924Board.org

[Carrera]

I managed to acquire an original 937 IC and a larger original 937 turbo as well.
I had the turbo rebuilt and the IC cleaned and tested.
The IC came with all necessary original bits and pieces for a bolt-on installation. As my 931 is a 1981 RoW car the installation should be rather simple.

In order to increase the boost pressure I have a ball&spring type manual boost controller. I also have a VDO boost pressure gauge which I plan to install in place of the clock.

Also I have an extra hood from a normally aspirated 924 and a scoop to be installed on the extra hood. At first I thought about building the car to a CGT-look, but I wasn't quite convinced with the aftermarket CGT-kits. An original kit would cost a small fortune, if one would be available... So, at least for the time being, I will have a rather silly looking car with a narrow body matched with a scoop

Now to the real questions:
- What do you experts suggest as safe boost pressure in bar-scale? (I believe the original CGT has a boost of 0,75bar)
- How reliable is the old K-jet to hold its settings? I am questioning whether to instal an air/fuel meter. The sad fact is that the air/fuel meters look like Christmas tree decorations and they would completely spoil the original look of the interior

Any pointers on what else I would still need to consider for this mod would be highly appreciated
I will add some pictures and a note after the installation has been completed in early April.

... if anyone knows of an original CGT kit on sale on this side of the pond drop me a note
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931 S2, 1981

[ideola]

You could consider one of the units from PLX Devices, which don't have to be installed permanently in the car. The nice thing about them is that you can also purchase a USB connector and download their free software to do data logging, which should be very useful for rolling road tuning. Take a look:
http://www.plxdevices.com/wideband.html

Technically, you wouldn't even need a gauge, you could just get the sensor & module kit, and do everything by logging to a laptop. I have their AFR & Boost gauge in my car, with the modules neatly tucked away behind the kick panel. I even put a hinge on the kick panel for easy access to the modules.
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erstwhile owner of just about every 924 variant ever made

[Carrera]

[flosho]

Narrow band is essentially useless for "tuning". If you want to know just before your motor is going to melt down, get a narrow band. They shouldn't even make a narrow band a/f meter these days.


Wideband is much more accurate, and is a much better investment. Even if you think of a narrow band a/f as a 'stop gap' it will just be a waste of $50-75 and two hours worth of putting it in.

Do it once, do it right.


FYI, narrow band measures air/fuel from 1 volt to 0 volts and basically .5v is 'stoich' and on either side of that is 'rich' or 'lean', while the wide band measures 5 volts to 0 and produces much more accurate measurements.

Also, I have the AEM UEGO, its all in one gauge and system, won't let you datalog without software that accepts 0-5v signal (megasquirt, or AEM standalone), but it is only $240ish shipped.
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[This Space For Rent]

[morghen]

you paid for the very rare 937 IC and turbo...you want to upp the boost and you think a wideband setup worth 200 dollars is expensive?!
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Supercharger and EFI kits
https://www.the924.com

[Rich H]

I had an innovate LS1 that was good but no gauge as standard but gauges are easy enough to build DIY

As above narrow band will tell you when you cross 14.7 AFR it eaither says Rich (over 14.7) or Lean (Under 14.7) it is not proportional in any way. Essentially it step changeds it's state at 14.7 AFR from Low to High.

Worse than useless!
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

[Carrera]

Thanks guys for educating me on the subject of narrow vs. wide band AFMs

[alexvex]

You can buy an AEM EUGO wideband for $180 (I've used them on several cars).

Spending $200 on a wideband is much better than several hundred or thousand after grenade your motor due to bad tuning.

Do it right and do it once.
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--Alex--
1992 Porsche 968 (VW 2.5L I5 Turbo swap in the works)
1995 Audi 90 Quattro Sport (4.2L V8 Swap)
2010 Touareg TDI
Past Pcars: 80 931, 87 924S, 87 951

[Shurick]

[ideola]

[flosho]

[Carrera]

[Rich H]

That is what I had.
Ensure it's a new module as there are 2 versions a 6 wire and a 7 wire, the 6 witres used to die unexpectedly....

I was on the look out for an analogue gauge to fit in with the dash better but never did find one.
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

[Cedric]

The wide band lambda is the most important tool when you want to get your car running. But you dont need it in the car all the time after your tuning is done.

I used a Innovate lm-1 with a friend of mine in the passenger seat. He then read the results under acceleration at 4th/5th gear. Easy and enough for tuning at this level. The sensor was in the tailpipe in a home built adapter. No modding was needed on the original system. The wire was pulled throug the back window. An easy setup like this will cost less and need no modding of the car. you have an absolutely superb 931, i´m glad to hear that you want to keep it that way
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1980 924 Turbo
www.instagram.com/garagecedric/

[Carrera]