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tuurbo · Posted: Wed Mar 11, 2009 1:28 am Post subject: Sometimes surprises are good!

Hey I just bought an engine short block, head and turbocharger from a guy.

Here's the story. He rebuilt the engine for like a package price of $12K along with a new turbocharger through Porsche. He took it out for a few spins and the car made a bad noise and then was running on three cylinders. So he removed the engine and took the car to a scrap yard. He's had quite a saga with this car and he just got pissed off and scrapped it. I kind of understand where he was coming from...

as we all do.

I bought the engine for $125 as a rebuild 'project' but here's the skinny:

1. A mechanic I do trust says the short block is perfect. All four cylinders are in good shape - no honing necessary - leave the pistons and replace the #2 piston with rings. Sound ok? He's suggesting I use the same rod.

2. Head has some damage and a bit of a warp but a shave should do the trick. No evidence of bent valves yet. I'll take them out and inspect later on. Question: There's some pock marks from whatever was banging around in Cylinder 2 - what to do with those? There aren't many (a dozen) and they're small - maybe 1-2 mm. Even the head gasket was perfect.

3. The turbo is absolutely freaking perfect. There is zero axial or radial play and it spins beautifully - I've handled a few of these over the years and it's better than any of the rebuilds I've seen. I literally reefed on the the axle and couldn't detect ANY play whatsoever. So I'll rebuild this turbo instead and replace the seals - it's been out of commission since 2004 so the seals might be a bit dry.

Anyway, it's the best $125 I've ever spent. Very happy today! I've written a bit with Ideola and there were some excellent suggestions on the table I'm going to use. Any suggestions appreciated. I'm trying to do this for under $1000.

I'll keep this thread to post results as they happen.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

Smoothie · Posted: Wed Mar 11, 2009 2:09 am Post subject:

I wouldn't rebuild the turbo. Turbo seals are all metal, and don't dry out.
There is a high-temp rubbery (viton?) o-ring at the oil inlet, but that's at the outside and not part of a "turbo rebuild".
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

924RACR · Posted: Wed Mar 11, 2009 2:11 am Post subject: Re: Sometimes surprises are good!

ic932 · Joined: 11 Feb 2005 Posts: 1104 Location: UK

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Fifty50Plus · Posted: Thu Mar 12, 2009 3:23 am Post subject:

Tuurbo,
I have a set of 931 pistons that you can have for your rebuild. I only need NA stuff. Challenge others to pony up parts and keep your costs way down.
Regards,
Chuck

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Gah! Have? Dibs if tuurbo declines.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

tuurbo · Posted: Thu Mar 12, 2009 6:32 am Post subject:

Thanks very much for the offer Chuck - I've got what I think are the offset 7.5:1 compression pistons here so I think I'm ok! Cylinder and piston are measuring out at 8.65 mm using a tape measure (can't find my calipers yet - maybe a touch of measurement error there on my part). But thanks that's a very generous offer. I've got these two spares and I cleaned one of them up and it should be good to go because when I put it into the cylinder, crown first, it fits with about 1.0 mm of play from side to side - should be ok.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

Smoothie · Posted: Thu Mar 12, 2009 10:39 am Post subject:

tuurbo · Posted: Thu Mar 12, 2009 1:32 pm Post subject:

I'm confused. Probably need to clean these up.

Ok cylinder 86.98

Measured 14 mm from piston bottom edge perpendicular to the hinge as per Manual
1. Spare piston #1 86.44
2. Spare piston #2 86.95
3. Spare piston #3 86.42

The removed destroyed piston says ++++++ 86V53 A R011 inside it but it seems to measure out at 86.36 at the crown, 86.94 at the bottom.

Lots of dirt though - gonna clean it up and measure again.

Man they're hard to measure up consistently! Do you take an average of all your measures or what? lol

I might have a 2nd oversize cylinder there - I didn't think there were many of those out there.

Note:
Measured at crown
1. Spare piston #1 diameter 86.09; ++++ 86V53 offset dish
2. Spare piston #2 diameter 86.42; ++++++ 86V53 non-offset dish (3rd oversize I believe)
3. Spare piston #3 diameter 85.8; ++++ 86V53 offset dish
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

Smoothie · Posted: Thu Mar 12, 2009 1:56 pm Post subject:

The Haynes manual gives standard and oversize piston and cylinder sizes on pg. 49.
(Correct the misprints near the bottom of that - where it says "86.45" and "86.46" for 3rd oversize piston diameter, obviously change them to "87.45" and "87.46".)
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

tuurbo · Posted: Thu Mar 12, 2009 2:06 pm Post subject:

Thanks Smoothie - I think I've got 2nd oversize. But I need to clean more and take my time. Hmm. 2nd or 3rd oversize changes things a bit.

Chuck do you, by some small chance, have a 2nd oversize with the dish offset so it's a 7.5:1 compression (old style)? If not that's ok I can probably use the higher compression piston in that #2 spot if you don't.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

Lizard · Posted: Thu Mar 12, 2009 5:03 pm Post subject:

it doesnt matter if the seals at dry.

They are assembled that way.

Install the turbo without messing with it.
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3 928s,

Fifty50Plus · Posted: Fri Mar 13, 2009 1:30 am Post subject:

Tuurbo,
I won't be able to check sizes until weekend. I sent you a PM.
Chuck

emoore924 · Joined: 13 Apr 2004 Posts: 2822