924Board.org

[ideola]

Raceboy, when I get home from work tonight I'll take a look at the K27 turbine housing to see what numbers are stamped on it.

Gegge: A couple of clarifications: we opted NOT to go with the 3LDZ compressor wheel, as its map was not favorable for the targeted air flow. If you look at the two compressor maps posted above, you will see what I mean: I am anticipating that I will need somewhere between 17-21 psi of boost to achieve my BHP goals. Based on that boost level, I will need somewhere between .22 to .26 m^3/sec of airflow, at a pressure ratio somewhere between 2.1 to 2.5. If you plot those numbers on the compressor map, you will see that the 3LDZ wheel would be highly inefficient in that range, whereas the K27 wheel will be right in its sweet spot, somewhere in the range of 75% efficiency.

John @ Majestic was able to find a relatively inexpensive K27 wheel, which was ~$100 brand new from Borg-Warner, so that is the route I'm going. I'll post the part number and compressor map for it as soon as I get them from John.

As for being nearly bolt-on, you are correct. The ONLY modification required to any of these components is some slight machining on the compressor housing in order to accommodate the above-mentioned compressor wheel. Otherwise, everything else is simply plug and play.

I don't have the part number yet for the K27 backing plate, but I'll post it as soon as I get it from John.

The water-cooled bearing housing is definitely a K26 unit. However, John said he was not able to identify where it came from. It was an old core he had sitting on the shelf. He indicated that it actually may not have come from an automotive turbo, but could have come from a diesel truck unit, or even some other type of machinery. The part number is 5326-151-0089. So far, my initial google searches have not uncovered any clues.

The other interesting thing is that the water-cooled Audi unit I picked up from Vaughan had the identical turbine wheel and shaft as the stock series I 931 unit, so that is worth noting, as those turbos should be plentiful in Europe, and a possible source of parts. Also, given that the bearing housing on those units is a direct fit to the stock 931 turbine and compressor backing plates, they could provide an alternative method of creating an inexpensive water-cooled turbo. However, if you use that bearing housing, you would need the oil line attachments parts, you would have to modify them for use with the stock 931 oil lines, and you would have to fabricate your own turbo-to-block bracket. Someone with reasonable access to fabrication tools and skills could probably pull that off without much difficulty.
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erstwhile owner of just about every 924 variant ever made

[gegge]

[Raceboy]

I need the number inside the turbine inlet, it's stamped in a manner like "6" (on 931 S1, Audi etc).

Can you tell me what number is in 3LDZ housing?
_________________
'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

[ideola]

[gegge]

[Raceboy]

Bingo!

Sorry Gegge, I missed your answer on previous page...

If it's 11 stamped inside the turbine inlet, I'd like to have one of those turbine housings.

Gegge, I presume you have one leftover when you're making hybrid, right?
_________________
'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

[gegge]

I noticed something interesting going throu KKK lists yesterday.

The shaft and turbine wheel assembly for 924 turbo, 924GT, 924GTS AND 944 turbo S got the same number: 5326-120-5002.

The non-water cooled bearing house is the same as for early Audi: 5326-150-0011

The compresor backplate is the same for all 2660, 2664 and 924GTS: 5326-151-5701

By the way, all KKK info you ever need! A super website for look-up and reference:

http://www.turbo3k.com/

I don´t understand the language, but it doesn´t matter.

It is all there, crossreference, pictures and measurements!
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[ideola]

[peterld]

Brilliant Dan! And love the site you found. Cheers PLD

[gegge]

The compressor housing seems small for a K27, and is VERY similar to K26 from a 944? The turbinehousing is also familiar, 944 too?

Referring to www.356-911.com, do you know the details of the hybrid upgrades?

Guessing of:
V1 2664
V2 2667
V3 2670
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[ideola]

Very good Gegge!!! You are close, very close.

So, the part of main interest is the K26 water-cooled bearing housing, pictured above. What threw me off is that the part number stamped on the bearing housing doesn't match ANYTHING in any of the Borg-Warner catalogs, nor on the turbo3k.com website. For reference purposes, the part number on both bearing housings pictured above is 5326-151-0089. I've search high and low, and have found no reference to that part number (although there was a bunch of K26 stuff listed in the 5326-151- family).

HOWEVER, I am pretty firmly convinced that my bearing housing is in fact just a plain-jane stock 951 K26 water-cooled bearing housing, part number 5326-150-0020. On the turbo3k.com website, this is the ONLY water-cooled bearing housing listed for the K26, and it was used on the 951, the 959-Group B (!!!!), the Lancia Delta S4, and of all things, a "gas generator set" manufactured by company called MAN!

I don't understand the significance of the 5326-151-0089 part number, and I've never physically held a stock 951 K26 unit. However, considering the fact that this bearing housing is a DIRECT replacement not only for the turbine housing AND the compressor housing, but more importantly for the oil lines and 931 bracket, that it MUST be a stock 951 water cooled bearing housing...which of course is FANTASTIC great news for anyone interested in developing a direct bolt-in water-cooled K26 for the 931!

As for the turbo pictured on the right above, it is apparently a hybrid turbo that was developed by Majestic (possibly during the tenure of Majestic's previous owners). I found the photo on Greg Hammond's website, where you can find full details on his build.
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erstwhile owner of just about every 924 variant ever made

[gegge]

That´s the information I was looking for! Thank you!!!

[ideola]

[-nick]

Is there a reason to work so hard just to use a water-cooled turbo? I won't deny that it prolongs the life, but a rebuild is usually only $400 compared to the extra cost and complexity of using a water cooled unit. I'm also not sure how much extra life you get when keeping up with good synthetic oil changes.

Plenty of track folk are known to block the water lines and run a water-jacketed turbo with just oil cooling and I haven't heard of any catastrophic results.

It's cool to find a bolt-on swap, but I'm not convinced if it's worth it.
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[ideola]

Well, -nick, it's sort of a long convoluted story. When I first started down this path (in 2005), I had very little idea of what I was trying to do. I merely sent a stock 931 K26 unit out for rebuild, and was planning to drop it into the UWB project. Somewhere along the way, the UWB project became this insane thirst for the ultimate 931 build, or something close to it anyway.

At that point I started really getting my head around the numbers, and went back to the drawing board to try to come up with the best possible configuration. Based on a target of 350 BHP, I determined that the stock K26 unit could not possibly produce the CFM required, nor could it come close with any measure of efficiency. Of course, since inefficiency = heat gain, and heat is the enemy, my freshly rebuild stock unit just wasn't going to cut it. That started me down the hybrid path. My hybrid will be comprised of the stock 931 turbine, the stock 944 bearing housing, and a stock K27 backing plate+compressor wheel+housing. The ONLY modification required to ANY of this was some machining on the compressor housing that I provided. Everything else is totally completely off-the-shelf units.

As for the water-cooled part, I originally had no intent or desire to go that route because I didn't think it could be done without serious fabrication or cost. However, Vaughan gave me a nifty little Audi unit that appeared to be direct bolt-on. I sent it to John to ask his opinion, and he came up with a bearing housing that was direct bolt-on, which I now believe to be the stock 944 bearing housing.

Since it now seems to be a completely viable and cost effective alternative, my thought is water-cooled = better thermal management. Particularly since I'm now planning to go with electric water pump, I don't have nearly the concerns that many of the racers do of adding heat soak from the turbo to the stock cooling circuit.

In any event, the cost of adding this is very very minimal. Once I get the final tally from Majestic, I'll post the numbers, but I think you will ALL be surprised at how affordably this hybrid turbo can be made. Considering that the main failure mode on the 931 unit was bearing failure due to excessive heat, an option to add a water-cooled bearing housing using a direct bolt-on part seems very attractive. In fact, I may go back and redo all of my turbo cores in this manner. 944 bearing housings should be readily available, and based on the price John quoted me, it only adds 15% to the cost of a stock rebuild. Everything else from a stock 931 K26 can be used in a street / moderately boosted application.
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erstwhile owner of just about every 924 variant ever made