ESE's works engine tuner

[Frits Overmars]

The original 8 plus err.. 1 gearbox pic Yow Ling posted has what looks like a set of Bevel gears at the rear underneath is this an ancillary drive (IE Pump) or part of a earlier design? of the gear selector mechanism.

It is the water pump drive. But it's not underneath; in the picture showing the 9-speed gear box the engine was upside down.

@Mental Trousers:
Shane, I could upload the complete collection of Jamathi pictures like I did with the Aprilia-files. Then I would not have to post individual pictures all the time. What do you say?
Another matter: the last couple of days, when I try to attach an PNG-file, is does not seem to function. When I convert the file to JPG or GIF, there's no problem. Any suggestions?

[Frits Overmars]

In the pic you posted, would that blue port make engine peakier, because of the sharper exhaust pulse?

In theory, maybe. But there are other, stronger effects. The sides of the wide red exhaust port are much closer to the A-transfers than is the case with the narrower blue port. That would provoke short-circuiting

[TZ350]

I could upload the complete collection of Jamathi pictures like I did with the Aprilia-files.

The Aprilia Files? .... where can I find the Aprilia files?

[TZ350]

STA stands for Specific Time.Area. STA depends on rpm: the higher the revs, the shorter the ports are open per revolution. So I can only give you STA numbers if you specify for what rpm you wish to know them.

12,500rpm would be good.

I thought STA was transportable, ie an STA for a certain rpm could be made the same at a different rpm by changing the port area. Ie half the time double the mean angle area, same STA.

[TZ350]

teezee, i noticed on the exhaust print out there are values for the pipe volume cc and also a ratio of the pipe against the engine cc. what , if any , do these values play in the pipe design.. thanks

Thank you for asking, I was wondering myself, I am just a newbee to this ...

The exhaust exit "nozzle" was used first by Helmut Fath ( my hero ) when tuning for Honda where their V twin 250 had one stinger 150 long the other 450 long.

I have tested all manner of variations and the best is around 10mm of parallel nozzle and then 10mm of divergence to a stinger around 1.5mm bigger.

This reduces the effect of the waves bouncing up and down the stinger off atmosphere disrupting the rear cone waves.

The pipe vol/engine cc field in the pipe screen was added by Neels to the program when Frits noted that he had calculated this for the RSA - maybe he can elaborate on the relationship.

Note also that there is two fields for the length to end of header and length to end of diffuser.
I got Neels to add this as so few pipe designs are "correct" and its a pain to calculate all the time.The header end should be 30 to 32% and the diffuser should be 64 to 68%

I would try making the divergent header nozzle longer - very short ones can create shock waves and reduce the energy available to do positive "work" in the pipe.

Thanks for the info and suggestion, I will try it.

[Frits Overmars]

12,500rpm would be good.I thought STA was transportable, ie an STA for a certain rpm could be made the same at a different rpm by changing the port area. Ie half the time double the mean angle area, same STA.

With the angle.area values I posted, you should be able to work out the specific time.areas for 13.000 rpm. And these are universal; if you manage to get the same STA values for an engine with any cubic capacity and any rpm, you're doing fine.

But how did you come by the 'mean area' expression? Been reading Gordon Jennings, have you? That was a very coarse approximation of the time.area concept in an era where Gordon did not yet have a computer at his disposal. He certainly would have approached it differently nowadays.

[TZ350]

But how did you come by the 'mean area' expression? Been reading Gordon Jennings, have you?

That was a very coarse approximation of the time.area concept in an era where Gordon did not yet have a computer at his disposal. He certainly would have approached it differently nowadays.

Thank you for the time you put into this.

Yes ... after reading Gennings and his idea of measuring the port area uncoverd by 50% of the crank rotation between just opening and fully open that not all port shapes will amount to the same equivalent angle area, tall versis wide for instance.

My post might not have been a good use of the word "mean" maybe eqivalent effective area might have been better, ie wider at the bottom would not be as effective as wider at the top.

[koba]

But how did you come by the 'mean area' expression? Been reading Gordon Jennings, have you? That was a very coarse approximation of the time.area concept in an era where Gordon did not yet have a computer at his disposal. He certainly would have approached it differently nowadays.

Just because it is interesting:

...any study of port-time area would have to be based on number not readily available unless one has endless hours to devote to collecting information either locked away inside the engines themselves or the manufacturers archives. It is possible to work out time-area number on a purely theoretical basis, but this approach is even more time consuming, involving as it does some really nasty work with integral calculus equations. Also, this approach virtually demands that one make some fairly shakey assumptions in a number of areas - and that a computer be at hand if all the calculations are to be completed this century.

From "Two stroke tuners handbook" by Gordon Jennings c.1973

It seems the computer issue has been solved to some extent. They could always be faster though.

I bet you are still hoping someone sorts the endless hours problem though, eh Frits?

[wobbly]

TeeZee, the ceramic coating on the piston and the chamber is a secret weapon used for years on KT100 Yamaha engines.
Its not actually stated in the rules as being illegal, but the way the rules are worded they say that if it doesnt say you are allowed, then you are not.
The coating doesnt need to be clear, its only done that way so you cant see it.
HPC do all manner of coatings, but I know nothing at all about the clear version do I.

Also re STA - you have the perfect tool for calculating what the RSA must have to make 55Hp @ 13000.
Assuming that is at the sprocket ,add say 5% and put it into EngMod2T - it will spit out the target values, and I can tell you for sure that the end result will tell you
VERY close to what is needed in reality, to make that power.
Its been proven so many times now I never think to question the results - for example I wrote down the numbers ( yes ,with a pencil no less) for SpeedPro years ago on how to get 30 Hp from his MB100
and here we are, now that the mechanical version is starting to resemble the one I had in my computer,the thing makes 30 Hp.
Everyone said it was rubbish for years - and it just couldnt be done, but the dyno tells no lies, and I dare not as well - too many smart people about.

[Frits Overmars]

Just because it is interesting:
...any study of port-time area would have to be based on number not readily available unless one has endless hours to devote to collecting information either locked away inside the engines themselves or the manufacturers archives. It is possible to work out time-area number on a purely theoretical basis, but this approach is even more time consuming, involving as it does some really nasty work with integral calculus equations. Also, this approach virtually demands that one make some fairly shakey assumptions in a number of areas - and that a computer be at hand if all the calculations are to be completed this century.
From "Two stroke tuners handbook" by Gordon Jennings c.1973
It seems the computer issue has been solved to some extent. They could always be faster though.
I bet you are still hoping someone sorts the endless hours problem though, eh Frits?

Which endless hours problem do you mean, Koba? The time I spend on this forum? Oh well, it keeps me out of the pub .

[bucketracer]

Its been proven so many times now I never think to question the results - for example I wrote down the numbers ( yes ,with a pencil no less) for SpeedPro years ago on how to get 30 Hp from his MB100
and here we are, now that the mechanical version is starting to resemble the one I had in my computer,the thing makes 30 Hp.
Everyone said it was rubbish for years - and it just couldnt be done, but the dyno tells no lies - about.

And it was the Team ESE dyno no less ... you can't imagine how much TeeZee vomited when he saw he was beaten to the first usefull 30hp Bucket, particuarly funny as TeeZee was recording the runs while Speedpro was spinning the bike up, talk about rubbing TeeZee's nose in it ....

[Strokerhaus]

The idea is good. But your logic is not always... "There would not neccessarily be a reduction in gross flow as the port duct could be enlarged to allow for the divider". Yeah, right. Then you could also enlarge the port without putting in the divider.That would give you even more flow area.

Then why is it still a good idea? Because you reduce the port height in the curve; the ratio of inner curve radius to outer curve radius becomes larger, and that is very good for the flow. Look at any air conditioner ceiling-outlet: they are all shaped like that.
To my knowledge the idea was first proposed by a german researcher, Ernst Ansorg, around 1965. I have seriously thought about applying it, but incorporating thin-walled curved guides in a cylinder casting proved too difficult at the time. It might still work though.
Yes, the guides will heat up the passing charge. But the net result will probably be positive; especially if the guides are kept short, only in the upper, curved part of the ducts.

I also like the idea of closing off the outer/ upper transfer ducts. It would prevent wrongly-timed exhaust pulses from shoving fresh charge from the cylinder back into the crankcase, and that would yield a very civilized power curve.

Is there not another effect as well with "adding a divider" which is to change the resonance of the transfer port, yes you loose flow area but you could well gain by a shift in resonance frequency of the port. I suspect I have seen negative effects that appear in some wide transfer ports which I am beginning to think are an out of phase resonance. Which is why I suspect the TZ350 ended up with 6 transfer ports and an increase in power, instead of the larger ports that flowed better.

[Frits Overmars]

Is there not another effect as well with "adding a divider" which is to change the resonance of the transfer port, yes you loose flow area but you could well gain by a shift in resonance frequency of the port. I suspect I have seen negative effects that appear in some wide transfer ports which I am beginning to think are an out of phase resonance. Which is why I suspect the TZ350 ended up with 6 transfer ports and an increase in power, instead of the larger ports that flowed better.

Thin (< 1 mm) dividers in the transfer ducts will hardly have any influence on the system's Helmholtz frequency. But I assume you are talking about radial dividers, not about the curved dividers we mentioned earlier.
The four large transfers of the old TZ350 did not flow better; they just flowed more, but not in the desired direction. Because the cylinders were so crowded, there was no room for sweeping ducts; they were squatted between the bores without any directional capabilities.
Adding the radial dividers that sub-divided the TZ350's B-ports, gave some more steering to the flow. That reduced short-circuiting, thus influencing the exhaust gas temperature and hence the pipe frequency.

[jasonu]

And it was the Team ESE dyno no less ... you can't imagine how much TeeZee vomited when he saw he was beaten to the first usefull 30hp Bucket,

But it has yet to be proven 'useful' and sorry to say the same goes for the rest of the big HP buckets and I include No Mates' bike because as far as I know it has yet to finish a GP on a big track.
Not trying to be a knocker but thems the facts as I see them and I am hopeing to be proven wrong as I am a 2 stroke guy too.

[wobbly]

You are dead right - but we are dealing with buckets here after all.
The dead set fact remains, that if and when a 100cc bucket is correctly made, and assembled, and tuned, then is ridden by a competent rider in a good chassis on good tyres,there will not be a 4T within site.
Its simply physics - not rampant bias or dreaming.
So that is the main reason I am here helping guys out - the end result is without question, its just finding a way to get there.