ESE's works engine tuner

[TZ350]

p412

If I were to explain pipe design I would need to write a book,but in general things are pretty straight forward in relation to the % values.

End of header is always 31 to 33% and end of diffuser is always 62 to 68%.

To see the effect of a silly long header, you can watch the pressure ratio at the Ex port, and thus the effect this has on the depression in the cylinder.

We are looking for the lowest and widest negative ratio we can get around bdc when the transfers are fully open.

A long header delays the beginning of the depression too late in the cycle, when in the power band.

In a race 2T we are always fighting power range Vs peak power.

Shorter diffusers create steeper angles, thus greater wave amplitude, but this narrows the effective band width.

So - in general the best compromise is around 66%.

P413

The % I quoted for header means that portion of the length from piston to rear cone end.

Its from the piston to the beginning of the diffuser, what happens in between isnt relevant.

Unless of course you use a small Ex duct and a bigger header, that makes more power.
And of course same for the diffuser end, that is simply 66% of the length from the piston to the end of the rear cone.

So to start with, I understand some of the key elements are.

(1) The end of header is always 31 to 33%

(2) The end of diffuser is always 62 to 68%.

(2) We are looking for the lowest and widest negative ratio we can get around bdc when the transfers are fully open.

Time to warm up my EngMod2T program and use the Pipe Development part of it to get started.

In a race 2T we are always fighting power range Vs peak power.

Shorter diffusers create steeper angles, thus greater wave amplitude, but this narrows the effective band width.

The plan is a peaky pipe at 9k rpm and to extend its range using the Trombone effect.

[husaberg]

oh got that wrong more than usual.......
can't find the post either ROB but found these.........

I thought, though likely wrong that the trombone shortens to gain over rev.Rather than lengthens to gain low end power???????
i certainly are no expert but it took me a while to get my head around that it may be better to first aim for the peak that you want.
(This is two strokes in general) i think it came from Wob or Frits, when i asked about trying to spread the power by tuning say inlet to a sightly different rev than say exhaust
it was said that it was better to use cunning tricks like solenoid carbs and ignition tricks and maybe a trombone pipe to spread the power by increasing the over-rev. rather than using other methods to broaden the power down low. but i am pretty sure this is a half quote probably out of context.........

i think this was the one i was looking for

You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.

Although this was before the advent of the trombone pipe i think

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

this was the post where Frits showed the beautifully made FOS cylinder with the pictures well worth going back and having another look.

Here are some of the pictures. Most of them have not been shown on an open forum before.
Pictures 1 and 2 show development stages; both are several years old now.
Picture 3 shows doctor of physics Denis Klemm (left) and myself with the first 50 cc FOS cylinders. Denis was of vital importance in applying the Selective Laser Melting process that allowed me to produce the shapes I wanted.

Pictures 4, 5 and 6 show these cylinders from some different angles.

on a passing note someone made a comment about the asians ripping off the the europeans in regards to scoooter stuff.
Well i found this funny.

Boost bottles
........
This could be accomplished with a diaphragm. Much like a pressure vessel on a Water pump you could even plumb it with a butterfly valve.
Could this be a create an effective Plenum chamber? Down steam from the carb.
Also a variable factor to crankcase volume? Musing aloud here. A lot of could's and Ifs but..............

I linked a site on the post in the next post as an example of some different boost bottles. Well now when i was going back (looking for frits post) i looked at the link well now they have variable size boost bottles :killingm
http://www.sip-scootershop.com/files...ndex.html#/309

[Frits Overmars]

Frits i think you way have misunderstood my question.....

Yes, I misread it; sorry about that.

The request to ask Jan (if it was all right as a courtesy) for me to post some of Jan chassis pictures he had shared out of another thread, may be better received from his friend.

Probably. But then Jan would probably ask me which pictures exactly, and I wouldn't have an answer. You are right about the courtesy, though.
But anyway, when Jan posts something on an open forum, you may safely assume that he won't mind you using it. And the same goes for me.

The Excalibur project i assume failed.... but i can find only brief mentions of it in the press.....Do you recall the English project?

No, I don't.

[Frits Overmars]

This is the perfect time for me to step in and tell you to stop dreaming. 40Hp at 9,000 for a 125cc engine = 16Bar = 230 psi bmep.
ABSOLUTELY IMPOSSIBLE, NEVER BEEN EVEN REMOTELY APPROACHED, AND NEVER WILL BE.
New Years Wake Up Call.

New Year's Encouragement Call:
Aprilia RSA125:
maximum power: 54 gearbox-HP @ 13000 rpm
maximum torque: 29.75 gearbox-Nm @ 12517 rpm
By definition the Brake Mean Effective Pressure is the constant pressure, working upon the piston, that would yield the same power or torque value as produced by the engine.
So to find the RSA's maximum BMEP first we must convert the gearbox-torque to crankshaft-torque.
Calculating with 5% loss in the primary transmission and 5% loss in the gearbox, we will find a maximum crankshaft torque of 32.725 Nm.
That gives us a BMEP of 32.725 * PI * 20 /124.8 = 16.47 bar (derivation: see http://en.wikipedia.org/wiki/BMEP).
So it can and has been done. But it ain't easy. And without liquid cooling I wouldn't even try .

[husaberg]

Yes, I misread it; sorry about that.
Probably. But then Jan would probably ask me which pictures exactly, and I wouldn't have an answer. You are right about the courtesy, though.
But anyway, when Jan posts something on an open forum, you may safely assume that he won't mind you using it. And the same goes for me.
No, I don't.

No worries the fact that so many Europeans can so readily swap between so many languages never fails to amaze m e while we kiwis struggle at time with one,

Another drawback was the lack of fuel supply as the "tank" almost
was empty, there was too little height difference between the "tank level" and
the float chamber level. We have that Minarelli solved by a
small 'funnel' to the nose fairing and this set than with a
tube the "tank" under pressure. After that time never had problems with it.

[ief]

Tuff cookie to crack teezee, how you're getting along?

[wobbly]

The impossible part of the bmep equation I was alluding to was trying to achieve 40 Hp at only 9000.
As you point out Frits it is achievable at 13000, but only with every tuning advantage known to man, along with optimum duct shapes etc.

[TZ350]

Tuff cookie to crack teezee, how you're getting along?

Hi Ief

I am pretty confident that by using a trombone pipe arrangement, that a pipe designed to give its best at 9,000 rpm can be made to carry the peak on to 12,000 but it is going to take some time to work through the development process.

[ief]

Tell me about it

My efforts thus far, your shown setup with some (verry) small changes. I took my approach and went for a steady torque curve as long and high as possible...

Wonder what the setup would do with a proper normal exhaust btw.

Bit high in the rev range perhaps but anyway...

oops > edit: trombone with 60 mm travel.

[SS90]

Hi Ief

I am pretty confident that by using a trombone pipe arrangement, that a pipe designed to give its best at 9,000 rpm can be made to carry the peak on to 12,000 but it is going to take some time to work through the development process.

There are a few of us that sincerely hope you can make a trombone exhaust work, however, I think it prudent to remind you that to a flat power curve it is not necessary to have a trombone pipe, or any other expensive (but nice to have) part.
It can be achieved with EXPANSION CHAMBER DESIGN, cylinder head design, and a basic reading ignition. (no power jet carb, or any other such item).
By all means, make a trombone pipe, but I have shown before you can achieve the power needed to beat 4T 150cc with conventional set up, and I would like to see ESE actually put up a fight on the track.

I would have thought an ATAC header set up would be easier to achieve, and of more benefit that a trombone pipe, it is something I have worked on myself (ATAC, not trombone, as Engines I build have curved headers, making a trombone header not possible), and they can, and do work wonders... As Wobbly has already mentioned numerous times.

Quite some time back, someone (cant remember who) posted a very old article that Frits had written, regarding expansion chamber design, I recommend that you consider this priority reading, while it is not in English, learning another language is par for the course for some of us, and if that is not realistic, a few hours with a dictionary and pen and paper, you will be able to understand everything he mentions, it goes someway to explaining how to get the type of power curve you have finally decided to aim for.

There is a fundamental design difference between the exhaust you have been using (RS125), and
One that will enable the power curve you want.
Yes, it will bring it's own set of headaches (ones that many of us have had to deal with), And I personally am keen to see how you resolve them, but like I say, go to the effort of translating that article. It will point you in the right direction.

I find Germanic languages reasonably easy learn when reading, as many technical words are somehow logical in their root, and technical information is logically written, Dutch and Flemish (particularly) is quite hard, but they do follow a logical pattern in their syntax. When you start the article, start a side column building vocab (the single most important process in learning a language), and by the second page, you will already have learned a minumum of 20% of the necessary vocab (likely more, as technical articles are, by nature on one subject).

[TZ350]

Hi Ief, it looks good and I am sure the idea can be made to work.

At the moment I am still getting to know how EngMod works. One of the mistakes I made was designing a pipe for 600 deg and I didn't realize I also needed to enter that number in the "Edit Temperature Data" file before running the simulations and wondered why my simulations peaked at a rpm that was a touch higher than they should have. So I have a bit to learn about pipes and how to use EngMod to design and simulate them.

[TZ350]

I think it prudent to remind you that to a flat power curve is not necessary to have a trombone pipe

It can be achieved with EXPANSION CHAMBER DESIGN, cylinder head design, and a basic reading ignition.

I have no doubt that's true and have seen some impressive dyno graphs but they were limited in range, they had a 3,000rpm spread at best.



I currently have about a useable 4,000 rpm spread.

I am looking to plump up the lower part of the power curve and widen it for a flater high powered 6,000 rpm wide power spread which I am sure can be achieved with a trombone pipe.

If you can post any graphs from a fixed pipe that have a high powerd flat 6k power spread I would be very interested in seeing them.

[SS90]

I have no doubt thats true and have seen some impressive dyno graphs but they were limited in range, they had a flat torque curve for 3,000rpm at best, I currently have about a 4,000 rpm spread.

I am looking for a high powered 6,000 rpm power spread which I am sure can be achieved with a trombone pipe if you can post any graphs from a fixed pipe that look like that I would be very interested in seeing them.

Having built and raced these engine for a few years now, I can assure you that the power spread you need is achievable with what perifrials and facilities you currently have, I agree that extending the rev range higher than 10,500 is desirable (and again achievable), that is evryones goal, but I suggest that if you aimed for a starting point you can develop from (the current cylinder is, from what I see a major step in the right direction.

In regards to expansion chambers, I started in Winter 2007 using a dyno graph from an engine that a friend from A major Euro bike manufacturer built, and used that was my bench mark, (and with his help, I beat the peak power, but never the massive mid range...actually, still have not managed to come close to that, or the massive over rev) one if his (many) big hints was to look at
Motocross and enduro expansion chamber designs, and compare them to the peaky RS125 pipe designs I was trying to use. This will also help you.

Remember, you only have 5 available gear ratios.... With the right exhaust, this is in someways an advantage, with the wrong exhaust, a big disadvantage.

[TZ350]

Having built and raced these engine for a few years now.....

I admire your enthusiasm and capacity for talking but I would be more impressed with a 6k wide power graph from a fixed pipe.

[ief]

With regards to ex wall temp input. On the rd/rz files a good figure seems to be 55 degrees, seems like a bodge and perhaps it is but I'm told that's what it needs. If I'm right Wob provided some of your files and perhaps the temp file as well? If so i'd suggest use those.

Best way would be to use one of your known designs and dyno curve and match them up?

With regard to the fos exhaust article, allready posted here once but there are imho more current, more detailed and above all, more english pieces to be found.

- Randy Norian, rg 500. -