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K26 Billet Compressor Wheel
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Moparboy72  



Joined: 29 Jul 2014
Posts: 36
Location: Naperville, IL

PostPosted: Wed Aug 29, 2018 2:02 am    Post subject: Reply with quote

Fasteddie313 wrote:
http://www.924board.org/viewtopic.php?t=40119
What are the tag numbers on the turbo you pulled off your car?
2664 or 2660?

Unfortunately, there is no tag on this turbo; I did find a portion of what may be a rebuilders/reman tag on one of the compressor housing bolts but there is not enough of the tag to make anything out of it.

Fasteddie313 wrote:
What do you think is wrong with your turbine wheel? Is their a crack in the blade or just the carbon on it or what?
There is a crank in the blade in the photo, A number of the blades on wheel look worn, a bit deformed.

Fasteddie313 wrote:
I'm not 100% sure about your compressor wheel by the photo.. Does it have damage on the inducer like it ate something? Was it scuffing the housing on the blade edges? Look shiny..
Comp wheel has passed some debris, no scuffing on the housing but it looks to have been sand blasted as some point and there is a fine grit on most surfaces. The bypass valve was seized in its housing due to this grit/sand.

Fasteddie313 wrote:
I think your housing crack is a bit on the larger side but if it isn't touching the wheel, or threatening to, then it's probably fine..
I have a spare but it has a crack, just like the one I'm running has a crack..
Understood; that seems to be the consensus around here. I'll move forward with this housing as is for now.

Fasteddie313 wrote:
If you have a 2660 turbo I don't think I saw comp wheels for it, but I have seen billet comp wheels on ebay for the 2664..

I ordered up the one from ebay which per the measurements would be near correct. I plan to follow up once it is received.

Fasteddie313 wrote:
How is the turbine piston, comp piston, ring grooves, cylinders on both sides? Are you buying a rebuild kit?
How is the turbine shaft where the bearings ride? No groove? Bearing housing fine where the bearings go?

The rings in the turbine piston look a bit worse for wear (loose); alot of coked oil deposits on the turbine heat shield (may be normal for age). I am planning on buying a rebuild kit, thought the bearing housing and bearings I have seem fine, I am in need of the o-rings for the comp cover and base plate.

Where do you source genuine Borg/kkk parts from? I was thinking of also replacing the compressor wheel nut.

Thanks again,

Andrew
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Mike9311  



Joined: 14 Dec 2004
Posts: 873
Location: Chicago-ish

PostPosted: Wed Aug 29, 2018 9:39 pm    Post subject: Reply with quote

My turbine housing in the S2 is also cracked but working fine
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA M650 Herausnehmbares Dach
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2038
Location: MI

PostPosted: Thu Aug 30, 2018 9:09 am    Post subject: Reply with quote

the large cast part number on your compressor housing can identify the turbo, their should also be a part number on the back of the compressor wheel..
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2006
Location: Somerset, UK

PostPosted: Thu Aug 30, 2018 10:37 pm    Post subject: Reply with quote

Fasteddie313 wrote:
the large cast part number on your compressor housing can identify the turbo,


Turbine housing size, not turbo pe se

Fasteddie313 wrote:
their should also be a part number on the back of the compressor wheel..


Not always. But the casting number on the compressor housing will lead you to which wheel in inside, unless the housing has been machined for an alternative wheel.

I supplied what I believed to be a S1 K26 2470 6.10 and a S2 K26 2664 4.10, both RoW to a turbo rebuilder. Both turned out to be K26 2660 6.10. Both did not have compressor wheel part numbers. I have educated myself a little more since then.

The other issue is RoW and US specs of S1 and S2 turbos have changed and posts on here can be a little confusing for the less knowledgable.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Moparboy72  



Joined: 29 Jul 2014
Posts: 36
Location: Naperville, IL

PostPosted: Fri Aug 31, 2018 11:39 pm    Post subject: Reply with quote

The compressor wheel has the following number hand written in marker on the back face, K26.123.2017D .

The part number cast into the compressor housing are 5326 101 5190F

The number cast into the inside of the turbine housing inlet is "4".

I have received the replacement turbine and compressor wheels. The only other point to make in addition to Ciprian/morghen's note of needing more turbine shaft length due to turbine wheel height increase. The replacement turbine wheel I sourced (eBay/Taiwan) is now M7x1.00 RH thread instead of M6 as the original shaft.

I will be sending out the rotating parts for balancing once I source a M7 CCW nut.
Thanks again for all the input!

-Andrew
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2006
Location: Somerset, UK

PostPosted: Sat Sep 01, 2018 9:59 am    Post subject: Reply with quote

With those part numbers you have a 2660 compressor wheel and housing. You have a #4 turbine housing.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Moparboy72  



Joined: 29 Jul 2014
Posts: 36
Location: Naperville, IL

PostPosted: Thu Sep 06, 2018 3:59 am    Post subject: Reply with quote

I spend some time further cleaning up the turbine housing and found that it had previously been repaired where the largest crack is. Further research also pointed me to the technical bulletin 81-04 which shows the three types of turbine housings which gaskets are used and part numbers.

According the bulletin, the turbine housing I have is a type II, which uses a sealing ring for the turbine inlet and a flat metal gasket for the outlet. This tells me the turbo was a reman/exchange unit at some point as this type of housing was only factory fitted to 1980 MY 931s. 1981MY+ would have a type III with a sealing ring for the turbine inlet and outlet.

Lastly I did some weighing of the old/new turbines and the old/new compressor wheels. The caveat here is the kitchen scale is not the most accurate but I was just curious to gauge any differences.

Compressor (old/new) 60g/50g
Turbine (old/new) 280g/305g

I will try to post some photos later to show the differences.

Thanks all,

Andrew
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Moparboy72  



Joined: 29 Jul 2014
Posts: 36
Location: Naperville, IL

PostPosted: Fri Sep 07, 2018 12:51 am    Post subject: Reply with quote

Turbine compare, new turbine is longer (not trimmed):



Turbine compare, new wheel is thicker in the fins/blades especially at the base:


New wheel with old turbine, showing a bit short on threads:



New wheel with new turbine, showing a bit long but may be short on threads, I will have to see how the M7 nut measures up:



Turbine housing with previous weld/repair:



A pin hole through one of the down pipe stud holes below:

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Flow  



Joined: 02 Nov 2019
Posts: 9
Location: NZ

PostPosted: Sat Nov 02, 2019 4:14 pm    Post subject: 2664 vs 2658 Reply with quote

Cédric wrote:
If I remember correctly there ia a 2664 wheel in the KTS catalogue, hence should be possible to order. Im not sure about the minimum order quantity though.


Hey folks, it is so great to find spot in the where folks really know their K26s.

Has anyone compared the KTS 2664 vs 2658 wheels? See the spread sheet for my short list.

I have one of these on a 1.6L in a Lotus 7 replica.
It is currently running 225whp at 14 psi I am aiming for 250whp mostly through efficiency gains.

On the turbo side I have a S2 951 5326 970 7041:
5326 151 5710 Compressor Backplate - exducer recess 67.26 mm

5326 123 2201 Compressor Wheel
Blades: 6/6  
Nose Diameter: 13.52 mm
Inducer Diameter: 46.18 mm
Exducer Diameter: 65.98 mm
Tip Height: 6 mm
Total Height: 30.94 mm
Blade Height: 22.6 mm
Nose Length: 8.34 mm 
Super Back: 0.0 mm

5326 101 5213 Compressor Housing

The two in red look best to me when looking for a bit more efficiency and flow without compressor housing mods. They are the 2664 and the 2658. The orange ones will need compressor housing work but have nice small posts that would need to be reamed to fit the shaft. They should work with a turned down 12 point flange nut. Green is the factory replacement 2663 by the looks.

Which do we like the look of most? Any others in the list with potential after compressor work?

The KTS 2658 with the 46.56 mm inducer would bring the compressor housing clearance down from 0.7 mm to 0.34 mm 

Also are we worried about the 2.7mm Superback on the 2663/64 setting the base proud of the 2.1 mm exducer recess?

Cheers!
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2006
Location: Somerset, UK

PostPosted: Sun Nov 03, 2019 1:03 am    Post subject: Reply with quote

Had I not bought Morghen’s K27/26 hybrid, I’d probably have rebuilt a turbo with 2670 billet wheel I have. Used in the Carrera GTS and 250bhp 944 turbo. Using and machining a 924 compressor housing would mean its bolt on. Or you could use a 944 turbo compressor. But would mean fabricating new pipe work and needing a remote blow off valve. But then I was going for more boost and bhp. For a stock motor and boost I’d go with a 2664 and #6 turbine housing.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Cédric  



Joined: 27 Aug 2004
Posts: 1994
Location: Sweden

PostPosted: Sun Nov 03, 2019 2:20 am    Post subject: Reply with quote

The post is a bit confusing. But If you already have the 951 2670 turbo there is no need to look at those smaller trims. You will need the bigger one for 250whp. There is billet wheels available for the 2670 wheels as mr RSR points out above.

I have it in combination with a #6 turbine housing (smaller than the #8 you probably have). Im super happy with the performance so far, i have only tried up to 1bar, but it could give much more if you want to.. I bought my wheel from slturbo.com while he did some balancing work etc at the same time. But you can by it at other places aswell.
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Flow  



Joined: 02 Nov 2019
Posts: 9
Location: NZ

PostPosted: Sun Nov 03, 2019 3:23 am    Post subject: Reply with quote

Thanks for chiming in guys.

I guess I should paraphrase by saying starting with the standard Compressor Wheel 5326 123 2201 and running the Compressor Backplate 5326 151 5710 - exducer recess 67.26 mm and the 5326 101 5213 Compressor Housing. Would the best upgrade for my goals be the KTS part# 2664 or KTS part# 2658?

See the spread sheet for my short list of KTS billet wheels that might fit.

Does that clear things up a bit?
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Cédric  



Joined: 27 Aug 2004
Posts: 1994
Location: Sweden

PostPosted: Sun Nov 03, 2019 4:28 am    Post subject: Reply with quote

Haha, sorry, got confused with the 2664 nr, which is a different kkk wheel. I would probably go with the std tip height, and not bother with remachining the profile of the housing, only risk of stuff going wrong. The regular wheel will reach your targets, but probably will not 25whp only from the wheel.
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Flow  



Joined: 02 Nov 2019
Posts: 9
Location: NZ

PostPosted: Sun Nov 03, 2019 5:19 am    Post subject: Reply with quote

Thanks Cédric

If that link to the Google Docs spread sheet is a bit hard to read here are the three contenders. Two need no compressor housing mods and one that does.
Check out the blade heights superback and tip heights / tappers.


5326 123 2201 Compressor Wheel Standard
Blades: 6/6
Nose Diameter: 13.52 mm
Inducer Diameter: 46.18 mm
Exducer Diameter: 65.98 mm
Tip Height: 6 mm
Total Height: 30.94 mm
Blade Height: 22.6 mm
Nose Length: 8.34 mm
Super Back: 0.0 mm
Compressor Housing: OE



KTS 2664
Blades: 6/6
Nose Diameter: 13.50 mm
Inducer Diameter: 46.20 mm
Exducer Diameter: 65.94 mm Tapered Tip 70.64 mm
Tip Height: 4.91 mm
Total Height: 33.64 mm
Blade Height: 29.50 mm
Nose Length: 1.44 mm
Super Back: 2.70 mm
Compressor Housing: OE


KTS 2658
Blades: 6/6
Nose Diameter: 13.58 mm
Inducer Diameter: 46.56 mm
Exducer Diameter: 65.94 mm Tapered Tip 70.64 mm
Tip Height: 5.08 mm
Total Height: 30.95 mm
Blade Height: 28.08 mm
Nose Length: 2.87 mm
Super Back: 0.0 mm
Compressor Housing: OE


Here is one that would need compressor housing mods with a nice small post slightly bigger inducer and a bit lighter than the rest.
KTS 1623
Blades: 6/6
Nose Diameter: 11.84 mm
Inducer Diameter: 47.50 mm
Exducer Diameter: 65.94 mm Tapered Tip 70.70 mm
Tip Height: 5.12 mm
Total Height: 27.90 mm
Blade Height: 23.84 mm
Nose Length: 4.06 mm
Super Back: 0.0 mm
Compressor Housing: Custom - bored inlet and plugged. I would also need the wheel bore reamed out from 5.41 to 6.80 mm

PS. I am porting polishing and thermal barrier coating the turbine housing interior and exterior, the turbine wheel and the hot side of the central housing and heat plate. The exhaust manifolds, intake manifolds and head are also being tidied up.


Last edited by Flow on Sun Nov 03, 2019 5:38 am; edited 1 time in total
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Cédric  



Joined: 27 Aug 2004
Posts: 1994
Location: Sweden

PostPosted: Sun Nov 03, 2019 5:32 am    Post subject: Reply with quote

I wouldn't dare to go tighter on the compressor play, the std 0.7 is set with a good reason, the shaft moves around quit a bit on boost, though tightening it upp will get you some better efficency for sure, but very very high risk.

I worked with turbo system development at an OEM, I've seen alot during the years
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