Pinky in 13's

Need some setup advice, have some stories? For organized racing stories only! No street racing here!
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1988GTU
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Pinky in 13's

Postby 1988GTU » Thu Oct 30, 2008 6:07 am

If I could suggest you to do one thing about your fuel situation.  When you swap in a 255 pump, I would cut a good portion of the bucket at the bottom out.  Not so much where it interferes with the leveling arm, but just a good section on the opposite side of it.
Kind of what I had in mind:


Under a factory spec pump with OEM factory spec pressures/volts the bucket may not starve in it's "home" (the bucket) .  Add in an upgraded fpr and or up the volts to the pump to over work it and it will probably start cavatating in the bucket.  When you add in the higher flowing/pressure pump the condition may not change or will get worse since your main restriction is still the bucket.  Those relief valves are just not big enough to keep up with the flow. ÂÂÂ
Hope this could help you.  :)

Note* Keeping a 1/4 tank will become a must for WOT times.


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Pinky in 13's

Postby 3X00-Modified » Tue Nov 04, 2008 1:31 pm

Good call, I'll look into that when I do the pump.



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Pinky in 13's

Postby rweatherford » Tue Jan 20, 2009 8:52 pm

I'm a little late to this party.....


I was running 55 lb/hr injectors at factory pressure.  I was able to support 104 MPH and about 240 wheel HP on short injector durations (up to 7200-7400 RPM), so it can be done.  However I think I was about at the limit and I think Norm felt the same with his V-6 car.

Decreasing FP and increasing injector size can increase the available volume.  The factory pressure is the only thing that allowed me to do that.

Try finding a pump volume vs pressure graph.  Might open some eyes.

You do need to add a fuel pressure guage somehow and see what is happening.  I'd lean your direction that you are at the limit on the factory pump.  I don't think I'd sneeze any N2O at it.






Rex Weatherford
92 Beretta GTZ Quad4 Turbo / 5-speed (sold)
Best 1/4 ET =  13.523 @ 105.16 mph

07 Mazda 5 Black on Black (it's slow)


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Pinky in 13's

Postby 3X00-Modified » Mon Feb 23, 2009 10:11 am

Your reminding me of a possible issue... I'll have to look into this before I think of running the nitrous at the strip... if it be a FP gauge to watch it closely or just biting the bullet and pulling the Walbro out of the red car and swapping it into the pink one... Unfortunately that means downing both cars for a short duration but if its gotta be done its gotta be done...



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Re: Pinky in 13's

Postby 3X00-Modified » Wed Apr 08, 2009 8:59 am

1988GTU wrote:If I could suggest you to do one thing about your fuel situation. When you swap in a 255 pump, I would cut a good portion of the bucket at the bottom out. Not so much where it interferes with the leveling arm, but just a good section on the opposite side of it.

Under a factory spec pump with OEM factory spec pressures/volts the bucket may not starve in it's "home" (the bucket) . Add in an upgraded fpr and or up the volts to the pump to over work it and it will probably start cavatating in the bucket. When you add in the higher flowing/pressure pump the condition may not change or will get worse since your main restriction is still the bucket. Those relief valves are just not big enough to keep up with the flow.

Hope this could help you.

Note* Keeping a 1/4 tank will become a must for WOT times.


Took your advice, Check my members rides thread for the pictures... It should help a lot since once I saw what it had to suck through to get any fuel I was stunned... I swear the relief valve for the bucket inlet was the size of a straw!

Now the base of the pump has direct access to fuel, and yes over a 1/4 tank is now UBER necessary to prevent problems.




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