To Sleeve or Not to Sleeve? 16v 3.0 Turbo

Talk and Tech about turbocharged 924/944/968 cars
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Jotronic
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I was asking in a previous thread what people were using for pistons lately and realized I hadn't asked a qualifying questions.

Of the members that have 16v 3 liter motors, is your block sleeved, alusil or nikasil?
THEN what pistons are you using?

I'm not crazy about waiting six to eight months just for pistons and the prospect of having to wait so long is making me consider other options.

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Bergerac
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Alusil with Custom Mahle motorsport pistons. Check on the lead times, was two years ago when I ordered mine, their backlog may have cleared.

If I was starting with a used block I would send it to Millennium Technologies to be Nikasiled, see MM's thread from a few months ago. What does your engine builder recommend and work with?

Nothing is going to be quick with this process, at least your car is still running in the meantime.

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Jotronic
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My builder is recommending a sleeved build and hasn't named a piston yet as that is part of our pending detailed discussion when I finally pull the trigger on this. I've had various suggestions from online guys with Chris White saying MM are "perfect", Albert Broadfoot saying he uses JE with a design of his own making (sleeved) and Bas saying Wiseco is the way to go (sleeved). Diamond, CP and Omega have also been mentioned. The rest seems pretty straightforward as far as rods (Molnar) bearings (ACL or Glcyo), etc. It's just the piston choice is the big variable at this point.

#3

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Tom
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Jotronic wrote: Sat Jun 28, 2025 8:29 pm My builder is recommending a sleeved build and hasn't named a piston yet as that is part of our pending detailed discussion when I finally pull the trigger on this. I've had various suggestions from online guys with Chris White saying MM are "perfect", Albert Broadfoot saying he uses JE with a design of his own making (sleeved) and Bas saying Wiseco is the way to go (sleeved). Diamond, CP and Omega have also been mentioned. The rest seems pretty straightforward as far as rods (Molnar) bearings (ACL or Glcyo), etc. It's just the piston choice is the big variable at this point.
Be very careful with builders who want to sleeve. Unless they've sleeved a couple dozen 944 blocks with success, I'd pass. There are too many horror stories about quality builders who thought they could sleeve these motors and fail. @chris white has a system perfected, for example. But unless the block is damaged, I'd give another vote for Nikasil and bespoke pistons. @michaelmount123 may be able to help with specs for a faster JE piston that would work in Nikasil. On the other hand, what's 6 months in the grand scheme of things?

And as a PSA: google Albert Broadfoot Complaints before commissioning him to build anything.

#4

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chris white
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The only sleeving I will do is the MID system....which is now so expensive that it only make sense for full on racecars, 'regular' sleeves can be trouble prone for most builders.
And now Millenium Technologies just had a fire in their shop delaying production by a month.
BTW - I just (yesterday) installed a set of Wossners that a customer supplied - much better fabrication quality than previous. 3 of the pistons weighed the same to.01g - nice tolerance! nicer quality rings than before.
if you are getting pistons play close attention to the rings, there have been some quality issues lately, even Total Seal has put some iffy rings out there.

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Tom
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chris white wrote: Mon Jun 30, 2025 3:52 am The only sleeving I will do is the MID system....which is now so expensive that it only make sense for full on racecars, 'regular' sleeves can be trouble prone for most builders.
And now Millenium Technologies just had a fire in their shop delaying production by a month.
BTW - I just (yesterday) installed a set of Wossners that a customer supplied - much better fabrication quality than previous. 3 of the pistons weighed the same to.01g - nice tolerance! nicer quality rings than before.
if you are getting pistons play close attention to the rings, there have been some quality issues lately, even Total Seal has put some iffy rings out there.
Just corrected the confusing typo in my previous response. Was trying to say you had a system down --i.e., you had a proven sleeve system, in contrast to so many others that think they can sleeve a 944 block, fail, and then blame the customer's tune. :roll:

#6

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