Follow-up fuel question
Thread Starter
Racer
Joined: Apr 2002
Posts: 353
Likes: 0
From: Tuscaloosa AL
Follow-up fuel question
I just posted above about my off-idle problem and now I have a fuel question. I have an '88 with rebuilt motor (ZZ9, miniram, 52mm TB, ported stock aluminum heads with 2.02 valves, 1.6 full roller rockers, cold air induction kit, Bosch+4, MSD, true dual exhaust - cat bypass, modified MAF, level VI PROM, etc. According to TPIS this set-up should be good for 420-430 hp. I also run balanced Bosch stock rated fuel injectors and a Grand National fuel pump - pressure is set at about 49 psi. Two things. First, I have heard conflicting opinions about whether I have enough fuel getting to the engine. TPIS thinks that I am right at the edge, but I should be OK (apparently they have gotten 450 hp out of stock injectors). Any other opinions out ther? Second, in this scenario is the fuel pump or the injectors more of a limiting factor? Are there any good fule pump alternatives that easily accept the stock harness and mouting bracket - I don't want to end up with some "rigged up" electrical connection in my tank along with a noisy non-rubber insulated pump assemly vibrating all the time. Any feedback would be greatly appreciated. :confused: :confused:
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Follow-up fuel question (Mark L. Warner)
I personally think that the fuel pump is the first limiting factor. That being said, your heads would have to flow VERY well IMHO for you to make that kind of power with 113 castings. Do you have flow numbers for them? Also, I am using a set of stock injectors on an LT1 with a stock fuel pump, it makes somewhere over 400fwhp and I have never had a fuel delivery problem at 45 psi. Hope that helps some!
Thread Starter
Racer
Joined: Apr 2002
Posts: 353
Likes: 0
From: Tuscaloosa AL
Re: Follow-up fuel question (ANTI VENOM)
Hey Anti Venom, thanks for that info - it is very helpful. That horsepower estimate is from TPIS directly - apparently they have done dyno testing with that exact set-up and the stock heads. Lingenfelter also speaks very highly of the stock aluminum heads from '88 and up which is what I have. It wouldn't completely surprise me if that number is a bit high, however, being in the Heart of Dixie (Alabama), my engine shop does work for some Grand National racers and they do tend to be very good at head porting, etc. More importantly, however, is your info on your LT1. Correct me if I'm wrong, but the LT1 came with 24# injectors. You handle 400 hp with stock injectors and pump - perhaps since L98 injectors are 22# (really 19#) and I have the HP GM pump from the GNX, perhaps I should keep the pump but get bigger injectors. Tell me your thoughts. Thanks.
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Re: Follow-up fuel question (Mark L. Warner)
I actually had 24lb SVO injectors on the car. Then I was trying to diagnose a problem and I switched them out to the TPIS 19lb or 22lb what ever they call them.(from my L98) I tuned for them and found out that the injectors were not the problem. I left them in. I ran at the track and my results were pretty much the same as the year before with the 24lb SVO's. I am running somewhere around 9.5 ms of pulsewidth at WOT. That is about as high as I want to get, but they seem to work. My friend made 371 RWHP and is running factory LT1 injectors with a stock fuel pressure regulator. The stock injectors are capable of quite a bit, but they will have to work for it!
