Hey all -

I'm building a 355 block and was going to throw on zz4 heads and a zz4 cam. I also was going to throw on a complete aftermarket TPI as well - and from what I've heard I should be about ~350 HP. A while back I bought 30# Ford SVO injectors, but now I'm thinking they're too big and I should just throw in some 24#ers. Any advice?

 

The 24 #/hr Ford injectors are the best for you along with an AFPR. You could maybe get away with the 30s, but an EProm chip modification is required.

I am at the limit of my 24s on my 395 cu.in. stroker. I intend to buy 30 #/hr injectors this Spring.

 

24lbs are what u need. with a adjustable regulator. the 24lb should support 400-450hp.... 30lb are good for 500-550ho. NA of course. go with ford SVO... they are better and the 30lb ford SVO is the same as 32lb accels etc. they flow more than the lb rating.

im got 30lb SVOs for my HSR 383. with about 460-500hp.

 

yep 24's will be perfect match. 30's are for hotter 350's and mild to medium build 383's. hot 383's will want 36's+

 

I have 36lb injectors on my vette, and it runs just right, of course it has been tuned well also.

 

I personally have had good luck with the GM LT1 injectors, they are 24# @ 43.5 psi. I run a set in a TPI 305 that has the factory GM regulator @ 46 psi. Couldn't ask for better performance or fuel economy.

 

Fast355: what you posted is NOT entirely correct. LS1 cars came with two types of injectors, my '99 factory injectors would flow 24 #/hr at 43psi (as you stated), however, 2001 and 2002 ls1 cars came with the equivalent of 26 #/hr injectors. At the fuel pressure (58 psi) in the LS1 F-bodies, these injectors are rated at 26.5 and 28.5 #/hr, respectively.
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BTW: the Ford Racing (formerly SVO) fuel injectors are the highest quality injectors that you can buy.

 

He said LT1 not LS1 i thought?...

 

yep, he said LT1 and they had 24 lbs injectors

 

yep, I stand corrected!!!!!

 

Not to hijack, but with an AFPR and LT1 24#, do I need a new tune? Opinions seem to vary with only a 2# difference from stock.

 

you can get away with it, but depends on the other mods. 2lbs of difference will definately make the car run rich and most factory tunes are rich with stock injectors. I know my car was.

If you have supporting mods like great exhaust, and alot of TPI bolt ons or other intake, then it will work better but still will be richer than it should be.

 

Our ECMs make fuel adjustments as high as 23% more fuel, to 16% less fuel, while the ECM is in closed loop. A 2# difference in fuel injector flow rate is about 9% change. So for cruising around the ECM should be happy. The question is what is the AFR at WOT. That is where we need an AFPR and do some testing, or better yet, use a wide band O2 sensor.