In-Cylinder Pressure Measurement Mounting

[UAMotorsports]

Hello everyone,

This is my first post on this forum. I would just like to say thank you for having me aboard, this appears to be an amazing resource for many.

My Project:
1993 Honda Civic 1.6L Turbocharged for use in Time Attack

Question:
I am mounting a Fiber Optic Pressure Transducer that is made by the company Optrand. This Pressure Transducer is intended to operate at 350 degrees Celsius continuous operating temperature maximum.

There are really only 2 locations where I see feasible to mount this transducer, that is in between the exhaust valves (plenty of room) or in between the intake valves. This Transducer is essentially a probe, it is very small and is drilled into the head.



My concern is that if the transducer is mounted in between the exhaust valves, the temperature will get too high and it will burn the transducer out. My experience is that exhaust valves reach an average of 650 degrees C, while the intake valves only reach an average of 250 degrees C.



I understand that the quenching distance of gasoline is roughly 2mm. This probe's mounting instructions call for a 1mm diameter window into the combustion chamber. So the transducer itself is never actually exposed directly to the flamefront. This should result in a significant reduction in temperature.







On the Intake valve side, although the temperature will be lower, there is not enough room to drill straight through from the top of the cylinder head to the combustion chamber, instead the machining will have to go through the intake port on the way. Because of this I will run into a sealing issue because the intake port is being drilled through, the incoming air charge now has a means of escaping via the machined hole to the upper cylinder head. Also the pressure transducer is placed at the end of a braided line (1.5m) and this line will be blocking some of the intake stream.



My real question here is will the transducer survive being mounted between the exhaust valves? Does anyone have any simulation software that they could run this through quickly?

Many thanks

[langwadt]

Hello everyone,

This is my first post on this forum. I would just like to say thank you for having me aboard, this appears to be an amazing resource for many.

My Project:
1993 Honda Civic 1.6L Turbocharged for use in Time Attack

Question:
I am mounting a Fiber Optic Pressure Transducer that is made by the company Optrand. This Pressure Transducer is intended to operate at 350 degrees Celsius continuous operating temperature maximum.

There are really only 2 locations where I see feasible to mount this transducer, that is in between the exhaust valves (plenty of room) or in between the intake valves. This Transducer is essentially a probe, it is very small and is drilled into the head.

https://fbcdn-sphotos-a-a.akamaihd.net/ ... 7381_n.jpg

My concern is that if the transducer is mounted in between the exhaust valves, the temperature will get too high and it will burn the transducer out. My experience is that exhaust valves reach an average of 650 degrees C, while the intake valves only reach an average of 250 degrees C.

https://scontent-a-iad.xx.fbcdn.net/hph ... 8440_n.jpg

I understand that the quenching distance of gasoline is roughly 2mm. This probe's mounting instructions call for a 1mm diameter window into the combustion chamber. So the transducer itself is never actually exposed directly to the flamefront. This should result in a significant reduction in temperature.



https://fbcdn-sphotos-b-a.akamaihd.net/ ... 7875_n.jpg

https://scontent-b-iad.xx.fbcdn.net/hph ... 6180_n.jpg

On the Intake valve side, although the temperature will be lower, there is not enough room to drill straight through from the top of the cylinder head to the combustion chamber, instead the machining will have to go through the intake port on the way. Because of this I will run into a sealing issue because the intake port is being drilled through, the incoming air charge now has a means of escaping via the machined hole to the upper cylinder head. Also the pressure transducer is placed at the end of a braided line (1.5m) and this line will be blocking some of the intake stream.



My real question here is will the transducer survive being mounted between the exhaust valves? Does anyone have any simulation software that they could run this through quickly?

Many thanks

you are not mounting it in the valve, you are mounting it in the head. I don't see how you can have huge differences
in temperatures in a big block of alu with coolant running through it

[autogyro]

With a 1mm hole I would be more concerned with carbon build up.

[jayeshrc]

i'm not sure you can do this so well, without burning out the transducer.

most sensors for this come as part of the spark plus packaging, and you dont have to worry about anything else. but obviously you wont be able to mount yours in cylinder either.. hmm

[Brian.G]

Skim reading the above but how are you going to expect the head to remain watertight after drilling down from cam area to mount that?
Id say forget that sensor and get one integrated within the plug itself.

http://www.optrand.com/fliers/psiplug_%20060201.pdf

This is then non destructive too should you have 80hrs invested in a port and polish job...

Brian,

[Brian Coat]

In a past life I always put dia. 5 mm piezoelectric pressure sensors into the intake side *under* the intake ports.

The problem on exh side won't be the alum temperature it will be the water jacket between the ports, not to mention the leads frying on the exh man.

The hole which breaks out needs to be <5 mm of course. It will come through as an oblique break-through between the inlet valves, on the pent roof, close to the bore diameter periphery.

2mm I seem to recall but 1 mm may be right for this sensor.

The drilling usually needs to be slightly angled to the deck face to get the right 'tunnel' through good metal, I seem to recall.

If you do not have a good CAD model of the port/chamber area you may need to make a bit of a 'geographical survey' because it's tight!

I notice your sensor is also M5, so this should work.

For what it's worth, Kistler *was* the sensor to use

In-plug type has its fans but the trouble with these is you are restricted on plugs (e.g. heat range change= New special plug) and also the high frequency content of the signal always used to be less accurate than going directly into the chamber, although this may have changed. I also found taking plugs in and out for routine horoscope checks to be a bit of a pain with that lead in the way. Special tool and great care required.

Hope this helps.

EDIT: "routine horoscope checks" is a typo I just noticed. It should be boroscope. The typo tickled me when I saw it.