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When looking at the JH engine specs versus the Golf engines, same cylinder size, piston rod and stroke - is it the shape of the piston that gives the 10:1 versus 8.5:1 compression? aren't the cylinder heads essentially the same (except for solid versus hydraulic lifters)? thanks
Compression ratio is the ratio of the total cylinder and head volume w/ the piston at the bottom of it's stroke over the remaining volume of the cylinder and head w/ the piston at the top of it's stroke.
While I haven't had a Golf 10:1 motor apart, I do believe that the shape of the piston 'dome' is different, and subsequently decreases the amount of 'residual' volume when the piston is at the top of its stroke.
This volume represents a much smaller portion of the total volume than it does the residual volume, that's why the CR goes up.
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MARRS #25 ITB Rabbit GTI
Bill is correct, the pistons are different. They have a smaller volume dome.
Peter
Hmmmmm...so if I slap on a set of these 10:1 pistons on my Rabbit motor........... http://www.theunholytrinity.org/crac...dvv/eplus2.gif
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Glenn
MARRS ITB #07
dead...for now
[This message has been edited by GTI Cup (edited October 12, 2001).]
It will be illegal in ITB!!! http://Forums.ImprovedTouring.com/it/smile.gif
But it will be legal in GProd!!!! http://Forums.ImprovedTouring.com/it/smile.gif
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MARRS #25 ITB Rabbit GTI
[This message has been edited by Bill Miller (edited October 12, 2001).]
Forget golf pistons, how bout Audi pistons. I can't remember what model, but you will end up with 10:1 cr and a total displacement of 1870cc. All totally illegal of course.
Peter