eric951turbo

Hey all, I am rebuilding my engine and I found a machinist that could install some cast iron sleeves to fit my oem pistons...

I just need to provide the rings.

Does anybody know what ring kit to use for this.

Car: 1986 951

thanks

bw993

Total Seal makes a ring kit for this exact application.

Chris White

Make sure your machinist knows what he is doing - high failure rates for first timers trying to sleeve a 944!

Ernie J

The stock pistons are iron coated and not meant to run in steel sleeves.The clearance used is .0005" for a aluminum bore, in a steel bore most pistons run a much larger clearance approx .008 . please note the difference its BIG.

eric951turbo

Thanks Ernie for your reply,

Does anybody else have any thoughts on this subject?

My story:

I Took the engine out of the car last fall to change ALL seals and gaskets, and fix a non oil pressure problem that occur while driving back in my driveway after a good spirit drive.

Then came the ''while I'm here'' part... decided to remove the head to check the condition of the piston cylinders and wanted to replace the piston rings (please note that I had the head gasket (wide fire), valve springs and some lifters replaced and head checked 2 years ago by my 944 mechanic Michel Beaudoin in Montreal, who recently passed away).

So I found this :

Some say by these photos that the cylinders dont look that bad, some same they do. Note that I can feel the scratches with my nails, and that all 4 cylinders have scratches.

I finally found yesterday a machinist near me that knows these engines and he's the one that offered me to install some cast iron sleeves to fit my pistons, and it was for me to find the right rings. I called my Mike at LR after I posted this thread yesterday and he told me to use the GOETZE PISTON RING SET 100mm used in the 911 TURBO '93 thru '94. That's what he as been suggesting to other clients that have done it before, and he never had a return on those.

That idea was well received on my part because of the price it would cost to do this. I wasn't planning to spend top dollars on the engine, I just wanted to do a small refresh by changing the rings and all seals and gaskets to stop (or try to) any leaks.

That being said, I found Refresh 951 page yesterday doing some research on the web concerning his 2.85L Hybrid Stroker Engine Build and found this extremely interesting... on both improvement and money side...

But money is hard to make these days and I just want the car back on the road for spring and finally be able to enjoy it. So I would probably go with my machinist option... if it works?

If it doesn't, then I would probably go the extra mile with Refresh 951's 2.85L Hybrid Stroker Engine Build, now that I found a machinist. The way I see it, its pretty much the same thing, by adding pistons and rods and more machine work to the list.

Note that this is a street car for occasional DE events.

eman930

Honestly... Your wasting money... Clean up all that carbon and install new rings, engine will be fine, those scratches are mild.... Also check your valve guides and seals, heavy carbon on your pistons is usually from oil getting in and burning... Or a bad tune

lejams

Or do it right, buy these and rebore & re-hone https://rennlist.com/forums/944-turb...1-pistons.html

Chris White

Yep, good advice.

Those scratches are very minor and will not affect performance. The Carbon caked on the pistons is most likely a result of worn valve guides. The other possibility that should be checked is too much bore taper. The first clue is it there is a ridge at the top of the ring travel. If you can feel a very noticeable ridge then you may need to rebore it, if not then a clean up and rering will save you a butt load of $

BTW - how many miles are on the engine?

eric951turbo

Thanks a million for the replies guys.

137K miles on the engine Chris. 'm gonna check tonight if theres a ridge on top of the ring travel. But if I remember well, there wasn't any.

That would be an excellent scenario... new rings and valve guides. Would work well with my wallet

I'll keep you all posted.

thanks

Chris White

You engine has less scoring than most 951 engines out there and it looks very shallow in the pictures. the only other source for oil in the intake is a bad Air/Oil separator. The internal baffles do collapse on rare occasions.

lejams

The scratches do look typical. If the bores present no problem and there is no significant taper wear at this relatively low mileage, is there really an advantage to do rings? Why not just do a valve job, put it together and drive it?

Maybe you can save the "while you are in there" $ for another time.

Chris White

I would agree if the engine was still in the car - but since its out I would do the rings and bearings. That will give him the chance to really clean up everything - it looks like there was a lot of carbon built up. rings and bearings are a small cost when you add up all the gaskets and labor to R&R the engine.

eric951turbo

I'm very happy about the sound of all this, the best thing is that these are all new parts I can get here in Montreal without paying shipping/duty fees

eman930

Yea, You already have the engine out, Full reseal, New rings and bearings, new guides and a valve job, Belts and rollers, might even wanna do the clutch while the engine is out, Then you'll be good for another 100,000

eric951turbo

I am doing the clutch... Another 1k there, thats why i was getting nervous lol