ESE's works engine tuner

[husaberg]

My wife is going a couple of days to her sister, then I will do it.....
At least if more than 1 person is interested!

Keener than kernel mustard's potato peeler

[ief]

Interested as well (offcourse) but what I'm even more interested in is... how much of it was thinking/ calculating/ theorising and how much just try and see what came out of it.

My feeling is a lot of the latter with gut feeling as a precursor? (witch comes back to thinking/ calculating and theorising I guess )

[F5 Dave]

Alternatively if you've picked up any tips for making the perfect PadThai

. . , sorry, its coming up to lunchtime and I'm hungry.

[ief]

Dave, you are a funny one

[jamathi]

We are many that will love to read a short step describtion of going from 46 to 54 and I will like very much to hear how a Jan Thiel 125ccm engine would have looked with freedom and money no problem.Pure phantasy.
Please?

How can I upload drawings and pictures?
That would make it a lot more interesting.

Why is it so complicated?
I downloaded this with pure luck, don't know how I did it
Now I finally understood|

[jamathi]

Interested as well (offcourse) but what I'm even more interested in is... how much of it was thinking/ calculating/ theorising and how much just try and see what came out of it.

My feeling is a lot of the latter with gut feeling as a precursor? (witch comes back to thinking/ calculating and theorising I guess )

Of course I read a lot of books and articles about 2-strokes.
And saw a lot of what other people were doing.
A flow bench was very helpful too.
And a lot of thinking, not much calculation, except for exhaust pipes.
So first you think, and later have to try to see if what you thought works......
It is really not just try and see!

[husaberg]

How can I upload drawings and pictures?
That would make it a lot more interesting.

Seems I finally found out!

Is it true that you had to design the cylinders arround existing pipe designs as these were initially not allowed to be changed?

[jamathi]

Is it true that you had to design the cylinders arround existing pipe designs as these were initially not allowed to be changed?

I started working with an existing engine, a ROTAX, with an existing cylinder and exhaust pipe.
During the year dozens of different exhaust pipes were tested.....
The original Rotax A duct was something like this....

[jamathi]

I started working with an existing engine, a ROTAX, with an existing cylinder and exhaust pipe.
During the year dozens of different exhaust pipes were tested.....
The original Rotax A duct was something like this....

A Dutch friend of mine, Thijs Hessels, had improved the original cylinders by epoxying the outside curve, and giving the mixture a more upward direction.
His private Aprilia proved faster than the 'works' bikes.
The Aprilia racing boss, Jan Witteveen, demanded that Thijs should give those cylinders to him.
Otherwise Thijs would not be able to get any more spare parts for his bike!!
With this modification a ROTAX cylinder gave 46,5HP instead of the normal 44.
This happened in 1994, a year later I started working for Aprilia.
They were still epoxying ROTAX cylinders, but had decided to make their own cylinder.
The development of this cylinder was to be my work.
This cylinder was called the APC, and was destined for all 125 and 250 private riders.
It gave the same 46,5HP, but of course without epoxy.
I got the oldest dyno there was, and had to learn to use the computerized system.
As I had never touched a computer before it was not so easy.
But I quickly learned, the system was very precise and repeatable.
I was given the casting models and had to go to the foundry to have some cylinders cast,
While waiting for the castings to be machined I worked with ROTAX cylinders.
I won some power by making the auxiliary ports bigger, but they were already too high I thought.
So I made sure the APC cylinders had lower auxiliary ports, and I also filed their sand cores to make the exhaust duct a lot smaller, as I had already, successfully, tried on some ROTAX cylinders.
There were some small mistakes in the casting models, they were quickly corrected.
And then real development could begin!
I started by making the B-ports and ducts as wide as I could, and this improved bottom power, without losing at the top.
And I had one casting with a narrower C-port, made by filing the sand core.
Here the B-ports could still be made wider, and it proved to be the best cylinder of the lot.
So we got to 48HP
We also bought a lot of dentist tools and burrs, and a filing machine.
And a flow bench.
Power improved by making the auxiliary ducts longer, and wider.
But at a certain point we made a hole, ending up in the cooling water space!!!!
To cure this the casting model had to be modified.
I also had a wooden model made for use on the flow bench.
To determine the best size of the auxiliary ports and ducts.
They seemed to 'like' having a downward angle.
The casting model was modified in this way, and so we reached 49HP.
I decided to try to make te exit of the exhaust duct, and the flange, a bit wider, and won another 0,6HP
Take a look at the photo if I succeed to attach it.

[Grumph]

Some time back, I commented in response to pics Frits had posted, that after looking at pics of the early Rotax engine as tested by Cycle magazine with the race kart barrel, the differences were subtle. Visually they are very much the same layout - but obviously the devil - and the time - is in the detail.

I'm curious as to the manufacturing/design process. After establishing what the new parts for next season would look like, were the hand made prototypes turned over to a draftsman for copying ? Or was it a process where you and a designer collaborated with you saying what was wanted and them specifying casting details and flange thicknesses etc ?

Locally we've had the example of John Britten where he laid out in a general way what he wanted in the engine - and basically the guys making it made the decisions from there....

Greg

[jamathi]

Some time back, I commented in response to pics Frits had posted, that after looking at pics of the early Rotax engine as tested by Cycle magazine with the race kart barrel, the differences were subtle. Visually they are very much the same layout - but obviously the devil - and the time - is in the detail.

I'm curious as to the manufacturing/design process. After establishing what the new parts for next season would look like, were the hand made prototypes turned over to a draftsman for copying ? Or was it a process where you and a designer collaborated with you saying what was wanted and them specifying casting details and flange thicknesses etc ?

Locally we've had the example of John Britten where he laid out in a general way what he wanted in the engine - and basically the guys making it made the decisions from there....

Greg

First we went to a model maker, later we made all models ourselves.
I have no pictures of the models, but I have some of the sand cores.
In the end they were printed!

[Niels Abildgaard]

Thank You Jan

I did not know how extreme the ratio ring support/guiding to open area is in modern two stroke port belt.
Wonder what my old MZ301 could have been made to give?
Volume ratio 295/125=2.35 gives linear ratio 1.33 and thus maximum blowdownarea 1.8 times bigger.
power 56*1.8=100 horsepower?

[F5 Dave]

This is gold, thank you. I remember looking at a mates 256 back in the day, and thinking that it was the most advanced thing I had ever seen in my life,

[jamathi]

To be continued tomorrow....

[JanBros]

My wife is going a couple of days to her sister, then I will do it.....
At least if more than 1 person is interested!

please Jan, send your wife more money so she can stay longer and write that book you should have written all along