Just had an idea for making a tach for my turbo. these thing spin like what? 200,000; 300,000 rpm? the reason for this is to know if the turbo is properly spun down before turning it off. do some turbo timer already have this feature? is this even possible? TIA.

 

i have no idea how u could put a sensor on there, maybe put 2 magnets on the shaft and tell that way, but i doubt thats possible, so ya, not gunna happen

 

about 120,000 max

 

no, i've read a couple places before that said they reach up to about 220k rpms

 

I have also heard anything more than about 120-130k RPM's will blow **** up.

 

Depends on the turbo. I don't think anything used on a car will spin past 150k.

When you're idling, the turbo is barely spinning. It stops spinning almost immediately after engine shutdown due to seal drag.

The reason idling the car before sutdown is a good idea is not so the turbo spins down, it's so the turbo cools down. Residual heat in the turbine and the turbine housing is the real enemy, and idling allows oil flow, coolant flow, and exhaust flow (YES the exhaust can be cooler than the turbo under the right circumstances) to take heat away.

Easiest way to measure turbo speed is optically. A little line painted on the compressor wheel nut and a sensor to read it. You can also infer turbo speed by how much boost the turbo is generating - boost is pretty much a function of turbo speed. No boost? Turbo's barely idling.

 

good **** peejay