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newb.
 
eimkeith's Avatar
 
Join Date: Feb 2001
Location: Charlotte, NC
Posts: 2,037
why can't 3.3 930 P/C be used in 3.0 930?

I know, I know, the wrist pin location is different, I've read that, but how is it different? Could this not be corrected with modified/custom connecting rods?

or is it simply cheaper to have custom pistons made?
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keith
'75 RS/RSR-look | '67 Kaiser M715 | '73 CB750 | '70 TD250B

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Old 06-01-2005, 07:15 PM
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They can. The wrist pin on the 3.3 are 23mm vs. 22mm on the 3.0. You would need to change the small end bushing and maybe have them offset to make up the compression ratio differences, if you want to get creative.

The 3.3 pistons are designed to be used with the 74.4 mm crank. With the 70.4mm crank on the 3.0 turbos, you will end up with something less than the 6.5:1 the 3.0 motor developed with 95mm p/c's.

BTDT

Tinker
Old 06-02-2005, 09:40 AM
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Tinker, did you find a solution? I suppose it's a cost decision between longer rods or appropriate pistons...
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keith
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Old 06-02-2005, 05:55 PM
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The only real benefit to running the 3.3 p/c's is sometimes decent used sets can be purchased at a good price with low mileage from someone updating. Some have indicated the 3.3 cylinders are not the best as their design only has cooling fins on one side.

You can simply swap the p/c's and replace the bushing and go. It will run, but it's not an ideal match of components. You are only gaining about 121cc of displacement. Horsepower wise, it is probably a wash with the loss of efficiency due to the decrease in compression ratio.

A better cost effective alternative might be to use your existing nikasil 3.0 cylinders and get a set of custom pistons made with your desired compression ratio for less then $1k.

Tinker
Old 06-02-2005, 10:15 PM
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or possibly, get custom pistons made for the 3.3L cylinders, correct?

what possible explanationis there for cooling fins one only one side of the 3.3s?
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'75 RS/RSR-look | '67 Kaiser M715 | '73 CB750 | '70 TD250B

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Old 06-03-2005, 03:46 AM
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