ESE's works engine tuner

[Norman]

Imagine it's a hot day, say 35deg outside. Out in the yard lies a steel crowbar and a wooden handled shovel; they've both been in the sun for hours so they are both around the same temperature. But you just know that the crowbar is going to heat your hands up a hell of a lot more than the wooden shovel handle which won't hurt at all. I think the coating might be like the wooden handle - very hot but with a low thermal mass and a relatively low capacity to transfer that heat.

I should also mention that any work involving a large crowbar is inadvisable regardless of the weather....

If you would use the Fire Brigade's water hose on the steel bar during the day I would think you can handle it as the wooden shovel. Conclusion: No ceramic duct coating, needs all the cooling possible, with coating the cooling of the duct becomes less critical, and also more cooling capacity available at other places, with addtional positive effects? Will be very interesting to get the final confirmation from the "B"-test.

[oldjohnno]

If you would use the Fire Brigade's water hose on the steel bar during the day I would think you can handle it as the wooden shovel. Conclusion: No ceramic duct coating, needs all the cooling possible, with coating the cooling of the duct becomes less critical, and also more cooling capacity available at other places, with addtional positive effects? Will be very interesting to get the final confirmation from the "B"-test.

I understand what you're saying but how cool does the duct wall have to be to transmit less heat into the gas than a much less thermally conductive and lighter (thermally) coating? I guess if we knew the thermal characteristics of the coating, the port wall and the gases it could be calculated or modeled.

[diesel62]

I understand what you're saying but how cool does the duct wall have to be to transmit less heat into the gas than a much less thermally conductive and lighter (thermally) coating? I guess if we knew the thermal characteristics of the coating, the port wall and the gases it could be calculated or modeled.

Will be interesting to see the results. I'm not sure a relatively short port wall and the mass and speed of the exhaust gas will actually see any temperature difference at all.

[wobbly]

I will be logging egt and deto level in acceleration testing at the same rate as the engine is run on track.
Its my opinion as well that a shorter duct ( thus longer header ) would indeed make the header temp react faster.
But is that what is needed.
As you exit the corner at well less than peak power rpm, a cooler pipe will for sure give a wider dynamic power range, and its thus my belief the duct should be longer
due to this effect.
I have already track tested this by in effect cooling the back of the spigot by allowing water right around the duct and up to the flange back face.
I also concurrently cut Aux ears right thru the spigot, so the drop in track time by 3/10s cannot be attributed to one or other of the changes directly.
The Aux ears did not affect low end power on the dyno at all, but on track the driver, and the datalogger said it hooked up and drove out noticeably quicker - as well
as the big increase in overev power the dyno showed conclusively.
The pic shows the ears, and the slots.The red line is the new duct exit being cast at the factory now for testing as well.

[Jannem]

That's an interesting question,

How are you going to test this? Under which conditions? Steady state? Dynamic? Laptimes? And which parameters of the engine do you plan to change during the comparison?

I suppose a very well cooled exhaust port transfers about 8 hp more heat into the coolant which should then raise an engine temperature of 40 deg to about 44 deg. So as a starting point, the engine with the well cooled exhaust has a disadvantage of about half a pony or so. The question is then, can you gain more than that by throwing advance and compression at it until the same level of deto is reached? Probably yes, but the engine might need a shorter pipe first. If you can also run leaner this should recover some of the exhaust heat.

Is it really desirable to have the pipe heat up as fast as possible? If the heat up characteristic matches the track and the gearing this could also give an advantage due to a wider dynamic powerband, couldn't it?

The more I think about it, the more parameters come to my mind. This seems like at least a full week of testing if planned and executed thoroughly. I am looking forward to the outcome!

Agree. With pipe tuned to stock port and focusing on the power below the curve, the pipe ought to be more out of tune with coated port. Heat loss to coolant is a power loss, but how do you turn the new conditions impacting several variables into advantage at desired rpm...

[wobbly]

My logic is that it will be a cumulative, but single cycle event.
Each time the port opens, hot gas will run over the ceramic surface and thus heat that - with no sink into the alloy and water behind.
Then, the reverse pulse will push air/fuel that has been affected by that surface temp back into the cylinder - on every revolution.
The variable of bulk water temp isnt an issue as every test starts at 45* and I have a PLC setup that keeps the temp within a 2* hysteresis range of that
during the dyno run.

[Jannem]

My logic is that it will be a cumulative, but single cycle event.
Each time the port opens, hot gas will run over the ceramic surface and thus heat that - with no sink into the alloy and water behind.
Then, the reverse pulse will push air/fuel that has been affected by that surface temp back into the cylinder - on every revolution.
The variable of bulk water temp isnt an issue as every test starts at 45* and I have a PLC setup that keeps the temp within a 2* hysteresis range of that
during the dyno run.

If the target rpm is below existing peak, the pipe (and bike gearing) is fixed, and even IF the intake charge would heat up less in the ex.duct because of the insulating properties (poor heat absorbtion) and low thermal mass of the coating, the out of tune pipe with raised ex. temp could hurt more that what would be the potential gain from the cooler charge. That's not even considering what an impact pipe heat up speed in transient situation would do.

Looking forward hearing what you'll find out.

[wobbly]

I had a midnight thought about the Ex duct coatings effect.
I remembered back to testing pistons coated with ceramic, the end gases in the squish band detonated instantly.
Thus it must be the boundary layer formed above the coating that is way hotter.
In the pistons case, this transferred enough heat into the trapped combustion mixture to cause formation of free radicals and then deto.
I can see in the ducts case, the boundary layer having plenty of thermal mass to enable overheating of the returning over-scavenged air/fuel charge.
We shall see.

[jamathi]

I will be logging egt and deto level in acceleration testing at the same rate as the engine is run on track.
Its my opinion as well that a shorter duct ( thus longer header ) would indeed make the header temp react faster.
But is that what is needed.
As you exit the corner at well less than peak power rpm, a cooler pipe will for sure give a wider dynamic power range, and its thus my belief the duct should be longer
due to this effect.
I have already track tested this by in effect cooling the back of the spigot by allowing water right around the duct and up to the flange back face.
I also concurrently cut Aux ears right thru the spigot, so the drop in track time by 3/10s cannot be attributed to one or other of the changes directly.
The Aux ears did not affect low end power on the dyno at all, but on track the driver, and the datalogger said it hooked up and drove out noticeably quicker - as well
as the big increase in overev power the dyno showed conclusively.
The pic shows the ears, and the slots.The red line is the new duct exit being cast at the factory now for testing as well.

We made a shorter duct + longer header at Aprilia around the time Roland worked there.
It was done trying to lower the water temperature.
It proved completely useless, on the dyno and on track.....
I also belief that the duct should be longer!
Probably a case of usual 'kart-madness' I think.
A lot of people in karting seem to suffer this 'sickness'
Constantly changing things that are already known for years
I still wonder why a ceramic coating was not tried the next day you were at TM.....
After trying your water-cooled flange first!

When I made my first 'ears', in 1996 I think it was, I first tested the cylinder without.
Took it off, had it CNC machined and saw the big improvement, 1 hour later.
And without losing anything anywhere!
After that I never looked back....

[wobbly]

I think the big issue was ( and will be for a while yet ) that even though I have the CAD files and are about to do the pipe testing for the
new homologation TM engine,Franco made it very clear i was not getting into the R&D or dyno testing areas.
He has many secrets, and said that my " micrometer eyes " would know all of them in no time.
No one and I mean NO one, gets to look inside the 10 factory sponsored TM kart engines at any time - on or off the track.
It surprised the hell out of me when he sent me a pic of a new CNC head insert with MY secret design - so maybe the ceramic test has already been done.
For sure no one outside the factory would find out about that anyway.
I just have to hope that I can build enough trust, once the pipe program is completed.

[Jannem]

I had a midnight thought about the Ex duct coatings effect.
I remembered back to testing pistons coated with ceramic, the end gases in the squish band detonated instantly.
Thus it must be the boundary layer formed above the coating that is way hotter.
In the pistons case, this transferred enough heat into the trapped combustion mixture to cause formation of free radicals and then deto.
I can see in the ducts case, the boundary layer having plenty of thermal mass to enable overheating of the returning over-scavenged air/fuel charge.
We shall see.

I definitely don't claim to know better, but it's an interesting thought exercise. Alternative cause for deto could be simply elevated combustion temperature after ignition, because heat loss path via piston top was blocked. That's a big part of the surface area of the combustion space and ought to have a noticeable effect.

[Peter1962]

I think the big issue was ( and will be for a while yet ) that even though I have the CAD files and are about to do the pipe testing for the
new homologation TM engine,Franco made it very clear i was not getting into the R&D or dyno testing areas.
He has many secrets, and said that my " micrometer eyes " would know all of them in no time.
No one and I mean NO one, gets to look inside the 10 factory sponsored TM kart engines at any time - on or off the track.
It surprised the hell out of me when he sent me a pic of a new CNC head insert with MY secret design - so maybe the ceramic test has already been done.
For sure no one outside the factory would find out about that anyway.
I just have to hope that I can build enough trust, once the pipe program is completed.

wobbly, have you been able to convince them to alter the design of their exhaust duct, or was that not open for debate ?

[jonny quest]

What's the largest carb size tried on the RSA125?

You settled on a 41mm, right?

What were the negative effects of carb size above and below the carb size used?

I have a hunch a smaller carb caused worse detonation in the mid range

[ken seeber]

Talking of exhaust mfg, here’s something of interest. It’s about a place in Italy (Elto Racing) that mfg the multi piece KZ style exhausts. https://www.youtube.com/watch?v=Da-g7LTsGWM

Have a look at this one and you can see they do a lot of exhausts for lots of customers, inc TM. http://www.eltoexhaust.com/en/

As to the rolling, where Elto use the 2 roll principle (steel top roll and urethane bottom roll), this joint supplies them. https://www.acrotechinc.com/art-of-bending/ A shitload better than mucking about with the 3 rolls and gets the rolling very close to the edge.

Maybe there is an opportunity for you ingenious & recourceful kiwi guys, other than sending up satellites. Over here in Oz, there is a saying in the karting industry: ”You can make a small fortune out of karting, as long as you start out with a big one”.

[Frits Overmars]

What's the largest carb size tried on the RSA125? You settled on a 41mm, right?
What were the negative effects of carb size above and below the carb size used?
I have a hunch a smaller carb caused worse detonation in the mid range

The RSA was run with 42 mm and 43 mm carbs. Most riders prefered 42 mm because they felt it was more responsive to rider input.
Worse detonation in some rpm range because of a carburetter swap will probably stem from a too-lean mixture in that range. I do not think there is a direct correlation between this leanness and the carb diameter. In any case, there shouldn't be.