I remember seeing a guage in a magazine or something that would display your turbo RPM. I think it might have used a hall-effect sensor that you would drill and tap into the compressor housing. I've tried searching for it, but I can't seem to find it anywhere.

Anyone know where I can get it?

 

yea man ill ask my buddy and get back to you asap. his company named smith systems inc just sold that design idea to a few big turbo companys.

ill let him talk about details and all that.

more info asap.

 

We use speed sensors in many turbos. They are magnetic sensors, so to use them on the compressor end, you need to install a small magnet in the compressor wheel, and to use it in the center housing, you need to notch the turbine wheel in the design.

 

Is all that worth knowing how fast your turbo is spinning for the everyday driver?? I think not

 

couldn't imagine how fast a turbo could spin....i guess we could all find out now

 

The medium sized turbos spin to around 150,000 RPM, while the smaller sized turbos spin over 200,000 RPM.

It is important to know your turbo speed, because in matching a turbo to an engine you don't want to overspeed your turbo, and if you're dealing with any kind of dual turbo setup with transitions, it is critical to know turbo speed.

Kevin

 

I need to know the operating speed range of the turbo for a design project, but I'd rather use a different method than installing a magnet if at all possible.

 

I don't know how good of an idea it is trimming your compressor blades or placing anything foreign inside your turbo inlet period. I'm sure something can be used to pick up the pulses outside the housing.

 

You don't install it in your compressor blades, you install it near the nut on the top of the compressor wheel. Do you know much about sensors, and how difficult it would be to pick up a wheel speed of over 100,000 RPM without physically seeing the wheel without any modifications? ie outside the housing. The best way it to take the speed off of the turbine shaft in the center housing.

 

still man, modifying a part that spins at that speed isnt something I want to do. The weight would have to be perfect as to not cause an inbalance

 

I've been told by a guy who used to work for a factory-backed CAT truck racing team that they use an optical sensor that can picks up a mark painted on the compressor wheel nut. Apparently they aren't interested in boost pressure. Turbo speed is more critical in their game.

I've also seen a custom nut with two magnets opposite each other. Don't know if the guy ever got it working though.

 

We use the same type of optical tachometer on some of the equipment we work with. It's just crazy that it can be calibrated to measure the amount of rpm's that we're talking about here

 

I do know plenty about sensors, and turbo's for that matter. Plain and simple it's not smart to install something in that area period. You may be able to install some sort of magnetic pick up on the outside of the housing and adjust the sensativity to get a ball park. I'm not sure what manufacturers use to get an actual number when they measure the turbo's they built, but that aren't installed on a vehicle that is driven on the street. They are on mock up engines on stands with some serious equipment I'm sure.

I've never really heard of someone matching RPM's of the turbo to engine displacement or size like I saw mentioned on here.

 

omori used to list one

 

or you could look at a compressor map.

 

The map for that turbo is nice in that it shows the compressor speeds at various boost levels, but does anyone have a labeled one for a GT4294? If I had a detailed graph like that, I probably wouldnt need the gauge...

I swear I've seen the guage I'm talking about in a Sport Compact Car though...

 

I don't mean to be rude, but for some reason you are starting to frustrate me, because you aren't believing anything that I am trying to explain to you. I will try to explain it one more time, in more detail:

There are a few different ways to pick up turbo speed. For low speed balancing, you can put a white mark on one compressor blade and as it spins, there is an optical pick up to tell you the turbo speed. In low speed balancing, the pickup sees speeds of 0-4000 RPMs roughly.

In testing a turbo speed in a turbo not designed with a speed sensor, you can install small magnets in the compressor wheel nut, near the middle. While I wouldn't do this on an actual application (because there would probably be no need)

In OEM applications, the speed sensor is magnetic, and is installed in the center housing, and picks up off of a notch in the turbine shaft.

Speed sensors are used in OEM applications, and they can be very helpful in matching and tuning.

You've probably never heard of turbo speed being critical in turbo matching because most turbo matching done by backyard mechanics is crappy at best. I just had a discussion about this with Ramy last night, and there are a lot of parameters that go into making a turbo match an engine for good driveability and power. It is not as simple as "how much power do you want to make".

Factors like, intercooler efficiency, displacement, brake specific fuel consumption, power, load, ambient air temps, turbine exhaust pressure, compressor/turbine efficiencies, volumetric efficiency, turbo speed, etc.

-Kevin

 

i like the optical sensor idea it seems the most unobtrusive.

 

Thanks for sharing, Kevin. How long have you been working at Garrett?

Would you personally recommend measuring turbo RPMs on a street-driven car, or is there a better way for the average enthusiast to see if their turbo is properly sized and working correctly?


-s-

 

Well said!

 

I wouldn't recommend monitoring turbo speed in a street car because it wouldn't be that much help. Honestly, a good turbo match isn't easily obtained, so for the average enthusiast going by hearsay may be the only viable option. We have engine/turbo simulation software to properly match turbos here, but it takes a lot of time to setup properly and wouldn't be practical for everybody to do.

 

Maybe not for the average enthusiast, but I need a guage or device so I can figure out the operating range of my turbo like I said before. Anyone know where I can get one for under $500?

 

Why don't you just use the compressor map and calculate roughly your speed range of your turbo?

 

i made a thread with the info about this turbo tach.
check it out.
https://www.rx7club.com/showthread.p...15#post6671215

 

aaarrgghh you beat me to it !!