89 951 engine overhaul
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chris white
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the only difference between Glyco and Porsche bearings is that the Porsche bearings are Glycol bearings with an extra Quality control conformation. If you look close enough you should see where the thickness was measured.
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four0four
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Turns out there's a shop near me (recommended by Chris' German over in Redmond) that claims they'll machine and refinish alusil. Current plan is to get out to the garage this evening, measure taper and..astigmatism(? not the right term). If it's too far gone, plan on stripping the block and having the shop bring it up to oversize. If it's within tolerance...buy some AN30? I'm not settled on that yet.
Not worth the risk?
I spent too much time reading an old thread over at Pelican - They actually did what I was hoping, which is to toss the cylinders under a SEM. Problem is, they were mostly looking at bad cylinders pre- and post- process, which doesn't tell us anything about what a proper surface looks like! If anyone has a sacrificial block with at least one perfect cylinder...I can wrangle up a SEM
Not worth the risk?
I spent too much time reading an old thread over at Pelican - They actually did what I was hoping, which is to toss the cylinders under a SEM. Problem is, they were mostly looking at bad cylinders pre- and post- process, which doesn't tell us anything about what a proper surface looks like! If anyone has a sacrificial block with at least one perfect cylinder...I can wrangle up a SEM
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chris white
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Nikasil is the best way to go, you can have it returned to perfect factory dimensions and you don’t need an alusil only piston - in fact nobody is making pistons with the factory style coating anymore (too toxic a process). Check out millennium technology, they do all my nikasil work. Btw - Porsche used to nikasil coat their factory based 944/968 race motors!
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Tom
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Has Mahle stopped doing their enviro-friendly(ish) Ferroprint stuff? Or do you just put it in the category of all the other coatings that don't work....?chris white wrote: Thu Apr 14, 2022 3:01 pm Nikasil is the best way to go, you can have it returned to perfect factory dimensions and you don’t need an alusil only piston - in fact nobody is making pistons with the factory style coating anymore (too toxic a process). Check out millennium technology, they do all my nikasil work. Btw - Porsche used to nikasil coat their factory based 944/968 race motors!
If I ever rebuild my original 2.5 motor (i.e., once original cars hit the million dollar mark), my plan has been to do Nikasil just to have reliable/proven piston and ring options.
If you have a few days to kill, here's an interesting read....
http://lnengineering.com/files/2019-LN- ... ystems.pdf
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Tom
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I just posted 3D print files below for little plugs you can put in the sparkplug wells. 
And, because I sometimes can't stop myself, I made this promotional video for the covers and plugs.
And, because I sometimes can't stop myself, I made this promotional video for the covers and plugs. -
ROB III
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Love the sock!Tom wrote: Thu Apr 14, 2022 4:43 pm I just posted 3D print files below for little plugs you can put in the sparkplug wells.
Thanks for sharing!
Rob
89 944 Turbo
Musik-Stadt Region
89 944 Turbo
Musik-Stadt Region
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Tom
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The sock was my favorite too, with the mask a close second.
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chris white
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I am pretty sure they still do the ferroprint and I don't think there are any issues - but it is not the same as stock. There were some folks that complained about the early Wossner coatings. I never had that problem with them.Tom wrote: Thu Apr 14, 2022 3:22 pmHas Mahle stopped doing their enviro-friendly(ish) Ferroprint stuff? Or do you just put it in the category of all the other coatings that don't work....?chris white wrote: Thu Apr 14, 2022 3:01 pm Nikasil is the best way to go, you can have it returned to perfect factory dimensions and you don’t need an alusil only piston - in fact nobody is making pistons with the factory style coating anymore (too toxic a process). Check out millennium technology, they do all my nikasil work. Btw - Porsche used to nikasil coat their factory based 944/968 race motors!
If I ever rebuild my original 2.5 motor (i.e., once original cars hit the million dollar mark), my plan has been to do Nikasil just to have reliable/proven piston and ring options.
If you have a few days to kill, here's an interesting read....
http://lnengineering.com/files/2019-LN- ... ystems.pdf
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four0four
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Went out last night and hit the cylinders with acetone, then measured them. I'm assuming Porsche didn't mix tolerance groups in the engine, 'cause all my cylinders fit group 0...which is what's marked on the rods. I couldn't find the stamp on the block, and I'm too nervous to clear off the pistons in situ, so waiting to remove them...
Ordered some micrometers (do I really have to use imperial for this!? there aren't any that stride 100mm..all of em start or end there!), cause I need an extra digit/digit-and-a-half beyond what my Mitutoyo calipers give.
If taper looks good, I'm leaning towards doing the AN-30 refinishing process myself. It won't fix the bigger scratches (but will probably smooth the edges, which is fine. I don't see the need to re-bore already square cylinders.
Don't hate me
Ordered some micrometers (do I really have to use imperial for this!? there aren't any that stride 100mm..all of em start or end there!), cause I need an extra digit/digit-and-a-half beyond what my Mitutoyo calipers give.
If taper looks good, I'm leaning towards doing the AN-30 refinishing process myself. It won't fix the bigger scratches (but will probably smooth the edges, which is fine. I don't see the need to re-bore already square cylinders.
Don't hate me