ESE's works engine tuner

[teriks]

Husaberg,
Not sure how to add the quotes you had.
But with the testing we have been doing, it seems that it is about 6 cycles before the mixture change effects the cylinder response. My son has a method of real time measurement of the glow plug wire resistance change, so in effect monitors the combustion chamber for rich or lean. If we have the engine running at peak and pinch the fuel line, there are 6 normal cycles before the plug monitor shows the change in cylinder conditions. Like wise when the engine runs lean and the servo richens the mixture, it is at least 6 cycles before the engine recovers, but to the ears sounds like almost instant.

Cool stuff!

One thing about the plug resistance measuring. The wire, although a very small mass with a lot of surface area, has a heat capacity and will need some time to react to the new conditions in the combustion chamber.
That may very well be the explanation to some of those six cycles lag you are seeing.

//Thomas

[Frits Overmars]

One thing about the plug resistance measuring. The wire, although a very small mass with a lot of surface area, has a heat capacity and will need some time to react to the new conditions in the combustion chamber. That may very well be the explanation to some of those six cycles lag you are seeing.

You do have a point there, Thomas. But we measured the time from main jet to combustion chamber in a spark-ignited engine via a different method and found about five crankshaft revolutions, so Lightbulbs six cycles won't be far off the mark.

[sonic_v]

Why not a short rod, better dwell, as the side load on the piston is not there, it's all taken on an oil feed guide under the piston. This (rod length) is more telling than any thing else, the spacer is almost cetainly to hold this guide (like a large valve guide) as the spacer is NOT needed for a long rod. Easy to seal off the bottom end. 199 exhaust timming I see. If the piston is not touching the bore any more can the exhaust port be wider? How wide before the rings become a problem? It's a pitty we still need rings!

There is still a side load on the piston but the cylinder bore is not carrying the load. The piston has two diameters with the lower part being the smaller diameter. This part of the piston carries the thrust force acting on the bore within the 30 mm plate.

I suspect the short rod is purely for packaging as opposed to any particular engineering reason such as longer dwell at bdc.

It is interesting that the homologation only quotes 1 exhaust port. Will not be surprised if this turns out to actually be 3.

This is unlikely to be remotely as clean - emission wise - as all the claims. The saving in lubrication oil is only a fraction of the unburned hydrocarbons from the fuel. At the one test point that they quoted - 5000 revs/min part throttle - the delivery ratio would be so low that very little fuel goes out of the exhaust port. As soon as the throttle is opened it will be almost as polluting as any other two-stroke without Direct Fuel Injection.

[Frits Overmars]

It is interesting that the homologation only quotes 1 exhaust port. Will not be surprised if this turns out to actually be 3.

I would be very surprised if any engine manufacturer would deliberately enter data that would make the homologation invalid.

As soon as the throttle is opened it will be almost as polluting as any other two-stroke without Direct Fuel Injection.

You seem to know the engine better than I do .

[Lef16]

Hey wob,
can you please explain us some basics about 2 stage header?
I think some hundred pages ago you said that a minimun header angle should be 3*.
But what applies for a two-stage header?
And one more,I think that a Honda-style exhaust pipe with the last diffuser been the steepest,could perform better on a street bike with compromise tranfers with small inner radi and without PV.
I'm bulding a pipe for my own bike now,and I think I should prefer this design over Aprilia's "more racing" design.
Cheers

[Haufen]

The only downside I can see to the new engine being CIK homologated is that now it will HAVE to be copied by all the
Italian factories or they will all go out of business .
But if its tied up in any worthwhile patent document, then no one CAN copy it, so karting at the highest level is doomed to a one make
class - good for the patent holder, crap for the sport and everyone else.

I think they will be allowed to copy it if they pay some fees to to the patent holder. But the patent holder has to agree, and the sum is negotiable. But we don't know what exactly has been patented, yet, and if that is responsible for the performance oder eg the emissions only.

I don't know much about the regulating body in karting, but what I read here was that they seem rather strict and eg don't even allow plastic inserts in the crankcase or something like that (Modena?). So, after that I can not come to think of how on earth they would homologate something like the ryger engine. Don't they know what they are doing to their sport in doing so?

[Haufen]

You do have a point there, Thomas. But we measured the time from main jet to combustion chamber in a spark-ignited engine via a different method and found about five crankshaft revolutions, so Lightbulbs six cycles won't be far off the mark.

Did you measure the number of cycles at different rpms, too? What was the influence of the engine speed?

[Frits Overmars]

Did you measure the number of cycles at different rpms, too? What was the influence of the engine speed?

We only measured at max.torque rpm. You don't want to spend too much time messing around with radioactive isotopes...

[Frits Overmars]

I don't know much about the regulating body in karting, but what I read here was that they seem rather strict and eg don't even allow plastic inserts in the crankcase or something like that (Modena?). So, after that I can not come to think of how on earth they would homologate something like the ryger engine. Don't they know what they are doing to their sport in doing so?

They probably want to make it more environmentally friendly .

[Haufen]

They probably want to make it more environmentally friendly .

yeah right they should switch to electric powered karts with solar charging then. From the ppm values I saw from the ryger engine, it is not as good as a four stroke, yet, let alone a four stroke with catalytic converter. (If a four stroke can be anything like "good", that is.)

For the radius at the top edge of the exhaust port a practical reason is that it would be quite difficult to get it perfectly tangential with the curvature of the cylinder bore. And for both the exhaust edge radius and the piston edge radius, making them completely tangential will not help the flow.
Both pictures below will show that a full tangential piston edge radius would take away so much of the edge that the ring groove would need to be relocated.
With the piston in BDC it would also create a deeper trough between piston and bore which would create turbulence instead of helping the flow cling to the piston crown. And when the piston is half-way in front of the port and the flow is bumping against it, that lower bit of tangential radius won't make a difference, whether it is there or not.
Attachment 314215 Attachment 314214

If you just radius the piston edge, you will increase the port timing and improve the flow. Improving the flow is fine; increasing the timing is not always desirable.
We could drop the cylinder until we have the same angle.areas as before the radiusing, but that does not take the improved flow into account.
What we really ought to do, is include the flow coefficient in the angle.area calculation. But that is beyond the scope of engine simulation programs like EngMod; it would require true 3-dimensional CFD.

By the way, thanks for the above explanation, I got it now. On the VHM website I saw a combustion chamber which was nicely shaped to follow the piston dome with the radiused edge. But that was a design which protrudes into the bore. So I think I can now safely try radiusing, too. Before I saw that picture, I was always afraid that the outside of the dome might distort and provoke detonation.

it would require true 3-dimensional CFD.

And with quite a fine mesh, too! Sometimes I miss all the tools I once had at my disposal. Did they use 3D CFD at Aprilia? Personally, I don't think that's necessary in race engine development, but it sure is a nice help in visualizing the scavenging (and, more importantly, visualizing the differences in scavenging between two variants).

[seattle smitty]

[QUOTE=Haufen] yeah right they should switch to electric powered karts with solar charging then . . . (QUOTE]


Alas, not funny. As California goes on regulatory matters, so eventually goes everybody else. And California's chief "expert" on these matters is a 70-year-old woman liberal-arts major and lawyer. http://www.bloomberg.com/news/articl...-auto-industry The actual title of the article features the words, "may end the auto industry as we know it".

[Lightbulb]

Cool stuff!

One thing about the plug resistance measuring. The wire, although a very small mass with a lot of surface area, has a heat capacity and will need some time to react to the new conditions in the combustion chamber.
That may very well be the explanation to some of those six cycles lag you are seeing.

//Thomas

In our initial testing this was the case. But my son managed to create a method of recording the resistance in real time to 4 or 5 decimal places . He can record in enough detail, that on every cycle we see what is happening in that cylinder. So he can measure engine rpm over any 6 to 10 cycles and be within 60 rpm of what the digital tacho shows. Although delayed in time , there is still thermal cycling . We can see this up to 32k rpm, we have not yet tested it at higher RPM yet. Other things that have been seen is lean of peak in a cylinder, where rpm remains the same , but the temp drops a very small amount. With glow engines, if the load changes or if you go just a fraction leaner, the temp just rises, and then the engine slows. I think it slows as there is insufficient energy to keep the power to the required level. Then rapidly heats with dramatic slowing. So he is working on a system that keeps it to the rich of peak without being confused with the lean of peak from the programming. There is a hall effect sensor to detect direct crank rpm and is the reference for tdc with an allowance for the lag time of the electronics. It also takes into account pipe pressure average and how that is interrelated to the in cylinder temp and mixture position. I will ask my son for a picture of the glow wire graph in the cylinder if he will let me and post when I can to show you. Neil

[Haufen]

yeah right they should switch to electric powered karts with solar charging then . . .

Alas, not funny. As California goes on regulatory matters, so eventually goes everybody else. And California's chief "expert" on these matters is a 70-year-old woman liberal-arts major and lawyer. http://www.bloomberg.com/news/articl...-auto-industry The actual title of the article features the words, "may end the auto industry as we know it".

I think as long as there is no major breakthrough in battery technology, the typical family car 50 years from now will be some kind of hybrid car powered by a small turbocharged combustion engine, consuming half or less of what it would with todays technology. And although I am a fan of highly efficient engines, I must admit that I don't understand the reason why and how CARB wants to regulate some things. (And the by-fact that that woman drives an electric Honda car gives me goosebumps :-D) But I think CARB was never interested in any kind of racing, so let's hope they keep it that way.

By the way, speaking of highly efficient engines, these two companies here are doing quite well with their two-stroke engines, already achieving better specific fuel consumption as todays state of the art diesel engines (whilst also complying with todays emissions legislations). Their application is more truck related, but I would for sure drive a two-stroke powered car, even if it meant that redline rpm would be at 3000 rpm

http://www.ecomotors.com/
http://achatespower.com/our-formula/opposed-piston/

[wobbly]

Re the bridges and lubrication.
I routinely add a couple of 1.5mm holes in the piston skirt , slightly offset vertically on each side of the main Ex port, to lubricate
small bridge areas.
Works perfectly.
Re 2 stage headers.
This is where using EngMod will tell you all you need to know.Your average 3.2* incl angle header will be easily beaten in power by a 2 stage
with something like 3.5/5.5* for 2/3 - 1/3 lengths from the piston.
Then if you look at the the diffusers action,and how the angles affect performance - the closer the steeper angle is to the header, the sooner in the cycle around BDC
the biggest depression will be made.
This deep pressure ratio point proportionally moves rightward as the rpm rises, thus its best efficiency range is biased toward peak and overev power.
Where the steepest diffuser is up near the mid section,the deepest pressure ratio occurs late in the cycle around BDC,thus having more scavenging efficiency at lower rpm.
If the ports are also biased to this bandwidth, then the two elements work synergistically and mid power is boosted dramatically at the expense of peak and overev.

[peewee]

husaberg i tried to add more material than i thought i would need so i could grind it down to a desired shape. after looking at the photo i think i understand where i went wrong. like the rsa photo i should start the oval to round transition inside the exh port so the transition will be less extreme. maybe more like this updated photo

lightbulb there is no exh valve on this engine but even if there were im not sure how much good it would do as i only plan to use it for drag racing. the transmission isnt a true close ratio but i think the engine will have enough power that the slightly larger gaps at each gear change wont matter much