turbotach

[turbobug73]

No interior topic, so here it goes:
I was wondering if porsche ever made a turbo model with a mechanical boost gauge integrated into the tach. The mid-eighties 944T had one, but it gets its signal from the computer, not just a direct vacuum/pressure line. It seems a bit expensive to me to have a 944 computer just to use that gauge. Also, if and early 911T did come so-equipt would the tach work with a 4 cylinder engine?
thanks

[yetibone]

a 911 tach would work, but it would register a slower engine speed than your engine's actual revolutions. A 911 tach needs to see six breaks in the primary circuit for every 720 degrees of crankshaft rotation, where a 944's sees four breaks in 720 degrees. It would probably show 66% of your engine speed.

That's in theory, I've never actually tried.


Yetibone

[Wally]

Yetibone,
Your theory is correct also in practice: Therefore I had my 911 tach reworked by a specialist to work for 4-cyl.
I believe the 80's model 911 turbo's have the tach you want with the pressure gauge build-in.
Walter

[turbobug73]

but no mechanical boost gauge!?

[turbobug73]

whoops, thx wally

[yetibone]

Wally,
Did you have your tachometer re-worked by a local shop in your area, or did you send it away somewhere for the modification?
When I build my next GL, it will have a 911 style dash, and likely 911 guages. I'd thought of substituting a 911 tach for one out of a 914, but I think the guage bezels are different, and it wouldn't look right with the rest of the 911 guages.


Yetibone

[Wally]

Yetibone,
The tach was reworked by a 'local' bug-only shop here, who in his turn let it do by a specialist close to him. Its not really cheap to my knowledge, but the display is exactly the same as a 914 tach, but for the red-line which is near 6300 rpm. Mine goes to 7000, but some others go to 8000 rpm. At the time, t was the only porsche tach around (already have it for 15 years...).
Walter

[yetibone]

Thanks for the info Walter. With that in mind I think I'll use a 914 tach. We just got one on Ebay with the speedometer, the dummy guage on the left, and a pannel already made to fit a 1200/1300/1302.


Yetibone