Dirty Dave

iTrader: (8)

Just wondering what all you guys are using out there ? I have a fully built sgp motor, test pipes and getting exhaust. At most im looking to get 650 rwhp while at the track but, while driving around normally it needs to be streetable too. My installer reccomended 750 cc injectors, but as I recall talking to sharif a month ago he said anything bigger than 650 were very tuff to tune properly and get the car running right. What do you guys think I should use, cause the motor goes in next week ???

Thanks Dave

Jaki

iTrader: (21)

Its about right to say that the injector size is the same number as the HP number it can hold. For example, 650cc should be good enough for 650rwhp and a little above. So I would suggest you just run the 650 injectors since 650rwhp is your maximum goal.

sentry65

iTrader: (11)

so then the stock injectors being 290cc would max out at around 290whp or so?

that would be why i'm stepping up to 440cc injectors for NA...

Sharif@Forged

iTrader: (92)

SGP has a point.....if you follow the basic rules of injector sizing, then 750cc is rougly were you want to be. This assumes 42psi of differential fuel pressure and 80% max duty cycle.

For streetcars, you sometimes have to compromise, and that is what I was getting at during our last discussion. You might have to run slightly higher fuel pressure...about 52-58psi...and run the injectors closer to 100% duty cyle so you can size a smaller injector and maintain drivability.

We've gotten 550whp-580whp out of the 550cc injectors at 100% duty cyle, but the car idles and starts pretty normally. So 650cc's would be my recommendation for a street driven car and around 600-650whp.

SSR Engineering

Hey dave,

If you want stock like drivability, and the safety of an 80% duty cycle, you should look into methanol, or maybe additional injectors. Greddy has the AIC (Additional injector controller) and a large variance of injector sizing you can go with and program them accordingly.

Dirty Dave

iTrader: (8)

My installer also recommended methanol, I might look into that. Thanks everyone for the responces, im going to go with the 650's. Ill let you guys know how it run with them.

xsmallpaulx

iTrader: (3)

i have 650's in my car and the the idle is smooth and perfect . no problems so far