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The mkiv Supra Owners Club

comp/ratio


baldy

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hi chaps

 

write just had a headgasket done by leon.

 

 

has any 1 got the intelligents to work out the compression ratio 4 me?

 

the head had 11 tho skimmed off & he fitted a 2.0 mm gasket.

 

 

im just curious to know if the compression ratio has changed much

 

 

cheers baldy

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If I remembers right an inch is 25.4mm. So a thousandth of an inch is about 0.0254mm. If he skimmed 11 thou off that's just over 0.254mm right?

If the stock gasket is 1.5mm and he's replaced it with 2.0mm then the compression ratio has gone down. (All that calcreating. I even had to take my socks off)

Time to crack in some more air and fuel by my book then :D

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Right ho.

 

If the bore is 86mm then the stroke must be 86mm (0.5 litre displacemnt per cylinder).

 

If the stock CR is 8.5:1 then the compressed volume must be 66.61cc

 

If you have lost 11 thou' (-0.2695mm) from the flame face, but gained 0.5mm on the gasket then the overall delta is +0.2305mm

 

On an 86 bore (assuming the clearance diameter in the head gasket is the same as the bore - it is likely to be a bit bigger) then the volume gained is 1.34cc

 

This makes the new compressed volume 67.95cc

 

So your new CR is 8.35

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Originally posted by baldy

cheers T but i want the ratio really.

 

 

more feul n air means bigger injecters,hybrids,a big bill for parts,

 

 

ummm

 

 

i think i gona rob a bank:D

 

Hmmm bank robbery.... Likes your thinking. Thing is we'll all end up argueing over who's going to be the getaway driver like..

 

Let me I've got the fastest car,

No no let me I've seen getaway in stockholm the most.

 

Truth is most of us probably can't drive for sh*te anyway.

 

Just get a bigger fuel pump and then thrash the stock turbo's within an inch of their lives.:devil:

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Originally posted by Darren Blake

Right ho.

 

If the bore is 86mm then the stroke must be 86mm (0.5 litre displacemnt per cylinder).

 

If the stock CR is 8.5:1 then the compressed volume must be 66.61cc

 

If you have lost 11 thou' (-0.2695mm) from the flame face, but gained 0.5mm on the gasket then the overall delta is +0.2305mm

 

On an 86 bore (assuming the clearance diameter in the head gasket is the same as the bore - it is likely to be a bit bigger) then the volume gained is 1.34cc

 

This makes the new compressed volume 67.95cc

 

So your new CR is 8.35

 

I haven't got the foggiest what any of that means, or whether its correct - but it sure sounds impressive :D

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Remember that by running 1.4-1.5 on stock turbo's you are not just risking destroying your turbo's, you're also risking blowing up your engine as your EGT's will be sky high.

 

Some people seem to think, so what? if I run 1.4 and kill the turbo's I'll get hybrids. They could be in for a very nasty suprise.

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