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-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

Hey Folks,
I just got my new/rebuilt turbo from Zuffen (thanks Bob!). I was planning on using the compressor housing from the Audi K26 I picked up. According to the numbers, both turbos had the same inducer/exducer sizes on the compressor wheel- which was true. However... they are slightly differently designed, enough so that the Audi housing hits the top of the exducer blades before it's able to sit all the way down. Of course, grr...

The 931 exducer blades are actually taller than the Audi blades. Everything else is the same. I imagine the 931 wheel can scoop up a little more air. How much more is anyone's guess. I've heard these Audi K26's just blow hot air after about 14psi, so our's are likely good for a bit more. Unfortunately it looks like I'm going to have to swap out compressor wheels in order to use the Audi housing (which simplifies plumbing immensely).

Or- has anyone ever heard of or tried machining a compressor housing to fit a different compressor wheel? I'm curious how nasty of a job it would be and if it would be worth checking out at all.

Thanks!
nick

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Changing compressor wheels and modding the housings is done all the time. But the whole unit has to be rebalanced after that.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

Have any idea how involved of a process machining the compressor housing to match the compressor wheel is? I know my turbo guy can swap wheels easily enough. I would prefer to keep the wheel that will push more air.

Thanks,
nick

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Nothing impossible, just really accurate measuring is needed when machining.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Zuffen · Posted: Sat Aug 13, 2005 6:43 am Post subject:

try the 944T cold housing before you pull the compressor, I had one ( I think it was a 951 unit) laying there and I should have seen if it would fit.

If you can find a local shop that you can borrow one from that would be ideal.

The bell in the housing can be machined and is actually press fit in there.

My 81 race motor has a machined 931 housing with a 951 compressor wheel. But there may be too much clearance using the 951 housing, but that KKK open snout cold housing is a common housing style.
_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Bob,

Did you ever figure out what was used to rebuild my 81? BTW the lag is about the same as the original but my seat of the pants dyno indicates it gets to max boost a little faster than stock.

Dennis
_________________
81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

hey dpw-
If you send the K26 numbers on the numer plate to me, I can decipher them and tell you what you have.

nick

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

Nick,

Thanks for the offer. The numbers are from the original 81 but the hot side was changed as my old one was cracked. Bob (Zuffen) wasn't sure which hot side he provided to the rebuilder. Thought he may have figured it out by now.

BTW I want to publicly thank Bob for ALL of the assistance he has provided to me and many other listers in their rebuild efforts.

Dennis
_________________
81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black