Hitting a wall in boost

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Oct 2, 2005 | 09:08 AM

longrange4u

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From: Reston, VA

Hitting a wall in boost

Guys,

Running in 4th hard in full boost (8.5lbs) when I get to about 4k RPM its like I hit a wall and loose a ton of power and my A/F drops through the floor.

I have my setup (See sig) and I do have a Wal 255... and I can only get it to do this in full boost 8.5lbs vs 5lbs. Is this fuel? Are 42lb injectors enough? Is the Walbro 255 enough? What about buying the Racetronix kit less the fuel pump (sense I already have it) what would that do for me?

Thanks all!

Jared

Oct 2, 2005 | 08:26 PM

longrange4u

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From: Reston, VA

Ummm anyone?

Oct 2, 2005 | 09:46 PM

DeltaT

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I would say your injectors are too small, and you are running out of fuel. I had to upgrade from 50's to 75's to keep my duty cycle around 80%, and yours are smaller than mine.

Can you read what your duty cycle is?

What about the rest of the gears? What's your redline or shift points?

Are you sure you are not hitting some kind of rev limiter or speed limiter?

Jim

Oct 3, 2005 | 12:30 AM

longrange4u

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Rev is set to 6k I am drowning at 5K or so.... I have only experienced it in 4th. I am only putting 431 to the wheels right now, I would think that the Walbro 255 would keep up, but that was what I was thinking too.... Would adding the Racetronix harness help?

Oct 3, 2005 | 05:31 AM

Slowhawk

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From: Bridgewater,Ma

If the A/F is going pig rich(to the floor) the cause should be either valve spring's or boost leak inbetween the MA and intake.Your pump shouldn't be a problem on a turbo car at that power level.

Oct 3, 2005 | 06:05 AM

Inspector12

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From: Pearland

YOu could buy the Racetronix kit it is not the same pump though. The 255 you have should be fine I would try a MSD boosta pump or Kenny Bell make one two. That is if you are dropping fuel presure. The 42#'s are fine I made 575 on 38#'s before having to change. Casper sells a voltage booster also its cheaper than both although you will have to provide some of the installation wire etc... A FPR in the return portion of your fuel lines in the back of the car will help you out a lot also FYI. Hope this help you a little.
Jeff

Oct 3, 2005 | 01:51 PM

longrange4u

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From: Reston, VA

Slowhawk.. Inspector.. thanks!

I did keep the tune on the rich side a little bit but it is just barely in the green when WOT.. not Pig rich or anything. I have 918's in the car... boost leak... wouldnt I see that elsewhere too?