ESE's works engine tuner

[Yow Ling]

the relay contacts might be a bit noisy compared to an open collector transistor, also easy to contaminate with virtually no current

[TZ350]

Can't you just wire directly to arduino from ecotrons ecu.? I don't think you will need the relay as there is no current.

With a relay there is no forward resistance either.

I am not sure what the Ecotrons power switch is looking for and it is the 0.5V across the collector emitter junction at saturation that concerns me. It might look like a dirty contact to the Ecotrons.

Anyway I will start with the relay but would prefer to do without it if it proves possible.

[TZ350]

It will sadly enough not be a smooth transition when switching maps i guess.

I called it a map but in reality it is a table of Lambda values that are used to divide the current cell value in the active map to enrich-en it for maximum acceleration power, hence the name "Power Switch".

So instead of dividing the current map cell value by say 0.85 to enrich-in the mixture for acceleration I could divide it by say 2 to lean it off because the pipe is not sucking and there is 50% less air being drawn through the motor.

[TZ350]

the relay contacts might be a bit noisy compared to an open collector transistor, also easy to contaminate with virtually no current

An open collector transistor sounds the go but I am just feeling my way with this.

To tell if the motor has or has not fired I am very tempted to try and measure the actual combustion pressure.

[Brett S]

Would a crank encoder be able to sample a period of time after ignition event, be fast enough to determine whether combustion took place or not?
This may be trying to determine the impossible though, possible better than my optical sensor pointing up xfer idea.

[Frits Overmars]

I am very tempted to try and measure the actual combustion pressure.

That's the way to go anyway. And it will make a deto sensor superfluous - provided your pressure sensor is detoproof.

[Niels Abildgaard]

To tell if the motor has or has not fired I am very tempted to try and measure the actual combustion pressure.

Do You really need the absolute pressure or only the presure history 30 degree on both side of Top Dead Center?
If it is more or less symmetric it has not fired and if not it has.
In that case two small piezo disc with holes under one of the cylinder- head holding down nuts can maybe work.

[Flettner]

opps wrong message

[Nath88]

Would a crank encoder be able to sample a period of time after ignition event, be fast enough to determine whether combustion took place or not?
This may be trying to determine the impossible though, possible better than my optical sensor pointing up xfer idea.

This is the most common misfire detection method used by OEM ECUs. Compare the time between teeth of the crank X degrees before TDC and X degrees after. Worth investigating, you can buy off the shelf ICs for that exact purpose. I think the trouble areas would be when the clutch is dropped or slipped, the rapid change in crank speed might cause false indications. Although you could probably measure the overall crank acceleration as well and have it as a factor in the output.

[Nath88]

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The plan is to have a pulse trigger on the flywheel that corresponds with the exhaust port opening and a pressure sensor in the exhaust tract close to the exhaust port.

I like this approach. The pressure pulse delay from the port to the sensor is significant (but should be more or less constant) so suggest having a delay in the code from the exhaust opening point before sampling. Then take samples over 0.5ms or so and use the highest value. Then compare to your threshold value, I'd have that as an input from a potentiometer, but you could just hard code it. If its above the preset threshold, set the output to your relay high, and wait for the next trigger. You might want to have an output toggle when the sampling window is active, so you can watch the input and the output on a scope to dial in your delay.

If your trigger is not exactly at exhaust port open, you'll need to add a delay that varies with RPM. I'd probably set it 10 degrees early and incorporate that anyway. Measuring time between triggers for RPM.

If the microsquirt could do all this, tuning would be much easier.

Or there are some of these Wika pressure transmitters lying around work. There is a variety of pressure ranges up to 500 bar. So I could easily measure the combustion pressure directly and when its over a certain threshold ie the engine has fired then the 4-20mA output through a small power transistor could be arranged to switch the relay.

Response time of the sensor will be the only issue, testing will tell. This is where the piezo will excel over the pressure sensors.

The relay board you have would most likely switch the ground for the relay coil, you could connect the ecotrons input here to eliminate the relay itself.

Directly measuring combustion pressure would be the duck's. Maybe incorporate one of the Beru PSG range of diesel glow plugs with built in pressure sensors? They're very long though.

[Nath88]

Do You really need the absolute pressure or only the presure history 30 degree on both side of Top Dead Center?
If it is more or less symmetric it has not fired and if not it has.
In that case two small piezo disc with holes under one of the cylinder- head holding down nuts can maybe work.

That could work well, integrate the output of the piezo from -30 to +30, if it's substantially positive, fire has occured, and we should expect an exhaust pulse. Might go looking for piezo washers now.

[peewee]

hey guys can anything be said about the color on my piston top ? this is after about 1/2 gal nitro. so far 15% mix was the highest I could reach as the needle was just to lean in the throttle closed position. its mostly light brown with alittle darker color near the exh side but some of the dark color is shadow from the camera. its really good shape with no erosion at the edges or anything else that would indicate deto or other tuning problems. honestly I was wondering if the brown meens im just a bit lean still and its heating the crown a bit to much or its ok ?

ive since picked up a virgin head in order to drop the com ratio. 11cc more than the previous head is what I need to add. in order to accomplish this, the head has to be raised so ill spend some time over the weekend welding the face and chamber then remachine it. also I had one of my existing needles richened in the slide close position, hopefully its enough. and the other thing is I increased the float bowl capacity even further incase fuel flow into the bowl cant keep up, as the third jet is half open now and Im not sure if ill need a fourth jet as I get closer to 20% mix but that remains to be seen just yet. my goal is to get to about 23% nitro by volume /approx 30% by weight. I think the lower end is strong enough as it has prox cr500 conrod with welded crankpin and large nj207 germany roller bearings

[TZ350]

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In cylinder combustion pressure sensors:- https://www.avl.com/pressure-sensors...tion-analysis1




https://www.avl.com/-/GO15DK

The GO15DK has the slimmest contour due to an M3 cable connector and is an M5 monitoring sensor especially suited for pmax monitoring with maximum amount of knock. The Double-Shell™ design decouples the piezoelectric elements from negative influences of mechanical stresses that can occur due to the mounting of the sensor into the engine. In addition to this, it has an improved membrane material and geometry. This makes the sensor to the standard solution for monitoring with maximum levels of knock.

[jonny quest]

I've designed and built a lot of 2 stroke pipes back in the day, one thing that always baffled me....

Some engines don't care if youput a 360 loop in header, some engines loose a lot of power with the slightest bends? This is compared to a straight test pipe.

Why are some engines much more sensitive?

[Tbh37620]

This ran over a welded in central port bridge that had added boost ports down each side.

Wobbly, do you have any photos or info on this welded in bridge(Parent materials, filler metal, etc)? I have several cylinders I would like to weld bridges into to expand the width of the ports. Id imagine the H1 cylinder was a cast iron sleeve in aluminum casting?


Thanks,