Pump 91 - how much boost

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Apr 10, 2014 | 08:48 PM

02SOMSS

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Staging Lane

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From: Iowa

Pump 91 - how much boost

I'm ordering springs for my gates, those of you running just 91 pump gas, how much boost are you running?
My combo is:
LQ4 shortblock
LS3 heads
Martin cam
S476r

Eventually I will be adding meth but for now I'd like a bit more than the 8# it's at.

Apr 10, 2014 | 09:37 PM

LILHEMI

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From: in my neighborhood

i run 18 psi with windshield washer fluid in the meth tank and 11* timing. made 750 to the wheels which is how i drive it every day lol you can get away with 14-15 psi with no meth. just keep your a/f fat and timing low.

Apr 11, 2014 | 07:01 AM

Old Geezer

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W/ intercooler, or not??

Apr 11, 2014 | 07:03 AM

02SOMSS

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Staging Lane

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From: Iowa

Yes, air to air. Sorry should have mentioned that.

Apr 11, 2014 | 12:23 PM

geoff17

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I've been running 15-16psi on my lq4 with no meth and its been fine. I do run 93octane though as opposed to your 91

Apr 11, 2014 | 02:09 PM

Sales@Tick

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From: Mount Airy, NC

Don't limit yourself to a set boost number. Every combo will move more or less airflow for a given boost number based on volumetric efficiency.

Manifold pressure is not 100% indicative of cylinder pressure and shouldn't be used as an absolute for octane requirements.

I'd personally stop around 700 rwhp on straight pump 91. Considering a safe amount of timing is being utilized.

Apr 14, 2014 | 12:10 AM

Fast86z

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Just know you're playing with fire. Turn it up too high and just a bad tank of gas will pop the engine. For what it's worth I ran 14 psi on pump 93 for a month with multiple track passes. Ran it hard after filling up and it broke doing a burnout behind a grocery store.

Good luck