ESE's works engine tuner

[katinas]

At the moment it's proving that my exhaust duct ideas work. Despite the mild 190° exhaust timing, the pipe pulses are the strongest I've ever experienced.
Which is great, except that the torque dip at 2/3 of max.torque rpm is also the worst I've ever seen. We're working on that now, other activities permitting.

Frits, very interesting and glad to hear about your work results. Thanks.

Maybe this is not help, but simply one interesting idea about flow direction from transfers with two EX on opposite sides.

[husaberg]

At the moment it's proving that my exhaust duct ideas work. Despite the mild 190° exhaust timing, the pipe pulses are the strongest I've ever experienced.
Which is great, except that the torque dip at 2/3 of max.torque rpm is also the worst I've ever seen. We're working on that now, other activities permitting.

Is that resonance if you arre getting the stongest pipe pulse wont you also get the strongest interrupting wave also? or is it not at the right rev scale to be this.
I tried to find a 4T pic to map it out. also not sure if i am using correct term but its the dips you see on a power curve that repeat themselves at regular intervals

[lodgernz]

The difference is that the 40mm Lectron has a 36mm venturi behind the slide.
Thus at 1/2 throttle it acts like a 36mm carb, at WOT it acts like a 40mm carb.
The area change is even greater in a 30mm body as they use in 50cc racing.
At 1/2 throttle it has a 26mm venturi,giving 33% more velocity /fuel signal than a parallel bored 30mm carb.

Wobbly, I'm curious about the venturi behind the slide in the Lectron carbs.
Is it a smaller diameter, so the entire throat is reduced, or is it offset so it is only in the lower part of the throat?

[SwePatrick]

A question(or some questions)

As i have found out that my bike loves the heat in my dyno when i have forgotten to switch on the coolingfan,, yes i has happenened
And everytime when i forgot i set a dynorecord for my engine, it runs on 97% methanol and 3% Shell Advance Racing M oil.

So i drew this paralell, as i have studied methanol needs 64,7degree of heat to boil(or convert to steam) and petrol is variable depending on pressure(boil/steam point, i dunno the correct word).
I figured why not help it get there more quickly as it is a dragrace engine for short distance(1/8mile)
I need my power early in the race.
I have also found that when this happens it needs even more fuel, does it set the oxygen in the fuel free at above boilingpoint?
I can add more fuel with my powerjet when this happens and gain 3-4hp.

So why bother with this?
The engine revs ~13500rpm and make peak power at 13200rpm, this make me think there is very little time to make the fuel convert to 'steam'.

So i came up with this design:


As you can see i have deleted the waterpassages above the camber, but have added surface area next to the squish, to make this somewhat cooled in a small way.

Is there by any chance this will work?

Rgds.
Patrick

[Frits Overmars]

Is that resonance if you arre getting the stongest pipe pulse wont you also get the strongest interrupting wave also? or is it not at the right rev scale to be this. I tried to find a 4T pic to map it out. also not sure if i am using correct term but its the dips you see on a power curve that repeat themselves at regular intervals

I'm not sure if I understand what you're saying Husa, so I'll just write my own eludication.

If the initial pulse entering an exhaust pipe is stronger, so will be all other pulses in the pipe, that is correct. Foul-strokes can show a number of power curve ripples along the rpm scale, usually caused by higher harmonics in their inlet and exhaust systems. But on a pipe-dependent two-stroke there is one big 'dip' at 2/3 of max.torque rpm, caused by the returning pipe pulses arriving back at the cylinder before the appropriate ports are closed by the piston.
The stuffing pulse arrives when the transfers are still open, pushing the fresh cylinder contents back into the crankcase. Next, that stuffing pulse is reflected at the open exhaust port as a suction pulse that sucks whatever mixture was left in the cylinder, out of it, so there will be hardly anything left to ignite. This causes the torque dip at 2/3 of max.torque rpm. And since my cylinder produces beautifully strong initial pulses, the torque dip looks like an abyss.

Of course we tried the usual remedies. There are no exhaust power valves because they would mess up my beautiful exhaust ducts and ditto cooling system.
Water injection or trombone pipes would probably work, but that would be too much effort for now. Besides, it would violate my KISS-principle.
Raising the compression ratio might help a bit but I don't want to make modifications that can't be permanent (the present low comression ratio will be an important factor in achieving power).

Advancing the ignition timing to well before TDC leads to an early onset of combustion and a high expansion rate between the end of combustion and the beginning of exhaust opening. Therefore the spent gases will be cooler when they exit the cylinder, and they'll carry less energy with which they could create chaos.
But in our case even 35° ignition advance wasn't enough to solve the problem. Which makes me think that it's not only the pulses that create a mess, but also the gas flow itself, moving to and fro with a Helmholtz frequency that has the same effect as those too-early pulses.

Next step: cutting the end cones completely off and see what that does to the dip. When we start the engine, you might be able to hear it down under...
If that works, we'll try to recreate proper expansion pipes, using my variable end cone exit.

[husaberg]

I'm not sure if I understand what you're saying Husa, so I'll just write my own eludication.
If the initial pulse entering an exhaust pipe is stronger, so will be all other pulses in the pipe, that is correct. Foul-strokes can show a number of power curve ripples along the rpm scale, usually caused by higher harmonics in their inlet and exhaust systems. But on a pipe-dependent two-stroke there is one big 'dip' at 2/3 of max.torque rpm, caused by the returning pipe pulses arriving back at the cylinder before the appropriate ports are closed by the piston. The stuffing pulse arrives when the transfers are still open, pushing the fresh cylinder contents back into the crankcase. Next, that stuffing pulse is reflected at the open exhaust port as a suction pulse that sucks whatever mixture was left in the cylinder, out of it, so there will be hardly anything left to ignite. This causes the torque dip at 2/3 of max.torque rpm. And since my cylinder produces a beautifully strong initial pulse, the torque dip looks like an abyss.

Of course we tried the usual remedies. There are no exhaust power valves because they would mess up my beautiful exhaust ducts and ditto cooling system.
Water injection or trombone pipes would probably work, but that would be too much effort for now. Besides, it would violate my KISS-principle.
Raising the compression ratio might help a bit but I don't want to make modifications that can't be permanent (the present low comression ratio will be an important factor in achieving power).
Advancing the ignition timing to well before TDC leads to an early onset of combustion and a high expansion rate between the end of combustion and the beginning of exhaust opening. Therefore the spent gases will be cooler when they exit the cylinder, and they'll carry less energy with which they could create chaos.
But in our case even 35° ignition advance wasn't enough to solve the problem. Which makes me think that it's not only the pulses that create a mess, but also the gas flow itself, moving to and fro with a Helmholtz frequency that has the same effect as those too-early pulses.
Next step: cutting the end cones completely off and see what that does to the dip. When we start the engine, you might be able to hear it down under...

Thanks for the explanation.
Atac chamber is in keeping with KISS
Farmaken did a nice one

[Frits Overmars]

Thanks for the explanation. Atac chamber is in keeping with KISS

Yes, more or less, and we seriously thought about it, I'll give you that. But it too would mess up my exhaust ducts.

[husaberg]

Yes, more or less, and we seriously thought about it, I'll give you that. But it too would mess up my exhaust ducts.

mount it further back

So this is where I am up to so far, Butterfly valve seems to be a long way from the header ID so plan B is to make up a spool valve like a Yamaha power valve and fit it in the same place as the collar which is currently on the header so that the OD of the spool is flush with the header ID when closed .
Attachment 263880Attachment 263879Attachment 263881

Hi TZ, ran the ATAC this weekend - hard to know how much difference it makes but does seem to work

Cows are dry, that means more time in the shed

Here is the latest version ; using a jaycar frequency counter/switch to drive a R1 servo motor to operate the spool valve on the header pipe

Using a DPDT switch mounted on the servo to reverse the motor - unless someone can point me at an electronic limit/polarity switch to make use of the servo`s in built potentiometer ??

[Frits Overmars]

mount it further back

Thanks Husa, I'd just started looking for 'Farmaken'. I'll keep it in mind.

[husaberg]

Thanks Husa, I'd just started looking for 'Farmaken'. I'll keep it in mind.

closer would be better, but the spool valve can go close,closer, than a butterfly, hondas atacs were never that close anyway its only an idea to see if it can be tuned out without running manx norton style megaphones. or should that be 50's DKW's

[Frits Overmars]

...it's only an idea to see if it can be tuned out without running manx norton style megaphones. or should that be 50's DKW's

It must have been before your time, or you wouldn't ask Husa. A Norton Manx would have been blown off its stand by a DKW.
During the 1998 Centennial TT I was in the pit lane, at least 20 meter behind a DKW. The pulses coming from its megaphones hit me in the chest, taking my breath away. And you could hear it go all around the circuit, no matter how much other traffic there was.

[Michael Moore]

I recall reading an IoM article in Motorcycle Sport magazine, late 1960s/early 1970s, where for some reason the racer put megaphones on his Yamaha 2T twin. I think there was some surprise that they apparently worked OK, for certain values of "OK".

[karter444]

Hi Wobbly
can i presume that all other things being equal a barrel with the aux exhaust port passages ground out wider all the way into the exhaust manifold will produce more power than one that hasnt been extended
cheers Richard

[Haufen]

I'm not sure if I understand what you're saying Husa, so I'll just write my own eludication.

If the initial pulse entering an exhaust pipe is stronger, so will be all other pulses in the pipe, that is correct. Foul-strokes can show a number of power curve ripples along the rpm scale, usually caused by higher harmonics in their inlet and exhaust systems. But on a pipe-dependent two-stroke there is one big 'dip' at 2/3 of max.torque rpm, caused by the returning pipe pulses arriving back at the cylinder before the appropriate ports are closed by the piston.
The stuffing pulse arrives when the transfers are still open, pushing the fresh cylinder contents back into the crankcase. Next, that stuffing pulse is reflected at the open exhaust port as a suction pulse that sucks whatever mixture was left in the cylinder, out of it, so there will be hardly anything left to ignite. This causes the torque dip at 2/3 of max.torque rpm. And since my cylinder produces beautifully strong initial pulses, the torque dip looks like an abyss.

Of course we tried the usual remedies. There are no exhaust power valves because they would mess up my beautiful exhaust ducts and ditto cooling system.
Water injection or trombone pipes would probably work, but that would be too much effort for now. Besides, it would violate my KISS-principle.
Raising the compression ratio might help a bit but I don't want to make modifications that can't be permanent (the present low comression ratio will be an important factor in achieving power).

Advancing the ignition timing to well before TDC leads to an early onset of combustion and a high expansion rate between the end of combustion and the beginning of exhaust opening. Therefore the spent gases will be cooler when they exit the cylinder, and they'll carry less energy with which they could create chaos.
But in our case even 35° ignition advance wasn't enough to solve the problem. Which makes me think that it's not only the pulses that create a mess, but also the gas flow itself, moving to and fro with a Helmholtz frequency that has the same effect as those too-early pulses.

Next step: cutting the end cones completely off and see what that does to the dip. When we start the engine, you might be able to hear it down under...
If that works, we'll try to recreate proper expansion pipes, using my variable end cone exit.

If your engine is not able to overcome the torque dip alone, why not help it a bit? Rev it into the current max. rpm, then shift a gear or two down and see what it is capable of when in the powerband. Another way would be to use the clutch. Quickly done, and helps with finding the reason for its behaviour, too (besides the smile the result might put on your face).

[guyhockley]

Frits, would it be worth trying perforated end cones a la 100cc kart pipes before cutting them off completely?