Custom Turbo S2k / Stock Fuel Injector Ques.
07-23-2004, 07:09 PM
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Custom Turbo S2k / Stock Fuel Injector Ques.
Hello, I have owned an S2k for about 8 mos. now, I've been a previous owner of three 300-400+ HP DSM's. I just can't live w.o Boot so I've decided to go turbo in the S2k. My question is simply, "what is the limitation of the stock fuel system in our cars?" What size injectors are stock, how much HP can they handle, I am only looking to run about 5-6 PSI of boost. I already have the manifold and turbo. I'm building the kit myself! I plan to use a 12:1 FPR unit w. an V-Tech AFC unit. I want to know if I should plan to upgrade the stock fuel system. I know with DSM's the stock injectors are 450cc and are good for about 280-300hp then the most logical upgrade would be 550cc. If anyone could shine any light on the situaton I'd appreciate it! Thanks...
Dan
Dan
07-23-2004, 10:24 PM
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Wow, these are issues that have never been broached before. 
Seriously, this ground is well covered. You have a lot of research and reading to do on this site.
Firstly, I strongly recommend against boosting in any form (and particularly turbo) with no more than FPR, V-AFC (BTW, it's VTEC), and bigger injectors. At best you will spend a lot of very frustrating time trying to get it right and probably won't ever get it perfect. At worst, you'll get to know the insides of your engine first hand.
The problem with the V-AFC is that all it does is fake the MAP signal. The ECU doesn't like anything above ambient anyway so trying to up fuel this way is futile. In fact you need a Boost Signal Limiter to hide the boost from the ECU. Your idea of using the bigger injectors to provide more fuel and then pulling fuel down low with the V-AFC has some merit but it's till a tricky set up. BTW, you may require an uprated fuel pump also.
My recommendation is to go with a standalone ECU like the AEM EMS. It'll do everything you need, properly and first time around. Depending on the FPR rate 440-550cc injectors should do the trick.
If that is too rich for you go E-manage. This does a similar thing to the V-AFC, but can also drive the injectors directly so you can use a lower ratio FPR with lower static fuel pressure and just drive your injectors harder under boost. 440cc injectors and a bigger fuel pump should do the trick (infact that's what I'm running now with 8lbs).
I'm about to upgrade to a smaller SC pulley, AEM, and 550cc injectors.
Seriously, this ground is well covered. You have a lot of research and reading to do on this site.
Firstly, I strongly recommend against boosting in any form (and particularly turbo) with no more than FPR, V-AFC (BTW, it's VTEC), and bigger injectors. At best you will spend a lot of very frustrating time trying to get it right and probably won't ever get it perfect. At worst, you'll get to know the insides of your engine first hand.
The problem with the V-AFC is that all it does is fake the MAP signal. The ECU doesn't like anything above ambient anyway so trying to up fuel this way is futile. In fact you need a Boost Signal Limiter to hide the boost from the ECU. Your idea of using the bigger injectors to provide more fuel and then pulling fuel down low with the V-AFC has some merit but it's till a tricky set up. BTW, you may require an uprated fuel pump also.
My recommendation is to go with a standalone ECU like the AEM EMS. It'll do everything you need, properly and first time around. Depending on the FPR rate 440-550cc injectors should do the trick.
If that is too rich for you go E-manage. This does a similar thing to the V-AFC, but can also drive the injectors directly so you can use a lower ratio FPR with lower static fuel pressure and just drive your injectors harder under boost. 440cc injectors and a bigger fuel pump should do the trick (infact that's what I'm running now with 8lbs).
I'm about to upgrade to a smaller SC pulley, AEM, and 550cc injectors.
07-24-2004, 06:03 AM
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The stock injectors are 310cc I believe. I myself are running 650cc injectors with an intank hi-flow 255gph fuel pump and a VAFC2. This setup can support up to 14psi or about 375hp with NO FMU. My high throttle settings are at 0 all he way across the board. I use a check valve to bleed boost from the MAP sensor so the ECU never sees boost. If you want to run more boost you can add an FMU and run up to 20psi. Many say that EMS is better and it is, but this setup works fine also as long as you get it dyno tuned.
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