ESE's works engine tuner

[JanBros]

@ Frits :

a spreadsheet is so much easier than calculating again and again, and you can see the pipe change with different data which is more efficient than numbers that change. And with a click you can compare different pipes.

It should contain your latest version (0.34/0.32/0.08/0.26 L factors) and your drawing is included, as is Wobbly's duct.

I will add your accompaning text ;-)

[Frits Overmars]

Jan, my main objection was that not everybody keeps the concept updated. Did you also catch the "D5=3,1 * ...." ? That was my most recent adjustment.

[JanBros]

Did you also catch the "D5=3,1 * ...." ? That was my most recent adjustment.

indeed , I did

[Frits Overmars]

the greater the bmep, the higher the mass gas flow thru the engine (delivery ratio) thus a bigger stinger is needed to maintain the optimum pipe residual pressure.

The greater the BMEP, the higher the mass gas flow per revolution through the engine. Past max. torque_rpm the BMEP and the mass flow per revolution will drop,
but since the revs are still increasing, the mass flow per second can still increase, together with the power. Hence the direct connection between crankshaft power and restrictor area in my exhaust concept.

The bigger the stinger, the better the power is in the lower mid range, as the reduced back-pressure reduces the pipe's efficiency when the return wave comes back too early.
This is what is needed in MX , so the road racing smaller stinger would not be optimum.
A TM kart engine makes 2 Hp more at 9,000 with a 24mm stinger, but makes 2 Hp more at 13,500 with a 22.8mm insert nozzle in that same pipe. Nothing is close to a free lunch.

You're right, of course. And even on the Aprilia RSA, with all those goodies that you're not allowed to use on a kart engine, like electronic power valve, pulsed power jet and 3D-ignition timing, a less restrictive restrictor could have its use. That is one reason I designed the restrictor-bypass shown in the drawing below (the other reason was to avoid high-rpm part-throttle detonation). But Jan Thiel retired before it could be put to the test.

How the hell can a simple spreadsheet accommodate all those variables - it cant, obviously.

It can't, and it's not supposed to. Like I wrote, it's just a simple concept, meant to help beginning tuners on their way.

[jasonu]

Anyone made front fork tubes with 4130 Chrome molly tube. There is some 3 mm wall thickness stuff for sale which looks promising. The 1964 Duke I'm working on has 31.5 mm tubes and new are US$500 plus postage !!! Only found one supplier so far. Next option is to bore the fork legs out to 32 mm and use a GN125 set. .

Option B sounds easier and more likely to work.

[wax]

Is there an optimal pressure in the pipe. My thinking is can we then make a bellows that opens and closes the stinger diameter to allow you to maintain the perfect pressure.. I understand that what you were looking at Frits but im talking about having it constantly adjustable

[F5 Dave]

Was to suggest fed from Det counter but that would be way to late for a mechanical device to react I guess.

Didn't TZ try a midpipe solenoid bleed? Or did I dream that? No there's a picture in my head.

[wobbly]

You dont want " constant " pressure in the pipe.
Jetski racing uses a very large stinger , to get a very low residual pressure at low rpm that pumps up the midrange power.
Then using PWM or rpm switches they turn off solenoids that allows high pressure water to dump into the stinger , squeezing down the effective area , and thus increasing the pipe back pressure around peak power.
This works really well.

[Ocean1]

You dont want " constant " pressure in the pipe.
Jetski racing uses a very large stinger , to get a very low residual pressure at low rpm that pumps up the midrange power.
Then using PWM or rpm switches they turn off solenoids that allows high pressure water to dump into the stinger , squeezing down the effective area , and thus increasing the pipe back pressure around peak power.
This works really well.

You'd probably want to be up front somewhere before pulling that trick on a bucket though, eh?

[wax]

You dont want " constant " pressure in the pipe.
Jetski racing uses a very large stinger , to get a very low residual pressure at low rpm that pumps up the midrange power.
Then using PWM or rpm switches they turn off solenoids that allows high pressure water to dump into the stinger , squeezing down the effective area , and thus increasing the pipe back pressure around peak power.
This works really well.

Thanks Wobbly i know I will always get a good response from you. Yes i inject water in to my stinger to try and get more top end. I was thinking about trying to regulate that by pressure in the pipe , had you come back saying yes you need this pressure

[SwePatrick]

Stinger diam.

I´ve seen in simulations and in my dyno that a stinger that is 'correct' for peak power is almost always to small for a wide powercurve.
Well,,that is a known fact.
But the losses vs gains is so small with having, say a 250cc engine single cylinder that needs a 25mm stinger to reach maximum peak power, it will loose like 1hp at peak and gains 4-5hp in midrange if having 26mm stinger.

I choose the later.. more torque is good.
When having a very peaky engine one has always a 'dead' engine before hitting powerband.
And almost always when looking in my dynodata, i see more average power in used powerband with the later example.

[jbiplane]

I find this description on Ecotron site

2-Stroke Small Engine Fuel Injection kit is designed to run 2-stroke small engines. This kit can drive 2 injectors per cylinder (one big injector, one small injector). During idle, and low part loads, ECU only opens the small injector for small fuel quantities; it will switch to the big injector for mid, or mid-high loads; and it will activate both injectors at WOT conditions. The transitions between the injectors are transparent to the driver and they are so smooth that the driver can not feel it. This setup controls the accurate AFR (lambda) from idle all the way up to 16000RPM. We have a

The whole idea of 2 injectors (one small, one big) is based on the need: 2-stroke engines have only half the time to inject fuel compared to 4-stroke (360 vs 720 degrees), and the 2-strokes usually (esp. high-end engines) have such a wide range of RPM (2000 - 16000rpm, for example). One injector is not able to cover the whole RPM range, simply because every injector has its physical limit: the fixed flow rate. If you use a big injector to cover the high end, then you will have too-rich idle. If you use a small injector, to have a good idle, then you don't have enough fuel for WOT. Given a certain inject flow rate, you can only run an engine either at low RPM range or high RPM range, but not both (from 2000 to 16000rpm).
For example, an engine runs at 16000rpm, you only have max 3.75ms time-window to inject fuel. In this short time, you have to inject enough fuel for WOT conditions. If you pick a super big injector, you will not be able to run idle (too rich even at 1ms pulse width). So what can you do? add more injectors. At low load, use one injector, and at high load/high RPM, use 2 or more injectors. That's why you see a lot of racing engines have 2,3, or even 4 injectors per cylinder. Our system is better: while others use the same size of injectors, we use one small, one big injector. Why? because at idle, you need a very small size of inject, and at WOT, you need a big size. The benefits: you can run the engine at ideal AFR over the whole wide range of RPM, with only 2 injectors (again, save cost compared to 3 or 4 injectors). The tansitions from idle, to WOT, will be: the small injector works at idle, low load; then it switches to the big injector at mid-high load (the small one shuts off); then at WOT both injector works together. And all these are made transparent to users!
This is our unique technology for 2-strokes, not even big companies have this.

I want to implement same or similar in my EFI. Is this specs rational enough or someone advice corrections?

[TZ350]

I find this description on Ecotron site. I want to implement same or similar in my EFI. Is this specs rational enough or someone advice corrections?

Yes totally on the money but only half the story.

Ecotrons use the Alpha-N topology for their 2S fueling map and it works well on 2S's that are not very pipe dependent like 250cc Enduro bikes but Alpha-N does not support high performance 2S's like GP125's where they make a lot of power through clever use of their pipe.

Because Alpha-N is a fixed pre determined fuel squirt amount for every TPS vis RPM cell on the MAP. This only works half the time for a high performance GP engine because AN cant be both correct for when the engine is on the pipe and when it is not.

I use the 10/10 concept. Anything less than 10,000 RPM and 10 bar BMEP is probably possible with an Ecotrons but anything making more than 10 bar BMEP and 10,000 RPM needs something more sophisticated for their fuel mapping. Having said that, in my experience Ecotrons will fuel accurately to 13,000 rpm on WOT but the problem arises when you throttle off and the pipe resonance collapses. AN fueling can't cope with the change in air flow.

My current EFI 2S efforts are aimed at solving this and am looking for ways to see the actual changes in airflow through the crankcase. Currently I am looking at the difference between maximum and minimum crankcase pressure and how it changes when the engine gets on or comes off the pipe.

[peewee]

hey guys I did a lot of pencil work and made a 2d drawing to scale so hopefully I can get it right or mostly right the first time . based on port area at the bore and spigot ID, ill have a 35mm x 43mm oval half way down the passage which will transition toward a round 36mm spigot exit. I chose 35 x 43 because I think that will be the best compromise with least amount of welding inside the passage so the cyl skirts have less chance of warping. aux ears will carry on to 10mm before the spigot entrance at which time it will be fully round passage about 38mm ID then go through the spigot to 36mm at exit. im ready to start cutting and welding now but something I recently thought of, since the duct and outer water shell will be so long I have to first check with the local machinist and be sure he is able to machine the top and bottom decks and bore it without any interference of it sitting flat on his machine table. I hope this isn't the case but other wise I may have to make the whole duct assembly removable with bolts near the half way point and that will be a real pain in the ass

[jbiplane]

Ecotrons use the Alpha-N topology for their 2S fueling map and it works well on 2S's that are not very pipe dependent like 250cc Enduro bikes but Alpha-N does not support high performance 2S's like GP125's where they make a lot of power through clever use of their pipe.

Thanks for valuable comments. Will try follow your ideas!