Exhaust Pressure Readings

[Andycostin]

Hey all,
Just wondering if anyone knows where to source a high temperature Pressure Tranducer from. I'm looking at measuring Exhaust Port Pressure at high frequency (eg. around 4,000Hz, so must have a good response time). Already have Thermocouples to log Temperature, but unsure who supplies good quality (but cheap) Pressure Sensors that can withstand these sort of temps(eg. 800deg Celcius or 1400+F).
What sort of money should i be expecting to pay.
Or should I be looking into a lower temp tranducer and tapping a line into the exhaust runners so that i can remotely mount the sensor?
Only problem that i see with this, is that I won't be able to log pressure waves vs crank angle/combustion cycle, as the waves will take time to travel to the remote sensor??

Greatly Appreciated,

[Andycostin]

Hey all,
Just wondering if anyone knows where to source a high temperature Pressure Tranducer from. I'm looking at measuring Exhaust Port Pressure at high frequency (eg. around 4,000Hz, so must have a good response time). Already have Thermocouples to log Temperature, but unsure who supplies good quality (but cheap) Pressure Sensors that can withstand these sort of temps(eg. 800deg Celcius or 1400+F).
What sort of money should i be expecting to pay.
Or should I be looking into a lower temp tranducer and tapping a line into the exhaust runners so that i can remotely mount the sensor?
Only problem that i see with this, is that I won't be able to log pressure waves vs crank angle/combustion cycle, as the waves will take time to travel to the remote sensor??

Greatly Appreciated,

[John Bucknell]

Andrew,

Bad news, what you want to do isn't cheap. Both Kistler and AVL make water-cooled transducers to do what you want to do, at around US$3500-5000.

Remote sensing is a possibility - but rather inaccurate, and for the frequency you are sampling starts to show duct resonance where the sensor is mounted. You can filter out the duct resonance to some extent, but it skews your data. In that case an automotive MAP sensor is sufficient (sourced from some boosted application so you can get 3 bar absolute range).

John

[Ben Inkster]

I think most MAP sensors are limited to sub atmospheric pressures, or at least the ones I have dealt with are. Although I'm sure its not hard to find better ones then I have used.

Cheers

Ben Inkster
(now ex)UWA Motorsport

[Andycostin]

Thanks John, that was what i was fearing. Have priced the Kistler sensors for around $5K Australian, and was hoping that uni would front for them as lab equipment in the last budget, but no luck.
Have also found that there is the possibility of renting the sensors from a company called Orbital in Western Australia, but also quite expensive (around $AUD100 per day).
Anyway, may just settle for steady state measurements.

Thanks too Ben, but don't think that the MAP sensors will be appropriate temperature wise.

Thanks again guys,

[Colin]

keep dreaming Costin, it's not going to happen $$$http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Ben Inkster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Thanks too Ben, but don't think that the MAP sensors will be appropriate temperature wise. </div></BLOCKQUOTE>

What John is saying is that you can place a sensor remotely from the hot exhaust gases using a small pressure line (John correct if I have misread you) but this pressure line will induce its own harmonic pressure oscillations that you might be able to filter out.