ESE's works engine tuner

[Nath88]

Totally looking forward to hearing how your piezo sensor experiment goes. I have been trying to re map my CPU for all low throttle fully on pipe running in the hope I will be able to get a piezo sensor switch from you sometime to see if I can use it to switch between low throttle on and off pipe maps.

I did another test just free revving, signal output looks better than before, I'll do another road test this afternoon. The sensor follows the rise and fall of the overall pressure in the pipe, throws the cycle to cycle numbers off a bit so I'll add a filter to get rid of that. Hopefully a switch isn't too far off, putting the pressure on!

Current test rig:


A more general question, if the engine is 'clear' but it's blowing some blue smoke at low-rpm full throttle, is it too rich? Is there any harm in going leaner until the smoke clears?

[nitro2tfx]

A small aircooled twostroke(novarossi) Nitro blend engine(20%) runs best at about 90-105degree celsious.
But, you might need to run it a little bit lower in temp to still have some margins to piston meltdown

And guys!
Remember to setup engine for increases heats.
More gap on the rings, more tapered piston.
As all tempratures get´s higher the margin to when piston melts is getting closer.
And you do not want to have smeared aluminium all over the bore that increases blowby.
And thereby heats the piston even more.,,, aaaaaaand 'good night' as result.

You want more gap on the rings to have more margins to when the ring warps in the ring groove.
If it warps, it´s also 'good night' but often with nicasil pulled off the cylinder.

I recommend steelliner in cylinder with nitro.
Just because it can take some beating and still beeing able to use again.

If there is a particular reason to run 20% nitro or some other fixed amount, and you want the most power for that fixed nitro%, then run decent compression ratio, higher water temps, best air/fuel ratio and modify the engine to suit the heat. However, that's only true if you are deadset on getting the most power out of some set in stone nitro %.

If you are not deadset on the nitro %, then the easy way to get the same desired power and not hurt anything, is to drop the compression ratio quite a bit, lower the water temps, run a richer than ideal mixture, and increase the nitro %.

The fuel can be a fantastic coolant/engine saver, and dropping the CR a good bit drops the peak pressures back to where they already were on gas.

[tjbw]

Simple idea
V-2 with stepped pistons and isolated crancase, like Ryger or similar

60 years ago in Soviet union produced 2-stroke star engines, 23...500 hp range. They had good reputation.
Sorry for picture with russian comments, seems clear enough without translation.


Design with numerous exhaust pipes and transfer ports... A bit remind FOS

About 77 years ago Ransome Olds patented a stepped piston engine. Transfer ports link to an adjacent cylinder!

More recently Bernard Hooper, of Villiers, also patented a similar stepped piston engine. However neither of these patents resulted in production of stepped piston engines.
IIRC a prototype of Hooper's engine is on display at the National Motorcycle Museum near Birmingham UK

[tjbw]

Thank Norman, Frits and others. I found here many interesting ideas. We are small company which works like "engine atelier" for small aircrafts, UAV and other applicarion where weight and fuel economy are vital. To the moment numerous codes like ~bimotion ~mota ~Ricardo Wave ~Lotus concept
gives irreal results on boxer 2-strokes engines I produce. So one of my present objectives is to make parametric CAD model linked with CFD simulation of 2-stroke engine complete from intake to exhaust. I believe will sucseed in ~4+ month by myself and understand what have to be changed.

Did you try to model your engine with Engmod?
Quite a few here use it, though I'm not sure if it would need to be tweaked for altitude.

[peewee]

If you are not deadset on the nitro %, then the easy way to get the same desired power and not hurt anything, is to drop the compression ratio quite a bit, lower the water temps, run a richer than ideal mixture, and increase the nitro %.

.

that's the approach im going to take, lower com ratio and increase nitro %. since I just ride for fun theres really no reason to try and tune it to the breaking point with risk of hurting parts. got a couple richer needles on the way and a different cyl head for lower compression. 12:1 seems like a good place to start and see what happens. probly give it a go with one of them r7376 also.

[katinas]

Same operating conrod-free engine

https://www.youtube.com/watch?v=dwwvidC8CWo

In second video, he said that bigger engine 1600cc 45kg 200hp.

https://www.youtube.com/watch?v=_fuR3HLz-0A

Its very very precise and too much moving parts

https://www.youtube.com/watch?v=LboS59_0j1w

[Niels Abildgaard]

Yeah, I know the feeling.

Anyway, I wonder about a couple of things. I think the trailing cylinder will receive less mixture and do less work than the leading cylinder.
When the leading piston is about to close its transfer ports, the trailing piston is still moving downward, increasing the scavenging pressure in your common crankcase. But by the time the trailing piston closes its transfer ports, the leading piston will already have moved up quite a bit, noticeably lowering the crankcase pressure.

And to what extent will your scavenging depend on exhaust suction? A tuned exhaust needs strong primary pulses. Exhaust ports can provide these, because they open with a speed of about 1,5 x mean piston velocity. But exhaust valves, as shown in your drawing below, can't, because they open with an initial speed of zero.
Exhaust valves will also make it difficult to achieve sufficient blowdown time.area, unless you plan to stick to really low rpm numbers. But that would mean a low power-to-weight ratio, which is not desirable, especially not in a light aircraft engine.
Attachment 333083

It is not a nature law that two pistons in a V2 -twin shall be same diameter.Same mass and do same work yes.
The aircraft engine shown is directly coupled to airscrew where limit is ca 200 m/se tipspeed for noise reason.
Two grown up in an arcraft need 80 horsepower to go places and a propeller of ca 1.6m diameter.40 RPS OR 2400 RPM.
Piston speed is ca 12m/sec at take of rpms for aircraft engines be they small or big.We need a a stroke of 150 mm.
About 90mm bore looks nice and make 2 litre.
Two litre two-stroke at 40rps at pme 7.5 bar gives 80 horsepower.
My MZ301 (Kanuni) did 80000km unopened with me as driver at this power level.
BMW WW1 inline six engines was ca 15 kg/litre and worked sligthly harder.
If I can make a 2 litre/30 kg 80hp engine the sky will be ROTAX free

[Grumph]

It is not a nature law that two pistons in a V2 -twin shall be same diameter.Same mass and do same work yes.
The aircraft engine shown is directly coupled to airscrew where limit is ca 200 m/se tipspeed for noise reason.
Two grown up in an arcraft need 80 horsepower to go places and a propeller of ca 1.6m diameter.40 RPS OR 2400 RPM.
Piston speed is ca 12m/sec at take of rpms for aircraft engines be they small or big.We need a a stroke of 150 mm.
About 90mm bore looks nice and make 2 litre.
Two litre two-stroke at 40rps at pme 7.5 bar gives 80 horsepower.
My MZ301 (Kanuni) did 80000km unopened with me as driver at this power level.
BMW WW1 inline six engines was ca 15 kg/litre and worked sligthly harder.
If I can make a 2 litre/30 kg 80hp engine the sky will be ROTAX free

I've posted this elsewhere previously. It's the Martin jetpack engine based on CR500 Honda components.
Rumour has it that it's to be replaced by a small turbojet. I've got my hand up for one of the prototype engines....

But I'm not hopeful.

[jbiplane]

Did you try to model your engine with Engmod?
Quite a few here use it, though I'm not sure if it would need to be tweaked for altitude.

No, I tried expensive
Lotus engine simulation
and Ricardo Wave
Results too far of what we measure.

Probably cause our engines have very different of "moto" geometry and exhaust.
So I afraid Engmod will not give us some useful guidance. We are going to prepare full scale CFD
calculation from intake to exhaust.

May be anyone can share Engmod user manual or complete tutorial?
I hate ask for evaluation and be regularly advertized.

Same operating conrod-free engine

https://www.youtube.com/watch?v=dwwvidC8CWo

In second video, he said that bigger engine 1600cc 45kg 200hp.

https://www.youtube.com/watch?v=_fuR3HLz-0A

Its very very precise and too much moving parts

https://www.youtube.com/watch?v=LboS59_0j1w

Guys. Dont waste your time on "conrod free" like many factories in Soviet union
Step engines in different flavors should be much more sucsessfull.

[Frits Overmars]

drop the compression ratio quite a bit, lower the water temps, run a richer than ideal mixture, and increase the nitro %. The fuel can be a fantastic coolant/engine saver,
and dropping the CR a good bit drops the peak pressures back to where they already were on gas.

The nice thing about a low compression ratio is not only that the peak pressure remains decent, but also that this pressure does not drop so much during expansion.
So even with an unaltered peak pressure there will be a much higher average pressure pushing the piston down. You gotta love nitro, don't you?
Well, maybe not always...

[41juergen]

[QUOTE=jbiplane;1131069175]No, I tried expensive
Lotus engine simulation
and Ricardo Wave
Results too far of what we measure.

Probably cause our engines have very different of "moto" geometry and exhaust.
So I afraid Engmod will not give us some useful guidance. We are going to prepare full scale CFD
calculation from intake to exhaust.

May be anyone can share Engmod user manual or complete tutorial?
I hate ask for evaluation and be regularly advertized.

Don't worry, Neels is nice guy engineer... :-) he is more in technology rather than asking people to buy his (very good!) software...

[WilDun]

. You gotta love nitro, don't you? ............Well, maybe not always...

So where is the rider??

[Frits Overmars]

So where is the rider??

Cooling down, I guess. He probably won't be using nitro as a deodorant again any time soon.

[guyhockley]

Under the picture of the Hooper V4, the caption reads, "BERNARD HOOPER evolution of Poliakov engine". When their stepped piston prototype was announced back in their Norton Villiers days Hooper and Flavill said they were inspired by an earlier motorbike engine, not sure anything would have been known about Russian technology by the general public in those cold war days...
Anyway, I'm away from my computer at the moment, so couldn't just look it up. Went a-googling, didn't find the answer but found this
http://www.ac-aero.com/jet-a/
Thought this bit was interesting;
Maintenance.
Our technology eliminates most of the maintenance operations required with conventional two and four-cycle engines. Operating conditions in the crankcase of a stepped piston engine are very similar to those in a four-cycle engine. The copious supply of oil to the working parts minimises wear. However, blow-by gases, to which the bearings and the oil are usually exposed, are isolated above the piston step. Bearing corrosion problems, well known, especially in two-cycle engines, are therefore completely avoided.
In addition to these more obvious points, analysis of oil, taken from one combined cycle automotive engine, revealed that after 400 hours the lubricant was still within the specification for new oil. Normal degradation of the additives had not occurred.
In a four-cycle engine all of the oil passes at some time into the high temperature region adjacent to the piston compression rings and is then returned to the crankcase. Therefore in a four-cycle engine all of the oil is exposed periodically to temperatures well in excess of the degrading point of the additive pack. This causes the qualities of the oil to decline throughout the period between oil changes.

[Frits Overmars]

this engine had some problems with overheating pistons because no cooling from fresh mixture under dome.

after 400 hours the lubricant was still within the specification for new oil.
in a four-cycle engine all of the oil is exposed periodically to temperatures well in excess of the degrading point of the additive pack.

So those stepped pisons perished but the oil remained as new. I think I'd prefer it the other way round, with oil squirting upward to cool the pistons from the inside.
But what am I talking about; I don't even fancy stepped pistons, let alone use foul-stroke practices to keep them alive.