How to lower compression???'s

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Clone TIE Pilot

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Aug 14, 2011
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Using a thicker headgasket increases quench which promotes detonation. Because of this you need to run the thinest headgasket possible to make the quench small.

quench.png
 
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Streetbu

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May 22, 2011
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That is your static compression ratio, but what is your dynamic compression ratio? Depending on your camshaft you might be perfectly fine running 93 octane on the street.
 
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Streetbu

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Did you check the link I provided? Yes. Because your camshaft bleeds off some of that compression. Put all of your info into the calculator. -7.8cc, .010 deck surface, 64cc chamber, 4.190 gasket diameter, 64° IVC, 4.155 bore, 3.75 stroke, 5.7" rods.
 
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64nailhead

Goat Herder
Dec 1, 2014
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Did you check the link I provided? Yes. Because your camshaft bleeds off some of that compression. Put all of your info into the calculator. -7.8cc, .010 deck surface, 64cc chamber, 4.190 gasket diameter, 64° IVC, 4.155 bore, 3.75 stroke, 5.7" rods.

OK AWESOME THANKS

Yes, you can get away with this, but there is a big ‘but’ (not butt). It will run on 93 with an extremely careful tune and NO, and I mean NO coolant or intake temps issues. Heat soak will be your enemy.

I’m going to assume that you can keep this below 190 cruising (if you can’t, then you need to get that under control ASAP). The heat soak will kill you and your motor. For example, pull into a gas station to fill up on an 80-90 degree day and go to leave with an engine bay at 210-240 degrees and you’ll pound these pistons and rod bearings to death in short order.

You can make it work, but you need a better than average air induction system/setup. You can always put the timing in the toilet at light throttle cruise vacuum, but that just generates more under hood heat when you stop. And it’s not the coolant/engine heat that gets you, but rather the heat off from the headers. If you don’t have them wrapped, then you need to. A cowl hood with a kick *ss electric fan that you turn on with the engine off will help as well.

But dude, you need to be on top of the tune. Forget fuel economy, you can’t run this lean at cruise or idle (creates heat).

On the other hand, head to the track and chuck in some C16 and add 5-8 degrees of timing with a distributor twist (timing light to check) and this will add another 50-90hp.

Should also mention, forget any gas less than 93 octane. If you live in one of these max 91 octane areas, then you need to be adding a gallon or two of C16 or leaded 110 octane fuel for every 10 gallons.
 
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64nailhead

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If you added another .010” head gasket and cleaned 2 cc out of the heads, that would drop you into the mid to upper 12’s for static. Mill .020 of the pistons would drop another .3-.4 as well (or somewhere near that.)
 
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dickeymoore

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May 6, 2009
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I run 93 octane and have the best lincoln mark viii fan and griffin aluminum radiator and edelbrock 8811 aluminum waterpump and it runs 185-190 in hot 90 degrees in the south now in standing traffic 😳
 
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