Mahle 2.9 9.8:1 Pistons/Cylinders

[jgparker]

I'm looking for any opinions on using the Mahle 2.9 9.8:1 Pistons/Cylinders versus the obligatory 2.7 RS 8.5:1. I know it will add over $1K to my rebuild, but it should give a good boost to HP. Any ideas how much?

Also, I hear the heads need a slight camphor to accept these cylinders. Anyone know what that would involve?

For reference, I have a 7R case, and am running Webbers and an early dual sports exhaust, and will go to S-cams. I run only 94 octane.

[farleyd]

I was (am) on the same avenue - RS p/cs, Webers, E-cams. But i bought RS 8.5:1 Mahle p/cīs mainly because i had a good price (lower than 1200US$ new in box).

Wayne mentionned that if he were to go to RS p/cs on his 2.7CIS, hed go to 9.8:1.

Wayne and B. Anderson both agree that even the 8.5:1 are good for 210HP on our set-up.

Id suggest that you check what those 9.8:1 would give you vs the 8.5:1 vs the 1K$ vs the torque/HP vs head work, etc.

In the end, does 10HP or so really worth it? Depends on what you want to do. On my side, i decided that 210+HP and 180lbs/torque are more than enought on such a light car as m7 914/6 conversion. More than this, and up goes the price tag: stiffening kits, extra oil cooler, etc.

Good luck!