Carrera 3.2 top end rebuild

[preston_brown]

Hi everyone,

Back in April of this year, I finished tearing down the top end of my 3.2L carrera motor. It had been performing OK, but leaking quite a bit of oil, and consuming a little bit as well. The motor has almost 150k miles, so I figured it was a reasonable time to do the work.

I sent the heads, rockers, and camshafts off to be reconditioned. The heads came back nicely media blasted, with new hardware, valve guides, and intake valves. The cams were reground to 964 specifications, the rocker faces were reground, and the rockers were rebushed. I'm planning on getting a Steve Wong chip as well to go with my new Fabspeed premuffler and M&K 1 in 1 out muffler.

Here's the beginning of the reassembly. I've got the cylinders, heads, and cam towers back on. I did end up taking off the cylinders to make sure I had no broken rings or other weird looking issues with the pistons; there were none.

I'll use this thread to document progress and ask for help if any issues or questions come up. Glad to have the help of all contributors, frequent or seldom alike.

Thanks,

Preston

[Henry Schmidt]

The work looks top notch. Just one thought: Reusing Alusil cylinders with 150,000 miles on them is a gamble extraordinaire.
The nature of the 3.2 engine suggests that the rod length to stroke ratio creates excessive side loading on the pistons. This side loading causes wear beyond the wear you might find in other Porsche engines.
Good luck.

[cstreit]

Henry is giving good advice there... Did you do a compression and leakdown before this work? If not, I'd do one afterwards just to see where you're at.

Looks like you're doing a nice job!

[SP2]

Looks great Preston. Keep it up!

As for the Alusil re-use, ask Superman on this board about his experience. His came out fine. Good luck!

[fly4val]

As did the re-ringing of my p/l's a few months back......my comp check was 190 post
with about 2500 miles since.....

Currently have about 114k on the speedo....

[efhughes3]

Nice looking work!

Henry: How did you know these were Alusil cylinders? I thought the 3.2's were Nikasil.

[preston_brown]

I had the same question, I thought they were Nickies too.

No, I didn't do a compression test before teardown. It was running "fine" aside from the mess.

[Henry Schmidt]

Thirty years of looking at Porsche cylinders tells me they are Alusil.
It's just a picture so of course, I could be wrong.
Good luck

[preston_brown]

Originally Posted by Henry Schmidt

Thirty years of looking at Porsche cylinders tells me they are Alusil.
It's just a picture so of course, I could be wrong.
Good luck

Henry,

How can I (or others) discern the difference between Alusil and Nikasil? Is there something I could look at in particular? I know the picture could be misleading because of lighting, flash, etc.

Edit: Upon searching, I found the following:

Nikasil cylinders have a yellowish internal coating, and the oil control ring on the pistons is not plated.

Alusil cylinders have no coating, they are just raw aluminum. The oil control ring on the pistons is chrome plated.

I definitely have coated cylinders and unplated oil control rings, so I think I can safely say I've got a set of Nikasil P&C's.

[john walker's workshop]

the milky white appearance of the bore suggests alusil. what's the brand? mahle or kolbenschmidt (KS)?

[tom1394racing]

I think in all cases for 3.0 and 3.2 cylinders, KS will be Alusil and Mahle will be Nicasil. Nicasil cylinder bores will be magnetic while Alusil will not be.

Your pictures look like Alusil to me.

[preston_brown]

OK well now you guys have me nervous. The pistons have the following stamped at their bases:

13
U5B

If they are indeed Alusil, am I totally gambling to reuse them when they have 148k miles on them? I don't want to have to pull the motor back out in 20k more miles to replace more parts that I should have dealt with today, but I'm not too keen on shelling out $4500 for a new P&C set. I'll do it if required for reasonable longevity though.

[YTNUKLR]

Nikasil will be very slightly magnetic. Alusil will not be magnetic at all. A magnet is the only sure-fire test, because Mahle did make some with Alusil. I recommend a low-mileage used set of 3.2 P/C, of course within specifications, as they are a pretty good value...$5-600 for a good set. I personally would not re-use Alusils at 148k, but I'm not you.

[Henry Schmidt]

Originally Posted by YTNUKLR

Nikasil will be very slightly magnetic. Alusil will not be magnetic at all. A magnet is the only sure-fire test, because Mahle did make some with Alusil. I recommend a low-mileage used set of 3.2 P/C, of course within specifications, as they are a pretty good value...$5-600 for a good set. I personally would not re-use Alusils at 148k, but I'm not you.

Scott speaks the truth, take it to the bank.

[preston_brown]

I tested the cylinders with a magnet this morning -- not magnetic. Crap.

Anyone have a low mileage set of used Nikasil P&Cs available? If not, suggestions on who to call? Seems like a much more economical route than a brand new set. This is my daily driver, not a race car.

Thanks for all the help everyone.

[Porsche_monkey]

Post a 'want-to-buy' in the classified section. Someone will have them.

[tom1394racing]

Preston

I think I have one more set of used 3.2 Nicasil piston and cylinders left.

PM me if you are interested.

[MBEngineering]

HI try hear for some cylinders,

http://stores.ebay.com/QSCUSA

or

http://www.supertecperformance.com/

regards mike

[preston_brown]

I spent about an hour and a half last night pulling off the head assemblies, then the cylinders, and cleaning them up. They look pretty good to me, I could even see the factory crosshatch pattern in all of them until I scrubbed them out lightly with a medium scotchbrite -- that put its own pattern in the bores. Despite reading the whole million-page alusil thread, and believing the cylinders are probably reusable, I've got this nagging fear in my heart that when I check the pistons for tolerances, they might be out or at the limit. My motor does have almost 150k on it. Of course, the controversy isn't settled.

But as I've said, this is my daily driver and peace of mind that I won't have to pull the motor again in six months is pretty important, so I'm going with a set of QSCs and JEs. 3.4, why not?

Do you think I'll have to split the heads/cam housings when I install the new cylinders? I assume so because they might have minute variances in height compared to how the old alusil cylinders sat. Or will the torquing process compensate for any variance?

[YTNUKLR]

They should all be the same height if they are machined and rebuilt, so no need to disassemble the heads/cam housings. The case must also have the cylinder seating surface flat and level, which it probably does, being aluminum.

Make sure to measure the piston/cylinder clearances very carefully.

Not a deal-breaker IMHO but some people feel strongly about chamfering the edge of the head combustion chamber to 98mm when they upgrade the pistons/cylinders.