Porsche Enthusiasts Club Forum

If this can help anyone ,I have taken all my sunnen stones , pads and paste up to Modus Engineering (kent) for a BMW V12 engine they are repairing but they will also undertake boring ,honing and polishing 944/968 engines in future. Couldn't find many places to undertake this when I was looking .

That’s good to know

Discussed before, but I think Serdi and Capricorn can do it properly. I talked to several other shops that thought they could do it, but there didn't seem to be much supporting evidence. The bores of my project 104mm block are around 0.001-2" out of round. I've wondered if that could be corrected just by honing, and in the process opened up sightly to suit the increased clearance aftermarket forged pistons require.

I'd make sure that the forged pistons require an oversize bore, mine were undersized so they fit in the stock bores with the correct clearance

I think off the shelf forged standard replacement 2.5 and 3.0 pistons are usually undersized to fit standard bores. Should have said I was talking about custom 3.0 turbo pistons.

I'm in the process of rebuilding my 944 Turbo engine (which has scoring on cylinder #2), keen to find out if anyone has experience of Modus Engineering and can provide any recommendations? I'm looking to keep the alusil bores, so will need to find someone who can do the job properly. Unfortunately Serdi no longer do machine work and Capricorn I believe will only Nikasil the block.

Thanks and HNY

What pistons will you be using for the rebuild.....

Mahle Motorsport

A few years back I was planning to order a set of those for an Alusil 3.0 build, then I read that someone in the US had an issue with the coating failing on them. Coincidentally Wossner had the same issue not long after. If I ever was to build a 3.0 now, I'd use nikasil plated or iron liners for peace of mind.

Funny you should mention that, I found the exact forum thread on rennlist that you are referring to. I'd say that is a massive assumption that it was the piston coating that caused the failure in that particular case.

I've not read of any other issues with Mahle Motorsport pistons, forums are full of rumours.

BMW M3 and M5 alusil engines come with Mahle Motorsport pistons and I also know of at least one recent S65 M3 engine rebuild with Mahle Motorsport pistons which is running well.

Mahle use their own coating for the pistons and were an original supplier to Porsche (and BMW).

I've done my research, Nikasil was an option, but the amount of effort and cost when alusil was still an option didn't make it a viable option for me.

As you've done your research, you'll know the original Mahle Alusil coating is long gone. And I don't recall reading of a successful 944 Alusil rebuild, since Wossner had issues a while back. Good luck.

Be nice to find some new / old stock Woosner pistons before the problem coating .
You know anyone hoarding them Pauly ?

TBH I don't know if the coating on our Wossners is for Nikasil or works on Alusil too? Did you ask Racers Edge when you spoke to them Simon. Perhaps I'll follow the BMW route, and start peeing on my 2.7 block to harden it .

I never bothered finding out as they are a spare set for the ones in the nikasil bore just in case.

Everything I have to build a 3.0, is just in case now.