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morghen
Joined: 21 Jan 2005
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Location: Romania
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 Posted: Wed Dec 08, 2010 1:47 am Post subject: |
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How about a K26-K27 hybrid?
K26 hot side and K27 compressor and wheel.
i have two complete K26 units and a K27 unit with an unusably big hot side.
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gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
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| Posted: Wed Dec 08, 2010 6:12 am Post subject: |
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Well, I have found a lot of errors in the literature I am afraid but in this particular case they state that the CGT is bigger than the S2 which is partly right. A #6 turbinehousing will gain some hpīs but loose rpms.
What I do know is that the ROW K26-2470 is crap and the K26-2660 is on the limt for 200hp. I havnīt tested the K26-2664 back to back but Cédric has and he is pleased  . It should be capable of 220-230hp with an intercooler. Beyond 250hp go for the 951 K26-2670 and K27 over 300hp but that is not a bolt-on and requires some skill to get it right.
The compressor inducer set the hp and flow limit, see the enterance as a choke and that will strangle the engine if it is too small. The compressor exducer set the pressure or boost and the level of effectiveness - larger is better but slower due to the extra weight. The part of the turbinehousing that is important is the size of the nozzle, larger means later response but better hp capabilities and smaller results in increased backpressure and heat. The size of the turbinewheel determines hp level.
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Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
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Cedric
Joined: 27 Aug 2004
Posts: 2809
Location: Sweden
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| Posted: Wed Dec 08, 2010 6:16 am Post subject: |
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In your post gegge you say that 2664 is on s2 and us s2, is that really correct? I dont remember what i had on my s2 turbo could it be 2660, it was at least smaller than my s1 2664. The best thing is just to get the part numbers before you buy anything. Turbos could also been swapped during the life time of the car..
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gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
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| Posted: Wed Dec 08, 2010 6:34 am Post subject: |
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| Cédric wrote: | | In your post gegge you say that 2664 is on s2 and us s2, is that really correct? I dont remember what i had on my s2 turbo could it be 2660, it was at least smaller than my s1 2664. The best thing is just to get the part numbers before you buy anything. Turbos could also been swapped during the life time of the car.. |
No that is not correct  , the 2660 is a S2 as far as I know. I belive the 2664 is a US S1, but I am not sure. Agree, partnumber tells you more than model, year or region.
Where did I wrote that 2664 is a S2? Canīt find it..  tired or getting blind.
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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 |
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Cedric
Joined: 27 Aug 2004
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Wed Dec 08, 2010 8:23 am Post subject: |
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[quote="morghen"]How about a K26-K27 hybrid?
K26 hot side and K27 compressor and wheel.
quote]
this is what I have now, mates right up...
Stu
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Nein37
Joined: 29 Dec 2009
Posts: 513
Location: New London, CT
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| Posted: Wed Dec 08, 2010 9:57 am Post subject: |
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So the 2664 is the US Spec S1 turbo. Same turbine and housing but with a larger compressor. The larger compressor will move the spin-up by around 800rpm but the larger wheel will also reduce the amount of heat the turbo transfers into the charge by increased effciency?
If you also add the larger turbine housing from the 4.10 to the 6.10 this will also reduce the amount of heat present in the charge?
Is this about the crux of it?
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gegge
Joined: 27 Jul 2007
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Location: Sweden
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| Posted: Wed Dec 08, 2010 8:02 pm Post subject: |
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| Nein37 wrote: | So the 2664 is the US Spec S1 turbo. Same turbine and housing but with a larger compressor. The larger compressor will move the spin-up by around 800rpm but the larger wheel will also reduce the amount of heat the turbo transfers into the charge by increased effciency?
If you also add the larger turbine housing from the 4.10 to the 6.10 this will also reduce the amount of heat present in the charge?
Is this about the crux of it? |
The 2664 has got a larger inducer that doesnīt choke the flow, the compressor doesnīt have to work as hard as the 2660 at 200hp. IF there is an 800rpm delay with the 2664, I asume that is because of the compressor wheel is of an older design compared to the 2660. The exducers are about of the same or similar size(and therefore weight); 2.6".
The #6 turbinehousing does reduce the amount of heat in the exhaust manifold and head (but not in the charge), backpressure and risk of detonation BUT will move the rpm range up compared to the #4. If you compare a #4 with a modern hotside it is still HUGE. (The Mitsu TD04 in my +200hp Subaru has got a tiny 40mm turbinewheel and a cute snail as turbinehousing wrapped around it  .)
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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 |
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Wed Dec 08, 2010 9:13 pm Post subject: |
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| leadfoot wrote: | | morghen wrote: | How about a K26-K27 hybrid?
K26 hot side and K27 compressor and wheel.
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this is what I have now, mates right up...
Stu |
did you have the chance to test this setup?
did you do any calculations on what HP can this setup deliver?
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9xx
Joined: 18 Jun 2006
Posts: 627
Location: Jarvenpaa, Finland
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| Posted: Wed Dec 08, 2010 10:58 pm Post subject: |
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| gegge wrote: | | Well, I have found a lot of errors in the literature I am afraid but in this particular case they state that the CGT is bigger than the S2 which is partly right. A #6 turbinehousing will gain some hpīs but loose rpms. |
So changing a recently rebuilt S2 turbo into original CGT turbo is not perhaps worth it? I'm not looking for huge power.
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All gone: 931 '82 Alpine White, original option "220" G31 with LSD + 3 x 944 |
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Dutch924-racer
Joined: 23 Jul 2007
Posts: 1081
Location: The Netherlands
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| Posted: Thu Dec 09, 2010 5:39 am Post subject: |
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http://www.924board.org/viewtopic.php?t=15595&highlight=kkk
931 Turbos:
79 M31.01 RoW
K26-2470 R 6.10
KKK p/n 5326 970 7007
compressor exducer= 61mm
compressor inducer= 42.7mm
trim= 49
compressor map: http://not2fast.wryday.com/turbo/maps/k26_map2.jpg
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80 M31.02 US
K26-2664 G 4.10
KKK p/n 5326 970 6401 series I
6403 - Audi 200T '79 2.1L
6404 series II
6406 series III
6407 "
watercooled: 6411 - Audi 200T-III '84 2.22L
6413 - Audi 200T '81 2.1L
6415 - Audi 200T-II '82 2.22L
6416 - Audi 200,Ur-q 1/'83 2.1L
compressor exducer= 66mm
compressor inducer= 42.24mm
trim= 41
More info on the 6407:
Turbine housing p/n: 5326 101 6365
housing-exhaust diameters (reasonably accurate):
outermost 2 7/8"
inner 2 3/8"
innermost 2 7/32"
man-housing diameters:
outermost 2 1/16"
inner 1 21/32"
innermost 1 17/32"
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81- M31.03 RoW
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81-82 M31.04 US
K26-2660 GA 4.10
KKK p/n 5326 970 6020
6022
compressor exducer= 66mm
compressor inducer= 39.6mm
trim= 36
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Carrera GT (M31.50)
K26-2660 GA 6.10
KKK p/n
Compressor cover part number 5326-100-5104
Compressor wheel 5326-123-2017
Turbine housing 5326-100-6328
compressor exducer= 66mm
compressor inducer= 39.6mm
trim= 36
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Thu Dec 09, 2010 6:14 am Post subject: |
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Lets start with the turbine...the hot side....so the shaft and turbine wheel are all the same...the only difference is the A/R of the housing.
Which one is the best for what?
After we've set the two best turbine housings we can move to the compressor side.
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gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
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| Posted: Thu Dec 09, 2010 9:53 am Post subject: |
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Best for what? Depends what yourīre looking for and hp target.
As I stated before #6 is relative large and can handle 350hp, if you donīt belive me check out the 951 guys with K27/6 turbos with even more hp. http://www.tonygarcia.org/dyno.htm
Iīd say stick to the #4 on a mildy tuned streetdriven 931.
Regarding the compressor, again, the 2470 is awful, 2664 quite good and a 2670 the real deal. Note that the 2470 has itīs sweetspot at 3000-4000rpm and get very ineffevtive at 6000rpm. Compare that to the Audi 100 turbo with the same amount of hp - a perfect match for a 200hp car. The Porsche 944 turbo is at itīs peak at 250hp and can handle approximate 50 hp more. The K27 from a Porsche 911 turbo starts at 300hp. NB, the increase efficency of the larger exducer!
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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 |
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morghen
Joined: 21 Jan 2005
Posts: 9095
Location: Romania
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| Posted: Thu Dec 09, 2010 5:29 pm Post subject: |
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Gege, dont get me wrong, its not about believing 
I guess we are all after the most HP you can get and good response.
so i'm trying to take it systematically starting with the hot side.
Which one allows more HP and which one delivers the faster responce.
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gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
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| Posted: Thu Dec 09, 2010 7:50 pm Post subject: |
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OK sorry for that  .
Let us agree that the #6 can handle 300hp wihout too much backpressure. If the numbers corresponds to an area at the nozzle for example - I would like to belive that the #4 can handle 66% of that, 200hp and the large #8 400hp. As an approximate...
What you want is the smallest nozzle possible to speed up the exhaust gases feed to the turbinewheel without too much backpressure. If the area gets too large you need more flow (boost and rpms) to get it started.
But for a racecar it is a simple equation to live with poor response or lag for a small gain in peakpower and less heat because itīs range of power is above the critical boost treshhold all the time. Remember the pressure ratio between intake and exhaust; over 2 is just bad, 1,5 is ok in a streetdriven performancecar and max 1 in a racecar.
3K numbers equals an area somewhere in the turbinehousing regardless of the diameter of the turbine. That is why it is difficult to translate a #6 into A/R. A/R is actually a stupid measurement if you want to know hp capabilities since it is a ratio, a small area divided by a small diameter turbine got the same A/R as a huge area and humungus turbine .
The GT3271R has got a turbinewheel with 64mm inducer and 55mm exducer exactly like K26. I did measure the two extremes of the K26 turbinehousing: a #4 and a #10. The radius of the channel after the opening of the nozzle of the #4 was ca 5cm and the #10 was 5,5cm. Difficult to measure but the area was close. That equals to A/Rīs of 0,8 and 1,8
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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 |
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