ESE's works engine tuner

[Ocean1]

i suspect the Aprilias non pocketed piston and wrist pin capping stopped this happeningAttachment 330875

i have been trying to make port map up from the " Aprilia files" posted way back to see what it looked like but wasn’t able to find all the info to do it and as such some of it was guess work.

Frits / Jan/ Wobbly are you able to show the aprilia rsa / rsw 125 port map? i have tried searching on the net, so as not to bother you, but have drawn a blank.

From your dwg. Does this look close?

Only roughly to scale, and there's a port missing, (just too close to tangent and resolution too low).

[karter444]

As far as I'm concerned, you just lost that bet Trevor, because I have no way of knowing how that modification would influence the transfer balance.
Increased time.area is useless if it worsens short-circuiting. I'd need all data of all the transfer ducts before I could make an educated guess.

Having said that, even increased short-circuiting can have its merit. It drops the EGT, so the powerband may commence at a lower rpm value.
If you ever worked on a 100 cc direct-drive kart engine, you may remember the big single B-port, doing just that.

when you refer to short circuiting I assume you mean when the a port and ex port are open . That is piston heading to bdc . Where in the power curve do you think this problem would show up . I would have thought lower in the rev range as there would be more time for this to take place ?
cheers

[peewee]

If the Aux ports are around to the centerline that piston will link them to the A port big time with such a deep pocket.

Re the RSA, it had the main Ex floor lifted by some 3mm from memory.

yes of course but even if the cutout was farther rearward couldn't it still link to the void via the wristpin hole ? a oval located farther up may be a better idea

[peewee]

Because they don`t know and don`t care about real high performance engines. It`s all about fast selling and making money....as usual.

its simple. they never intend for the exh ports to be enlarged. so who cares where the cutout is

[wobbly]

Here are the sim inputs for RSA125, about as good as it gets.

[jamathi]

From your dwg. Does this look close?

Only roughly to scale, and there's a port missing, (just too close to tangent and resolution too low).

We never made port maps, sorry...
Only the distance from the top was measured.
And the chordal width, which is what really counts.
Using the circular 'feelers' shown in the picture.
They are attached to a piece of welding rod so you can bend them any way you want.
Very useful for measuring ducts and ports!

[chrisc]

Here are the sim inputs for RSA125, about as good as it gets.

Thank you Wobbly. Answers a few of my questions

[husaberg]

i suspect the Aprilias non pocketed piston and wrist pin capping stopped this happeningAttachment 330875

i have been trying to make port map up from the " Aprilia files" posted way back to see what it looked like but wasn’t able to find all the info to do it and as such some of it was guess work.

Frits / Jan/ Wobbly are you able to show the aprilia rsa / rsw 125 port map? i have tried searching on the net, so as not to bother you, but have drawn a blank.

Pretty sure those files have all the dimensions you would ever want to construct a port map.

its simple. they never intend for the exh ports to be enlarged. so who cares where the cutout is

Villiers and Hepolite must have been thinking ahead.

The pins about 3 inches too low though, plus the rings are brittle and only good for 7000rpm

[wobbly]

The drawings released by Frits years ago ( that are now all over the Interweb ) were very early iterations of the Aprilia, he did not want to be lynched the next time he ventured into Italy.
Here is the STA result from the late model RSA - and so before you wonder why Jans superb transfers are so far ahead of the Exhaust - ponder this.
The outflow Cd of the Exhaust is hugely influenced by the large radius that was machined onto the timing edge - the strictly theoretical Exhaust timing was around 79* ATDC, but the effective open time of
the duct top edge was closer to 82*.
Thus in reality the STA FLOW numbers match perfectly - remember this when dealing with crap transfer ducts, or Exhaust ducts that are WAY too big - ie most of them.

[dutchpower]

Can you show the inlet port Wobbly

[jamathi]

Hi Wobbly,

During 2003 our boss, you know him, designed a new exhaust., no 102.
It gave a lot more midrange, but killed revs, the engine stopped at 13000
So the radius of 2,5 was arrived at to recover max. revs....
With this radius also the midrange returned like it was before.
And so it stayed....

A couple of years later, after my DERBI interval, he was not there any more.
It was decided to compare the latest 6 exhaust pipes.
First they were all cleaned on the inside.
Which, by the way always cost some power, the power used to come back after a week of testing.
With these cleaned pipes the best carburation was determined for each pipe.
There proved to be quite some difference.
Then each pipe was tested with its best carburation.
The result was: nearly no difference.....
So much about pipe design and development, during some years, it is not easy!
Those tests were, of course, made with a radiused exhaust port.
Sometimes I still wonder what would have happened if we had insisted with an unradiused port.
And the older exhaust pipe!

[jamathi]

Refilling the damper and cleaning the pipe on the inside used to cost about 0,5-0,6HP
After a week of daily testing the normal HP returned.
At the races all the teams refilled their dampers and cleaned their exhausts before the race.
What do you think of this Wobbly?

[jonny quest]

Whst is meant by refilling damper?

[husaberg]

Whst is meant by refilling damper?

Repacking the exhaust Silencer.
http://www.xpsa.com.au/assets/alt_1/DEP-DEPMSS2.jpg

[41juergen]

Here are the sim inputs for RSA125, about as good as it gets.

Thank's a lot Wob, would there be a chance also to get intake and carb data?