Turbo tachometer

[Wankel7]

Does anybody know of a turbo tachometer? I would guess it would be an optical based sensor.

Thanks

 

[Berkut]

If you're handy enough you can build one. I've seen some guys with turbocharger-based jet engines make them.

You need an optical pickup to read the RPM and generate one pulse per RPM. Then you can convert that signal to voltage using something like an LM331 IC. You can read that on a voltmeter calibrated in RPM.

Make sure you put your optical pickup on the cold side of the turbo.

As far as buying one, I dunno.

 

[avbug]

If you're talking about a piston turbocharger tach, why would you want one?

Generally tachs for turbine equipment use tach generators which are magnetic, and generate an electrical signal. The gauges are self-powered using this signal. The tach generator is a small generator, or in some cases only a signal generator, producing a value that is displayed at the instrument as an RPM, or more typically, percent of RPM.

With respect to a piston engine using a turbocharging unit, manifold pressure provides most of the information you need. The speed of the turbo unit isn't particularly important, or relevant to your actions from the cockpit.

Besides, that little hummer is turning faster than you really want to know, as a pilot. It would probably just keep you worrying. Ensure that your fuel flows are proper for your power settings, that your manifold pressures are where they should be relative to a particular throttle setting and expected fuel flow, and that your lower end manifold pressure is where it should be at idle (throttle plate closed)...higher indicates induction leaks.

Where turbine units have a dedicated RPM observation function, an accessory pad is provided somewhere on the unit to drive the tach generator. This signal may be used only for cockpit instrumentation, or may also provide input for other functions, such as overspeed and fuel governing functions. Often this drive is coupled with another engine function, such as another accessory like the oil pump. In other words, whatever's turning the tach generator is also often turning something else. Knowing what is coupled to what may be an important clue in the event that you have a malfunction indication in the cockpit. For example, a tach loss may be associated with shaft failure when coupled to an oil pump; lose the shaft and you lose the oil and the tach signal. Understanding your systems may give you important knowledge and insight into not only what you have, but the appropriate course of action under any given set of circumstances (and even the appropriate checklist to use...).

Magnetic pickups are also used for RPM functions, but not generally for heated and stressed components such as a turbocharger.

 

[Wankel7]

Actually, I wanted it for my cars turbo. I know it would not be something that is needed. However, if I could get it done for under $300 I would like to have it.

It would be very interesting to datalog it and see where you are on your compressors map. If your past the surge limits or just have the wrong compressor or AR size for your car or driving habits.

I have found a few optical based ones but that look lab grade and $$$.

Nice write up .... good read.

Wankel

 

[RafaelThielmann]

Aircraft components are $$$ and usually not for car use. If you want to improve your turbo readings, you could install a Pyrometer after the hot section (about 2-3" from the gas exhaust) and control the exhaust temperature for too poor or too rich fuel mixtures, and to control the turbo Rpm's you could compare inlet-outlet pressures..... Just an idea.

aircraft equipment are for aircraft applications.... don't get mixed up.

 

[Wankel7]

Aircraft components are $$$ and usually not for car use. If you want to improve your turbo readings, you could install a Pyrometer after the hot section (about 2-3" from the gas exhaust) and control the exhaust temperature for too poor or too rich fuel mixtures, and to control the turbo Rpm's you could compare inlet-outlet pressures..... Just an idea.

aircraft equipment are for aircraft applications.... don't get mixed up.

Yeah, I have an egt gauge in her now. It gets warm at full power 900C +. But it is hard to use since there is lag time with it. I have had good luck tuning with holding the car at a certain rpm / load. I also have a wideband oxygen sensor that makes things a little easier.

Wankel

 

[DeltaAir423]

EGT and PSI gauges are all you should really need. The big thing to realize is your boost limits, before you start to either blow a seal or melt a piston. If your car is OBD II, you can purchase a really good scanner for around 1k and it will give you a true to life sensor readout so you can adjust things like fuel/air ratio mapping.

 

[Wankel7]

EGT and PSI gauges are all you should really need. The big thing to realize is your boost limits, before you start to either blow a seal or melt a piston. If your car is OBD II, you can purchase a really good scanner for around 1k and it will give you a true to life sensor readout so you can adjust things like fuel/air ratio mapping.

Ah, I just wanted the gauge because I am an info freak. Gotta love data

I am running a standalone engine managment system on the car. So, basicly I can control everything to do with the engine with my laptop. I have maps for everything. Fuel and timing. All load based maps. So the left scale is either injector open time or advance. And the bottom bar is vacuum/boost.

I was having low horsepower problems and the EGT was sky high 900C + with the sensor right behind the turbo. And it was rich (I have a wideband oxygen sensor ) like 11:0:1 AFR.

Then we started advancing the ignition almost 4* in every range. Power went way up and the EGTs at full power are now sitting 800-820C. Starting to make progress!

So , the high EGTs were fuel burning off in the turbo and didn't have enough time to burn in the rotor housing since the timing was to retarded.

Wankel