3.0 SC to 98MM. conversion

[Wil]

I'm thinking of going to larger P/CS
Heres my setup:

1979 3.0 SC
stock heads
CIS
stock cams
SSI's
8.5:1 compression ratio 172 HP (owners manual)
87 octane regular gas


I would like to go to 98 MM QSC P&Cs and retain:
stock heads, CIS, cams. Is it possible? what modifications would I have to do?

would going to 9.5:1 P&C's still allow me to run regular gas without any mods? are 8.5:1 P&C's available? can I use the new pistons with my stock piston pins without mods?

What would be the HP gains? would it change other engine characteristics?
Anybody out there actually done this?

[gestalt1]

many have done this, i did but i have not gotten to the point of starting it yet. you will need to chamfer the edge of the heads to meet up with the larger diameter cylinders. be sure to check what head sealing system the cylenders and heads are, the stock sc engine uses CE rings, many cylinders don't use anything so yo may need to fly cut the heads to get a flat surface. this will increase the CR. 9.5:1 CR is fine for single plug, nothing over this however. i think there may be cheaper/quicker upgrades than swapping pistons and cylinders. why use stock cams, just swapping those for 964 cams will allow the use of cis and give a good performance gain.
-matt

[Dennis Kalma]

I have that exact combination, as prepared for me by the Kremer brothers in Germany, except i have the 9.8 compression pistons.

It runs great, lots of power, no issues whatsoever, been good for the 10 years I have been running it on the pump premium here in Calgary.

Kremer also did a mild port/polish, the fuel distributor is the Euro one as it was based, of course, on a European engine - 930/03 to be specific and it was boattailed internally.

I don't think you can tell at all that it is a 3.2, other than people who ride it say it seems fast compared to their 3.0, but then again I also have a 7:31 rear end and my car is fairly light (no ac, less sound deadening etc).

Dennis

[mb911]

I would not use QSC pistons.. not heard anything good about them only the cylinders(I run them On my car)

[Dennis Kalma]

Oops, update....my P/C's are Mahle.....

Dennis

[euro911sc]

Originally posted by gestalt1
...this will increase the CR. 9.5:1 CR is fine for single plug, nothing over this however...

My stock 3.0 is running 9.8:1. Ran like a champ for 8 years. 9.8:1 is fine as long as you make sure your fuel is of high quality. Henry says he does not like to go over 9.5/3:1 for a single plug, IIRC. But, he has to fix it if it breaks later You may choose to be a little conservative as well... or not

Best regards,

Michael