1980SC

I've been reading comments on this forum about the European engines having higher compression ratios than the US versions. I have a 1980 Euro with the 930/09 engine, and according to the 'Porsche 911 Performance Handbook' my motor has only 8.6:1 vs the USA 1980 having 9.3:1. Am I confused or something?

- Rob
1980SC Euro

DohcV8

In 1981 the ROW cars had the compression ratio upped to 9.8 to 1 and the HP upped from 188 DIN to 204 DIN. They were noticeably stronger than the earlier models.

Regards,

Jerry Kroeger
82 911SC targa

1980SC

I assume this compression increase was done with taller pistons? As the bore and stroke remained constant.

-Rob
1980SC Euro

Stephen Masraum

Rob, Yes it was done with different pistons. Changing the bore or stroke either one or both will not alter the compression ratio. Neither will changing the rod length. It would take different pistons, milled heads, or I guess in these cars you could mill the cylinders.

DohcV8

Changing the length of the rods does affect the compression ratio. A shorter rod will reduce the compression ration because it increases the effective volume of the combustion chamber. A longer rod, if it doesn't cause the pistons to impact the cylinder head, reduces the effective combustion chamber volume and raises the compression ratio.

Regards,

Jerry Kroeger
82 911SC targa