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931 stock boost levels /safe boost levels on stock internals
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2287
Location: Somerset, UK

PostPosted: Wed Dec 28, 2022 6:22 am    Post subject: Reply with quote

Mike9311 wrote:
Carrera, there is always something extra you did with your build you don't see the first 8 times looking at it with that subtle alternator tweak. This also means you did it with class


The devil is in the detail, lots of head scratching, and heaps of help from good people to arrive at the solutions that most folks miss.
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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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kondzi  



Joined: 02 Jul 2018
Posts: 375
Location: Poland/EU

PostPosted: Wed Dec 28, 2022 7:02 am    Post subject: Reply with quote

Well it seems moving the alternator away brings a lot of valuable space back

Port spacing is not that bad in this situation. I need though to make an angled adaptors to bring the plenum up, closer to the bonnet.



It seems I should be able to relocate the alternator under the expansion tank - using the AC mount as a support with some adaptor.

I will use the 944 expansion tank anyway, the one mounted on the inner wing, so this seems to be a best new location for the alternator.



Still waiting for the throttle body to do some serious measurements / fitment tests.

As of the intake runners, these are as follows:




Ports in the head:



And the runners in stock intake manifold:



I will calculate briefly the area, just posting photos quickly.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)
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kondzi  



Joined: 02 Jul 2018
Posts: 375
Location: Poland/EU

PostPosted: Wed Dec 28, 2022 7:19 am    Post subject: Reply with quote

I know it's not meaning anything, as this is not at 90 deg cross section, but...

Stock intake area is ~1072 sq-mm and the other one with more flat ports is ~977 sq-mm, so about 10% less...
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)
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Mike9311  



Joined: 14 Dec 2004
Posts: 1487
Location: Chicago-ish

PostPosted: Thu Dec 29, 2022 3:47 am    Post subject: Reply with quote

How are you thinking of adapting the new intake? It seems like you have two issues if not three. Port shape and the transition from one shape to the other. That you might be adding an additional turn for the airflow as it enters the head port since the new intake hooks up into the head port so that the injector faces straight in. Finally the alternator issue you are working on already
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
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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kondzi  



Joined: 02 Jul 2018
Posts: 375
Location: Poland/EU

PostPosted: Thu Dec 29, 2022 6:29 am    Post subject: Reply with quote

Nah, that’s easy
It’s a low cost try to test fit.
I was trying to find something that could be used as bolt on (with adapter), facing forward, easily available, cheap and looking oldschool.
That’s Audi A3 1.8T intake.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)
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BauerR  



Joined: 13 Apr 2022
Posts: 3
Location: Baltimore, MD

PostPosted: Thu Dec 29, 2022 9:11 am    Post subject: Reply with quote

MikeDanger wrote:
you really need to add an IC. honestly can't believe it didnt come with one.
and Front mount, not the idiotic top mount.

Im running 13psi. so far so good (with US 8.0:1) pulls quite good, except it goes way to rich at full boost, I can't even get any where near redline because it's too rich and starts to bog. Would be nice to see what happens if i could wind it out, but i'd already been in Jail speed at that point.


You could, in theory, allow unmetered air into the system to help with this problem. Between the AFM and turbo is where you want to intoroduce the air. Obviously you would need to sneak up on it by installing some type of adjustable flow valve but it should work.
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kondzi  



Joined: 02 Jul 2018
Posts: 375
Location: Poland/EU

PostPosted: Mon Jan 16, 2023 10:12 am    Post subject: Reply with quote

So I finally removed the turbo today.
Well it was tricky. The old rule that you either see or can touch the bolt, but not both at the same time is certainly true.

I packed everything and will ship to a turbo rebuilder this week to see what he can do with it.

The hot side seems to have only a minor crack.
Before sending I did place both compressor wheels side by side...



Wow that's huge difference when looking at them.
On the caliber is the diameter of the billet wheel in the widest part.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)
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Mike9311  



Joined: 14 Dec 2004
Posts: 1487
Location: Chicago-ish

PostPosted: Mon Jan 16, 2023 11:19 am    Post subject: Reply with quote

Yes, that is because the extended tips angle out into the open air in the housing. That area isn't operating close to anything so they can angle the tips out into that space
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
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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Mike9311  



Joined: 14 Dec 2004
Posts: 1487
Location: Chicago-ish

PostPosted: Mon Jan 16, 2023 12:28 pm    Post subject: Reply with quote

Konrad, I want you to be the first. Either with your intake or the original, angle it like this

With the stock intake, you need to cut the flange off and change angle. Then also do what CarreraRSR did with his but you will have to lower the throttle body compared to his, or you will hit the hood, and relocate a bunch of stuff . Only front mount IC guys can be this radical

From this



to this


_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
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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Cedric  



Joined: 27 Aug 2004
Posts: 2455
Location: Sweden

PostPosted: Mon Jan 16, 2023 7:53 pm    Post subject: Reply with quote

kondzi wrote:
So I finally removed the turbo today.
Well it was tricky. The old rule that you either see or can touch the bolt, but not both at the same time is certainly true.

I packed everything and will ship to a turbo rebuilder this week to see what he can do with it.

The hot side seems to have only a minor crack.
Before sending I did place both compressor wheels side by side...



Wow that's huge difference when looking at them.
On the caliber is the diameter of the billet wheel in the widest part.


Wait a minute, the one to the left is the 2470, the euro s1 compressor. Its an ancient 70s design, it also has a smaller diameter than all he other K26 wheels (61 instead of 66mm). It shouldnt be on your s2, and you can feel extra good about putting in the effort
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kondzi  



Joined: 02 Jul 2018
Posts: 375
Location: Poland/EU

PostPosted: Tue Jan 17, 2023 9:30 am    Post subject: Reply with quote

@Mike I'll check what fits under the bonnet. It will take some time anyway, but why not. I was thinking (after my porting exercise) about welding the injector ports in the 1.8T intake and porting them. Why not change the angle as well... Need to check what fits and how.

First thing is to relocate the alternator though, then I have enough room to play with the intake.

BTW shorter runners in intake = more HP but less torque at lower RPM, right?

@Cedricit's fantasy of the PO. I have also the early pistons with bigger dishes. I checked the engine No and it's S2. Also I had DITC (again S2). Anyway it's a car to check my ideas how they work (and your's as well it seems )
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2287
Location: Somerset, UK

PostPosted: Wed Jan 18, 2023 7:37 am    Post subject: Reply with quote

Regardless of S1 or S2.... I always say never assume your car has the correct engine, pistons, turbo, clutch fitted. Any previous owner or garage could have changed, swapped, bodged other non age related parts. This isn't a problem. Once you know what you have, you can adapt your spec for the future
_________________
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
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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kondzi  



Joined: 02 Jul 2018
Posts: 375
Location: Poland/EU

PostPosted: Fri Jan 20, 2023 9:06 pm    Post subject: Reply with quote

Turbo rebuilt properly with K2660 housing and billet compressor.
Also the compressor housing plate was replaced with a new one.






It's so much easier and faster when someone else does things for you
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)
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Mike9311  



Joined: 14 Dec 2004
Posts: 1487
Location: Chicago-ish

PostPosted: Sun Jan 22, 2023 11:46 pm    Post subject: Reply with quote

2664 you mean

Indeed, it is nice when something just gets done and handed back to you
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
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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