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04-25-2002, 05:59 PM | #1 |
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Join Date: Apr 2002
Location: n.c.
Posts: 5
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is my fuel pressure too high under boost?
All right heres the deal,I have an 88 LX hb stock from the intake down.I have a Trick Flow street heat intake,65mm TB,76mm C&L mass air meter,30# inj.,K&N conical filter, Vortech S-trim puttin' out 9lbs of boost,Vortech FMU,190lph intank pump,T-Rex inline pump,Holley adj. fuel press. reg. set at 38psi.My question is, how high should my fuel pressure be under full boost?It will hit almost 80psi.The fmu is calibrated for 12:1,Does this mean, for every pound of boost, my fuel pressure is raised 12 psi?
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04-25-2002, 10:25 PM | #2 |
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Join Date: May 1999
Posts: 5,246
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The injector safety limit is about 100psi, so you're safe by that measure. If it was 12psi of fuel pressure for every 1 psi of boost you'd be at 9 x 12 = 108 + 38psi = 156psi.
The best way to know if your fuel system is functioning adaquately or if it's overpowered is to get some fuel/air ratios off a dyno run. The analyzer seems to think your combo can support up to about a maximum of 600hp pushing your injectors to the limit. |
04-25-2002, 10:46 PM | #3 |
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Join Date: Apr 2002
Location: n.c.
Posts: 5
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Thanks for the help. I will be building a 331 soon and hoping every thing will be adequate.
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04-26-2002, 01:37 AM | #4 |
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Join Date: Jan 1999
Location: Sugarland, TX
Posts: 458
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I think your calculations might be a little off. (Then again so might mine)
It is true that the fuel pressure will be raise 12 pounds for every pound of boost. But that is not in addition to your 38psi. The FMU is on the down streem side of the fuel system so the FMU will block the fuel going back to the take at specifiec pressure. For instance. If you are building 3 PSI, the FMU will block off the fuel until it reaches 36 PSI and then start bleeding it toward the tank. The fuel regulator that is set at 38 is still making it hold 38 psi at the injector. Once you go to 4 psi the FMU blocks off the fuel until it reached 48 psi. Now the FMU is regulating the Fuel pressure and not you regulator. It basically is like the fuel regualtor is not even there at this point. If you are going to run 9-10 PSI I would have to say switch to a 8:1 FMU calibator.
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306DSS, AOD, T-Trim Vortech #3325 w/ driver 6.9882@100.33 1/8th |
04-26-2002, 07:32 PM | #5 |
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Join Date: Nov 2001
Location: Sunny, Hot, Sebring, Florida
Posts: 725
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Forget all that, An 88 with a 76MAF and a blower? HHHHHHMMMMMMMMMMMMM?
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