[_yb2s]

You can rebuild modern engines by boring out the block and installing a sleeve of the same block material and coating material, it’s just a lot more expensive. For a valuable car like a Porsche 911 this is typically done- the sleeves alone will cost 5-10k: https://lnengineering.com/porsche-996-997-987-3-4-or-3-6-96m...

[rasz]

Might be cheaper to send whole engine to Poland :)

http://www.krasnobrodzka-racing.com/alusil/ https://www.youtube.com/watch?v=_985nH-gUiU

Alusil sleeve job ~$4K for 6 cylinder, BUT you can go ~$1500 cast iron sleeves.

Mahle manufactures those sleeves in Poland https://www.youtube.com/watch?v=3GgPPIZHl-c always surprising to see how they "season" new parts by letting them rust in open air to relieve casting stresses. There is a good story about BMW racing engines being build from selected used blocks just sitting rusting away behind factory building for years.

[_yb2s]

Thank you! My daily driver is an early Boxster and this is great info on the Alusil. However, general advice I’ve seen on forums is that the iron sleeves don’t last in Porsche engines. The idea of sleeving with dissimilar metals sounds like a bad engineering idea as there will be constant relative motion with heating and cooling, and a galvinic cell near coolant passages.

[rasz]

This particular job from video was 996. In another video shop owner mentioned Alusil goes on most of them over >$100K range and iron sleeves will last at least that long. With iron sleeves you need different pistons/rings to match expansion rate.

[_yb2s]

It's a very controversial topic in the Porsche community, but overall it seems like the people that really know what they are doing and build reliable good running engines avoid the iron sleeves (e.g. https://flat6innovations.com/cylinder-bore-scoring/). Like you said- it requires using loose clearances which makes for a noisy, oil burning, short lived, and low performance engine... not what you want in a Porsche.

The factory coatings do fail in some cases- usually in specific engine configurations with issues, but very often last 300k+ miles... on the smaller bore M96 engines cylinder/coating failures are almost unheard of, even with very high mileage and lots of hard track use. Personally, I'll just stick with the smaller bore engines, and in the unlikely event it fails get a good used block where the factory coating is still intact. There's tons of the 2.7 and 3.2 M96 Boxster engines out there still running great with 300k+ miles, and you can buy a good used one for a few grand.

[rasz]

>Like you said- it requires using loose clearances which makes for a noisy, oil burning, short lived, and low performance engine... not what you want in a Porsche.

Thats opposite of what I said :) Only the startup noise applies, but lets not pretend M96 sound great :)

When something becomes veblen good logic goes out the window. >$100K 30 year old car restorations arent meant to make them peak performers, it becomes matched numbers everything as factory wankfest for cars sitting in a collection or driven only occasionally on the weekends. There is very little incentive doing cheap repair when everyone believes in expensive ones.

>There's tons of the 2.7 and 3.2 M96 Boxster engines out there still running great with 300k+ miles, and you can buy a good used one for a few grand.

Wanna bet they all have scored cylinders? :) Same goes for BMW Nikasil, no such thing as cheap used block with intact coating.