Pistons and cylinders in 3.0 sc case
 

Posted this over in 930 forum, haven't heard anything yet but was going to go turbo route on my 83 sc 3.0 and want to do 930 p's&c's I know the rods need rebushed for 23 mm wrist pin. What compression ratio do you think I will end up with is my main concern thanks.

The 3.3 turbo pistons have a dome of about 5cc.
The heads cc at about 89.
With the reduced stroke, .75mm rod length difference (pin height issue) you will be lucky to get 6.37 to 1 compression. If you off set the wrist pin bushing by .030" you can get it back up to 6.70:1

Thanks Henry. Is that going to be to low? Is there another way to raise it up closer to 7:1 ?

The 3.16 turbo conversion is very nice. By redoing the rods you will find that the 6.7:1 number will work just fine. By doing this conversion you also get the added bonus of longer rods (reduced rods angle and better rod length to stroke ratio.)
I've done it many times.


BTW: the 3.0 turbos were rated at 6.5:1.