Turbo tach

[kmartind]

I recently noticed that it looks like FP has started carrying an optical tachometer for measuring turbo RPM. It has an AC adapter so I assume it's intended for shop use, not for an in-car gauge or a logger data source, but that got me to thinking it might be possible to tap a similar sensor right into the compressor housing and get a real-time turbo RPM reading. Why? Mostly because it would be really cool, but not in a rice kind of way, it would provide real information about the function of one of the critical components of the vehicle. Seeing the wheel spin unexpectly fast for a particular boost level? Start looking for boost leaks. Seeing it spin slower than expected? Check for exhaust leaks, shaft play, intake restrictions, etc. Sure there are other warning signs for such things, but I'd be interested to know how far out of spec some of the various hybrid turbos may be running on our cars at times. Being able to log turbo RPM might be an interesting tuning tool, but I've never heard of anyone actually doing it. I assume if FP sells a turbo tach, someone must be buying it though (at least for shop use).

 

[Defiant]

I'd seen these on the web someplace, but expensive as heck.

I think it'd be fascinating. What's a turbo doing at idle? It has to be moving a few hundred (if not thousand) RPM. Seems like an IR eye mounted on housing shouldn't be that complicated.

 

[MNGSX]

Being able to log turbo RPM might be an interesting tuning tool, but I've never heard of anyone actually doing it. I assume if FP sells a turbo tach, someone must be buying it though (at least for shop use).

That is the whole point... Compressor RPM will let you know where you are in the efficiency range.

got me to thinking it might be possible to tap a similar sensor right into the compressor housing and get a real-time turbo RPM reading.

Dont do it there... Do it in the center section. Holset does this on their VGT's A section of the shaft has a small flat ground off of it. A magnetic sensor senses this flat once per rev.