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Engine Rebuilds---
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wdb  
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PostPosted: Wed Jul 24, 2002 12:49 pm    Post subject: Reply with quote

I posted a site in the links section home made turbo.com they have mounted various turbos to thier cars, they show adaptor plates to mont turbo to exhaust man. as well as ducting and boost controllers. one even had electronic controls for additional injectors, when to turn on and how much fuel to add.
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Cbass  
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PostPosted: Sat Jul 27, 2002 7:18 am    Post subject: Reply with quote

So is there a rebuilt kit for the 931, or do I have to source all the gaskets and bearings and valves myself? How much am I looking at spending here?

Also, what does a set of ROW 8.5:1 pistons go for?
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Dave951M  
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PostPosted: Sat Jul 27, 2002 7:22 am    Post subject: Reply with quote

There are rebuild kits for the 931, but from my research, you'll come out much better by doing some homework and cross referencing the parts. Some parts will be Porsche only, many others are Audi. That's why I wanted the parts cross reference information. So far, I've had much better luck just kibbitzing with knowledgable parts guys.

[ This Message was edited by: Dave951M on 2002-07-27 07:26 ]
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ignatzjr  
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PostPosted: Sun Aug 04, 2002 12:57 pm    Post subject: Reply with quote

Good tech info! On a stock 924 turbo - is the 150 HP or so stated in the spec sheet a conservative rating? And if so, what HP increase could one expect from merely gutting the cat ? I too am into speed but want to go one step at a time. I have a 924 and 924S right now - both run well with 924S definitely taking over in mid to high speed ranges. Have not driven the 924T yet as I need to do the head gasket thing. All info is appreciated!
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Peter_in_AU  



Joined: 29 Jul 2001
Posts: 2743
Location: Sydney, Australia

PostPosted: Sun Aug 04, 2002 4:18 pm    Post subject: Reply with quote

Porsche are always very conservative when quoting speed and engine output. Probably a good strategy - the guys in the car mags seem to love beating the factory quoted figures.

You'd give your 931 an extra 25hp by just bringing it up to euro spec with no loss of reliability.
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Dave951M  
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PostPosted: Mon Aug 05, 2002 3:53 am    Post subject: Reply with quote

CBass-

EBS has a rebuild kit for the 931, it lists at $445US. I don't know yet what's included, but the ad also listed a top end kit and a master rebuild kit. The ad was in the latest Excellence on pg 125. I'm planning on giving them a call on Monday to figure out just what I need to do.

BTW- in the turbo end, my 82 unit was toasted completely except for the hot side housing. I was told that the turbos from the 80 and 81 models are the same on the compressor side. Since I had an 81 on the floor, a quick check comfirmed it. My 81 unit needs rebuilding, just the shaft, seals, and exhaust impeller were bad, compressor side is just fine. Time to forge ahead.
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Cbass  
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PostPosted: Tue Aug 06, 2002 7:19 pm    Post subject: Reply with quote

For that sort of money I would hope pistons are included! I'm used to V8 rebuilds, and those have twice as many parts, but still manage to be cheaper...

My big question would be how much are a set of Euro pistons worth? Would it be cheaper to get custom pistons?
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Dave951M  
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PostPosted: Wed Aug 07, 2002 8:57 am    Post subject: Reply with quote

For my car, I'm inclined reuse the pistons if no boring is required and if they're still within tolerance limits. I'm sure that I could cut the reciprocating mass a bit with new forged ones, but there are much more cost effective ways to get hp. The short block on my garage floor will probably suffer much more radical surgery. One of the guys at the plant was telling me about a shop that custom makes pistons, I wonder what the cost would be there v buying the "official" ones.

Dave
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Rick MacLaren  
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PostPosted: Wed Aug 07, 2002 10:26 am    Post subject: Reply with quote

I paid around $750 USD for 8.1:1 compression pistons (reportedly) (0.20 over) complete with rings. The problem I found is that when you reference the Mahle parts catalog that contains the specs for each piston for every Porsche made, the differences between the Euro and US spec cars wasn't apparent, at least by number. The only solution was to get out and measure using a pipette the actual displacement of the dished centre. I'll check when I get home, but from memory, the parts numbers were problemmatic - 931 103 054 01 was I think the US number. And the number does not appear on the piston itself, rather, it's on the packaging. You've gotta squint to find any discernible numbers on the pistons.

If you can get an 8.5:1 compression pistons, I think you might have some trouble running pump gas if you don't have an intercooler. I noticed with mine, post rebuild, I really had to have the intercooler and run 94 octane to ensure no detonation. Could just be my imagination, but if you're going to the trouble of rebuilding your motor, and you're upping the compression, you're probably in the best position you'll ever be in to install a cooler.

I dunno, I opted to get rid of my 7.5:1 compression pistons for just one simple reason: When you've got about $2000 in parts, without even considering the 25 hours of labour, the cost of pistons with rings seems pretty miniscule by comparison. A good boring then makes the whole thing pretty much like a new motor.

I checked out other piston makes and Mahle just seemed to be pretty much the best pistons around. The only complaint I have is their weight, which seem heavier than the Kolbenschmidt.


[ This Message was edited by: Rick MacLaren on 2002-08-07 10:33 ]
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Dave951M  
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PostPosted: Wed Aug 07, 2002 10:22 pm    Post subject: Reply with quote

The reason I'm considering reusing the stock pistons in the first engine is one mainly of economy. The performance rebuild will be the other block sitting on my garage floor. I can take my time and really do it up right. If I get the head the way I want it, an intercooler set up, cooling system sorted, then a straight swap to the performance engine is in order. Since this isn't my daily driver, there are a bunch of options.
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Rick MacLaren  
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PostPosted: Fri Aug 09, 2002 5:11 am    Post subject: Reply with quote

Yes there's no 'need' to have new pistons, especially if you've the luxury of multiple engines hanging around. A friend of mine just did a basic rebuild to his 944 engine for about $2.5K to 3K CDN. So rebuilding ours should be cheap, just the usual stuff like rings, bearings, seals. I think the kit for mine, including rings (which we didn't purchase) was around $400 CDN before rings were subtracted out.
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Cbass  
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PostPosted: Fri Aug 09, 2002 12:16 pm    Post subject: Reply with quote

Now that's more like it! Where did you get the kit Rick?
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Rick MacLaren  
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PostPosted: Thu Aug 15, 2002 2:49 am    Post subject: Reply with quote

Direct from Porsche. When you order over $800 in parts through Porsche you can get up to 20% in discounts, over and above what any garage can get for the same parts.
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Joes924  
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PostPosted: Wed Aug 28, 2002 3:38 pm    Post subject: Reply with quote

Thanks to all who posted good information
Im attempting a rebuild because of a #1 cyl. rod bearing failure destroyed bearing is more like it.I have another motor I thought was rebuildable it turned out to have a bad #4 piston.So far I Have new rings.clutch ,throw out bearing,and am investigating bearing costs
the block just gonna be cleaned and honed
and the reciprocating parts balenced. No knife edging of crank, although I would like to get the flywheel lightend.

Thanks again

[ This Message was edited by: Joes924 on 2002-08-28 15:41 ]
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