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Author Can someone confirm this is right (dave/broster/phil sutton etc)
jr
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Registered: 20th May 02
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30th Apr 08 at 08:20   View User's Profile U2U Member Reply With Quote
Trying to work out my comp ratio on my xe

as far as i know, it is worked out at:

86.5 bore
x
86.5 bore
+
86.0 stroke
+
Volume of Combustion Chamber
Divided by
Volume of Combustion Chamber

Sound about right ?? obviously havent done the CC yet



[Edited on 30-04-2008 by jr]
willay
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30th Apr 08 at 08:31   View Garage View User's Profile U2U Member Reply With Quote
gotech?
broster
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30th Apr 08 at 08:43   View Garage View User's Profile U2U Member Reply With Quote
jr, use this

http://www.csgnetwork.com/compcalc.html

willay, smart
jr
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30th Apr 08 at 08:56   View User's Profile U2U Member Reply With Quote
Cheers mark, but is my calculation correct ?
dhdev
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30th Apr 08 at 09:05   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by jr
86.5 bore
x
86.5 bore
+
86.0 stroke
+
Volume of Combustion Chamber
Divided by
Volume of Combustion Chamber
[Edited on 30-04-2008 by jr]

**Not sure how it's worked out, but that doesn't seem right
That would equate to Bore^2+Stroke+1**

Edit! I see what you were getting at, and you were on the right track!

[Edited on 30-04-2008 by dhdev]
dhdev
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30th Apr 08 at 09:16   View User's Profile U2U Member Reply With Quote
Essentially you need to know the Volume at TDC and Volume at BDC, the compression ratio obviously being the ratio between these. So if you know the Bore, Stroke, deck height, volume of combustion chamber in the head and gasket compressed thickness you can work it out.
Say the piston sits flush with the top of the block at TDC and the compressed gasket is 1mm thick,
The volume at BDC will be :-
((Pi x Bore^2)/4) x stroke + ((Pi x Gasket Bore^2)/4) x 1mm + Combustion chamber volume
The Volume at TDC will be:-
((Pi x Gasket Bore^2)/4) x 1mm + Combustion chamber volume.

Then the ratio between Vol at BDC and TDC is the compression ratio.
broster
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30th Apr 08 at 09:23   View Garage View User's Profile U2U Member Reply With Quote
or do it the easy way and input
dhdev
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30th Apr 08 at 09:25   View User's Profile U2U Member Reply With Quote
I agree use the calculation site, but JR wanted to know if he was right
jr
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30th Apr 08 at 09:45   View User's Profile U2U Member Reply With Quote
yes oli

am i correct in thinking the deck height is the volume/measuremeat between the deck face and the piston a TDC ?

also, what does ^ mean i have an understanding of the CR, but not the equation to sort it
jr
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30th Apr 08 at 09:45   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by broster
or do it the easy way and input


yes but i like to know how things work
dhdev
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30th Apr 08 at 10:04   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by jr
yes oli

am i correct in thinking the deck height is the volume/measuremeat between the deck face and the piston a TDC ?

Yes
quote:
Originally posted by jr
also, what does ^ mean

Bore^2, means bore squared, its a superscript 2.
jr
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30th Apr 08 at 10:10   View User's Profile U2U Member Reply With Quote

 
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