If i'm running lean? I have a pretty good tune right now... very rich... and i'm still running lean.. my injectors are at 96% duty cycle at WOT... if i get 32's... will this put down better numbers?

how much can the fuel pump provide?
whats the max HP people get with the Stock pump?



thanks

 

How do you know it's "lean", how lean is it, what mods do you have, etc.?

Rich Krause

 

will its lean cause the computer tells me it is?

ok.. mods..
355 CID, CC305/1.55RR's. RK Sport Headers.. cat back... CAI... WP... and, you know.. all the other goodies that goes with all that... hehe.

 

u forgot to mention u have stage II heads dumbazz

his O2s are reading lean at wot .. ask matt what the readings were ... and if ur injectors are maxing out then YES U NEED BIGGER ONES .. since u already bought them then just stick them in...

 

I would say the stock fuel pump is good for about 375 flywheel horsepower any more than that and I would consider an upgrade. With the CC305, good heads and headers an LT1 properly tuned should be capable of around 425+ flywheel horsepower. 30lb injectors should be plenty for your setup with about a 45psi fuel pressure.

 

My stock fuel pump was fine with 450fwhp...

Dave

 

Just thought of one other thing if you have stock fuel injectors you will need about 50 to 55 psi fuel pressure to maintain a reasonable duty cycle. This should be considered as a bandaid until you get larger injectors as it puts more electrical stress on the injector which could cause a failure over time.

 

LPE Dave I am certainly not trying to say it is not possible for the stock pump to handle more I would just want a little insurance for a 375+ horsepower car. Look at the nitrous kits made for LT1's anything more than a 75 shot and they recommend an auxilliary fuel pump for that safety margin.

 

Nothing wrong with a bit of insurance, I'm just trying to help show what will actually work, so folks can tell where they do and don't need it.

Most of the time, an aux pump on a nitrous kit is made to raise fuel pressure about double, for a dry kit. That's kind of a different story.

Dave

 

dont forget to get the car tuned for bigger injectors

 

LPE Dave I don't want to get in a big fuel debate with you but fuel pressure can be raised to 70+ psi with the stock pump but when you demand more fuel volume from it to make more horsepower whether it be Nitrous or just heads and cam it will not maintain enough volume of fuel to keep the pressure at a fixed value. Hence the need for an auxilliary pump not for pressure but for volume.

 

well my stock pump CERTAINLY wouldnt hold volume at stock pressure past 4500 rpm !!! thats just a heads / cam car

let alone if it were set to higher pressure, the volume would probably die at 3000

 

Stock FP, 30 lb injectors, stock fuel pressure - 390rwhp/415rwtq. RPM is what causes duty cycle issues. A "big" cam will continue to make power at higher RPM - this usually necessitates bigger injectors or more pressure because of the reduced amount of time available to shoot fuel.

I personally believe bigger injectors is the answer as the FP becomes less efficient at higher fuel pressure.

-Alex