ESE's works engine tuner

[TZ350]

Attachment 313065Attachment 313064

This exhaust port floor dam gave a very positive result on the dyno but the cylinder was written off before I could finish the experiment. An exhaust port floor dam is something I am defiantly going to include in my next motor.

We Know for a fact that on a 54.5mm stroke race engine lifting the Ex floor several mm made more power.
It was tested properly in a real back to back by Mr Thiel.
Blindly thinking lifting it more will automatically be better is a dangerous assumption, and could well end up like most assumptions
in just being an error waiting to be revealed.
Sure a longer stroke would need alot more, but how much has still actually to be tested properly.
TeeZee tested it on a cylinder that was a good one, he buggered that up in some way, then added a high floor or dam and made it better.
Not very conclusive or scientifically relevant to a non buggered up cylinder.

There was some talk about razed exhaust port floors.
This is Team ESE's attempt. Alloy insert shaped to the exhaust duct floor. Retained by screws and sealed with high temperature epoxy.
It worked well enough, certainly didn't have any catastrophic negative effects on performance like so many of our other out of the box ideas have done.
Was it better, yes it looked like it but hard no know definitively. It showed promise. If it was easy I would do it again.
The hand dug side ports worked out Ok too.
We eventually destroyed this cylinder trying to improve it, as you do.
The pursuit of one off special cylinders that take a lot of work were abandoned by the team as replicating them for other team members was not practicable.

[aljaxon]

As with all of the results gained from the black art of pipe design everything is a compromise and no free lunches are available.
To gain front side I would go with a slightly steeper single stage header say 4* with a two stage diffuser , making the second cone quite long and steep.
But 18* is very steep in any mans pipe design manual ,so I think shooting at that number is too limiting , if a smallish center section is deemed desirable.
Why the emphasis on a pipe with a narrow belly , this is only mandatory in old engine designs with lift shaft transfer ducts and no inner radius to keep the transfer streams on track,
away from the Exhaust port.

thanks for the reply wobbly, i appreciate your help. re the 18° i saw an r1 pipe design of yours on here with a last steep section of 24° and just dumbed it down a bit and plucked 18 out of the air. skip to last bit if you want to ignore my ramblings ***

re narrow belly, if i use the same angles as 125/200cc pipes my 25mm start diameter grows to 100mm or more. remembering your tz750 that wouldnt run well with 100mm
ive only just noticed this that smaller start diams grow much larger proportionatley despite using the same angles.
2t calc blair and frits suggest less than 3.5 x start diameter for the belly. this ensures that smaller start diameter pipes = lesser header diffuser angles.
to use the same angles on my 25mm my pipe will have a much larger pipe volume to cyl volume.
i need to research this.


******
it was messing with my head but then i looked at it this way. i start at 20mm smaller diameter than a 125cc pipe. and using the same angles i carry on always being 20mm behind. so a 130mid section on a 125 pipe i am 110mm. or if 130 is only for race bikes a 120 mid i am 100mm.

and im only 74.6cc's

so can i use the same angles?

[aljaxon]

with those angles i get a belly of 113.8. thats sticking to 32% 68% good or bad?


purely by searching through all this threads millions of pages and cherry picking stuff which is said to work well this is the pipe i'd love to build.
but i know how it works. in real life there will be one or two major flaws in the design which no matter of clever fancy ideas can override. still at 32% 68%

[Frits Overmars]

....2t calc blair and frits suggest less than 3.5 x start diameter for the belly.

I did? Damn, I really did. And it's only 45 years ago so it must be state of the art .

A belly diameter of 2.9 times the initial diameter was incredibly fat at the time. The predominant response was "He's crazy".
Oh well, that was also said when I preferred a large crankcase volume to a small one and a low compression ratio to a high one.




















​

[aljaxon]

about as up to date as me....

ive never seen anyone suggest that 4.5 x could work and thats what mine would be if i stuck to those angles.
ive only just realised that the 3x or whatever belly factor dictates smaller angles on smaller diameters. amongst other factors.
and thats why i previously quoted the belly factor as if it mattered because on all the calcs or software ive used it only refers to that as opposed to actual angles.

ive searched on here but cant find anything to tell me at what point too much pipe volume/cyl volume is bad.

i see it referred to on pipe dimension diagrams but no explanation.

i prefer low pressure nowadays. im on 5mg of ramipril.
maybe i could put some into my fuel tank?

[jonny quest]

Aljaxon, your center section doesn't need to be straight.

Put some taper in it to get the diffuser and tailcone angles you want.

[aljaxon]

yeah thanks johnny quest, ive noticed that looking at some of the designs on this thread

but that would be throwing yet another variable into an already cluttered mix.
im thinking my rear cone is steep enough for what i want?

but i will remember that for a future design.

its for a road bike where cruising needs more front end power and maybe a wider power band?

ive just made a turntable for my welder and am impatient to get a pipe designed so i can see how my welds will improve.

[wobbly]

Looking at extreme examples and taking those as useful guides is a doomed exercise. The R1 pipe design took 3 months of continuous simulation/build/dyno time to achieve what was the most powerful
current 125 race engine on the planet , the TZ750 had the worst port/duct geometry ever conceived and was instantly overscavenged at the drop of a hat by anything even approaching an aggressive pipe.
Both tell you nothing of any use in a somewhat properly designed small modern roadbike scenario.

Back to basics - a 24* rear cone , no matter how fat the pipe , is going to suppress overev in a small roadbike to the point that you would need to shorten the TL so much , all the front side will be lost.
If your porting layout is done somewhat properly then the 3 to 3.5 belly is just fine as with a long TL and the 32/68% points in place , then all the angles will be shallow by nature.

One of the lessons I have learned is that a very strong arbiter of a powerband fit for the end use , is a combination of Exhaust timing and TL that achieves superposition to increase power where its needed most.
There is an infinite number of combinations , but quite a narrow band of useful ones that achieve superposition at a chosen useful rpm.
The old guide of using around 192* of Exhaust duration also just happens to give a wider range of useful combinations.

Same with the intake tuned length , usually the 3rd harmonic is the most practical combination of length that will fit , and effectiveness.
But of course both these effects can only be compared in a good simulation code.

[JanBros]

A belly diameter of 2.9 times the initial diameter was incredibly fat at the time. The predominant response was "He's crazy".
Oh well, that was also said when I preferred a large crankcase volume to a small one and a low compression ratio to a high one.
​

and when you proposed a reedvalve in the top of the piston, they loved it

[Frits Overmars]

and when you proposed a reedvalve in the top of the piston, they loved it

Yeah, that was a great April Fool's joke

[Wos]

Al, it would be a shame if our paths parted in this way. But the aspect in which the FOS exhaust concept distinguishes itself most from other concepts is the determination of the initial diameters. And if those are too large in an existing cylinder, you have just two options: throw it away or apply an insert, like Wobbly just wrote. In almost all cylinders you can do that without changing their outer appearance.

Looking back at my contributions I found this picture of a KTM 50SX cylinder with a clearly oversized standard diameter, and of the same cylinder with an insert.
This picture is over ten years old and I posted it in KiwiBiker, Pit-Lane, Facebook and four other forums, so there has been ample opportunity to find it.
I know it's nearly impossible to check everywhere, but you must realize that it's totally impossible for me to tell every questioner where to find the answer to every question.
That is your own responsibility.
​Keep asking questions, but also do your own research so you won't have to repeat every mistake I and others have made in the past.
Attachment 353967 Attachment 353966

HELLO Frits,

Our Rotax 124 cylinder has a exhaust diameter of 41,5 mm🙃🤣

Welding is to risky as cylinders are hard to find and very expensive...

So we like to do a insert to reduce to about 35.

Please give us some advice

Which is best way to go and avoiding overheating of the insert.

Shrink ist in? Glue it with jb weld?

Which aluminium alloy for the insert?
Something like the diecast Alu of the cylinder?

Thanks Frits! 😀

Vielen Dank
Grüße

Wolfgang

[Frits Overmars]

Our Rotax 124 cylinder has a exhaust diameter of 41,5 mm. Welding is to risky as cylinders are hard to find and very expensive. So we like to do a insert to reduce to about 35. Which is best way to go and avoiding overheating of the insert. Shrink it in? Glue it with jb weld? Which aluminium alloy for the insert? Something like the diecast Alu of the cylinder?
Wolfgang

A very light shrink fit would be best, combined with some heat resistant glue if you wish. I'll leave the choice of material up to you.
But I have a different suggestion: if Rotax 124-cylinders are expensive and hard to find, you might think about using a modern kart cylinder.

[Wos]

A very light shrink fit would be best, combined with some heat resistant glue if you wish. I'll leave the choice of material up to you.
But I have a different suggestion: if Rotax 124-cylinders are expensive and hard to find, you might think about using a modern kart cylinder.

Thank you Frits

Think we try aluminium alloy with hi silicium, with equal heat behavior

The classic enduro reglementation Frits🙄.
Have to stay with watercooled

Are there aircooled modern available rotax in kart sports?

Job on the crank is done Frits, wobbly etc😃...3 mm less in diameter...radius for better flow😉👍

Frame is all complete ...waiting for rotax 124🤩

Grüße Wolfgang

[wobbly]

Frits is right , counterbore the cylinder with a light press fit - you dont need any glue , the insert will be located in the duct by the step and cant move outward as its retained by the flange face.
Been there done that , it works perfectly.
Edit , the insert can also be only welded around the exit face on a spigot type duct - I have done that as well with no issues.

[Wos]

Frits is right , counterbore the cylinder with a light press fit - you dont need any glue , the insert will be located in the duct by the step and cant move outward as its retained by the flange face.
Been there done that , it works perfectly.
Edit , the insert can also be only welded around the exit face on a spigot type duct - I have done that as well with no issues.

Thanks wobbly and frits

Light shrink or press fit will give best heat transfer👍...but only with small tolerances and perfect shape, when there is realy no gap between..

Other idea to use thermal paste in addition...it is ressistant up to 230 celsius degree...

Thanks again!👍

Grüße Wolfgang