924Board.org

[TurboJak]

My 924 smoked a lot of oil so pulled the engine and discovered 4 dead pistons a cracked ex-manifold plus a dead turbo
Ordered some VW flattop pistons and the manifold is weldable but the turbo needs replacing.
The hot-side housing is cracked and the wheels are dead.



Any suggesting on what to do?
Is it possible to replace with a newer turbocharger without to much work (think not)?
Or is it possible to rescue the old KKK??
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'76 924 + '82 924T engine + GT look

[tuurbo]

Things look pretty grim. Four blown pistons - I've never even heard of that - usually we complain about just one of them. Did someone throw some nuts and bolts in the short block before reassembly? Wow.

Bytched housing - coked shaft. I dunno how much coking is acceptable but that impeller looks way beyond challenging - I think you're right - it's toasted beyond repair. You'd have to buy so many components I doubt it is worth repairing.

Someone please chime in if I'm off base. I will be cracking open my turbo for the first time in a week or so so I'm really a noob.

If it were me, I'd look into a good solid used turbocharger and see if it needs a rebuild (probably) or see if it's been recently professionally rebuilt. I'd get another one and fix it up, but I'm cheap. eBay probably has some cheaper than this one (drool).

http://cgi.ebay.com/ebaymotors/KKK-Turbo-Complete-5326-970-6406-for-Porsche-924-1980_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247QQcategoryZ33742QQihZ007QQitemZ170227538643QQrdZ1QQsspagenameZWD1V

If you're feeling courageous, you 'could' get another turbocharger, toasted but with a good hot side housing, and impeller, and put the two together. Maybe $100 for a 'surprise box' turbo? I paid $250 for mine and it's still ok but it's a gamble. You can get a guaranteed one for maybe $500? That's the range as I see it.

Dan is creating a hybrid and my memory is poor but I think he put two together. Smart too because you can, within limits, tailor it to your needs.

Rebuild kits are $110. I'm going to try rebuilding mine in a few weeks once my wife goes back to NJ and I have a table I can use in the office.

Maybe I don't understand - are flat top pistons the right thing for a turbo? Have you got some special setup like a BAE system or some inside knowledge? If so, please spill!

Why do you think all four pistons blew?
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

[skytrooper]

I just completed a turbo rebuild. I had some usable parts and bought another turbo from a fellow on these boards. You really have to take a close look to see if anything from your old turbo is salvagable, I am guessing by the heat discoloration on the shaft that the answer might be no. On mine the compressor wheel had no fins but the hot side was in good condition along with the shaft. Most of the turbo fellows here will say to send it to "Majestic Turbo" and let them professionally rebuild it. In your case it makes a lot of sense. They would probably just use it as a core and send you a rebuilt unit...most likely cheaper and faster, than you can do it yourself (consider the 100,000 RPM balancing). I had a lot of equipment available to me that most folks do not plus over 30 years of maintenance experience (granted it is mostly on aircraft), that I decided that it was something I could tackle. Getting parts for these can take a long time. If I had to do it again...I would get a rebuilt unit

Good luck to you...you have your work cut out for you.
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Matt

1987 - 924S "Black Pearl"
1982 - BMW 633CSi
1984 - BMW 528e
1983 - 944 N/A "Blue Max" (Gone)
1981 - 931 "Scarlet Harlot" (Gone)
1976 911S Targa (Gone)

[TurboJak]

Well I had the turbo at a prof. rebuilder. But he could not get the parts needed for the rebuild (new core plus hot-side house). So he suggested adapting a new turbo to the 924... But thats alot of work..
I am searching for a rebuild turbo or a turbo in good shape but have not found any yet (any suggestions or good links?)

The engine must have been running hot at some point, all the pistons were burned on the exhaust side, so the top-ring land was destroyed and the second-ring was broken... (look at my www-link for pictures)
Got the flattops because new 924turbo pistons are pretty expensive and scarce. U get 4 flattops (plus 4 unusable vw bubble cylinders) for the cost of half a 924turbo piston
The flattops raise the CR a bit to around 8.7:1, and the standard (euro) run 8.5:1... So should be ok... might add intercooler to cool it down.
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'76 924 + '82 924T engine + GT look

[ideola]

As for the turbo, I highly recommend Majestic Turbo. Their standard rate for a rebuild is $335. You will need to add into that cost the charge for some new components. Your cracked turbine housing is a common issue. The turbo can be rebuilt using the housing provided that the cracks don't impede the impeller on the turbine wheel.

You might want to consider going with a 944 bearing housing (since yours is probably toast anyway) which is a direct replacement for the 931 bearing housing, and gives you the advantage of a water jacket. You can reuse your stock hot and cold side components, but it appears from your pix that you will need both the turbine shaft and the compressor wheel. Compressor wheels can be had for ~$100-$150. Turbine shaft will be more expensive, so best to try to source a good unit from another core. I have had success sourcing used 931 K26 complete cores for $50 on multiple occasions, so if you're patient, this might be the best route to go.

See my water-cooled turbo thread for more details on part numbers and related discussion. Nick's all-you-want-to-know thread is also an invaluable reference.
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erstwhile owner of just about every 924 variant ever made

[924turbo_sout_africa]

Yours looks a bit bad ,i rebuild mine last year and well i had a bolt fall into the turbo and ya it was not nice

but i sent mine to a KKK agent and they got the whole thing rebuild in about 3 weeks so see if you cant get an agent that side and my total rebuilt cost me R5000 which is about 625 dollars and its brand new
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Porsche ...where dreams are a reality
'79 924 turbo canada spec
'98 Formula Vee (M3 eater)

Time in the 931 is a dream come true !!