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Maker

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Pump gas compression
« on: July 22, 2015, 06:00:05 AM »
What is the max compression ratio for a pump gas iron headed Olds   I've have been told 9.5 on the low and as high as 10.75
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mobboss

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Re: Pump gas compression
« Reply #1 on: July 22, 2015, 06:42:10 AM »
It depends, there are a few factors but let just say 11.1.  I have seen 12.1 work but outside temp was low.   At the point of 10.1 you really want to use some sort of additive.

Sent from my VK810 4G using SoCal Jet Boats mobile app

  • Boat #1: boat less
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GT Jets

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Re: Pump gas compression
« Reply #2 on: July 22, 2015, 06:43:48 AM »
What is the max compression ratio for a pump gas iron headed Olds   I've have been told 9.5 on the low and as high as 10.75

Somewhat depends on cam shaft selection and what is available as "pump gas".

I have always considered 10.5:1 as the upper.

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Maker

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Re: Pump gas compression
« Reply #3 on: July 22, 2015, 06:49:57 AM »
I'm looking at the Schneider baby solid flat  its 248-254 @ .050  .528 lift on a 108    I would like to be at or as close to 10.5 as I can  without having to spike the gas with race fuel
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