Turbocharger speed/pressure sensor

[JAM]

Looking at the possibilities of adding a couple measurements to my setup-

Has anybody successfully used a speed sensor on a turbo with the MS3 ?
With this said is knowing the high RPMs of the shaft, is PT4 / PT5 capable of a frequency this high?

Also is there a pressure sensor or method that people have used on the hot side of the turbo setup that they could recommend? like a 0-5V pressure transducer that can be tied to an ADC input?

[billr]

If the turbine-speed sensor frequency is too high it is pretty easy to divide that down to an acceptable range, just some simple counter chips.

[elutionsdesign]

Also is there a pressure sensor or method that people have used on the hot side of the turbo setup that they could recommend? like a 0-5V pressure transducer that can be tied to an ADC input?

While there is a lot of fancy stuff out there I've found the MAP sensors used in Megasquirt to be the easiest and most cost effective. You can pick one up in the pressure range you expect (2.5 bar, 3 bar, 4 bar) on digikey for just a few dollars. It needs 5V power feed, sensor ground and the pressure signal wires and you can use a small ABS or aluminum box to contain it, again from Digikey. To protect it from heat I just ran a loop of 1/16" SS tube from the tap on the exhaust manifold to the sensor, maybe 1.5-2 ft long. Since its dead ended no heat flows through, you're just getting it far enough away for the tube to cool things. Smaller diameter is better than larger diameter.

[JAM]

To protect it from heat I just ran a loop of 1/16" SS tube from the tap on the exhaust manifold to the sensor, maybe 1.5-2 ft long. Since its dead ended no heat flows through, you're just getting it far enough away for the tube to cool things. Smaller diameter is better than larger diameter.

I had wondered if it would be possible in a method like this to avoid a high heat type pressure sensor, thanks for the info on the method- very helpful to know somebody has done this.

While there is a lot of fancy stuff out there I've found the MAP sensors used in Megasquirt to be the easiest and most cost effective. You can pick one up in the pressure range you expect (2.5 bar, 3 bar, 4 bar) on digikey for just a few dollars.

I think this is the sensor on the MS, is this what you were referring to? I will show my ignorance here-first turbo setup i am planning to run about 15psi on a turbo that I believed is sized correctly. I know there are many variables but i am thinking the back pressure on the exhaust side would be within range of this sensor?

http://www.digikey.com/product-detail/e ... -ND/464053

and you can use a small ABS or aluminum box to contain it, again from Digikey

Thanks for the tip, i will look around. if you by chance have a PN that you have used that would be appreciated-

[dontz125]

Given the size and apparent robustness of the MPX4250AP, would it not be practical to simply solder wires to the pins (0.1uF cap across the 5v and gnd pins!), use double-wall heat-shrink, and crimp on a water-tight connector? Zip-tie it somewhere safe, with a suitable rubber pad under it. Speaking of ruber padding, would it not be better to have the length of SS tubing join up with a length of rubber tubing leading to the sensor? This would allow not only flexibility in installation, but also dealing with vibrations.

I can't comment intelligently about the back-pressure on the cylinder side, but that sensor is rated to 1000 kPaA, or 130 psig. The back-pressure on the exhaust side should be in the order of single-digit psi.

[JAM]

I can't comment intelligently about the back-pressure on the cylinder side, but that sensor is rated to 1000 kPaA, or 130 psig. The back-pressure on the exhaust side should be in the order of single-digit psi.

I would think the back pressure should in range but I thought that sensor was about 21-22psi gauge/36 absolute? Are we talking about the MPX4250AP?

[dontz125]

Sorry - the FAILURE pressure is 1000 kPa. The signal pressure range is 20-250 kPa.

[JAM]

Sorry - the FAILURE pressure is 1000 kPa. The signal pressure range is 20-250 kPa.

Got it- so it can see a large amount of pressure before it causes damage- thanks

[xrattiracer]

you can expect a turbine inlet pressure of up to 2x boost pressure for a typical factory small turbo setup. obviously the larger the turbine (among other factors) the lower that ration will be.

[masterx81]

Td04 on subaru for 2bar absolute on the cold side have 3 bar absolute on hot side... small turbo!
I've used a copper brake line and a brake line fitting. Tapered the header and job done

[JAM]

Thanks for all the feedback on this.

Considering this is the hot side and should not see vacuum if i had the proper adapter to the 1/8" npt and using the remote plumbing method that is described in this thread- is there any reason I could not use one of the honeywell sensors ? I think i have a couple of these units sitting around-

http://msextra.com/doc/ms3/genericsensors.html#settings