ESE's works engine tuner

[TZ350]

.

Using EngMod2T to save wasted hours on the dyno.

If I have modeled the F81M engine correctly in EngMod and that is a big if then I can develop an ignition curve using EngMod.



Did multiple simulated runs with fixed line ignition advances.

And by using the pointer I could pick out the best timing for any RPM.



The best ignition points make a curve that starts of very advanced and drops off as it starts making power and then there is an uptick in the past peak power area.

The shape of the initial big advance that then drops off to sensible values looks very much like the curve people have described to me for methanol.



Power trace using the developed ignition curve.

Using KW's at the crankshaft for the curve is my lazy way of accounting for loses in the drive train and indicating what RWHP should look like.

I will try this ignition curve as soon as I can get back to working on the 250 again.

[TZ350]

Two stroke Stuffing.

[husaberg]

The details of his inertia dyno is here.

Yep
Attachment 316720

Thanks!

All I did was tear out the windigs.
Attachment 316742
Attachment 316743
Attachment 316744

follows on from here.

[TZ350]

.



Ignition curve and performance simulation developed using EngMod2T.



Ignetec Ignition curve and dyno results so far.

More work to do to get rid of the bumps at 7k rpm and the lower rpm range. More advance and/or needle.

EngMod shows an advance bump at 7k rpm. I will try that.

When the timing is pretty much spot on I will try playing with re sizing the main jet.



I took a 100ml sample of my Methanol mix, 90% meth, 10% acetone and 30:1 oil.

I added 2.5cc of water to the 100ml in the jar and let it sit to see if there was any fuel separation. Looks good, no separation.

Water in Methanol greatly adds to its cooling and anti knock effect. Might try a batch of this brew in the bike next and crank up the advance.

When I am in the ball park with the ignition and jetting I will strip the motor and see what can be done about the balance factor and getting rid of that horrendous vibration.

[Vannik]

For those that are interested in a biography of Jan Thiel in English, send an email to:

So far we have received 83 emails from people that are interested in the English version and 22 for the Spanish edition.
We need at least 200 requests to start printing, so we have to wait a little longer... Mail to English@LegacyJanThiel.com for English prenotations

[Frits Overmars]

I've noticed that some people find it easier to work with lengths rather than angles. That is why I'm considering a graphic representation in which, instead of the various axial angles of the transfer ports, their positions and target points are expressed as percentages of the cylinder bore.
This may also be helpful in drawing the desired flow paths on a piston dome.

And here it is: the ability to draw transfer port positions and flow directions without having to use a protractor.

There is also a drawback: for ports close to the front and rear cylinder walls, for example the C-port, specifying position points by means of bore percentages is not as accurate as using angles. That is why I did not quote an optimum position percentage for the C-port.

[wobbly]

TeeZee , I see you are running the Turbulent Model in the Combustion page.
You only need to do this once , when all the Combustion related parameters are finalized , ie Ignition , Compression , MSV . You then redo it if any of these are changed.
Then save this as a new name and transfer all the Delay /Vibe numbers into your sim.
Run the Turb sim , open that iteration and its says Write New Combustion File , do that and save it with a new name then open that as an Existing File ( transfer it out of the project folder into Two Stroke ).
The Turbulent sim is god awful slow , as its recalculating all the values each time ,and Neels has recently made the sim speed way faster.

[porttiming124]

And here it is: the ability to draw transfer port positions and flow directions without having to use a protractor.

There is also a drawback: for ports close to the front and rear cylinder walls, for example the C-port, specifying position points by means of bore percentages is not as accurate as using angles. That is why I did not quote an optimum position percentage for the C-port.
Attachment 352436

Thank you Frits

[wobbly]

Frits , thought it might be helpful to add 33% as a nominal width of the C port as many people have no idea where to start with this.

[diesel pig]

Just an interesting factoid for those fiddling with butterfly things in the rear cone.
This setup was used in direct drive karts ( chainsaw engines ) many years ago but they had a simple fixed flat plate @ 50% area about 1/2 way down the rear cone - this was called a plate pipe ( funny that )
These were quickly replaced by the "new" technology of having a series of perforations spaced radially down the rear cone, within an enclosed muffler tube that was simply an extension of the mid section.
This methodology has been standard fare on kart pipes for 30 years.

Even today this is used in several direct drive International classes.
When it came to modelling the things in EngMod , the assumption ( wrong ) was that there were two functions involved.
Firstly was that as the bulk flow thru the pipe increased the effect of the holes gradually reduced , and the volume of the parallel " muffler " tube would resonate at a particular rpm , effectively then
making the holes disappear.
Thus the return wave was smeared out in amplitude at low rpm , reducing the effect of the pipe being too short down low, and causing the return wave to arrive at the port too soon.

But then a customer , working for the Tony Kart factory , bought the TFX system and it became clear this is not how it works. ( Frits is now using this same piece of gear ).
At low rpm the rightward wave is transmitted thru the perforations , and is reflected back , at a much longer TL by the flat plate at the end of the " muffler " tube - well past the rear cones exit hole.
Then at high rpm the tubes resonance effect overcame this , and the holes do virtually disappear.
Neels changed the code to reflect this new line of thought , and boom , we had way better correlation with the TFX results.

The system works unbelievably well , in situations where the crank is connected directly to the load - be that a wheel or a propeller.
And is KISS to the extreme.

Very interesting, It reminded me of a diagram of a kart pipe in bell's 2 stroke book but pulling out my old bell's book show that was all it was a diagram. Either he didn't know how it worked or didn't care. The fact it can be modeled in Engmod just makes me more interested in the program.

[Frits Overmars]

Frits , thought it might be helpful to add 33% as a nominal width of the C port as many people have no idea where to start with this.

Thanks Wob, you do have a point (pun intended). I must think of a way to incorporate a port width percentage within the position points approach.
Then again, the C-port has to fit between the B-ports rear position points, so there isn't much anyone can do wrong there.
Hopefully I'll get a brain wave. It's early days yet, and all comments are very welcome.

[wobbly]

I just thought that as you are proposing optimum port wall % crossing points , and the C port doesn't cross this line , having a reference % width is in essence the same thing when
its walls are parallel to the centerline.

[Frits Overmars]

I just thought that as you are proposing optimum port wall % crossing points , and the C port doesn't cross this line , having a reference % width is in essence the same thing when its walls are parallel to the centerline.

Yes it is. I just need to give some thought to presenting it clear and simple. The ability of some people to misread and/or misunderstand something is amazing .

[JanBros]

And here it is: the ability to draw transfer port positions and flow directions without having to use a protractor.

There is also a drawback: for ports close to the front and rear cylinder walls, for example the C-port, specifying position points by means of bore percentages is not as accurate as using angles. That is why I did not quote an optimum position percentage for the C-port.
Attachment 352437

so automaticaly a question pops up in my head :

optimum for what ? only absolute high revving power seakers or all 2-strokes ?

[Frits Overmars]

so automaticaly a question pops up in my head : optimum for what ? only absolute high revving power seakers or all 2-strokes ?

All two-strokes Jan. They will all benefit from depositing the fresh mixture where it is needed, while minimizing short-circuiting losses.