ESE's works engine tuner

[koenich]

Great you enjoyed it and nice to meet you

Thanks for the flowers gents!

[yatasaki]

Here is a short report on the racing at Liedolsheim.
It's not too detailed, basically due to laziness and a lack of ability to make things interesting in written form.

I decided to take a look at this race after asking a very helpful person on here for info on different race options.
I was surprised to see a countdown with a small number on it, so off we go!

The race has been run since 1994, on a 1KM Kart track.
There are 3 classes, badly summarised here:

*Open 50cc
*Restricted 50cc (Aircooled, other stuff)
*125cc 4T "Stock"

There is the usual practice, qualifying etc. We turned up at just the right time, as the bikes were being rolled out to the dummy grid.
This was really cool, it was oddly familiar for me; basically buckets.
The classes are a little different but almost all of the bikes would have worked for NZ bucket racing. Likewise, NZ 50's and some 4T 125's would have fit here.

Le Mans start, always fun! This time uneventful, other than the slight jump with people running at the raising, rather than the drop of the flag.

Then, lots and lots of exciting racing.
There were about 6 teams showing really good early pace.
The fastest were really impressive but after the time wore on, and on, and on, it started becoming clear that there were two main contenders.
#29 and #91.
Other bikes were faster in a straight line and for short runs but these two really both had a lot of things working right.
The rider changes and refuling were done well, all riders were fast, they cut through traffic very well (and cleanly).

8 hours.
8 hours is a fucking long time.
That is 8 1-hour shifts on the bike, the teams have a maximum of 3 people.
I've done a 1 hour shift on a 50 before and it wrecked me pretty badly, It's another level (Respect!) to then go and do it twice more.

So, this kind of racing, the nerds can crunch some numbers on pace, time laps left etc.
It was amazing to see it was still a competitive race until the end!

Then there were beers, music and things.

Bloody good time, I met some cool people there.

Something that was really good was the lack of crashes, there were a few, I got a good eyeful of a decent highside- that was, picked, up, taped up, back out!

moto5.de has more info.

So, if you are reading this and are able to take a look next year; it is well worth it.

You should try MEC 24 hours in Kula, Serbia ..
We were holding 3rd place ten minutes before end ....than bracket of dellorto sha broke..
Ended fifth😔
How much performance you have to give for reliability 😎

[Gradella23]

Great you enjoyed it and nice to meet you

Thanks for the flowers gents!

congrats for your win Koenich!
may i ask which engine are you using? do you have some pics and some dyno curves?

I also won a 50cc championship this sunday in Italy, using my own components. I'd love to compare with other european competitors in the coming years.
We always race in short and slow circuits so I've been forced to privilege relatively low rpm usage, having peak power at 12700 with a nice overrev and some hp earlier in the power range, but I'm happy for the torque figures we see, 11,4 Nm at 12400 at the wheel is a good result after just 2 races and a couple of dyno runs.
Some pics of my cylinder here:

[Jan Van Hamme]

JVH, the 50mm duct is WAY too short - and yes Neels has put the 75% area guide in the code, and that is the result you get when pressing the duct exit radio button
when having input a 3 port.

Regarding your recommendations for the 3-port, I've now come up with 84 mm for the port and 28 mm for the transition piece.
I tried a bit today with the 3-port 190° version, but I can't get it quite right. That's entirely my fault, of course.

[Muciek]

Onboard vid from last Freetech 50 race in Poznan Poland. driver #51 Sebastian Jonker



And results.

[Peter1962]

Onboard vid from last Freetech 50 race in Poznan Poland. driver #51 Sebastian Jonker



And results.

That is some beautiful racing ! And a very nice racing circuit. Long sweeping corners, very impressive.

[DSE]

The waves are essentially the same. Waves moving through a gas are local compressions of the gas where the molecules are closer together.
Compare it to circular waves on the water surface when you throw a stone into a pond. You see that the wave tops move outwards from the point where the stone hit the water, even though the water itself does not move, which you can see by looking at what is floating on the water.

The difference between exhaust pulses and a trumpet sound is not in the nature of the waves, but in the way you can describe their behavior.
For the trumpet sound you can use acoustic rules. And I deliberately write acoustic RULES and not acoustic LAWS because they are not laws. Those rules are derived from gas dynamics laws, simplified with a lot of assumptions that are acceptable as long as the sound pressure does not exceed a certain limit.
The wave pressures in a two-stroke exhaust exceed that limit by a factor of over a thousand. So forget about acoustics when you are dealing with waves in exhaust systems.

Now you may remember where you read it Jan .

I would like to welcome Mr. Frits Overmars and ask a question....
I have been reading your posts on the French forum and here for a long time with interest, I wanted to know your opinion.
Mr. Frits Overmars, do you think there is a need to cool the jumper in the exhaust duct?
I made 4 exhaust duct options in the models, and somehow such a question arose by itself.
I'm still designing the cylinder blank for the kart motor.
It will be an engine without a gearbox. Please excuse me for possible errors in automatic translation into English.

[DSE]

These are 2 variants of the 3-channel exhaust channel.

[DSE]

The second option is a 3-channel exhaust window.

[DSE]

And this is the exhaust duct with a jumper

[wobbly]

DSE - forget the T port - its well proven the 3 port is superior and more reliable.
With the 3 port design, your bridges between the main and Auxiliary ports are too long - in a 54 bore I have tested every conceivable length and shape.
15mm from the port to the center of a hollow 1/2 moon entry shape is best, not a straight edge parallel to the bore or perpendicular to the duct centerline.

The port roof should be down at 25* - not the centerline.
The roof should then have a convex radius centered over the side port entries.
The floor should exit perpendicular to the bore , then radius down as a ski jump, so the main port area reduces , exactly where the side port entries are increasing the CSA.
Past the convex roof and floor radi, the duct should be kept dead straight, no radiused shapes that do nothing but increase the volume and area.

Why is the floor of the boost port way below BDC - this promotes severe tumbling turbulence off the piston edge - with no inner wall to the duct.
Also having the Auxiliary ports at the same timing as the main, destroys power everywhere, due to the big difference in the wave fronts path lengths to the header entry.

[DSE]

DSE - forget the T port - its well proven the 3 port is superior and more reliable.
With the 3 port design, your bridges between the main and Auxiliary ports are too long - in a 54 bore I have tested every conceivable length and shape.
15mm from the port to the center of a hollow 1/2 moon entry shape is best, not a straight edge parallel to the bore or perpendicular to the duct centerline.

The port roof should be down at 25* - not the centerline.
The roof should then have a convex radius centered over the side port entries.
The floor should exit perpendicular to the bore , then radius down as a ski jump, so the main port area reduces , exactly where the side port entries are increasing the CSA.
Past the convex roof and floor radi, the duct should be kept dead straight, no radiused shapes that do nothing but increase the volume and area.

Why is the floor of the boost port way below BDC - this promotes severe tumbling turbulence off the piston edge - with no inner wall to the duct.
Also having the Auxiliary ports at the same timing as the main, destroys power everywhere, due to the big difference in the wave fronts path lengths to the header entry.

Still, sometimes Google Translate turns the text into a secret script, sometimes you have to filter what it composes when translating written material.
I'll write to you later. Thank you.

[Frits Overmars]

Mr. Frits Overmars, do you think there is a need to cool the jumper in the exhaust duct?

DSE, I assume that your 'jumper' is what Wobbly calls his 'ski jump', the hump at the bottom of the exhaust duct. And yes, is there is such a hump. cooling it will be good.

Wobbly already commented on your exhaust drawings, so I will concentrate on your transfers. Contrary to what you have drawn, the A-ports should have larger axial angles than the B-ports. You may want to take a look at the 'leaning tower of Pisa' story below for both the axial and radial angles.

I also noticed that the inner radii in your transfer ducts, indicated with Ri, can be made be way larger than they are now; see the constant-radius inner radius in the A-duct drawing below.