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K27/26 hybrid
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1983
Location: Somerset, UK

PostPosted: Mon Nov 04, 2019 3:27 am    Post subject: Reply with quote

CÚdric wrote:
Tidy! So much space in the area compared to my IC install Do you drive in salt, looks pretty aggressive corrosion going on?


Driven all year round, why wouldn't I?? More dense air in the Winter.....less traction under tyres though! Corrosion is very limited on most areas, just that pulley face looks bad. Time for some rust arrester on it. Will be swapped out next year when installing another new belt.
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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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Mike9311  



Joined: 14 Dec 2004
Posts: 846
Location: Chicago-ish

PostPosted: Sat Jul 25, 2020 6:23 am    Post subject: Reply with quote

I just noticed something important with this hybrid...

Its a 7-7

Could explain some of the midrange enjoyment

Stock wheels are 6-6. 6 Blades and 6 Splitters

I have a 7-7 billet wheel I am contemplating for the CS which has me counting blades every time I see a pic. Didn't notice this before

Edit: Also cool that you comment how good it sounds since I read somewhere 7-7's are supposed to be quieter
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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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CÚdric  



Joined: 27 Aug 2004
Posts: 1985
Location: Sweden

PostPosted: Sat Jul 25, 2020 7:40 am    Post subject: Reply with quote

Number of blades is not that significant as a desiign paramter, theres several others that control the performance charachteristics. Similar performance can be achieved with different amount of blades.

If you want a rough estimate of the maxflow you could measure the smallest area in the in the blade passage.
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Mike9311  



Joined: 14 Dec 2004
Posts: 846
Location: Chicago-ish

PostPosted: Sat Jul 25, 2020 8:02 am    Post subject: Reply with quote

At the top its 13.3mm in diameter and looks to be basically vertical down to the splitter height before radius starts. Splitter is 14.3mm down from tip. Main blade starts 1.8mm down from inducer tip. Its a S1 wheel except larger inducer at 44.5 / 65.94 Exducer. Extended tips at S1 exducer height and taller in general at inducer.

Still smaller than this K27 hybrid badboy it seems
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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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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1983
Location: Somerset, UK

PostPosted: Sat Jul 25, 2020 7:15 pm    Post subject: Reply with quote

Still pulling strong
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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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Mike9311  



Joined: 14 Dec 2004
Posts: 846
Location: Chicago-ish

PostPosted: Mon Jul 27, 2020 11:14 pm    Post subject: Reply with quote

Carrera RSR wrote:
Still pulling strong


That is also good to hear between you and fasteddie. High power reliability can be had
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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: 1994
Location: MI

PostPosted: Tue Jul 28, 2020 6:29 am    Post subject: Reply with quote

Mike9311 wrote:
Carrera RSR wrote:
Still pulling strong


That is also good to hear between you and fasteddie. High power reliability can be had


Uh.. Well it hasn't exploded yet...

Thinking about rebuilding my V8 FD though because the fuel spray isn't very even at very light load.. Does not follow the injectors in an injector flow test..

They don't come on to a trickle very evenly but once they are spraying pretty good they get pretty even.. The harder they spray the more even they get, so boost is fine..
Would love to have a fresh FD and 4 fresh injectors..

Makes idle pretty crappy unless it's at like 12.5-13.0 AFR for all cyls to start hitting all the time..

I tightened up my plug gaps pretty tight, and now I am getting some misfires at very light load cruise too (like 25mph), so think I'll open the gaps back up a bit and hope it goes away again..


Still need a 6.10 and another bigger compressor..
Think I need a compressor that'll make like 25-30 psi so I can finally blow this thing up...

I really should just stop screwing with my engine though and tidy up the rest of the car.. I'm just kindof addicted to playing with the engine and neglecting other areas that could use some attention..
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1983
Location: Somerset, UK

PostPosted: Tue Jul 28, 2020 6:04 pm    Post subject: Reply with quote

Mike9311 wrote:
Carrera RSR wrote:
Still pulling strong


That is also good to hear between you and fasteddie. High power reliability can be had


Last dyno was 240rwhp @ 1.05bar but was leaning out at the top end so we stopped pushing. The fuel metering head was rebuilt 10 or so yrs ago and was modified lightly I found out. Now its running 15% more than it was on the last dyno and 30% more than stock. So I had to lean out the WUR a touch as it was over fuelling..... Will get another dyno soon. Hoping to get over 250rwhp next time. This turbo keeps on pushing hard at the mid to top end!! 100mph++ is real easy. Would easily cruise at 90mph all day long with circa 0.3-0.4bar no stress.
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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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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1060
Location: The Netherlands

PostPosted: Tue Jul 28, 2020 6:12 pm    Post subject: Reply with quote

What can be modified on the fuel metering head ?

I thougt the fuel meterig head has adjustable fule delivery (behind the heaxgon nuts) or is this just to set al 4 equally ?
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morghen  



Joined: 21 Jan 2005
Posts: 8178
Location: Romania

PostPosted: Tue Jul 28, 2020 6:43 pm    Post subject: Reply with quote

Carrera RSR wrote:
Would easily cruise at 90mph all day long with circa 0.3-0.4bar no stress.


hmm, i remember 100mph was 0bar or 0.1bar at most for the GTS wannabe.
Maybe the lower gearing of the S2 gearbox and the 951 front end made this difference.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1983
Location: Somerset, UK

PostPosted: Tue Jul 28, 2020 8:56 pm    Post subject: Reply with quote

morghen wrote:
Carrera RSR wrote:
Would easily cruise at 90mph all day long with circa 0.3-0.4bar no stress.


hmm, i remember 100mph was 0bar or 0.1bar at most for the GTS wannabe.
Maybe the lower gearing of the S2 gearbox and the 951 front end made this difference.


Definitely on some boost over 70mph on previous and current turbo, more on 2660, less on hybrid ......I'll check exactly what next time out
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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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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1994
Location: MI

PostPosted: Wed Jul 29, 2020 1:04 am    Post subject: Reply with quote

Me too..

What kind of AFR do we need/want for that slight boost cruise?
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Mike9311  



Joined: 14 Dec 2004
Posts: 846
Location: Chicago-ish

PostPosted: Sun Aug 02, 2020 6:01 am    Post subject: Reply with quote

answer lies here...also very interesting thread

http://www.924board.org/viewtopic.php?t=42373&postdays=0&postorder=asc&start=60


Per CarreraRSR from that thread....

Quote:
For the turbo owners with thermal management be it intercooled or chargecooled and retaining the CiS fuel control, I cannot recommend any more highly the need to use a boost enrichment switch to help lean off the mid range fuel delivery. It gives far crisper throttle response, lower initial EGT's which is kinder to the manifold, the turbo and the engine bay temps and will return far better mpg which is a nice by product from better performance.

There are several ways to control this whether an S1 or S2. Brian Leask's kit is an easy buy but can be bought separately as I did as I did not need the MSD rev controller. I used my Zeitronix to control my solenoid switch but there may be other options out there which I dont know about.

The only time I now see a super rich 10 AFR's is on full boost above 4800rpm. All other times I see 14.7AFR on cruise, 13AFR when initially accelerating and high 11's before the solenoid switch kicks in. Spark plugs look great, I did go colder than stock.

So there you have it. Add this to your modification plan if not going down the EFi and/or standalone ecu route.
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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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