ESE's works engine tuner

[motorbyclist]

Am I reading that right?

"Hotter engines are more efficient right up to when they seize"?

I wouldn't subscribe to that at all.

Material properties are one of our limiting factors for power output. A cool chamber sucks heat (ie, energy) out of the combustion gases - this heat is driving the pressure we use to extract work.

A hot chamber doesn't suck up so much energy from the hot gas. However, our materials (and manufacturing tolerances) dont allow us to exceed certain temperatures before things get too big and lock up (ie, seizes) or the parts weaken too much and fail. Another way to look at it is if we used a strong insulator for the motor instead of metal; this way no heat is added to the intake charge, and no heat is lost during power stroke (wiki "otto cycle" and "carnot cycle"). The only heat lost is through the exhaust gas.

Watercooling is better than air cooling because we can extract more heat; This allows us to release more heat and extract more power without material failure, even though we're shedding most of the energy through the radiator and not the rear wheel.

the motor being cooler is not the reason it's better - it's the ability to remove all the waste heat. In theory a hot engine will get more power from a given amount of fuel, but to trump a watercooled system the thing would need to be made of silicon or a composite like what they use for turbos (I forget the name of it)

[motorbyclist]

Depends on what kind of efficiency you are talking about, maximum work extracted from minimum fuel used (like, lean burn) or maximum power achieved from an engine and air consumed (as in, rich best power).

well seeing as improvement to intake volumetric efficiency is a primary way to improve power, I run on per unit fuel. My point was that while and air-cooled motor is more efficient than water, we can get away with stuffing more fuel into the watercooled motor without melting it and extract more power overall. The temperature of the cylinder isn't the reason it's better.

Have you seen the new direct-injected petrol motors? They can run ultra-lean by just injecting a little pocket of fuel around the spark plug and using the rest of the intake air to insulate the piston from the heat. This gives a great boost to efficiency by using the heat to pressurise the gas, rather than heating the coolant.


EGR is another technique that can theoretically improve fuel efficiency by charging the cylinder with inert gas that allows the same pressure at a lower temperature. However, this is used to reduce NOx emission usually at a cost rather than a benefit.

[TZ350]

..........A cool chamber sucks heat (ie, energy) out of the combustion gases.........A hot chamber doesn't suck up so much energy from the hot gas.........Watercooling is better than air cooling because we can extract more heat; This allows us to release more heat and extract more power......... even though we're shedding most of the energy through the radiator and not the rear wheel.......the motor being cooler is not the reason it's better - it's the ability to remove all the waste heat.......

Yes these things make sense to me........

And I can see what you mean now, that the temperature of the water cooled cylinder isn't the big reason it's better, it is an ability to shed waste heat that makes a cooling system better.

But in the interests of running a hot engine for the sake of thermal efficiency there must be a point where a hot cylinder and head along with the heating effect of compressing the incoming fuel charge during the compression stroke results in overheating of the fresh mixture and causes spontaneous ignition throughout the fuel charge.

Surely this inevitability of detonation must be the limit to how hot surfaces within an engine can be run.

And from previous investigations into ways of keeping the thermal energy from combustion out of the cooling system we looked at insulating materials like ceramic coatings and in a high performance engine they don't make sense, because of their inability to pass waste heat to the cooling system. Making insulators or low conductive materials regardless of their thermal strength prone to overheating at their surfaces.

But I can see them being useful in compression ignition engines and low powered IC units looking for fuel efficiency, particularly ones running on fuels with a high latent heat of evaporation like alcohol where you don't want the evaporating fuel to over cool the engine, or too much of the combustion heat to be lost to the cooling system.

Now that you have explained it to me, direct injection petrol engines look interesting, making less combustion heat but getting more power at the wheels because less energy is lost to the cooling system through the thick blanket of un-combusted air, now there is a good idea.

I had always thought in terms of ingesting as much air as possible and burning up every molecule of oxygen, but yours looks at making less waste heat.

......... hmm....... darn, now you have got me thinking about what could be done......

I have been finding out, how hard it is converting a good idea into something that works, like using a plenum to get around the restriction of a 24mm carb.

Well we might have to find out, direct injection may be the project for next year, after Taupo........

[Spearfish]

Yes these things make sense to me........


Direct injection petrol engines look interesting for the reason you have given but I doubt my ability to make one .......... hmm....... darn, now you have got me thinking about what could be done.............and would it work???

.....well we might have to find out, it may be the project for next year, after Taupo....

That would be an easy project....start with a diesel engine and convert it to petrol...

[Buckets4Me]

That would be an easy project....start with a diesel engine and convert it to petrol...

so how many 125 2 stroke air cooled diesels are out there ?

[bucketracer]

.

Ok....just because you asked........

[SS90]

.

Ok....just because you asked........

I am confused, does the plenum work or not?

[Buckets4Me]

I am confused, does the plenum work or not?

what you cant read ???

did you not see the graph ?

where have you been ?


what happened to your other posts ?

This one is the Plenum (blue line) compaired with a conventional side carb (red line) and both running with Buckets first ever chamber designed by himself, maybe not spectacular but not a bad effort either.

[TZ350]

I am confused, does the plenum work or not?

Not confused, asleep....... it was all published a page or two back.................

....I earn my living from developing.... AIR COOLED, TWO STROKE 125 (AND 140) CC CYLINDERS.....

Buckets efforts with Thomas's help compaires very well with your own work tuning 24mm carb, rotary valve, 125 air cooled 2-strokes.

The Plenum idea works but it's not finished, I think we can do better than 20rwhp..........

[TZ350]

The race is on to find a small capacity 2-stroke air-cooled diesel motorcycle engine........

Not a motorcycle engine but close:- The Junkers Jumo 205 aircraft engine was the most famous of a series of diesel engines that were ... http://www.enginehistory.org/Diesels/CH4.pdf

[SS90]

All very interesting.

Try not to take offense here TeeZee, but the confusing thing for me is, previously you tell us you had 21 Horsepower WITHOUT the Plenum, now you have 20 with, and, what is it, 17 without?

Why is that?

[TZ350]

Breadth for Mt Welly or Power for Taupo, roll-up...roll-up and takes yours pick..half a chance this has been covered before...

[SS90]

breadth for Mt Welly or power for Taupo, takes yours pick.........

No, what I mean is you seemingly had more power without the Plenum previously.....3 horsepower more it would seem.

I was wondering what the difference was, because from your previous posts, you showed a "how to" of getting 17 horsepower, with an old RG250 pipe, no porting, and just raising the compression and using an original piston and cylinder head.

this engine is considerably ported, thin single ring piston, squish head and so on, and with no plenum produces the same as an engine with essentially no engine work.

Thats what I don't understand.

[TZ350]

Maybe hp doesn’t tell the whole story.......you have always been very interested in the torque curve.....

Certainly the shape of Buckets plenum torque curve is better than the ones in your graphs for driving around Mt Welly......

Or has something changed with your thinking now????

[SS90]

No, nothing has changed in that respect, I am trying to follow this development process, and actually encourage you to see the Plenum through (believe it or not)

And, in all seriousness, I cannot see why you have actually lost 3 hp, after viewing the images of the cylinder that your son posted, and then seeing a massive power loss on the power curve you posted, compared to previous figures you have quoted, it seems to me that something is wrong.

That new cylinder should clearly be able to, at the very least, match the old cylinder for power. The exhaust you posted pictures of, according to you, with the plenum, makes 20hp, but with-out makes 17.

That is a head scratcher for me.

Do you have any clues as to why?