Reducing Capacity by modifying Conrods?

[ber911]

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

[Wayne 962]

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

[ber911]

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

Robert

[jluetjen]

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.

[Walko]

Robert,

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

Michael