Peter87911

Hello,
I am a new member of this forum and am looking for advice. I have a '87 911 and am in the preliminary stages of a 3.4 conversion that will include 964 cams, dual plug, 10.5 CR JE pistons and upgraded exhaust. I have Alusil cylinders and was looking for advice regarding the advisability of re-boring my cylinders and re-plating with Nikasil. Thanks in advance for any thoughts.

Peter

blockhed

Sign up to forums.pelicanparts.com
PM me and I can help you provide more info.

Amber Gramps

Your advice is to go elsewhere???? Classic.

Steve Weiner-Rennsport Systems

Hi Peter,

Thats a nice combination if everything is done right. Naturally, you will need custom software for safe operation. 10.5:1 on pump gas may be a bit ambitious unless your timing maps are conservative so I'd think that one over very carefully.

Your current 98mm cylinders can be bored & re-plated with Nikasil quite successfully and we do this all the time.

Ed Hughes

Scratching my head too....

Ed Hughes

BTW, not that it matters if he's boring-he'll need to replate. But, I thought all 3.2's were nikasil?

Ed Hughes

One more btw, if the OP is going to PM anyone, I'd suggest it be Steve.

Steve Weiner-Rennsport Systems

OMG, no. Most USA engines had Alusil ones and most ROW ones were Nikasil. One has to look to be sure.

Ed Hughes

Hmmm, my '84 were Niks. I thought the change was made in SC range.

redridge

Porsche has been mixing Nik and Alus since 1974... luck of the draw which ones you have from the factory..

Peter87911

Steve, from what I have read my understanding is that 10.5 on pump gas would be safe with the twin plug ignition and custom chip.

Steve Weiner-Rennsport Systems

Only if you run with conservative timing maps, especially in hot weather. Remember, detonation thresholds are dynamic, not static and vary with outside air temp, cylinder head temp (load), throttle position, oil temp, and AFR's.

Such timing leaves an engine feeling a tad lethargic and not willing to rev freely.

JMHO, but I'd rather have less CR and more timing for a lively feeling motor,...

CW-VIESOCK

+911

Peter87911

From what I understand, the Mahle 3.4 MM P+C set with 9.8 CR are compatible with standard ignition; and if one wants to go wants to go with a dual ignition to allow a higher CR, it appears as if JE's 98 mm at 10.5 is the next step up. Is there something in between, or is there no reason to go with dual plug with a 98 mm piston?

Amber Gramps

Peter, listen to Steve, especially at your altitude. Even the Porsche God's trust Steve when it comes to engine builds.