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Reducing Capacity by modifying Conrods?

Would it be possible to build a 66mm stroke and 90mm bore engine at just under 2500cc's by modifying the conrods instead of using sleeved 89mm cylinders? If so which would be preferable?

Robert
Old 04-02-2005, 12:29 AM
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Changing rod length alone won't change displacement - it will just change the compression of the motor (it will lower it if you shorten the rods). You can possibly use a smaller journal on the crank, offset bore it on the original, and then increase displacement by using a rod with a smaller journal. This is how they stroked the 914 2.0L motor from a 1.7 crank.

But, this would be difficult, expensive, and complicated to do on a 911 engine...

-Wayne
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Old 04-02-2005, 12:58 AM
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Thanks Wayne - guess 89mm pistons and cylinders are the only way to go.

Robert
Old 04-02-2005, 01:04 AM
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But, this would be difficult, expensive, and complicated to do on a 911 engine...
Actually, that's roughly how they changed the 2.2 911 engine into the 2.4.
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Old 04-02-2005, 05:18 AM
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Robert,

There is a place in Australia that does a lot of the offset grinding on VW cranks.

Michael
Old 04-06-2005, 06:11 PM
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