Turbo Clocks in an S2?

[tref]

Ok... I can spend hours pouring over wiring diagrams and Porsche PET, or I can ask the question on the off-chance someone knows the simple answer!
After 430k miles my instrument panel appears to have a lot of intermittent faults and guessing the connector pads have fretted away... I have cleaned up all the connections, replaced bulb holders etc, but the problems persist. I have a set of turbo clocks, that I would like to swap my odometer into, and otherwise drop in a complete "new" set of gauges. The two issues I can think of are: I think there are two Speedo ranges on the turbo - not sure which I have or what the S2 one is, but do they work off the same sensor and recalibrated at the speedo (as would seem logical)? The second is the boost gauge - where does it pick up its signal? The car is running a 968 engine at the moment anyway, just to confuse the issue, but nevertheless, if it is a simple sensor fit (I don't recall a vacuum hose to the dash on the turbo?), I would be inclined to have it working for the first half of its range!

Cheers,

Tref.

 

[robwright]

Boost gauge comes from the KLR, which is unique to the Turbo. I think the final drive ratios on the S2 are different so potential speedo issues also.

 

[chrisg]

Boost gauge comes from the KLR, which is unique to the Turbo. I think the final drive ratios on the S2 are different so potential speedo issues also.

Rob is spot on - the boost gauge is an electronic feed from the KLR, this in turn has a pressure feed off a small 11mm banjo bolt that taps into the inlet manifold - 1 feed to KLR, 1 to Cycling valve 1 to the dump valve

C

 

[tref]

Ah yes, forgot the final drive ratio and KLR... Guess I'll just be looking very carefully at swapping the flexi PCB then!

Thanks guys, much appreciated.

Tref.

 

[Eldavo]

Early turbo clocks are 160mph later are 180mph. Don’t forget that early clocks won’t have the oil level sensor warning light either.

 

[tref]

Another good point! Thank you!

 

[James0]

Not sure if it helps or not but I've swapped between the individual gauges in my 86 turbo. It still has the original rev counter and Speedo but the two outer gauges are from a 2.7.
I did use the Speedo too at one point, when tracing a fault.

My turbo has an S2 gearbox and the indicated speed is slightly lower than GPS but still more accurate than some more modern cars I've driven.
Just have to remember if it shows 30, you're doing 31 rather than 27.

 

[tref]

Cheers James,

Yes I have replaced part of the odometer mech, and of course the infamous odometer gear in the past... I think I swapped out the Tacho previously on one of the others. My speedo reads low at lower speeds, and high at higher speeds as I recall - about 31-32 actual road speed at 30, at 60mph it is bang on, and then starts over-reading above 60, according to GPS, and those handy speed-check things they put at the side of the road now!

 

[924Srr27l]

Cheers James,
Yes I have replaced part of the odometer mech, and of course the infamous odometer gear in the past... I think I swapped out the Tacho previously on one of the others. My speedo reads low at lower speeds, and high at higher speeds as I recall - about 31-32 actual road speed at 30, at 60mph it is bang on, and then starts over-reading above 60, according to GPS, and those handy speed-check things they put at the side of the road now!

Final Drive Ratio for S2 gearbox is shorter @ 3.875 than the turbo's 3.375, this is why the S2 feels quicker than a Turbo for road driving![8D]

R

 

[James0]

True but I've just looked and the Speedo pick up is driven by a nylon? Gear on one of the output shafts so final drive ratio actually makes no difference.
I'd forgotten that.
Referring to the other thread. When my speedo was broken I once had the car bouncing if the limiter in 5th with the S2 transmission. Thought I was in third.... Honest.