compression question
compression question If we have lq9 and stock pistons, milled heads. 050, how much comp should we have? Building a max effort lol another one, for another buddy. Looking to get cam ideas from tooley or tick or? ??? Somebody Soon.
So, 11.05:1 using the oft quoted .006" milled off = 1cc formula.
Last edited by speedtigger; Sep 25, 2014 at 09:36 PM. Reason: Cuz I got it wrong initially too! LOL
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Steve, to keep my math easy, I just input all the stock info and then reduce the gasket by the thickness to be milled. Kind of a down and dirty method. LOL works up to a .050 cut 
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Don't be mad for me saying, but that is why you got it wrong. If you notice, the combustion chamber does not take up the same amount of surface area as the gasket.
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speed is right about the gasket giving more than the mill. However stock diameter isn't 4.060 on a GM 6.0 head gasket. Its closer to 4.100. On L92 heads the edges of the head chamber are larger than a 4.060 gasket (not that it presents a problem). The GM 6.0 gasket is larger than the chamber.
Last edited by The stunningman; Sep 25, 2014 at 09:29 PM.
speed is right about the gasket giving more than the mill. However stock diameter isn't 4.060 on a GM 6.0 head gasket. Its closer to 4.100. On L92 heads the edges of the head chamber are larger than a 4.060 gasket (not that it presents a problem). The GM 6.0 gasket is larger than the chamber.
Last edited by speedtigger; Oct 6, 2014 at 09:51 AM. Reason: corrected part #
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The calculator I used doesn't ask for a gasket bore diameter. So not taken into equation.
You have the deck height at -.006....I used 0. I see this is where the difference comes in.
I adjusted the one I used to input a stock LQ4 compression of 9.43:1, that is where I got the 0. With the -.006 I get 9.55:1
I also have to ask...with the combustion chamber shape being what it is, how can a single number (.006) equal a set amount of increase ?
I can see it to a point, but wouldn't it increase once you get past that point ?
So, yes, really should measure to be sure.
No argument here, and no feelings hurt.....I'm not a machinist by trade
You have the deck height at -.006....I used 0. I see this is where the difference comes in.
I adjusted the one I used to input a stock LQ4 compression of 9.43:1, that is where I got the 0. With the -.006 I get 9.55:1
I also have to ask...with the combustion chamber shape being what it is, how can a single number (.006) equal a set amount of increase ?
I can see it to a point, but wouldn't it increase once you get past that point ?
So, yes, really should measure to be sure.
No argument here, and no feelings hurt.....I'm not a machinist by trade
i think this project is put on hold. We have taken apart 2 motors, one had a broke crank and the block was damaged. The other had a busted piston and had some cylinder damage. I found him a LY6 on Ebay for 1750 plus 175 shipping, but he didnt buy it.