good afternoon. can i run 30lb injectors with stock fuel pump without it leaning out. . lt4 mods to lt1 engine. manifold cam,rocker arms,maf,tb,headers, with cats. 96 zed 6 speed...... thanks for your time

 

If you change injectror sizes you need to tune it for the new injectors. The stock pump will flow plenty of fuel and the injectors only use what they need and the rest is sent back to the tank.

 

Yup, you'll want a tune. Honestly I don't think your at your injectors limits yet though.

 

I'm running 32# injectors with the stock fuel pump with no problems. Have
not had the car on the dyno with the Ai heads but should be in the range
of 340-360 rwhp.

 

I run SVO30#'s on my 383 without any issues as on our motors with higher PSI they are actually flow about 32-33#. According to Lloyd Elliot the SVO 30's are good to about 425-430ish RWHP. You should be fine.

 

You can't base injector size on "RWHP". You have to know the flywheel HP. The 30# SVO's do not flow 32-33# at stock LT1 fuel pressure. The flow increase is about 5.4% (31.6 #/HR). A 30# injector will most likely be at the ragged edge of 100% DC at the RWHP you mentioned (obviously varies with whether you're making that 430 RWPH through a 12% loss M6 drivetrain or a 22% TH400 drivetrain) . I wouldn't recommend anything less than a 36 #/HR injector for the flwyheel HP required to produce that kind of RWHP.

 

Not trying to mess with your thread, but if you run 37lb injectors on a built 355 do you need a new pump. No boost or nitrous.

 

If the engine is capable of using all the fuel a 37 #/HR injector can supply, you will get the best results with a 255 LPH aftermarket pump.

 

Noway of knowing that unless you datalog it and look at the duty cycle it's at to see if the injectors are maxed out or know an idea of the FWHP you are at on this motor.

 

Obviously, but 430 was a rule of thumb that Lloyd mentioned. You are correct as you need to go off of FWHP, but Injuneer as you know most people on this forum don't go off that estimate these days and use RWHP as an estimate. And comeon 31.6 - man you are really splitting hairs these days.

 

Seems we have a bit of nit-picking here. I said "If the engine is capable of using all the fuel a 37 #/HR injector can supply,....". What is incorrect in that statement?