In Chamber Testing
 

I have been working with pressure sensors to try and understand what is going on inside the rotor chamber.
What I am finding is that the best peak pressures seem to be located around 45° ATDC.
But notice the variation of cycles. We think of a more even flow of power pulses.
This log is taken while accelerating through 5000 rpm. The range above this is still too retarded.

http://i287.photobucket.com/albums/l...relocation.jpg

The test equipment is made by TFX Engine Technology.
You can familiarize yourself with the program by going to http://www.tfxengine.com/hardware3.html

The test mule is a RE 13b running 12 psi (10 psi spring)
TO4s, HKS cast divided
50/50 meth water pre and post turbo.
HKS Twinpower
Power FC

More interpretation.
The red arrows indicate an engine misfire (in this case the mixture was too rich) .
The blue arrows depict a too retarded cycle at about 60° with subsequent lower pressure.
The green arrow show a cycle closer to 45° and higher pressure.
I am amazed at the scatter.

http://i287.photobucket.com/albums/l...location-1.jpg

Just roughly looking at this chart I would say we should add a degree to section 2 and two degrees to section 3.


http://i287.photobucket.com/albums/l...location-2.jpg

http://i287.photobucket.com/albums/l...tionrating.jpg


This is what the burn rate looks like. (One of the best examples of the 210 samples taken during this log.)
The red line is the pressure of rotor compression without ignition.
The blue line is ignited pressure.
The purple line is the temperature of the burning mixture. Notice it is still 1400°C when the exhaust port opens.
The pressure at exhaust port opening (EOP) is 91 psi.
A detonation rating of 65/88/0 shows up for this #64 cycle. Since it has 0 frequency I am assured by the Mentor that it is benign. (But whenever the peak pressure is advanced below 45° it gets some of these readings.)
The HP and torque readings are off in this sample because I am using the wrong displacement calculations.

Barry

Wow, I dunno how I missed this, but thanx for sharing such wonderful data!

Do you mind me asking where the location of the pressure and temperature probes were?


-Ted

Can you please show me where and how the sensors (pressure) are fixed into the rotor housings.

Where is the EGT sensor located? what type is it. What calculation (model is used) to guess the temperature at places aside from where a physical hard measure is taken?

How are you measuring the AFR exactly.

I thought about using their stuff but they could not answer any of my more detailed questions on their systems so I left it alone, interested to see what you have found and if you can shed any light on the above and also what cross checks you use to validate the outputs from their equipment.

First time seeing this as well. Nicely done. Care to comment on the last output and advancing the timing to move the peak pressure closer to TDC? Or do you feel that doing so would lead to a much higher chance of detonation?

I've always wanted to play around and learn more about what is going on in the chamber itself. I feel a better understanding will lead to more power/reliabilty. Seeing what's actually going on rather than reading and interpreting what the engine is spitting out.

If I had to guess the pressure sensors are directly bolted in to the combustion chamber via a spark plug hole as I doubt he's using MEMS. Temperature of the combustion chamber could be taken almost directly by placing a temp sensor on the housing immediately outside of the combustion housing (ie in the coolant flow). This would allow the modeling of the temperature fairly easily, though would be rather troublesome to do.

If what I said is true then I wonder how the pressure transducers affect your readings.

You'd think this would be an automatic, but this presents one problem...
This will almost always affect the spark ignition due to changing the location of the spark (plug).
It might be a minor thing, but this might throw the data off just enough...


-Ted

wish i could see the pictures at work...

My thoughts exactly. IT's a pity we can't have pressure transducers directly on the faces of the apex seals or combustion tub.

Yes if memory serves, Barry's sensors are the sensor/spark plug type.

This is awesome data, and could lead to some very neat results. Its just a pity that all of this data is essentially going to be setting up a bench mark being that no one's really looked at this - in the capacity of the end user - before.

Barry, have you done any comparisons yet between pressures with and without water? Can't recall if I brought that up at deals gap.....

:)

Interesting thread, subscribed

Awesome!

Thanks for sharing Barry! Next time I see you, I need to pick your brain again!