ESE's works engine tuner

[Yow Ling]

if you monitor the spark waveform it may be different for a ignition event compared to a non ignition event

http://papers.sae.org/950003/

http://www.autoserviceprofessional.c...lly-use?Page=3

http://www.powerguru.org/advances-in-ignition-systems/

[breezy]

[QUOTE=Frits Overmars;1131080908]Yes it would Breezy. I'd just like to know how you are going to achieve that kind of scavenging pressure, since the cylinder pressure at exhaust opening can be rather high: more than 11 bar in an Aprilia RSA.


Frits thanks for reply,

yes 160psi... mmmm. maybe some yet undisclosed phenomenon could be used to achieve this Frits in your years of experience have you ever encountered any strange gas dynamics in a 2 stroke engine which fly against the laws which you have believed to be right ?

[Frits Overmars]

yes 160psi... mmmm. maybe some yet undisclosed phenomenon could be used to achieve this . Frits in your years of experience have you ever encountered any strange gas dynamics in a 2 stroke engine which fly against the laws which you have believed to be right ?

Many strange encounters of the 2-stroke kind, but in hindsight there are no unexplainable events, just insufficient knowledge. We're working at it; it's an ongoing process

[husaberg]

My evil mind can't help noticing "the piston speed is lowest at top dead center on the compression stroke". Lovely. I'd add that the piston speed is zero at TDC,
and not just on the compression stroke but at every TDC.
Next, they juggle with the term engine speed. One moment it stands for piston speed, the next moment it's crankshaft rpm, which is quite a different animal.
Ultimately, it comes down to the fluctuations in crankshaft rpm because that's the only thing that can be measured with the encoder they are using. It has to be reliably connected to the crankshaft and it has to be an expensive encoder too, because those 'significant' fluctuations are maybe 1 percent of the nominal crankshaft rpm. Moreover, the cited papers discuss a four-stroke engine. The rpm fluctuations in a two-stroke engine are maybe half of what they are in a four-stroke, which makes it even more difficult to distinguish misfiring.
Compare that to measuring cylinder pressures: the pressure ratio between a firing and a non-firing engine just before exhaust opening can be 500 %.
That's a hell of a lot easier to detect.

Last but not least, if you insist on installing an expensive encoder and measuring the crankshaft speed, what exactly are you seeing? Fluctuations caused by cylinder pressure? Or fluctuations because of a slipping/grabbing clutch? Or a whipping chain? Or because of momentarily contact loss between wheel and road? Just listen to the rising and falling engine rpm on any Isle of Man-video.

I noticed that with the clusmy wording that was only aimed at the foul strokes but i resisted the urge to alter the wording but even with a 2 stroke assuming its half the difference
Its still pretty intesting how much the speed (well acceleration) alters during a misfire event.
Yes of course i agree pressure is a more direct measure and is a far better way but ony if it actually can be made to work.
Which at this point it is not.
There was another one thrown up that foul stroke use which was using a seperate ignition system firing a spark plug in the exhaust pipe and then measuring the ionization current through that plug.
Which differs if it ignites an actual unburnt mixture..

I should get some points for not putting that one forward.................. even though it might actually serve dual purpose,

three if you count blowing up the pipe.

(which is much the same as an antilag set up on a rally turbo) ,

The encoder... is that from the other patent i posted? not sure how they measure and compare the aceleration?

but from the first link of the system
the misfire looks pretty clear cut.... well using their own data anyway?

[TZ350]

Click through to the original post to see all the pictures and build details.

Building another Suzuki GP100 NSR 110 hybrid using a standard NSR250 cylinder and using a GP125 rotary valve cover and carb but otherwise keeping the GP100 bottom end pretty stock.



The whole motivation for this engine is to have a smaller diameter inlet tract. So I am leaving the original 24mm inlet tract un touched. Previously I would have made this as large as I could get away with.

Got a chance to try the new GP100 with its standard NSR cylinder tonight.



About 25.6 rwhp for the Suzuki GP100 bottom end fitted with a standard NSR MC21 cylinder.

(A Honda MC21 NSR250 is rated at 45hp @ 9k rpm)

My EFI motor with all the bells and whistles, all singing and dancing fully modified bottom end with a really big inlet rotary valve from a Kawasaki KE175, and with the same standard NSR cylinder only made 28 rwhp. So it takes a lot of work on the inlet and bottom end to get another 2.5 hp.

[TZ350]

Back to the EFI 2T project.

TZ, can i point out that DI would solve your part throttle problems? while TBI/port injection solves DI's "not enough time to inject all the go juice at revs" problem. combine the two systems and drop trying to detect misfires as they happen?

More complicated than my Ecotrons system can handle, but a very good idea and if I find myself developing my own ECU and EFI program it could very well be the approach I take. Thanks.

You nailed it TeeZee. Assuming the sensor itself is up to the job, the bottleneck in your case will be the 0,75 mm connecting bore. And since that is already borderline, you might concentrate on shortening it if possible, and reducing the cavity volume to absolutely zero.

I have even tried filling the cavity volume with water in the hope that there would be faster transmission of pressure through an un compressible medium. I haven't totally given up on the pressure sensor idea but ......

A short 0.75mm through hole and a $1000 USD 5mm diameter high speed piezo pressure sensor are used by the professionals, but that sort of gear is a bit out of Jo public's and my reach. I was hoping to find a way to do it with something simpler and more affordable for us home hobby tuners.

Ocean1 first suggested it to me in a PM then Yowling and Husaberg posted about it. Measuring ionization at the plug to determine the potential quality of the combustion mixture and to be able to see the difference between a firing and non firing event. I have followed the links posted by Husa and Yowling and it looks doable but then, so did measuring residual combustion pressure.....



Measuring Ionization at the plug .... sounds like its worth a look.

http://www.aces.edu/~parmega/efi/tem...on-Sensing.pdf

[Jannem]

Attachment 318365

The narrow part of the exhaust window is the original RG50 port and the wider part above the dam is 85% of the bore width.

Without the dam we could have something that looks like the RSA exhaust port.

Looking at the old posts... TZ, how did the 85% turn out IRL. Thinking rings, although I appreciate small bore is likely more forgiving.

[emess]

Frits

your beautiful MB40 cylinder and drawings of your FOS concept engine do not have a radius on the top of the exhaust port to improve flow on as on the Aprilia cylinders.

With shallow exhaust ports like the top of the MB40 T and the exhaust ports of your FOS concept engine do you consider port area more important than improved flow with the radius ?

Any news on the 50cc FOS engine you mentioned some time ago ?

Mick

[TZ350]

Looking at the old posts... TZ, how did the 85% turn out IRL. Thinking rings, although I appreciate small bore is likely more forgiving.

The ring survived but the tuning was all wrong. I think we over cooked the STA for the rpm. All we learnt from the exercise is that you can go quite wide on a 50. Much wider than a 125's 72% but 85% was getting a bit much.

[Frits Overmars]

Frits, your beautiful MB40 cylinder and drawings of your FOS concept engine do not have a radius on the top of the exhaust port to improve flow on as on the Aprilia cylinders. With shallow exhaust ports like the top of the MB40 T and the exhaust ports of your FOS concept engine do you consider port area more important than improved flow with the radius?

The Aprilia, developing its maximum power at a piston speed of 23,6 m/s, needed all the blowdown flow it could get. Huge auxiliary exhausts alone were not enough;
the main exhaust port had to be given a timing of no less than 202°, which is clearly too much for optimum resonance, but which was necessary in order to strike a compromise with sufficient blowdown time.area.
The MB40 engine has no piston ring, so the single exhaust port could be made as wide as we wanted, shown in the picture below. With 192° exhaust timing, which is fine for resonance, we could achieve sufficient blowdown time.area without having to wrestle for the last bit of flow coefficient.
It's more or less the same story with the FOS cylinder. It does have a piston ring, but it also has exhaust ports at both sides of the cylinder, again with 192° timing, and with more than enough blowdown time.area.
I must admit that I'd like to try radiused top edges, but that would raise the timing too much for my liking, or I would need new 'castings' (they're not really castings since the FOS cylinders were made via Selective Laser Melting).

[wobbly]

The Exhaust port radius was I believe necessitated by the introduction ( by the ever loved " Great Leader " ) of a new pipe design
that had no top end power.
Jan and his R&D team had to work very hard to retrieve the lost power,and in the end gained better mid as well.
I cant remember if it was Jan or Frits that commented they would have liked to have tried a non radiused port in combination with a better pipe
as this may have proved to have been " better ".

[katinas]

An interesting project and one sentence from the text: "I attributed the lost power to an overly large exhaust port (lazy port) in the cast cylinders…"

http://www.highwaymanbikes.com/the-h...ge-road-racer/

http://www.alloyavenue.com/vb/showth...cylinder/page7

[nitro2tfx]

You nailed it TeeZee. Sure, the sensor may be responsible, but even the fastest sensor can only register the delta_pressure/delta_time-variation in the system consisting of engine cylinder, connecting bore and volume in front of the sensor, the worst situation being a long, narrow connecting bore and a large volume in front of the sensor.

It's a bit comparable to an exhaust duct, where the return pulse from the exhaust pipe has to raise the pressure in the duct before it can do any good for the cylinder.

Assuming the sensor itself is up to the job, the bottlebeck in your case will be the 0,75 mm connecting bore. And since that is already borderline, you might concentrate on shortening it if possible, and reducing the cavity volume to absolutely zero.

Our own sensors will take the pressure and temperature and are plenty fast enough (accurate readings per crank angle degree) for TZ350's project, but they aren't cheap enough lol. With ours there is essentially no volume between the 0.75mm tube and the sensor. If TZ350 did that with his sensor, I suspect the temperature would kill it. Doubtful if it could be mounted with a near zero volume though because of the size of his sensor. A case where size does matter and smaller is better lol.

Agreed, maybe there could be some significant reduction in volume though, if the sensor was mounted in a less aesthetically pleasing location. However, no matter how small the volume, his sensor has to be able to keep up, which it may or may not be able to do.

[jamathi]

The Exhaust port radius was I believe necessitated by the introduction ( by the ever loved " Great Leader " ) of a new pipe design
that had no top end power.
Jan and his R&D team had to work very hard to retrieve the lost power,and in the end gained better mid as well.
I cant remember if it was Jan or Frits that commented they would have liked to have tried a non radiused port in combination with a better pipe
as this may have proved to have been " better ".

I still think the small radius was better...
After the 'great leader' had left we tested all 6 of his last exhaust designs.
Each pipe cleaned, and with its individually best carburation.
There was almost NO difference.....
All cylinders had the now STD big radius!
There was not a single unradiused cylinder left....

[jamathi]

I still think the small radius was better...
After the 'great leader' had left we tested all 6 of his last exhaust designs.
Each pipe cleaned, and with its individually best carburation.
There was almost NO difference.....
All cylinders had the now STD big radius!
There was not a single unradiused cylinder left....

One question to Frits:

Has a FOS cylinder ever been run actually?
50 or 125cc?
I an still curious after 10 years.

The somewhat similar 'Foekema system' was a complete disaster.....
Even worse than the RYGER.