TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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the procedure? Buy yourself an adjustable fuel pressure regulator and install it. You'll need a guage to check pressure for when you install and tune it. I have the Holley regulator. It more expensive than the others, but its really nice.
Horsepower? Maybe 5 or so, but you can adjust your air/fuel mixture to make more power. Also a little flatter power curve. Ive seen them take .1 seconds off a 1/4 et when adjusted right.
I just added A BBK FPR and BBK fuel Pump and I think I have bigger injectors on my 350 TPI car. I run a little more than 50psi and although my old fuel pump was weak it took me 2 a 15.0 quarter mile.,and now I can notice a big difference after I installed those parts + some headers.
Carefull not to run to much fuel pressure. You will dramatically shorten the life of your injectors due to the added stress of the injector trying to close against the higher that stock fuel pressure!
I can't remember where I saw it, but there was an independent dyno run made with a stock 5.7 tpi. The HP gains were substantial. Something like 20 or 30 hp. Apparently the fuel atomizes better at higher pressure causing a faster and cleaner burn. Sounds reasonable. If I come across the dyno stats again, I will post it.
Originally posted by Cdn Chopper I can't remember where I saw it, but there was an independent dyno run made with a stock 5.7 tpi. The HP gains were substantial. Something like 20 or 30 hp. Apparently the fuel atomizes better at higher pressure causing a faster and cleaner burn. Sounds reasonable. If I come across the dyno stats again, I will post it.
As much as I would like to belive it, I don't think it does. Couple of ponies at its best, but where it comes in handy is when you get better parts, you can tune the fuel pressure to make substantial power.
I knocked .24 secs off of my 1/8 mile time with a bbk regulator. I have pressure set at 48 psi. I did have a small fitting problem though. The bolt is to long and actually can not go any lower then 48 psi because it hits the plenum.
Since we are on the regulator, how do you know if you have a bad one? Also, what is the stock PSI on an 85 305? What would be the max that the stock injectors could handle?
Not sure what the stock setting is, I think 42 psi. I have a Jet AFPR bumped up to 50 psi. I noticed a small increase in power, but I am using stock 19 lb injectors and modified exhaust manifolds. Next weekend I'm putting 22 lb injectors in so hopefully I'll get a little more hp.
__________________ 85 Z28 Camaro-305 TPI, 700R4, Hypertech chip, Removed AIR Pump, 3 inch exhaust, custom ram air induction
