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Help with building your Speeduino, installing it, getting it to run etc.
By kettlekev
#46392
Rob

Awesome stuff.....thanks!!

I am getting there. Speeduio and simulator sorted.

Working out how input my spark retard curve into a spark table as a start.

Lots to read. Appreciate the help.

Kev
By kettlekev
#46449
Spark tables all done.

With the 9khz trigger input capability I can run a 36-1 wheel.

Dyno in a couple of weeks to get a carb baseline and check the timing map.

Next step is understanding what I need to do with fuel and MAP sensor. Might be interesting on a triple! I am still reading all the posts!!

Getting there.....
By kettlekev
#46523
Rob,

I've tried to go through and understand all the posts. Two questions.....

The threads imply that your pseudo MAP process is only needed on high revving engines? Am I understanding that correctly.

My peak power is probably around 8500 and I will top out at 9000. Can I just run basic Alpha -N (TPS/Revs) in that case?

I am also currently on a one injector plan (rather than staged). Thoughts?

Thanks

Kev
User avatar
By PSIG
#46565
kettlekev wrote:
Tue Nov 17, 2020 11:18 am
The threads imply that your pseudo MAP process is only needed on high revving engines?
As Rob isn't back yet, IMO his pseudo MAP could be valuable for any 2S application where the VE changes substantially (relative to rpm and TPS) due to external dynamics. Those can be dynamic factors such as harmonic tuning (tuned pipes, intakes, etc), which includes most 2S at some level.
By TZ350
#46815
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The Suter MMX 4 cylinder 500cc Fuel Injected Two Stroke
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https://youtu.be/X42r7fRdtWE
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https://youtu.be/i31XkNO89OU
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I think the Suter has a common single intake for an air box that feeds all four cylinders. I think you can see a small intake just below the front number board. If that is true I would imagine a common four stroke air flow measuring method like an air vane or hot wire would be the way to measure the mass air flow. And would be the way to go with any multi cylinder bike.
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An air box for a single might be possible but I have not tried that because of space restrictions. For my single cylinder two stroke it had to be done a little differently. Common four stroke methods like manifold pressure don't, hot wire or vane style air flow meters don't work.
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I started looking at changes in crank case pressure. Common 2.5 bar pressure sensors output there measured reading every mill second for one mill second. You can see the stepped pattern to the pressure curve in the attached pictures.
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The important thing to look for is the change in difference between maximum pressure near BDC and minimum pressure near TDC. (2 strokes are about face to 4 strokes). The greater the difference the greater the mass air flow.
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With a multy cylinder it may be possible to measure the change in one crankcase and assume all the cylinders are behaving in the same way.
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Things to remember:-
1) The average crank case pressure is highest at idle. Very near ambient. (crankcase is full of smog and backflow air from the exhaust.
2) The average crankcase pressure decreases a little when the engine is on the pipe. Makes sense when you think about it. Because the pipe is sucking hard out.
3) If you are using an oxygen sensor for testing, mount it as near the stinger as you can get it.
4) Mounting an oxygen sensor near the header is a mistake. Wash through will kill it.
5) When you are not on the pipe back flow air from the muffler and short circuiting air from the cylinder makes a oxygen sensor look lean.
6) At low speeds off the pipe a Wide Band O2 air/fuel reading will be like 18 or 20:1
7) As you come up onto the pipe the air/fuel reading will be like 13 to 14:1
8) At max torque where trapping efficiency is at its best you should see 12:1 (or richer).
9) As you go into over rev the air/fuel reading will trend back to 13 or 14:1
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It is the magnitude of change (delta) between the max and min crankcase pressure that indicates the change in mass air flow through the motor. Bigger difference = More air mas flow.
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Now that Speeduino can handle two maps and switch between them.
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I started by making an Alpha-N map and this works well at any RPM for anything above 20% throttle and on the pipe. The plan is to measure the outright delta of the crankcase pressure and with a bit of mathematical magic out put it as look a like ordinary four stroke MAP value to the Speeduino for use in the VE table for anything below 30% throttle..
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I started to get some good results with the Alpha-N table and was looking to develop the VE table when my engine cried "Enough" and quit. Not sure what went wrong, main or big end bearing don't like 14,000 rpm maybe. Or pealed a bit of chrome off the bore. I did a lot of porting without re chroming the cylinder. Hopefully I will get it fixed over the Xmas holidays.
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The pictures attached below are recorded on my actual engine while it was running on the dyno.
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Attachments
11580 RPM Delta P Trace.jpg
11580 RPM Delta P Trace.jpg (1.36 MiB) Viewed 510 times
High RPM.jpg
High RPM.jpg (1.96 MiB) Viewed 510 times
Low RPM.jpg
Low RPM.jpg (2.31 MiB) Viewed 510 times
Last edited by TZ350 on Tue Dec 01, 2020 6:43 am, edited 11 times in total.
By TZ350
#46816
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The Blue trace is the crankcase pressure and the Yellow trace is the ignition.
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The Blue trace is broken where the two stroke has a four stroke spasm. Ie corn poping.
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Attachments
Low RPM.jpg
Low RPM.jpg (2.31 MiB) Viewed 509 times
By TZ350
#46817
kettlekev wrote:
Tue Nov 17, 2020 11:18 am
The threads imply that your pseudo MAP process is only needed on high revving engines? Am I understanding that correctly. My peak power is probably around 8500 and I will top out at 9000. Can I just run basic Alpha -N (TPS/Revs) in that case? I am also currently on a one injector plan (rather than staged). Kev
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Hi Kev
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250cc a cylinder and less than 10,000 rpm you probably only need Alpha-N and don't need to worry about crankcase pressure and VE tables.
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Ambient air pressure and temperature with TPS and RPM for the Alpha-N map is all you need. Maybe cylinder/head temperature for refining the fueling. If you are running E85 or other Alcohol fuels, you can automatically richen up when the engine goes over 70 deg Celsius. This is important because what runs well for the first lap or two on alcohol detonates when the engine gets hot and the head goes over 80 deg C.
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There seems to be a natural limit. One injector is good up to about 10,000 rpm and 10 bar bmep. After that split injection seems to be required, on petrol anyway. Small injector for low speed, big injector for high rpm. A big injector dribbles to much at low speed for good fuel control. You can get away with more over fueling at the low end if you are running alcohol blends.
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I have a friend who is running Alpha-N and one logical injector (two physical injectors fired together) in the crankcase on a hot 350cc Kawasaki single running E85 https://youtu.be/ifSEql1X4R0 https://youtu.be/eleqBGvOM4M . And another running a Yamaha YZ 250 single running one logical injector https://youtu.be/UEQli7nuak4 . Two physical injectors fired together in the B transfer ports. The YZ is running on petrol. https://youtu.be/hOGZ5llowoU
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Attachments
Yamaha YZ250 B Port Injected.jpg
Yamaha YZ250 B Port Injected.jpg (156.39 KiB) Viewed 497 times
By kettlekev
#46827
Rob

Great feedback! Thanks. Seems like my lower revving engine might save me some grief which is good.

I am starting with the ignition (36-1 crank wheel laser cut now),..Off to the dyno next week to get a carb baseline.

I a probably going to use Triumph Tiger 120 throttle bodies as they are mechanically a good fit and I get a free fly by wire throttle.

Thanks again. When I get to fuel I am sure there will be more questions.......

Are you in NZ/OZ?
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