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

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

Thanks Wayne - guess 89mm pistons and cylinders are the only way to go.

Robert

Actually, that's roughly how they changed the 2.2 911 engine into the 2.4.

Robert,

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

Michael