Mahle Piston to wall clearance
#31
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Thread Starter
It's been a while... I receved an answer from Mahle NA ( actually very quick, first was some technical issues with the email) and they recommended to use .004 - .005 inch ( or .005 to .006 in if I removed the coating) clearance for dry iron sleeves. So I started the rebuild with iron sleeves.
#32
Rennlist Member
The ports between cylinders are effective and should be retained. Sleeving a block often blocks these ports, and if a section of the sleeves is cut out to match the ports, accurate honing is an issue. The lower portion of the cylinder will want to go out of round due to the missing section. If your machinist is telling you it's no problem, he either hasn't done it before, or he's lying to you. I trim the sleeve length to reach the bottom of the factory cylinder, but no deeper. This allows a majority portion of the port to stay open. Perhaps a bit of a compromise, but a round cylinder is all important, and the ports between cylinders will remain functional.
#33
Drifting
An informed answer to the question I've asked several times . Given the choice would you favour Alusil or an iron liner for an 8valve engine up to around 400 bhp?
#34
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#35
Rennlist Member
Agree, Nikasil. The key is round cylinders and a fresh hone for seating rings which the process provides. Millinnium Technologies in Michigan does a fine job. You'll have to use rings suitable for the Nikasil; I've used 964 rings with great success in 100mm bore engines.
The 944 block will come back with lots of crud in the oil galley. Be sure to brush them out thoroughly while you're scrubbing the block.
The 944 block will come back with lots of crud in the oil galley. Be sure to brush them out thoroughly while you're scrubbing the block.
#36
Drifting
Probably only one place over here that can Nikasil plate a 4 cylinder block, and their core business is the likes of Mercedes F1. Could liners be plated and then fitted to the block, or would the heat/chill process damage the plating.
#37
Rennlist Member
Cylinder sleeves won't be round after installation in a block. Therefore, honing has to be done after they are installed. Check around - there are probably several places that can do it in the race oriented UK. In fact, I just googled "nikasil plating in UK" and several outfits came up.
#38
Drifting
Most of the UK places can only do motorcycle barrels,want to ship the block overseas, or use their own brand coating. Capricorn are the only place I know of with a proven track record, but understandably they're very busy. Plus there was a rumour they'd only accept work via existing customers.
#39
Rennlist Member
Most of the UK places can only do motorcycle barrels,want to ship the block overseas, or use their own brand coating. Capricorn are the only place I know of with a proven track record, but understandably they're very busy. Plus there was a rumour they'd only accept work via existing customers.
MM
#40
Rennlist Member
Most of the UK places can only do motorcycle barrels,want to ship the block overseas, or use their own brand coating. Capricorn are the only place I know of with a proven track record, but understandably they're very busy. Plus there was a rumour they'd only accept work via existing customers.
/Peder
#41
Drifting
Thank you for your help. I know Capricorn can supply pistons, but I haven't heard of anyone using theirs in a 944.
Last edited by blade7; 05-07-2019 at 06:20 AM.
#42
Drifting
#43
Rennlist Member
/Peder