ESE's works engine tuner

[breezy]

Attachment 255754Attachment 255755Attachment 255756Attachment 255757Attachment 255758 bsa bantam grafting on rgv barrel. bucket style. still a fair way to go!!

well, thought i do some reverse engineering by attaching this rgv barrell id got lying around, to some bantam cases.i noticed, from other bikes in the bantam racing world,that they were restricted by the crankcase where the barrel sat on without some major alloy welding .so i decided to chopit off and build up a larger flatter surface to house the barrel( all with bolts at present, to later have welded on). this barrel its not legal with the current rules, but if it works out i can try to produce a legal barrel with the same spec.maybe. im hoping to get a barrell with the reed inlet already on as if i stick with the rgv im gonna have to some how find a away to get the fuel in, but for know its usefull as a mock up . ive just ordered up some alloy plate to use as a spacer under the barrel,as my last attempts to melt/sandacast almost removed all the skin from my throat whilst checking what was going on in my home made furnace... (yeah well funny)eye brows who needs em.so there you have it. DO or DIE......will post some more as i progress if only for entertainment factor, should my posts never appear again itll because my home made still has gone bang!!! ha ha

[breezy]

picture of the bike im hoping to race this year. 175c bantam rules.. this is what it looked like untill i decided to paint it british racing green(cant find picture in files at the moment). rs aprilia 125 fairing, tank, rear seat, rd 200 front forks and wheel. engine spec 3 speed close ratio box,steelplate clutch,34mm mikuni, standard head on at present(10;1), up and over home made exhaust , exhaust port 30mm from top of cast barrel, transfers 47mm from top of barrel,cant remember inlet duration.i did once post on u tube a while back , bsa bantam race bike,but not sure if its still there. ive not raced this bike yet,but ive got to get going this year as ive been to long messing around.

[Frits Overmars]

Question for Frits. What happens at Aprillia after 95-96. Aprilia has won the 125 and 250 gp champs. What does the team concentrate on? It it on making them more drivable, or testing new combinations? Lots of Pipe testing? No doubt all of the above. what does the development team do in an average day?

Can you remember what you were doing 16 years ago, Husa? Not me, not without diving into a cubic meter of paper work, which I don't fancy right now (or ever). So it's 'all of the above'.
What I do remember, is this. Jan Thiel joined Aprilia in early 1995. He started working on the 125 cc Rotax engine, while the 250-team was working on Biaggi's V-twin. The Biaggi-team used very special cylinders (in reality designed by the Austrian AVL company) and Jan wasn't even allowed a look into them - until the 250-team found out that Jan's somewhat modified run-of-the-mill Rotax production cylinders not only produced more power, but also had a wider power band.

On an average test day the average development team waits, talks and drinks coffee, and that's the truth. In the days before a test day a lot of schedules are prepared and a lot of material is collected and loaded into the team truck(s). On the test day you drive to Mugello (Aprilia's usual test track) or to Jerez in Spain where it's always sunny, even when Mugello is covered in snow (if it's Jerez, obviously you start driving a couple of days before the test day).
On the test day half of the test schedule cannot be carried out because some two dollar part was left behind, and the other half of the schedule is drowned by rain on the track (in Jerez...). Hence the waiting, talking (cursing, more like) and coffee drinking.

On a more cheerful note, the test rider was Marcellino Lucchi. His day job was driving the garbage truck in his home village, but whenever Aprilia needed him he made sure he was available to ride Biaggi's works bike. When Biaggi went on to ride the works Honda NSR500, the Aprilia test team had a good day in Jerez each time Lucchi was faster on the 250 than Biaggi was on the 500 (Jerez is that kind of track, and Lucchi could beat anybody there blindfolded. And superstar Biaggi had always been less-than-popular with the Aprilia mechanics).
Once a year Lucchi got a wild card and was allowed to take part in a real Grand Prix, at his home track Mugello. He usually grabbed third place, always the oldest man on the rostrum (he was well in his fourties then). Great character!

[dinamik2t]

Frits, may I ask a question too.. It's about port layout/axial-radial angles VS bore-stroke. For high performance engines at least.

Say this is RSA's port layout, which is a 54 bore by 54.5 stroke.



Also axial angles are 28-7-52.5 for TFRs A-B-C.

I believe I am thinking this one correct: Radials should form a shape like in the above pic, where Bs' flow collide in the middle of the lower bore half and -pretty much- As' flow surround them, also colliding in the middle of the lower half.
So, if we had a 60mm bore, it's the general shape that should be similar and not the numbers as stated in the pic. Ie the 60mm shouldn't have the Bs at -12/-16, but at -13.3/-17.8.
In other words, if someone had to create a similar pattern, he should use the normalized (to the bore) numbers. Yes?

Now, about the axial angles and the stroke.
The 28* (or 7 or 52.5) direct the flow at, say, height h1 in the cylinder. And it creates the perfect scavenge model.
If we had a 50mm stroke and used 28* wouldn't height h1' be different than h1? Then the scavenge model would be less perfect, correct?
I am not sure if this is the correct way to think, it' s static analysis after all. Perhaps the smaller amount of time the 50 stroke has to reach h1' compensates the difference. And so, radial angle desing might become more universal.

[wobbly]

My reaction would be that the RSA "model " that took years to develop and had a mile of devil in the details, will work best in any bore - as long as the stroke ratio is maintained.
Thus both the radial and axials could be copied as all you are doing is scaling equally in both directions.
I know Frits has done just that ( and so have I ) using the scale model feature in SolidWorks - easy.

The radial angles set the directions to minimise short circuiting, and the axials maximise the scavenging purity - both together form the loop shape and duration.
Anything other than a square bore/stroke and you have instantly compromised the angle area capability, and all the R & D done by Aprilia is null and void.

[husaberg]

Can you remember what you were doing 16 years ago, Husa? Not me, not without diving into a cubic meter of paper work, which I don't fancy right now (or ever). So it's 'all of the above'.
What I do remember, is this. Jan Thiel joined Aprilia in early 1995. He started working on the 125 cc Rotax engine, while the 250-team was working on Biaggi's V-twin. The Biaggi-team used very special cylinders (in reality designed by the Austrian AVL company) and Jan wasn't even allowed a look into them - until the 250-team found out that Jan's somewhat modified run-of-the-mill Rotax production cylinders not only produced more power, but also had a wider power band.

On an average test day the average development team waits, talks and drinks coffee, and that's the truth. In the days before a test day a lot of schedules are prepared and a lot of material is collected and loaded into the team truck(s). On the test day you drive to Mugello (Aprilia's usual test track) or to Jerez in Spain where it's always sunny, even when Mugello is covered in snow (if it's Jerez, obviously you start driving a couple of days before the test day).
On the test day half of the test schedule cannot be carried out because some two dollar part was left behind, and the other half of the schedule is drowned by rain on the track (in Jerez...). Hence the waiting, talking (cursing, more like) and coffee drinking.

On a more cheerful note, the test rider was Marcellino Lucchi. His day job was driving the garbage truck in his home village, but whenever Aprilia needed him he made sure he was available to ride Biaggi's works bike. When Biaggi went on to ride the works Honda NSR500, the Aprilia test team had a good day in Jerez each time Lucchi was faster on the 250 than Biaggi was on the 500 (Jerez is that kind of track, and Lucchi could beat anybody there blindfolded. And superstar Biaggi had always been less-than-popular with the Aprilia mechanics).
Once a year Lucchi got a wild card and was allowed to take part in a real Grand Prix, at his home track Mugello. He usually grabbed third place, always the oldest man on the rostrum (he was well in his fourties then). Great character!

Thanks Frits I'd like to Think I am not that mean to ask for all the details,But just an overview was what i was after. So thanks.
I had a look at the stuff on Lucchi (I had heard of him but only periphery)
Wow long career first race to last race. 22 years in GP's.

Marcellino Lucchi (born on March 13, 1957 in Cesna was an Italian Grand Prix. His best year was in 1998 when he won the Italian Grand Prix and finished 15th in the 250cc world championship.^[1]
Weight: 66 kg

Motorcycle racing career statistics
Grand Prix motorcycle racing
Active years	1982 - 1991, 1993 - 2001, 2004
First race	1982 250cc Nations Grand Prix
Last race	2004 250cc Malaysian Grand Prix
First win	1998 250cc Italian Grand Prix
Last win	1998 250cc Italian Grand Prix
Starts Wins Podiums Poles F. laps Points 78 1 5 3 1 278

Unfortunately i can remember what i did around that time with tedious detail as it mainly involved a lot of PD's on TRX300's @$6.66/Hour NZD
The main detail i was after was the structure and how many dyno test were done compared to track tests.
I recall something about Bud Askland doing something like 3000 dyno runs a year for Roberts so i assume this was on top of Yamaha's testing program as well.

Honda is credited with only 200 employees at this time in HRC out of 10000 Honda motorcycle employees.

I had seen there was something along the lines of the Aprilia GP race programs employees totaling 62, out of 450 of the total employees of the Marque.
Incredibly it is also said that they were an additional 60 odd were engaged in R&D of other sorts as well.
So that is an Huge investment in anyone terms and one that paid dividends as well.

I say investment as that is how i see it as what it was.
As assuming they (Aprilia) spent 6 Million USD of there own money in 95 on racing. That is incredibly cheap, compared to advertising on TV and compared to the print coverage Aprilia's success brought them.

Max Biaggi
I have read a lot of the stuff Max wrote and yeah er....interesting guy. Admittedly a great rider but not exactly humble. It must have been a challenge finding a helmet large enough to fit him.

[koba]

I've been trying to think of an intelligent question to ask of our learned contributors for a while.

There have been heaps of things that have sprung to mind but I've been able to find reasonable answers myself by looking around and reading widely, asking such questions here seems a waste of a good opportunity.

So my odd-ball questions:

What is the up with the radial exhaust port angle?

I'm not sure if I have the correct term so I have attached a [ATTACH=CONFIG]Picture[/ATTACH] to illustrate.

Some exhaust ports exit straight (pic on left) but I notice others, including the RS125 barrel I have sitting here, have a shape more like in the right picture.

I can guess at why this might be done but is there any general wisdom of perceived benefits/drawbacks?

I did notice one small reference to it in the large pile of books I've been working through, that was in Cesare Bossaglia's book 'Two Stroke High Performance Engine Design and Tuning' (Quite an old book but still interesting and informative, a greater scope than most) from my terrible memory he said it has been used to update old barrels to higher performance without a major redesign.

[Frits Overmars]

Frits, may I ask a question too.. It's about port layout/axial-radial angles VS bore-stroke. For high performance engines at least. Say this is RSA's port layout, which is a 54 bore by 54.5 stroke.
Also axial angles are 28-7-52.5 for TFRs A-B-C.
I believe I am thinking this one correct: Radials should form a shape like in the above pic, where Bs' flow collide in the middle of the lower bore half and -pretty much- As' flow surround them, also colliding in the middle of the lower half.
So, if we had a 60mm bore, it's the general shape that should be similar and not the numbers as stated in the pic. Ie the 60mm shouldn't have the Bs at -12/-16, but at -13.3/-17.8. In other words, if someone had to create a similar pattern, he should use the normalized (to the bore) numbers. Yes?
Now, about the axial angles and the stroke.
The 28* (or 7 or 52.5) direct the flow at, say, height h1 in the cylinder. And it creates the perfect scavenge model.
If we had a 50mm stroke and used 28* wouldn't height h1' be different than h1? Then the scavenge model would be less perfect, correct?
I am not sure if this is the correct way to think, it' s static analysis after all. Perhaps the smaller amount of time the 50 stroke has to reach h1' compensates the difference. And so, radial angle desing might become more universal.

Your picture did not show on my computer, so I will have to guess what you mean by 'the 60mm shouldn't have the Bs at -12/-16, but at -13.3/-17.8'. But I think I've got a pretty good idea.
Most two-stroke people define radial scavenging directions by quoting the distances where the ports would intersect the center line (the leading distance and trailing distance in the drawing below left). Gordon Blair used that notation in his publications, and 95% of us followed suit.
But there is a better, more universally applicable way.
I will explain with an example, not of scavenging directions, but of port timing: I might say that a transfer port height of 13 mm is perfect for a racing engine. That may be true for a 125 cc engine, but it would be nonsense for a 50 cc.
But if I say that a transfer port timing of 130° is perfect for a racing engine, then that is valid for any engine, regardless of its cubic capacity. Absolute distance values (millimeters, inches etc.) are not suited for universal guidelines. Degrees are, as are percentages of bore or stroke. rpm values are not; mean piston velocities are.

I express transfer duct directions in degrees. Each duct has a leading flank and a trailing flank. Each flank intersects the bore at a point which I can define with a positional angle. And each flank hits the fore-aft center line of the bore with an included angle which I call the directional angle. The drawing below left may clarify what I mean. And the drawing on the right is an example of an existing cylinder (it may be small, 6.5 cc, but it has been unbeatable for over 10 years).

Now you can express the radial characteristics of the transfer ports with positional and directional angles, regardless of bore and stroke.
And you can express the ports' axial characteristics with axial angles, but that only holds for engines with identical bore/stroke-ratios, as Wobbly explained.
Your approach of using a height h1 in the cylinder where the transfer port's roof would hit the opposite cylinder wall, is very good, but you need to express h1 as a percentage of the stroke. Then you will have a truly universal value. Then you will also see that short-stroke engines require smaller axial angles.

[dinamik2t]

If you're refering generally to Ex ports - meaning bridged too, like RS125 - then one thing it helps with, is AREA.
A port like RS, which extends (by the wall) towards the middle of the bore, would have less effective area if it was straight or like in the left pic. The longer it goes towards the center, the larger the side wall angle (EngMod uses this term) should be.
I believe it's the same with the Auxiliary Ex ports too..

By the way, there are a couple of CFD sims of the loop scavenge in youtube: (hope they haven't been posted again soon)

http://www.youtube.com/watch?v=w8sidsux9D0
http://www.youtube.com/watch?v=3F_0PvbKo44
http://www.youtube.com/watch?v=M53nersJJ3o

-------------

I've also read Frits answer now.

Firstly, this was the pic - hope it's viewable now. I turned it to .jpeg



Yes, you guessed very correctly. I first show this type of reference to radial angles in EngMod, to be honest, and then read it in Blair's book, which must be the original source for EngMod too.
Positional angles must be quite more easy to determine! In directional system, one must specify both the angle and the distance from the center.
I was curious about this for a long time, seeing your blue photos: have you created your own simulator/data program? I think that's great!
An amateur craftsman would start by using his bear hands and a few sandpapers. Then, as his experience and skill grows, he will be using the existant tools. At the time he starts making his own to suite his needs, he is no-word-to-describe-it-you-get-what-I-mean :P.

Continuing:

Your approach of using a height h1 in the cylinder where the transfer port's roof would hit the opposite cylinder wall, is very good, but you need to express h1 as a percentage of the stroke.

I actually thought of h1 as the point where port roof would hit the center, because it's there the streams meet. Would that be wrong?
edit: I realise on second thought, that it would be far far more diffucult to measure or refer to, than your way..

[Frits Overmars]

I was curious about this for a long time, seeing your blue photos: have you created your own simulator/data program? I think that's great!
An amateur craftsman would start by using his bear hands and a few sandpapers. Then, as his experience and skill grows, he will be using the existant tools. At the time he starts making his own to suite his needs, he is no-word-to-describe-it-you-get-what-I-mean

Bear hands? Not me; I started quite sophisticated, with a spanner # 10, a screwdriver and a hammer. After I while I felt the need for more dedicated tools which over the years led to writing a number of programs, including my own sim. And no, you need not ask; it is not for sale. I wrote it for my personal use only, so it is far from user-friendly and selling it would cause an avalanche of questions from users.

[Frits Overmars]

As we were on the subject of scavenging angles, now would be a good time to write something about the radial angles of the A-transfers.
Surely a duct with a radial angle of over 20° offers a smaller cross-section to the flow than a duct that enters the cylinder perpendicularly?
Yes it does. But there are two good reasons to angle it upward anyway.

First, perpendicular mixture streams coming from the A-ports would collide and slow one another right down. The upward angles provide for less velocity losses and less
pressure losses, so despite their smaller cross-section, upward ports may flow as much, if not more, than perpendicular ports.
(Now you may well ask why the B-ports do not get the same treatment; that is because the central scavenging column, resulting from all incoming scavenging streams together, must not have too much radial velocity, or the loop scavenging will result in a loop-loss into the exhaust).

Second, there is a thing called scavenging balance (I invented the word for my personal use, so this may well be the first time you ever saw it).
If you looked closely at the scavenging picture of the MB-cylinder I posted earlier today, you may have noticed that the 'radial scavenging directional resultant'
had a value of 101,045°.
90° would have meant 'straight up'; more than 90° indicates that the central scavenging column is leaning towards the exhaust side of the cylinder.
But we don't want that; it is bad for the scavenging of the rear part of the cylinder, and it is risky because it may provoke scavenging losses straight into the exhaust.

But how can we prevent a scavenging column from toppling over to the exhaust side like the leaning tower of Pisa? Not by pushing against its basis, but by pushing higher up. Hence the radial angle of the A-ports. The pictures will tell the story. (If only the Pisa architect had known a bit more about two-stroke tuning....)

[gamma500]

nice radial angles!

[dinamik2t]

And no, you need not ask; it is not for sale. I wrote it for my personal use only, so it is far from user-friendly and selling it would cause an avalanche of questions from users.

Sorry, I thought you might get that idea or that other people might ask for it, after confirmation. But I trully didn't have such an intention when I asked you. Just for the reason I said earlier and of respect. I am quite happy with EngMod at the moment.
After all, these sort of tools is what makes each 'craftsman' unique, whether they are material objects or pairs of 0-1..
That's all about that.


and for the Pisa explanation of A ports! Now I wonder what the axial scavenging directional resultant represents though.

[Frits Overmars]

and for the Pisa explanation of A ports! Now I wonder what the axial scavenging directional resultant represents though.

Your question is a perfect example of what I meant:

...I felt the need for more dedicated tools which over the years led to writing a number of programs, including my own sim....
I wrote it for my personal use only, so it is far from user-friendly and selling it would cause an avalanche of questions from users.

Please don't feel embarrased. Here's a short explanation: the sine of this 'axial scavenging directional resultant' is an indication of the scavenging column's axial velocity. If the column moves too fast in relation to the mean piston velocity, there will be severe scavenging losses; if it doesn't move fast enough, the cylinder will not be completely scavenged.

[dinamik2t]

Aha!
I guess my time for questioning you is up, but this might not fall into the-art-of-tuning subject:
Derived from those scavenge measures. Can those streams be described as they are in reality -from the physics point of view- or there is some kind of model, inducing a certain amount of inaccuracy?
I have no idea from this part of physics, but I guess there must be huge 3D equations to describe those movements..