How much compression is to much 4 pump gas
09-13-2005, 12:12 PM
#1
How much compression is to much 4 pump gas Title pretty much covers what I want to know
How much compression can I run with 91 octaine and how much with 93 octaine.
DO not include fuel additives
im looking for what you have above 11:01 how the car runs, any pinging, carbon?
and what heads you have ?
How much compression can I run with 91 octaine and how much with 93 octaine.
DO not include fuel additives
im looking for what you have above 11:01 how the car runs, any pinging, carbon?
and what heads you have ?
09-13-2005, 02:05 PM
#4
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I'll be running 11.5 on 93 in good ol' Florida heat. I will be running a colder plug, running a better quench, and will have the fans on to keep cooant temps under control. I feel pretty comfortable at this compression, but I don't know how much more can go till you run into issues.
BTW.....forged pistons and TEA LS6 heads.
BTW.....forged pistons and TEA LS6 heads.
09-13-2005, 02:23 PM
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Originally Posted by Phil'sC5vette
Title pretty much covers what I want to know
How much compression can I run with 91 octaine and how much with 93 octaine.
DO not include fuel additives
im looking for what you have above 11:01 how the car runs, any pinging, carbon?
and what heads you have ?
How much compression can I run with 91 octaine and how much with 93 octaine.
DO not include fuel additives
im looking for what you have above 11:01 how the car runs, any pinging, carbon?
and what heads you have ?
I'm running a 224/.560/112 XE with custom ported LS1 heads, milled .015 (64.2cc) for a 10.61:1cr.
I ran this combo for the last 2 summers without a single "ping". I think I could have gone with 11:1 but didn't want to take the chance with the crappy 91 octane we have here in Canada.
09-13-2005, 02:24 PM
#6
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It depends on variables such as how much timing your are running.
Originally Posted by Phil'sC5vette
Title pretty much covers what I want to know
How much compression can I run with 91 octaine and how much with 93 octaine.
DO not include fuel additives
im looking for what you have above 11:01 how the car runs, any pinging, carbon?
and what heads you have ?
How much compression can I run with 91 octaine and how much with 93 octaine.
DO not include fuel additives
im looking for what you have above 11:01 how the car runs, any pinging, carbon?
and what heads you have ?
09-13-2005, 03:51 PM
#7
As stated earlier, cam and timing and octane determine what you can run. You need to be concerned with dynamic compression (DCR), and keep that around 8.5:1. I'm sure you could run 12.1:1 or 12.5:1 on 91 octane with a huge cam. It would be such a joy to daily drive, though, that'd you be better off looking at 11.5-11.8:1 as the maximum CR and running a mid 230s duration cam to bring the DCR down to something manageable.
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09-13-2005, 04:17 PM
#9
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I run mainly 91 octane around town with 11.5:1 c/r at high altitude and with 27 degrees max advance. (I run 120 octane C25 in my 622 with 16:1 c/r and 29.5 degrees advance. trivia)
09-13-2005, 10:09 PM
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stock shortblock, MTI C2 cam, Patriot 6 liters with 59cc chambers and cometic gaskets. Rough calc for compression ratio is about 11.2 or so. I can run 91 -93 octane on 27 degrees advance timing with no detectable knock or pinging in 100+ degree weather.
