temp by about 20 degrees F, good stuff.

    These super lubes can free up about 1-3 hp, have much better gearbox and engine operation in very cold weather and directly help performance by keeping your engine in top shape for longer.

    In my opinion, you still need to change the engine oil at about 3000 miles for best results even with synthetics. I have noticed that the oil pressure at hot idle starts to drop at about 1500 miles with dino oil and 3000 miles with synthetics. I believe that this is caused by the oil’s shearing down under hard use. That’s where my 3000 mile opinion comes from. It is not scientific oil analysis but is based on some data. BTW, I have never had an oil-related failure in any engine I have ever built while following these rules.

    To my knowledge, the best oil filters are genuine Nissan. This is mostly because of the anti-drainback valve, which goes a long way to reduce cold start wear. Also, the bypass valve flow rates and the particle pass through size have been determined by the factory as the best compromise between effective filtering and good flow with low pressure drop. The factory filter also has a thicker shell and better crimping that your typical aftermarket filter so it is less likely to blow off if, for instance, the bypass valve sticks or the oil is super thick on a real cold day.

    Stock GA16DE exhaust manifold - "crapalytic converter" Hotshot header - much better design

    LEFT: The stock GA16DE manifold is designed especially to reduce power. The cat is right out of the exhaust port and each primary pipe is shared by two cylinders. This is clearly designed for emissions, not power. RIGHT: The Hotshot header is a high quality piece made of thick gauge steel and ceramic coated. As you can see, every cylinder gets it's own primary pipe, no more sharing. This is way better for both backpressure reduction and pulse tuning.

    Headers


    Headers are probably one of the biggest bang for the buck item in the modification list. Currently the best header for the GA16DE on the market by far is the Hotshot. The Hotshot header is constructed of heavy gauge mild steel that is ceramic coated for appearance and long life.

    The Hotshot header gives about 6-7 more peak wheel hp than stock and 9-10 hp around 5500 rpm according to our dyno tests. This is pretty impressive for a header on such a small engine. A Civic is lucky to gain half of this. Pacesetter has a header but it is a cheap copy of the old Hotshot design of about 2 years ago. Fortunately the new Hotshot has a revised primaries pipe layout so it should easily out power the Pacesetter, especially in the midrange.

    Stock GA16DE exhaust manifold ports Hotshot header exhaust ports

    LEFT: The stock exhaust manifold's ports have two cylinders dumping into one pipe! Check out the neck down. Not good at all for power. RIGHT: The Hotshot header is much better, one pipe per cylinder, no more sharing. This is so obviously better, it makes an amazing difference. The Hotshot header is the only decent GA16 header currently on the market.

    The fit of the Hotshot header is very good and the installation should be a snap. Just remember to order a new exhaust manifold gasket before you tear your car apart. Nissan dealers usually forget to stock this and the header does not come with a new gasket.

    When installing the Hotshot header on cars with a close coupled catalytic converter built into the manifold and/or 95 and later OBDII cars, you must get an SE-R cat or a Random Technology SE-R cat of the same year and bolt it to the header collector under the car. Screw the rear O2 sensor into the bung in the back of the appropriate SE-R cat. Now extend the wire harness for the rear O2 sensor and plug the rear O2 sensor in.

    Stainless steel mandrel bends High flow catalytic converter

    LEFT: A proper exhaust system should be fabricated from pre-made mandrel bends, not crush bent muffler shop pipe. A good fabricator cuts these bends apart and welds them together to make an exhaust with no neck downs. Normal muffler shop pipe benders crush the pipe by as much as 50% when making bends. These stainless steel mandrel bends are made by Magnaflow. Once welded, these can be polished like chrome. A naturally aspirated GA16 should not use piping bigger than 2" in diameter. RIGHT: The stock Nissan cat or just about any modern cat has hardly any restriction and costs almost no power. This is a high flow 3" Magnaflow cat which is excellent for turbocharged cars. Don't pollute.

    This is very important to keep the OBDII system happy and to make it so you can pass a roadside automatic smog inspection (yes we have these Nazi things in California. This is not legal in all states, but it will pass a California dyno smog test, although it will fail the visual part of the test.

    Do not remove your catalytic converter. On a GA16 with an SE-R converter, you will not gain any power and end up just polluting a lot. Lets do our part to keep the earth clean.

    Exhaust Systems

    Motivational Mike cutting mandrel bends.
    Motivational Mike is cutting mandrel bends to the right shape to help form the exhaust.
    Mike test fits the cut pieces together.
    After cutting, Mike test fits the cut pieces together.
    Mike tack welds the pipes in place.
    After test fitting, Mike tack welds the pipes in place with a MIG welder to get them in the right position.
    The bends are seam welded into there final place.
    After tack welding, the bends are seam welded into there final place with a TIG welder on the bench.

    Perhaps the most popular first piece of speed equipment is the exhaust system. The exhaust system on the GA16DE powered Sentra is very restrictive, it was designed for minimum noise instead of free flow. Most new cars only gain 2-3 hp from a cat back exhaust but not GA16 equipped Sentra! We found 6-7 hp to the wheels with our prototype Hotshot cat back system, an impressive gain. The Hotshot exhaust should be available by 3/2001.

    The final result.

    The final result is a beautiful all stainless steel exhaust better than any you can buy on the market for a Nissan, smooth and free flowing with absolutely no neckdowns like you would get at cheap muffler shop.

    This trick system is better quality than any you can buy and costs less than a Greddy.

    The Stainless mandrel bends, mufflers and hangers were all bought from Maganaflow. All welding was TIG with rust free stainless welding rods.

    We will probably polish this exhaust later so it can look really trick.

    For you do-it-your-selfers here are some general guidelines. If your engine is naturally aspirated, limit your pipe diameter to no more than 2" or you will lose some bottom end with no applicable gain on top. For turbo applications, 2.5-3" is the way to go. Try to avoid the typical muffler shop crush bends. You can buy mandrel bends from Kinsler, Burns stainless, or Bassani. That way your local muffler shop can cut and section these for smooth, non-crush bends in your system.

    Straight through mufflers are by far the lowest backpressure. The Walker UltraFlow, Apex'i, or Magnaflow are some common ones. Stay away from the generic louvered core glass packs. Even though those are straight through they have incredible backpressure, often more than stock. Look for a perforated core. This is a pipe with lots of small punched holes. The Walker and the Magnaflow mufflers are real loud by themselves and require a pre-silencer.

    The Walker Magnum glass pack that most auto parts stores sell here is good for this. It has a perforated core. Make sure that you are truly getting a perforated core! A 24" long Walker with an UltraFlow or Magnaflow creates a system with about 2 psi back pressure that is decently quiet. Dual path, straight through, perforated core mufflers like the Edelbrock should work well also, although I have no direct experience with them. You still need a pre-silencer with them.

    The common Turbo-style mufflers are not very quiet and have lots of backpressure, as do the famous Super-Trap and the Flow master, so don’t bother with them.

    If you are so inclined, you can do your own testing by welding a pipe bung right after the cat and running a silicon hose to a 0-20 psi gauge in your car. Then you can do 3rd gear runs through the rpm range recording backpressure. Use an old fuel filter as a surge accumulator to smooth gauge readings. Make sure all of the gas is gone! Better yet, use a new plastic one so you won't blow anything up!

    Louvered core muffler, not as good as it looks! Perforated core muffler, get one like this! JUN titanium muffler, with a perforated core.

    LEFT: The best mufflers for power production are straight through types. These have the lowest restriction. Not all performance mufflers are created equal however. This racy looking polished stainless muffler is actually quite poor for performance because it has a louvered core. Louvered cores can sometimes have more backpressure than a stock muffler! CENTER: Here is a properly designed straight through muffler, one that has a perforated core. These types of mufflers have about the same amount of backpressure as a straight piece of pipe, perforated core mufflers are the very best for power. Sometimes they can be loud. If you want a quiet exhaust, you can place a perforated core glass pack before your main muffler to act as a pre-silencer. Remember, no louvers! RIGHT: This JUN titanium muffler is the ultimate in trickiness for the person that must have everything. It weighs as much as a small cardboard box, is very expensive and yes has a perforated core!

    Unless you are turbo or run a large nitrous unit and are going for the maximum in power, do not bother with removing or gutting your cat. Unless the cat is melted it only has about 1.5 psi of backpressure or less and only affects power by 1-2 hp if that. This is even with a built NA motor. With a turbo or NOS you will lose some power. Remember, this (gutting the cat) is also a big time violation of federal law! Gutting the cat will cause a MIL light on post '95 Sentras which is to be avoided come registration time. There is little to be gained with aftermarket cats either, although they are priced well and if you need to replace your stock cat they can be a good value.

    Air Intakes

    The cheapest thing that gives a little more power is the infamous ghetto airbox trick, which involves removing the lower part of your airbox and ziptieing or tapping the filter to the upper part of the airbox. Just for laughs we dynoed this combo and found that we got about 1-1.5 hp out of it! Not bad for free although filtering probably suffers and it looks, well, ghetto!

    There are two types of air intakes, the CAI or cold air intake and the bolt on filter.

    The most common bolt on filters are the JWT POP Charger (POP stands for Performance Optimized Program) and the Stillen which are almost identical. Both are washable and reusable and come with a nicely machined aluminum velocity stack base. Be sure to oil them with K&N oil after cleaning in detergent and water. Don’t go crazy with the oil, a light even coating is fine. Too much oil can contaminate the hot wire in the MAF.

    There is also the HKS powerflow which does not seem to filter well. I put one on a white rag and tapped it and lots of dirt went right through it. One of my friends tested one on a flow bench and found it flowed better than the POP, but the Stillen and POP has more than enough flow capacity for the GA16 and personally I would rather have a filter than a boulder strainer.

    Greddy also makes a filter. I have no direct experience with the GReddy unit but it appears to be made of fine foam, which could filter better I suppose.

    Hotshot cold air intake system
    The Hotshot cold air intake is dyno proven to be the most powerful one on the market for the GA16DE, you can see the dyno results on the chart at the front of this section.

    There are also the Weapon R and several cheaper brands that I have never bothered to use or test but are essentially copies of the above filters.

    You can expect 1-2 hp with these units. This is a little better than the ghetto mod and surely looks much better. If you live in areas of high rainfall, then these should be considered because CAI’s don’t like deep water!

    If you want to test your own filters, simply use a multimeter to measure the voltage to the MAF. The higher the voltage, the more air you are flowing. Remember also that temperature and barometric pressure affect the readings so it is important to use only back to back data, not week to week.

    Perhaps the most potent air intake is the CAI by Hotshot. I have tested this combo and found up to a 5 hp gain at 4500 rpm with 3 more peak hp. I was involved in testing the Hotshot prototype and its unique 3"-2.5" stepped diameter was the result of that testing. This gave the most power over the broadest power range. This part is one of my bang for the buck recommendations. Place racing also has a good quality CAI.

    Place Racing cold air intake system
    Place Racing also makes a quality cold air intake for the GA16DE.

    The CAI stays cool to the touch even when everything else is burning hot. For every 10 degrees reduction in intake air temp, you can expect a 1% increase of power, in testing we have found that the CAI keeps the intake air about 40 degrees cooler than an inside the engine compartment filter. This does not necessarily show up in dyno testing.

    The CAI also uses engine resonance to help supercharge the mixture slightly. This is why a CAI gives more power than just a simple low restriction filter will.

    ECUs

    So far in my experience the only ECU worth considering at this point is the JWT unit. Without slamming anyone, to my knowledge most of the other ECUs on the market have some degree of code mistakes in them. JWT is also the only company to my knowledge at this time that can do reliable programming on Post 1995 OBD-II ECU’s. Without revealing specifics, when examining the code in other companies ECUs, mistakes have been found on just about all of the other manufactures chips. In fact, one famous manufacturer did not change one single bit of code in the program! They merely socketed the PCB, and put an E-PROM WITH THE STOCK CODE IN PLACE! They charge 600 bucks for this piece of crap. They advertise in all the major magazines. I won’t name a name but their ads feature an Eclipse burning out with a sunglassed ponytail looking dude driving it.

    If you want to buy another brand of ECU, ask these questions.

    1. Can you raise the rev limit?
    2. Can you eliminate the speed limit?
    3. Can you compensate for larger injectors across the entire operating range?
    4. Can you compensate for a different MAF?
    5. Do you use a Horiba A/F monitor?
    6. Do you understand offsets? Do you know what invalid time is?
    7. Can you program a OBD-II box?

    ECU comparison: stock on left, JWT on right
    Comparison of a stock (left) and reprogrammed JWT ECU. Picture provided by Wes Dumalski.

    If they cannot answer all of these questions then go to JWT and save yourself some aggravation. I am not paid by JWT so I am not biased, but I'm amazed by their technical competence and I am very hard to impress most of the time.

    JWT’s ECU significantly improves transient throttle response making the car feel much more lively as well as providing more total advance at WOT. The JWT ECU also leans out the A/F ratio at WOT to an optimal 12.6:1. The rev limit is raised to 7300 from 6900 and the VTC readvance point is eliminated.

    The JWT ECU adds an amazing 10 hp to the midrange of the power band and generally adds about 3hp on top. We found that the ECU gives the GA more power under the power curve than any single mod tried to date. If you follow the same driving pattern with the JWT ECU, it has the potential for better fuel economy, as well. Premium fuel is required and 8-10 degrees of set timing is recommended.

    For the 95 and later Sentra’s, the JWT ECU is almost essential as this car is saddled with an annoying 109 mph speed limiter and a crappy 6900 rpm fuel cut. The ECU really adds to the driving pleasure of these cars.

    On 91-94 Sentras you must first buy a ECU for an SE-R of the same year range and type, for instance you must get a 5-speed California SE-R ECU for a 5-speed California Sentra, from a junkyard or from the dealer to send to JWT. If you want the VTC variable cam timing to work, you need to have JWT enable it’s use with there add on control module, which is no big deal. For 95-97 Sentra’s JWT can reprogram your own ECU if you desire. For 98-99 models, a 95-97 ECU is needed and some minor rewiring of the rear O2 sensor and EGR solenoid is needed, again, no big deal. JWT can provide instructions for doing this.

    JWT can also custom program the ECU for high compression and turbocharged applications for a reasonable fee. In fact, if you are going to run 11:1 compression, a JWT ECU is essential if you plan to run on pump gas.

    Unorthodox Racing Underdrive Pulleys

    Unorthodox Racing Underdrive pulley
    The Unorthodox Racing Underdrive pulley is good for a few free hp with no negative side effects. It is CNC machined form lightweight aluminum eliminating a few lbs of rotating mass from the crank, making the car rev more easily. It is a worthy bolt on mod and relatively inexpensive.

    Being skeptical of the claims for big horsepower on the Unorthodox Racing web site, we ordered up their underdrive pulley to do some dyno testing. When received, the pulley was obviously CNC machined from billet aluminum and anodized a nice shade of red. It was significantly lighter than the stock pulley. We measured the TDC mark in relation to the keyway to make sure that the TDC mark was right on. It was.

    To install the pulley, we removed the passenger side wheel and wheelwell splash shield, exposing the front of the engine. An air impact was then used to remove the main pulley nut. A puller was used to remove the stock pulley.

    After running the car, our SOTP estimate of power gain was moderate, about 2-4 hp. The engine felt more eager to rev and there was less drag when the AC compressor kicked on.

    We plugged in a CONSULT to test for charging function and overheating. The battery output stayed above 12 volts with all electrical accessories going full blast. We tried to make the car overheat in bumper to bumper traffic, plus extended high speed cruising. The coolant temp never went above 94 degrees C. We also did some violent slalom maneuvers to test the power steering. There was no sign of power steering pump up. The AC was perhaps a little less effective but it was hardly noticeable. After all this testing I conclude that the pulleys are at least safe.

    Some list members have been concerned that the underdrive pulleys lack of an inertia ring as the one in the stock pulley could have some negative effects on motor life. We believe that this is not true. The GA16DE, unlike most domestic motors, is internally balanced. It does not rely on a counterweight on the front pulley and flywheel to give dynamic balance like Ford or Chevy engines. Highly modified domestic motors are internally balanced at a great cost but us Nissan owners get that stock! We believe that the damper on the stock pulley is mostly to damp out accessory drive noise. With the underdrive pulley in place there actually seems to be less idle and high rpm vibration. We could not detect any increase in accessory drive noise.

    On the dyno the pulley gave us 1 more peak hp but 3-4 through the often used midrange. We think we proved that the pulley does not harm anything. Overall the pulley is a pretty decent gain for the low price of this mod and gets the nod as a good bang for the buck from us.

    Cam Shafts

    In our testing we have found that the later 95-99 camshafts have a lobe center that is spread by a few degrees over the earlier 91-94 cams. Because of this, the 95-99 cams have a bit more top end power, while the early cams have a bit more bottom end power. Overall if you are doing some junkyard raiding, the late model cams will give an early car a couple more hp, not worth buying new cams but if you have a line on some cheap late model cams, it might be worth it.
    Stock (left) vs. JWT cam comparison
    The stock cam is the dark colored one on the left, the JWT cam is the silver colored one on the right, note how much bigger and taller the lobe on the JWT cam is. This shows the greater lift and duration.

    So far, the prototype JWT cams are about the only ones that work well on the market. The JWT cams are ground on new genuine Nissan billets so the factory base circle diameter can be maintained. This is important for easy installation as the GA16 has it valve lash adjusted with shims. Most of the time you can just use the stock shims without the hassle of reshiming when changing the cams. Other companies regrind the base circle smaller to get more lift and duration on a stock cam. This would require some custom shims under the hydraulic lash adjusters to maintain proper lash. Most companies that do regrinds do not supply the custom correction shims!

    In my testing, the JWT did not lose bottom end power from stock (the bigger the cam generally, the less bottom end) and were good for a solid 7-peak hp. The gains were recorded from 5000 rpm on. At 7300 rpm the cams produced an amazing 42 more hp than the stock cams!

    The cams have a slightly lopey idle and pull like crazy to the 7300 rpm rev limit with no perceptible drop in power. The cams took 0.4 of a second off of the cars ¼ mile time.

    For best results a JWT ECU is needed. The JWT ECU optimized the VTC operation points. We found a few unusual things about the VTC. The VTC likes to advance the cam at over 6600 rpm for some reason, perhaps to create a drop in power to encourage the driver to shift sooner. It also retards the cams too early for the JWT cams. The JWT ECU eliminates the high rpm advance, retards the cam at 6100 rpm instead of the stock 5300 rpm and gives more high rpm advance. Although it does not affect the peak power, the JWT cam optimized ECU really helps the area under the power curve, giving a much fatter, wider and smoother power curve.

    At this point the car is running [email protected] mph. That is SE-R sort of time with just bolt ons and no internal engine work in a full on totally ungutted car with a sound system and all! Only one other all-motor Sentra is faster and it had a fully built motor and was gutted.

    In a roll on the car was dead even with two of the feared Civic Si’s, both with an intake and Exhaust. The car eats modded D series powered Civics for lunch. Not bad for a bottom of the line, once forgotten1.6 eh?
  7. #7
    Avatar de -RoadRunner-
    Banned
    Fecha de ingreso Apr 2011
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    Headwork

    A first step to port your head.
    As a first step to port your head, scribe the port to the outline of the manifold gaskets.
    Next open up port to scribe lines.
    Next open up port to scribe lines with a die grinder and a carbide cutter.

    Unfortunately the GA16DE is cursed by a lousy stock cylinder head. The ports, especially on the exhaust side are small and designed for good low-end power instead of a top end charge. In fact when run on a flow bench, the ratio of exhaust to intake flow is the exhaust port flows 60% of the intake. Ideally 80% is about right. So it is best to concentrate on the exhaust port and work to get the 80% ratio. When disassembling a GA head I was amazed at how small the ports are compared to other 1600cc motors like the Honda D16 and the Toyota 4AG. This is not a bad point to dwell on however, all it means is that this motor should respond even better to headwork.

    Some good news is that the GA16 is blessed with a nice combustion chamber. Its chamber leaves the valves relatively unshrouded. In addition there is a lot of quench area for more resistance to detonation. Quench helps create turbulence in the combustion chamber as the piston approaches TDC which makes for a better burn and less likelihood of detonation.
    Feel the ports contours.
    While cutting, stop every few seconds and feel the ports contours with your fingers to make sure you are cutting the port evenly.
    Blend and polish the port.
    After the carbide cutter, blend and polish the port with a cartridge roll and a die grinder.

    Of the years of GA16, the better head to use for performance work is from the 95-99 GA16DE. This head has larger ports than the older 91-94 variant. The late head also has intake ports that are a straighter shot into the cylinder. The older head directs the port flow to the side which was probably done for more intake swirl. The later ports shoot straight in and flow better. The easy way to spot an older head is the manifold which kinks to the side on the older heads. The new style head is good for about 5 more hp over the old style head.

    If you are modding your GA, don't worry about the head too much. Since the head's ports flow poorly in stock form, we figure the GA will respond well to headwork and are planning to test it soon. JWT is currently reworking a cylinder head right now and we will test the results and post the dyno sheets right here. Although we have not documented exactly how the GA responds to mods yet, we will when we get there. We will explain the basics of headwork for your reading pleasure anyway.

    Here is the finished port.
    Here is the finished port.
    Blend the valve seat to the valve bowl.
    Using the carbide cutter, carefully blend the valve seat to the valve bowl of the port.

    Headwork entails enlarging the intake and exhaust passages in a head to allow for more flow. Good headwork entails subtle reshaping, not just hogging the whole port out bigger. Generally, good headwork leaves the floors of the port alone since most of the flow activity in a port is near the roof of the port. The roof is the outside radius of the bend going to and from the combustion chamber and by inertia, most of the air wants to flow up there. Good headwork usually rounds the floor hump which is the transition from the valve seat to the floor of the port. Stock, this is usually a sharp edge which causes non-laminar (turbulent) flow separation.

    The object of good porting is to increase flow as much as possible while keeping the port volume as low as possible to maintain as high of a flow velocity as possible. Big ports have low velocity at low rpm. This results in a loss of bottom end power due to the lack of energy available in the moving gas column behind the valve. The gas column has inertia which helps fill the cylinder, especially at low RPM. Generally porting your head will cause some loss of bottom end power. Good head porters might be able to increase flow in the head up to 40 percent with no loss in bottom end but that is usually for American Iron heads which are terrible to start with. Modern Japanese engines don’t usually see as big gains as their design is much better to begin with. Gains of 10-20 percent are typical with a modern Japanese motor.

    Here are the valve bowls after blending.
    Here are the valve bowls after blending.

    The other major area of headwork flow gain is in the valve job. A large percentage of gain can be in the valve job alone. The best valve jobs are called multi angle valve jobs with three or more distinct angles. The main angles are the throat cut, which is a 60-70 degree cut that blends the port wall to the seating cut. The seating cut is a 45 degree cut which is the sealing surface for the valve. This critical cut should be 0.040-0.060 wide for a multi valve engine like an SR20. Finally there is the top cut which is a 30 degree cut which blends the seating cut to the combustion chamber. The purpose of these cuts is to help the air flow smoothly around the valve, especially when the valve is starting to open or close.

    Another valve job trick is to place a 30 degree back cut above the 45 degree seating cut on the valve itself. This helps the air get around the valve better especially at low lifts. A five angle valve job uses two extra cuts to make the transition even smoother. The best valve jobs are radius valve jobs which are a 3 or 5 angle valve job which is hand blended after cutting for a perfectly smooth transition. The quality of a valve job is very important because it can contribute up to 50% of the flow gains that headwork will get you.

    30 degree back cut on a valve.
    This picture shows a 30 degree back cut on a valve. This cut helps low lift flow in many cases.
    A three angle valve job.
    In this close up picture of a valve seat, you can see the three angles of a three angle valve job.
    A Serdi valve seat machine.
    A Serdi valve seat machine does the best valve jobs in an easy manner. Look for shops that have one of these when getting your valve job.

    The best valve jobs are done on a Serdi machine. The Serdi is very high precision which insures that all the valve angles and depths come out equal. Most low price shops use stones. Stones can give a good valve job but the stones must be dressed frequently and dial indicators must be used to insure that the seating surface remains concentric. Stones require a highly skilled person who is conscientious of doing a good job. A butcher can make a big mess with stones.

    Unshrouding the valves is an operation where the edge of the combustion chamber is cut back by about 25% of the valve diameter so that the wall of the combustion chamber does not block the air going past the valve into the cylinder.

    Polishing the combustion chamber removes sharp edges that can glow red hot and trigger detonation. It also makes it harder for carbon to stick. Polishing should be limited to the combustion chamber and exhaust port. The intake port should be no smoother than 220 grit as maintaining some boundary layer turbulence is good for good bottom end. This turbulence makes the port virtually a little smaller at low flow velocities.

    Personally, my belief is that the best head porters for the GA16 head are DPR (Dan Paramore Racing), JWT and B.C. Gerolomy. My own personnel heads are done by DPR and Nissan Motorsports uses B.C. Gerolomy. JWT requires no further introduction here!

    Beware of bad headwork. Perhaps the most famous Honda builder who advertises very heavily and sponsors many 10 and 11 second Hondas does awful commercial headwork. I have seen heads from that shop that have huge, lumpy uneven ports. The valve jobs were 1 angle that were cut so deep that the valve would have to rise about 0.040 to get out of the huge crater of a seat cut! Talk about shrouding! The valves were cut so deep that I am sure that the stem tips would have to be faced off to maintain proper valvetrain geometry IF that was done! Perhaps it was the new guy that did these heads but I have seen more than one of them. This shop’s work could not be all bad because of their track record, but I have yet to see a good off-the-shelf head from them. Stuff like this is why many Honda owners complain that their cars end up slower than stock!

    Since we have not done headwork yet, we do not have dyno result. Currently JWT is working on one of our heads and we will fully test it and report the results.

    Pistons

    There are not many choices here. The only alternative is to have some pistons made up by a custom piston maker such as JE or Aires. Motivational Engineering is planning to have a forged 11:1 NA piston and 8.5:1 turbo piston eventually once the development of the GA16DE progresses to that point.

    You might be wondering if forged or cast pistons are better. Cast pistons are made by pouring molten aluminum into a mold. Nissan cast pistons are pressure die cast in an inert gas atmosphere. Pressure casting results in a stronger, denser part with less inclusions than the low tech pour in the mold method. A genuine Nissan cast piston is dimensionally more stable than a forged piston and can run extremely tight piston to wall clearances, as little as 0.0004"! Tight piston to wall clearances help with oil consumption issues, hydrocarbon emissions and piston ring life. The bad thing is that cast pistons are more brittle and tend to crack ring lands under detonation.

    Typically the number two ring land cracks on Nissan pistons. Under lots of detonation, nitrous or boost, the pin boss of the cast pistons can crack also. Usually this incident claims everything south of the intake manifold! Granted Nissan cast pistons are a high quality, strong cast piston and most list members, even you hard core ones will not get to this point.

    Forged pistons are made by smashing a heated billet of aluminum into a forming die with extreme force. This results in an compressed microstructure with good grain flow in critical areas such as the pin boss. Forging alloys are also ductile and strong in nature. Forged pistons offer superior strength and toughness resisting fatigue and cracking. Forged pistons can be made thinner and lighter due to their superior strength. Forged pistons can take detonation much better than cast pistons.

    Forged pistons can also handle the strain of high boost and Nitrous. All racing pistons to my knowledge are forged. The disadvantages of a forged piston are that it must run a larger piston to wall clearance than a cast piston. This is due to two reasons. The first is that forging alloys grow more with heat, the second is because of the violent nature of forging; a forged piston has more internal stress and is not as dimensionally stable.

    Old school forged pistons needed to run as much as 0.009" piston to wall clearance. These pistons sound like a diesel engine, rattling like crazy. Due to recent advances in piston alloys and skirt design, modern forged pistons can be run as tight as 0.006-0.003".

    Pistons that run on the high side of this scale will still rattle. Ones on the low side can be fairly quiet. Usually this has to do with the silicon content of the alloy. Low silicon pistons are the ultimate in strength and toughness but require big clearance because of the metal’s high expansion rate. These are pistons used in top fuel drag racers or the real nasty turbo Hondas. High silicon pistons run tighter clearances and are slightly less ductile but are still much stronger than cast pistons.

    I would not recommend a low silicon piston for street use no matter what. It would be noisy, wear rings quickly and be a oil burner after not so many miles.

    If you are going to push the edge with turbo boost, nitrous or are going to do some real racing, forged pistons are the way to go.

    By going to 11:1 CR with pistons, a GA16 should gain 5-8 hp across the board. As I have stated before, a JWT ECU is mandatory with 11:1 to prevent engine-destroying detonation regardless of piston type.

    The lower compression turbo pistons will be important for going past 10 psi on pump gas with turbo boost.

    Crank, Rods, Bearings, Machining, Balancing, Coatings, Manifolds, etc.

    The GA16DE is blessed with a strong bottom end. The crank and rods are forged steel unlike the typical cast iron that most American motors run. However since there has been little development for the GA16DE, there is little information on just how much the engine can take other that studying what worked and what did not in similar motors.

    The GA does have some limitations, as it is not as strong as its SR20DE big brother. For going turbo to maintain bulletproofness at about 10 psi of boost or for revving much past 7300-rpm frequently, new connecting rods will probably be needed. Crower, Cunningham and others can make them if provided a stock rod as a sample. Motivational Engineering will have some titanium rods in the works soon.

    Well know that, here are some general engine prep tips.

    The rods and pistons should be balance to within ½ gram and the crank dynamically balanced. I have found that Nissans are generally within 1 gram from the factory! A typical American car is usually off by as much as 5-12 grams! I like to polish the journal surface of the crank. You can have a local machine shop do it using the lightest grit of polishing paper belt. You don’t want to remove so much material that the crank dimensions change, just reduce the RMS of the surface by knocking off the peaks of the machining marks.

    The factory Nissan bearings are strong and durable. I recommend running bearing clearances in the middle of factory spec on a typical street motor. Clearances on an all out racing motor can be set on the looser side of factory. When buying bearings, I have also observed that if an engine has any kind of mileage on it, the next tighter bearing size can be used other than the number that is stamped on each journal of the block and crank. Remember to mike and bore gauge all the journals to confirm proper dimensions before assembling. If you don’t have access to these, at least use plastigauge to make sure that you are in the ball park.

    When boring or honing a block, it is better to use a torque plate. A torque plate simulates the stress of a cylinder head being bolted on your block. With a block that was machined with a torque plate, the bores will remain straight when the head is bolted on. Usually the block will distort and the cylinders will become out of round accelerating wear and reducing the effectiveness of the ring seal when the head is bolted on. Granted this is a small difference but is important if you want to build a good motor. For this reason the main caps should also be bolted on and torqued when the block is being machined.

    Boring and honing should be done on a Sunnan CK10 machine. This is a high precision machining center that makes the honing of a good round bore almost idiot proof. Since today’s low tension rings require a smooth surface to seat properly, plateau honing after the dimensional honing reduces the RMS of the surface for lower friction, better sealing, less oil consumption and longer life. JWT has pioneered the use of plateau honing on the SR20 and has the process figured out for a smooth bore surface that will still allow the rings to seat. When properly machined with a torque plate and plateau honed, it is possible to have an engine that leaks down at 2% or less!

    I am a believer in special coatings. Coatings are great for adding to reliability or to help control factors such as heat so special tolerances can be used. At the advice of Nissan Motorsports I used Swain tech coatings. Unlike the other to-be-named coating houses that use off the shelf coatings, Swain develops their own in-house coatings that are much more sophisticated. Where most other companies have a one layer coating, a Swain coating might have 3-4 different functional layers. I use Swain tech gold thermal barrier coating on my pistons. This is a severe duty 3 layer thermal barrier that reduces heat transfer by about 25%. This helps protect them from detonation and Nitrous abuse. By keeping the heat out of the pistons, I can run an amazingly tight piston to wall clearance of 0.0004 inches. That is 4 ten thousandths of an inch! My engine does not burn oil at all even with water-thin 5w30 Mobil 1 oil.

    I also use Swain poly moly dry film lubricant piston skirt coating. This coating uses molybdenum disulfide and tungsten disulfide for a dimensionally stable heat conducting matrix. This is better than the teflon that most other companies use because teflon distorts and creeps under load. Teflon is also a heat insulator. Since the pistons cool themselves by conducting heat through the skirts, it is not to good to insulate them. Poly Moly can help tame the clatter of forged pistons. Poly Moly also tightens your piston to wall clearance by 0.0014 or so inches so you may have to compensate in your bore machining for this added clearance.

    The guys at Nissan Motorsports tell me that poly moly significantly cuts piston and cylinder wall wear. Next time I go through the motor I will probably coat the valves and combustion chamber to protect them also. One of my friends had a 20 degree drop in water temperature, 300 rpm faster turbo spool, and 300 degree higher EGT's with a fully Swain coated motor. Swain also makes slippery flow improving coatings, heat dissipation coatings, wear resisting coatings and stealth coatings that are not detectable!

    Extrude Honing

    Extrude Honed intake manifold ports.
    Here is what the Extrude Honed intake manifold ports look like after the process is done, note that the ports are much enlarged and the normally rough cast surface is now quite smooth. This is better for air flow.

    The manifold's plenum chamber shows the polished interior.
    A view into the manifold's plenum chamber shows the polished interior and the radiusing of the beginning of the runners. This improves air flow. The Extrude Hone Process is amazing in this way.
    The Extrude Honed manifold from the cylinder head flange side of the manifold.
    Here is another look at the Extrude Honed manifold from the cylinder head flange side of the manifold. Check out how the process has enlarged the ports and polished them on the inside.

    Extrude Honing is a process where an abrasive putty is forced through your manifold or other difficult to port areas at a high velocity, removing material. Extrude Honing is great because it can port areas where it is otherwise impossible to do so, like in the middle of your very long runner manifold or deep inside your manifold's plenum chamber. Extrude honing is also very good at equalizing manifold runner flow.

    Smaller more restrictive areas in the manifold act like a venturi so the putty flows faster there. Faster flow equals more cutting action and thus the Extrude Honing process by nature removes material where it's needed the most. This cutting mechanism is very good at producing runners that flow equally.

    We tested the Extrude Hone process on our project GA16DE motor with excellent results. We experienced power gains from 4500 rpm on up with no loss of bottom end power. In fact we got big fat power gains from 4800 rpm on up, right in the zone where you shift at wide open throttle, so the whole useable powerband sees the increase. our gains averaged 3-4 hp in this range with a peak gain of 5 hp. Check our dyno chart at the beginning of this section to see our dyno proven no BS test results.

    After Extrude Honing our powerband is very broad and flat with over 110 hp available from 5400-7200 rpm! The motor rocks hard to the rev limiter! That's nice broad useable hp, not peaky narrow band Honda type hp. With the simple bolt on tricks we have been doing our project GA can hold a slight lead over a Civic Si even though the Si makes much more peak power. The GA16DE has less peak power but more area under the useable power curve.

    Extrude Honing really opens up and polishes the tiny stock manifolds ports. This mod is now a proven GA power adder and is well worth the cost of doing. The GA16DE responds to this process better than the SR20DE does.

    Big Bore Throttle Bodies and MAFs

    RC Engineering big bore throttle body
    The RC engineering big bore throttle body is 4mm bigger than stock. It gives more power with a JWT ECU and cams which allow the engine to rev into the range where the stock TB does not flow enough. On a stock motor, it does not help. See the dyno chart at the beginning of this section.

    The GA16DE has a very small throttle body. Since the Civic and other cars with the same size engine have bigger throttle bodies stock, and the throttle body is the smallest piece in the intake tract, we figured that perhaps the stock throttle body can benefit from getting a bigger throttle plate.

    We tested the RC engineering big bore throttle body. This throttle body is 54mm vs. the tiny stock 50mm. The workmanship and attention to detail are superb. The throttle body casting is honed to tight tolerances so a good idle can be maintained and the throttle shaft is aerodynamically profiled with streamlined button head bolts that are staked, much like OEM.

    Seat of the pants, the Throttle Body gave crisper throttle response and more punch at low rpm, with an improved top end. The power did not seem to fall off at all at high rpm.
    Porting out the intake manifold for the larger throttle body
    When installing a bigger throttle body, the manifold must be ported out bigger to match the new larger throttle.

    On the Dyno, the larger throttle body did not help the peak power more than 1 hp but kept the power curve flat across the top for 400 rpm and gave 2 more hp past the peak from 6300 to 7300 rpm. Now the power curve is virtually flat from 6000 to 7300 rpm with no more than 4 hp deviation! This is big fat useable hp, not like the peaky hp that Hondas typically have. An equivalently modified D series motor usually has a slightly higher but pointy power curve. This motor has a big fat slope that is flat across the top. Guess which motor is faster, the one with more area under the curve!

    We suspect that once we improve the head flow, the throttle body will make a larger contribution to the peak power. However we also feel that on stock cars or near stock cars, the only difference will be an improvement in throttle response.

    Our 1995 test mule has a late model plastic MAF. This MAF does not neck down like the early 91-94 metal ones do, however we have found on much more powerful SR20 powered cars that there is little to gain by switching to a larger MAF even though the neck down is rather obvious on the older cars. The main indicator that something is too small is the MAF voltage. If the engine is pulling more than 5.1 volts, then the car can benefit from a larger MAF. Our mules is pulling 4.71 volts at WOT on the dyno. So far only turbo cars seem to be capable of maxing out the stock MAF. To run a larger MAF you must retune the ECU for this. JWT can do this. Perhaps when we cross that bridge.

    Spark plugs and Ignition systems

    Heat Range of plugs

    Sparkplugs come in many heat ranges. This is so the plug can be matched to the type of use an engine receives. For low speed, short hop driving, the plugs electrodes must stay hot enough to burn away and self-clean fouling carbon deposits. For this type of driving a hot plug is needed. For high speed racing at high rpm, the plug can become too hot and glow like a diesel glowplug causing pre-ignition and detonation. This can quickly destroy an engine. To prevent this a cold heat range plug is needed.

    The length of the insulator of the center electrode determines a plugs heat range. You can tell a cold plug from a hot plug by looking at the center electrode’s insulator. If the porcelain insulator is short, it is a cold plug. If it is long and extends deeply into the steel shell of the plug, it is a hot plug. This is because a cold plugs short center electrode has a short path to conduct heat out of the electrode. A hotter plug has a longer path and dissipates heat more slowly.

    Most listmembers seem like they are unaware of matching the spark plugs heat range to the type of driving that they do. I wince when I think that many are squeezing nos or pumping turbo boost with the stock hot plugs.

    In my opinion the best spark plugs for the GA16DE are the stock Genuine Nissan plugs. I like the PFR6B-11 SR20DE platinum plug in the GA16DE. Platinum is a noble metal with a high melting point. Being almost inert, it is highly corrosion resistant even at high temperatures. That is why a platinum plug lasts about 3 times longer than a conventional plug. When used in the plug's electrode it resists erosion much better than steel.

    Chart of heat rating flow path.
    Courtesy of NGK Sparkplugs

    Stock Nissan plugs have platinum in both the center and ground electrode for really long life. Most aftermarket platinum plugs only use platinum in the center electrode. I prefer for most engines, even the stock ones, to run the PFR6B-11 spark plug. This is the middle heat range for the NGK plugs. GA16DE powered cars come with FR5B-11 plugs, which are one heat range warmer.

    The PFR6B-11 works well on high compression, turbocharged or NOS powered cars. For running extreme boost (more than 18 psi), a big shot of nos (more than 100 hp) or really high compression (more than 11:1) the cold PFR7B-11 plug is necessary. This plug will be on the edge of fouling during regular day to day driving so it can be considered a race only plug.

    The GA16DE has a shallow included angle of the combustion chamber. This makes for a quick burning, detonation-resistant chamber. I have also found that shallow included angle chambers for the most part do not like extended tip plugs. When experimenting with extended tip plugs I have found that the engine loses about 3-4 hp across the board. Many aftermarket plugs are extended tip. The theory behind extended tip plugs is that the extended tip puts the electrodes in a more turbulent section of the combustion chamber, thus helping them stay clean of fouling.

    In the GA16 an extended tip plug puts the electrode too close to the piston dome screwing up flame propagation, thus losing power. This is important to consider if your are deviating from the Stock Nissan recommendation. Make sure that the tip of the plug that you are buying does not extend further than the stock plug’s tip. If you are running flat top or domed pistons, this is even more critical as the tip of the plug is even closer to the piston dome.

    The GA16 has a powerful stock ignition that can fire through turbo boost and NOS. Gap the plugs at 0.045". If you experience misfire under squeeze or high boost (and the rest of the ignition system is in good condition, like the cap, rotor and wires) you can close the gap down to as small as 0.020" to prevent it. Go down in 0.005" increments until the misfire stops. Higher cylinder pressures cause by big NOS or high boost requires smaller gaps with the stock ignition. The smaller gap loses a little power but this trick can tide you over until you can get that snazzy turkey roaster ignition.

    High Power Ignition

    MSD Ignition
    If you are running turbo boost, big NOS units and or have a high compression ratio you can benfit from a powerful igntion system, MSD is one of the best. Most of the time the stock igntion is fine and upgrading provides little benefit.

    The stock GA16 ignition is good but if you are running more than a 50 shot of nos or 10 psi of boost, you might need a high power ignition. Jacobs ignitions are crap. I would not bother with them. The Crane Hi 6 has gotten rave reviews also but they seem prone to burning out (two of my friends have been stranded because of a burnt out Hi-6). These ignitions are very powerful, capable of firing the spark plugs for over 30 degrees of crank rotation. Just the thing for high cylinder pressures.

    On really built cars I now recommend the MSD 6A or SCI ignition system. On 95 and later cars with an internal coil, MSD makes an external coil conversion kit for Hondas that also works on our cars. Just be sure to cut the primary conductor from the stock coil and fill the resulting hole in the distributor cap up with silicone or some of the extra power from your new coil will be wasted.

    As a note, these ignition systems don't seem to work too well with Nology wires. I use either stock or NGK wires.

    These high power ignitions will not give you much more power but they will eliminate frustrating misfire and help starting and low speed driveabilty.

    Amazingly I have found the stock plug wires to be the best with the GA16.

    OTHER PLUGS

    Bosch Platinum

    I hate these plugs. They have a weird center electrode that is flush with the insulating porcelain. What happens is that this electrode quickly erodes so it ends up being a depression in the porcelain, making the spark shoot out of a hole. Sparks like to propagate from sharp edges so I think they have a hard time getting out of this hole.

    These plugs will absolutely not work for long in high compression, high rpm, boosted or NOS applications. They are marginal on a stock engine. In my experience they work OK for a few thousand miles then start to idle roughly and on modified engines misfire under load. It amazes me that an OEM level supplier like Bosch can make pieces of crap like these.
    Bosch Plus 4

    Although I have not had any experience with them, others have reported that they suck, including one source that I respect very much for information. These plugs have an unusual design with 4 ground electrodes much like a rotary engine plug. Personally I hate Bosch plugs so much, I will not test these!
    Beru
  8. #8
    Avatar de -RoadRunner-
    Banned
    Fecha de ingreso Apr 2011
    Edad 40
    Mensajes 2.173
    These plugs have a silver conductor for the center electrode. Since silver conducts electricity better than steel or copper it is reportedly better. The electrode material is still steel so I don’t think that these are much of an advantage.
    NGK V plugs

    These work fine, just change them frequently. Be sure that the tip does not extend further than the stock plugs.

    Split Fire

    I call these Miss Fires. They have an extended tip that the GA16 hates. The dual ground electrodes may have some merit by creating more sharp edges for spark propagation but this is moot when the extended tip causes hp loss.
    Champion, AC and others.

    I don’t have any experience with these. Make sure the heat range and tip length is appropriate for our motors. I think that these brands have some premium labels that have unique electrode configurations to have more sharp edges for spark propagation. Some list members have had good luck with these.

    The main thing to remember with GA16's is that, due to the combustion chamber configuration, the plug’s tip length must be close to the stock plugs or power loss will result and the heat range must be appropriate for the intended end use or engine-destroying detonation may occur.

    Look at the big front mount hidden behind the mesh grill. Please ignore the 600 hp twin turbo Z behind the Sentra.

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  9. #9
    Avatar de Junior_r
    Spammer
    Fecha de ingreso May 2003
    Ubicación doh
    Mensajes 3.514
    mae RR, si la guia esa es vieja de que año estamos hablando? la de kojima es del 01. LoL

    lo mejor que se le puede hacer a un motor de esos es refrescarlo y rebajarle la cara, bastante...
  10. #10
    Avatar de blopa2310
    Tunning
    Fecha de ingreso Dec 2010
    Ubicación moncho
    Mensajes 2.081
    en cuanto saldra hacerle a un motor de esos todo lo que dice en la guia ???
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