SPOautos

Hey guys, I was wondering if anyone on here has ever tested chamber pressure. Are there any products to datalong chamber pressure for a rotary?

Also, would anyone happen to know much about acceptable chamber pressures and how many psi is to much?

Thanks

BLUE TII

iTrader: (9)

One of my techs at work showed me a little piezo electric ring w/ lead that went under spark plug to measure cylinder pressure.

Is that the type of device you mean? I guess whether that would work depends on the outside diameter of the "ring" so it can fit in out recessed plug holes?

SPOautos

Yea, its along those lines. There are different types but most of the easiest to use are the spark plug types. All of the others would require major modifications to work right. Some of them you can even send them your spark plug and they will modify it.

I know there are some out there intended for 2 and 4 cycle engines, anyone have any ideas as to how one of those might could be used on a rotary? I guess the poblem is in the dataloging software, the hardware would work fine its the software thats all designed for 2 and 4 stroke that doesnt work.

Anyway, I was just wondering if anyone else has research this and had any usefull information

SPOautos

I looks like no one is interested in tuning with chamber pressures lol

Anyway, just in case someone IS interested (like me haha ) here is some info that I'm finding out with my research. I'm talking to the owner of a company that writes dataloging software that works in conjunction with just about any chamber pressure sensor including the spark plug types. They didnt have anything available for the rotory nor does he know a great deal about rotary, he is however interesting in adapting his software for use on rotory. Here is some information he would need to start doing this.....

***"Quite frankly we are not real familiar with rotary engines other than some of the basics. If we had sufficient concrete interest on your end we would undertake to develop the appropriate software for a rotary engine. In order to develop the software there must be a numerical way of determining the volume in the chamber relative to the rotor position. In a piston engine this is determined by knowing the stroke, connecting rod length, bore and compression ratio"***

Would anyone be able to assist me with some good information?

Thanks,
STEPHEN

Trout2

iTrader: (5)

I seem to remember some SAE technical papers that gave the differential equation for finding chamber volume. Far from the simple linear equation for a piston engine. I would have looked at this in the late 80's/early 90's while in college and doing research for an internal combustion engines class so it would have been an older document. Hope this helps.

Jack

SPOautos

Well, its a start...at least someone knows the chamber volume.

So.....anyone know what SAE papers that would be in and if so anyone know where I could get a copy of them?

STEPHEN

RacerXtreme7

iTrader: (2)

I've worked with pressure transducers here at work (NASA) on several different engines (aviation engines mostly). Most were the spark plug type, one of them we had to drill and tap a head (2 cycle engine) to place the sensor. I been giving this thought for my own engine so I can data log and tune my ignition so peak chamber pressures happen when i want it too instead of just tunnning it and hopping it doesnt POP. If we could get someone to make a pressure transducer plug that would be great!!. i was simply going to use a sensor on the trailing hole and only fire the leading just for data logging, but if i was able to still fire the trailing and data log that would be better.

one of the main problems is geting the crank angle accurate. I always had to retrofit a rotary encoder to all the engines I dynoed to get accurate engine crank angle. These arent cheap and I would rather not have to make adapters and brachets for this. Anyone know how accurate a reading I could get from the stock T II CAS?

~Mike.............

BLUE TII

iTrader: (9)

What encoders do you use? What style of coupling?

I work w/ encoders at work and have been thinking about retrofitting my Haltech for this as CAS to Haltech does not appear to be accurate.

RETed

You got enough money to handle the cost?
http://www.japanicity.com/~mak/


-Ted

BLUE TII

iTrader: (9)

Isn't that just a compression tester/logger?

RETed

Oh crap, I thought it was just compression testing.
It didn't occur to me they were talking about *combustion* pressures.

Yeah, you're right, this is the area of pressure transducers.
This stuff ain't cheap.
Normal combustion pressures are around 1,000 to 2,000psi.
Under detonation this can peak at 10,000psi!


-Ted

SPOautos

Yea Ted, I was speaking of chamber pressures during combustion. There are some systems out there that hook up to the sparkplugs and sence the chamber pressure. They also have dataloging software that goes along with it and you can pull up graphs that map the chamber pressure for everydegree of crank angle. So basically as soon as the rotor would start the combustion process the dataloging equip would log the chamber pressure for every degree of crankangle and you can use that information for tuning. It does a lot more also, it comes with pressure sensors for both the intake and exhaust as well. Its a pretty nice setup but it is rather expensive and like I mentioned earlier they dont have all the information that would be needed to make it work with a rotary....and neither do I. But if someone does have the information and its accurate I'll be sure to pass it along to them and maybe they can get it working for a rotary.

The next step would be using a standalone that works off of chamber pressure. I'm sure its only a matter of time before that is the direction things take. The OEM's are currently working on this and its only a matter of time before it goes to aftermarket....course I doubt anyone will make anything like that for the rotary

STEPHEN

RETed

Actually, this has been used by top-tier motorsports teams for a long time now.
In fact, Mazda has been measuring combustion chamber pressures on the rotary engines for a while now - see SAE papers for reference.
While common a those levels of automotive engineering, the technology just hasn't trickled down to private automotive enthusiasts.
Last time I checked, a 100bar to 1000bar pressure transducer is still several thousands of dollars.
The datalogger would be pretty simple and cheap to build, but you're still messing with a couple very expensive sensors!
Keep us updated!
I'd be very curious to see any developments as I think this kinda system would better than more common wide-band and / or EGT gauges (or even knock sensors) easily available now.


-Ted

FarNorthMotoring

iTrader: (2)

It would be the ultimate knock sensor. A friend was telling me about this about year and half ago, he was building experimental aircraft at the time and heard about a guy working on system for exp. aircrafts and we dreamed of the using it to tune with with, until we priced the transducers.

SPOautos

You are correct Ted, it is expensive but its not TOTALLY out of reach from consumers. The entire setup, sensors, datalonging equipment, software, ect ect would run about $3K if you bought just one. If a small group got together the price would go down. I know its expensive but its still cheaper than buying 3-4 engines.....which a LOT of people on this board have done. It would definatly be within reach for someone thats in borderline amatur/pro racing.

Do you have those SAE papers? I could probably have a kit developed around the rotary if I knew the exact champer size at each degree of eshaft. If you know any information that you think would help me it would be appreciated.