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Race gas stock fuel sys = 15psi = bad?

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Old Dec 19, 2006 | 12:00 AM
  #1  
Monsterbox's Avatar
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From: Birmingham, Al
Race gas stock fuel sys = 15psi = bad?

current mods are

-midpipe
-2.5inch catback with straight-through muffler (not much a mod more of restirction for creep)
-hks twin intakes
-PFS Purple Thing w/ 15psi setting
-Profec B Spec II

right now i run 12psi at high daily setting and 10psi normal driving
I want to race with a bunch of money a pretty quick mustang gt around here and i think the only way ill get him is with 15psi of boost out of my twins

so how risky/bad or good idea is it to run 100 unleaded or + leaded fuel (5 gallons) crank up the boost to 15psi and max out the injectors...or set fuel system for 13lbs of fuel equivalency and just run the race gas with engine at 15lbs

is this is a safe cheat to getting larger injectors and pump as i do not have time if i'm going to race this guy in 2 days
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Old Dec 19, 2006 | 12:37 AM
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Outlook not good. I see you added a 2.5" exhaust "restrictor" at least.

Last edited by DigDug; Dec 19, 2006 at 12:43 AM.
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Old Dec 19, 2006 | 12:58 AM
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rynberg's Avatar
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Do we really need to tell you that it's ******* stupid to risk blowing your motor for a race? Sigh....maybe we do. If you are really determined to do this, run straight 100 unleaded and run 14 psi.
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Old Dec 19, 2006 | 01:51 AM
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Don't risk blowing your motor... 15psi is to high. If anything, do what rynberg said, but I would leave it at 12psi anyhow... hope that helps.
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Old Dec 19, 2006 | 03:20 AM
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Originally Posted by Monsterbox
is this is a safe cheat to getting larger injectors and pump as i do not have time if i'm going to race this guy in 2 days
Uh, I don't see the humor.

Just overnight the parts from Japan. (now that's funny)

There is no cheat. More boost needs more fuel. Without more fuel, more boost means leaner AFRs.

You don't even know if your injectors are running at rated output. If one of them is a little gunked up you'll blow your engine.

Dave
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Old Dec 19, 2006 | 08:18 AM
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Could you do it? Sure. Has it been done before? Yes.

However, when I have seen it done using the stock fuel system, its was using either the PFC or the Pettit ECU. I'm not saying you couldn't do it with the PFS, but without knowing what (if any) adjustments have been made to the PFS no one can tell you that its safe.

Now having said that, is it a good idea? No. You can drive a car with your feet, but that doesn't make it a good idea to actually do it.

Good luck.
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Old Dec 19, 2006 | 03:38 PM
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well sounds like its too much of a risk, ill just run it at 12lbs maybe 13 and run 100 just for safety...ill keep it there until i get upgraded 1300cc's and fuel pump...its definately not worth blowing the engine, just checking to see if race gas really added that much protection
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Old Dec 19, 2006 | 04:07 PM
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From: Sterling, VA
Originally Posted by Monsterbox
well sounds like its too much of a risk, ill just run it at 12lbs maybe 13 and run 100 just for safety...ill keep it there until i get upgraded 1300cc's and fuel pump...its definately not worth blowing the engine, just checking to see if race gas really added that much protection

You've opened up airflow through the engine enough that you need to start thinking about supplying more fuel. If you're still running a tired stock pump with tired stock wiring, you're just asking for trouble turning up the boost any more than you have. Given your recent issues with boost control, sounds like you should be taking it easy.

I'd feel sketchy at 13PSI with a midpipe on a stock fuel system regardless of ECU myself, but to each his own...
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