Quick compression check

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Desertjr
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Quick compression check

Post by Desertjr »

Well i stating a new head for my motor after not liking how the last 1 turned out. current compression with new head is 9.8:1 static, 8.4:1 dynamic too much for pump gas? Quench height is roughly .030. ICVA is 53.95.
This is assuming 58cc chambers. The last head measured at just above 57cc stock, enlarged them and running LSx valves for a total just under 62cc. This time around I want to leave the chambers just about stock, with some deshrouding and cutting the odd protrusion across from the spark plug out. I didn't like how much changed on the last head so we are starting over..

It will run on 91 octane unless i have no choice. For that, I'd like to have a 87 oct. "safe" tune..I use my jeep for overlanding/exploring and quite a few times I've run into a station out in the middle of no where with only 87octane. I'm certain I can't run 87 with this high compression correct? Again the 87 option would be for a "oh shit" type moments.. Tuning will be done via a apexi safc II which gives you the options for 2 maps. Perfect for me.

Whats my options guys?
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Re: Quick compression check

Post by Desertjr »

Thinking of dishing the pistons out to 18-20cc or so. Dropping my compression into the 9.4-9.2:1 range which is more desirable for me personally.
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Re: Quick compression check

Post by grainofsalt »

I run .040" KB 944 pistons (21.73 dish), .043 MOPAR headgasket, 24# injectors, stock cam, all at 1000 above sea level. No ping and I still use low grade fuel.

The protrusion across from the spark plug helps with swirl.

This may or not help you.
Desertjr
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Re: Quick compression check

Post by Desertjr »

grainofsalt wrote:I run .040" KB 944 pistons (21.73 dish), .043 MOPAR headgasket, 24# injectors, stock cam, all at 1000 above sea level. No ping and I still use low grade fuel.

The protrusion across from the spark plug helps with swirl.

This may or not help you.

What's your actual scr & Dcr?
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SilverXJ
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Re: Quick compression check

Post by SilverXJ »

grainofsalt wrote:The protrusion across from the spark plug helps with swirl.
Not according to Hesco.
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Re: Quick compression check

Post by Desertjr »

SilverXJ wrote:
grainofsalt wrote:The protrusion across from the spark plug helps with swirl.
Not according to Hesco.

I was waitingfor this to come up. Chris right? I'm about to start on my 2nd head and have 2 weeks or so to get it finished. John(nosigma) told me there was some errors in the head porting thread...to open up the bottom of the port slightly more than the roof, and to also open it on the chamber side more..slightly. That it promoted swirl ect. He also pulled the ramp into the chambers a little.
1bolt lists its the other way around I believe. What's your options on all this? I know you did a great looking job on your head.
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