fuel injector size

I have a 1995 formula lt1. The motor is a 355 ci 9:1 compression,ati p600b with 2 core intercooler...10 or 12 lbs undecided as of yet, mild work on stock heads..I dont have the cam specs but were per rskrause recommendations. i currently have 24lb bosch injectors. Was wondering what size injector i should go with. Am hoping to have approximately 500 hp at the motor. Thanks for the help





Steve

50 lbs.

is an injector of that size really needed? im still using the stock fmu and a piggyback fuel pressure pump supplied by ati in my supercharger kit. if i go that size injector, will the car..be sloppy down low rpms or does a 50lb injector just have the ability to flow more...thanks




Steve

No, it can be tuned to be drivable at all rpms.

The #1 rule I've learned with my LS1s is to buy more than you currently think is required.

ok thanks for the input...












Steve

With 500hp, you would be borderline for 42s @ stock fuel pressure. Knock your pressure up a little and you could probably get away with a 42#.

42#@ 43.5fp - 488.73hp
42#@ 58.0fp - 564.33hp

Also, with injectors this big, you can ditch the FMU.

are there any drawbacks going to that size injector though.. for example the stock injectors i have now can handle something around 100 psi.why wouldnt a lower injector size like a 36lb/hr work if the injector can handle 100 psi etc? i'll go larger injectors..i just dont want to regret it..in any way...thanks for the advice






Steve

I have 57's in my combo and it idles and drives like a stock 5.7 with a little more exhaust noise untill I spin past 3000. My 57's are almost maxed out started with 50's and had to upgrade.
57's tune like a smaller injector e-mail jack at racetonix for info.

John Carpico

If I where i would just build the system right. get 42lb or 50lb inejectors get rid of stock intank and ATI inline and fmu replace with gss340. If you need more get a boost a pump and or wire harness.

Bill

Speaking of buiding it right I went with 50lber's on my 385 with 5lbs boost and was at 100% duty cycle at 5700 rpms. I went with 72#ers and the converter box which is what I should have done in the first place. They are more responsive and you get a good idle, Remeber you can't go to big

Originally posted by RCF925
Speaking of buiding it right I went with 50lber's on my 385 with 5lbs boost and was at 100% duty cycle at 5700 rpms. I went with 72#ers and the converter box which is what I should have done in the first place. They are more responsive and you get a good idle, Remeber you can't go to big


I will second that but at the time it was not in the budget.

Any high-impedance (57# and lower) will drive/idle just fine. You may have trouble on some of the bigger injectors (83# and up).

Also, most injectors won't like 100psi fuel pressure. I thought I read that the most you want to go on them is like 80#.