I have a 2002 Z06.

I am trying to make approximately 400 rwhp (or more if possible). Here are my mods that relate to rwhp: 1) vortex rammer, 2) power duct, 3) ported t-body, 4) coolant bypass, 5) fan controller, 6) 160 t-stat, 7) ASP underdrive pulley, 8) FLP headers w/o cats.

Caveat: I do not want to modify the computer's program if possible and do not want to pull the heads or change the cam, at this point (warranty reasons).

I have thought of doing roller rockers to go from a 1:7 to a 1:8, but for now, I am wondering whether 30# SVO injectors would give me more power. Does anyone know the answer? :-?

 

You will need to take traces of your car (with a laptop and autotap software) to see what the cycle duty of your injectors are turning. If the injectors are running at +100% at 6,400 RPM's then I would say yes larger injectors would help you out.

vetterdstr :cheers:

 

I agree with Vetterdstr, that you need to scan the car and find out. However, I'd be somewhat surprised if those mods required new injectors. Also, I if you are swapping injectors, you'll probably want a reprogram to go with it. The SVO injectors are of a different design, and addition to the flow rate that should be adjusted, the injector offsets are also different, and that is also controled by the computer. FWIW, my 415 RWHP LT1 doesn't have fueling issues with my GM stock 24lb injectors (although I'm pushing the duty cycles), so I would think similar HP with the larger Z06 injectors should be ok.

 

Thanks for the advice - might have to bite the bullet and buy the LS1 edit.

 

Stock Z06 injectors will hold a H/C so bolt-ons are no sweat. Larger injectors would mandate tuning just for that change. My 26lb injectors run 420rwhp no problems. :seeya

 

When I had my car on the dyno, traces were done and besides running lean, the maximum duty cycle of the stock injectors was 87.5%. The guy doing the traces said that I needed SVO 30# injectors, but based on what has been said in this thread and the fact that not many H/C guys seem to have them; I beginning to think it’s overkill. It seems like the 28# injectors would work just fine even when I have my H/C package.

In the meantime, I already got the SVO 30# injectors but haven’t installed them. Hopefully when I get my H/C next month the tuning will work with them. Or should I just peddle these and get the 28’s?

 

SFVetteman - 87.5% Max Duty cycle isn't that bad. What RPM is that, and for how long do they stay up there? Generally, it's best to keep the duty cycle below 80-85%, but some brief tomeover isn't going to matter much. You need to figure out why you are so lean and the cause of the knock issues -- the injectors are not why you are lean. I run my duty cycles over 100% (not recommended), but my car is still rich.

 

The injectors run 87.5% from 4800 on up at WOT. 18.1mSec is the maximum pulse width. Average duty cycle is 20.7%

I believe the main reason it is running lean with knock retard is because the GMS MAF and the Hypertech performance programming are combining to make it overly lean and advanced at WOT. At part throttle it acually runs a tad rich. LTFT average 1.38 (-6). O2 B1S1 and B2S2 are about .92.

 

I think you will also notice a difference with the 1.8 rockers :yesnod:

 

I have been trying to address this issue among friends for some time now (i.e. Quick Brick)

As stated in an earlier post, injectors should be kept around an 80 - 85% duty cycle. In order to do this with the stock injectors we must stay between:
360 - 380 Crank HP. (BTW, SVO injectors are 30 lbs/hr at 40PSI…@ 40 PSI Z06 injectors are @ ~20 lbs/hr)

Real world #’s:
SVO 30# injectors on LS1/6 = 36.1# @ 58 PSI

Stock injectors = 28.2# @ 58 PSI

SVO 30# in acceptable limits are designed to handle ~462 – 491 Crank HP. @58PSI

Stock Injectors are designed to handle ~360 – 380 Crank HP. @58PSI

People do take their injectors past their limits, as do all of us with our cars in general. Our cars will take more abuse then they are designed for, however, how long is the question we need to ask ourselves. If an injector breaks down due to heat (overworked) and doesn’t deliver fuel to a cylinder, who knows, BOOM!

Better safe then sorry.

Now for the good stuff…
Using larger injectors can still help those of us that don’t have the money to front for LS1 edit, or those of us that don’t need it.

The computer does not know that the larger injectors are in there. The use of larger injectors will cause an over rich condition in the motor. In turn we can use inexpensive MAFTs to tune our cars to a lean condition. With the lean condition the motor will advance the timing, and all the time there is no need to worry because we are running more fuel the entire time. More fuel + more timing = more power.

Of course there is some limitation to timing advances but there is a good 7-9 degrees available in a stock Z06 at idle.

Also it is important to note that you cannot change fuel tables as you can with LS1 edit, but it is definitely a cost alternative.

My car dynoes 371RWHP and all I have is an airbox and mufflers. With a 15% loss factor that would equate to 436 Crank HP.

For this I would recommend the use of 30# injectors (rated @ 43.5 PSI which is normally the standard for most fuel injector manufacturers).


If anyone needs the formulas I can post them up, but I am sure you all already know them. Of course the only real variable is BSFC which I used as .50 more accurately mine happens to be 0.49.