ESE's works engine tuner

[Frits Overmars]

PART 2. Sorry, but PART 1 is under Foundry...my stuff up.... Overall it was really great, so many thanks to Frits, Martijn and Henri for the day. And the giggle of the day was:Attachment 342341

Ken, your pictures in PART 1 work fine, but I can't open any pictures in PART 2. All I get is "Invalid Attachment specified".

[ken seeber]

Ken, your pictures in PART 1 work fine, but I can't open any pictures in PART 2. All I get is "Invalid Attachment specified".

Frits, you're right. Can't explain that one, but did experience a lot of troubles with the server I was on. Here they are:

[wobbly]

Just cant help yourself can you Luc
.It may come as a surprise to you but this forum was not specifically designed for you to post shit about how
fucking clever you are - or even were back in 2012.
If you posted what the designs actually were or how they were derived , we would all be happy to learn something useful.
But no , we just get the same self promotional shit that got you banned in the first place.
Go away.

[TZ350]

.
Lucf has re registered as Luc

Luc if you posted what the designs actually were or how they were derived , we would all be happy to learn something useful.

Yes, I to would love to read and learn something of Luc's tuning incites.

Like all good dinner parties, its the sharing that makes things great.



Luc we would love you to join the party and share your knowledge. This is a safe place where you could let your work speak for itself.

[SwePatrick]

I think he's planning to use a "retained" ring, i.e. reverse Dykes, so port width shouln't be a problem, nor should exhaust-to-transfer leakage as there would be no pin holes.

I honestly think the problem will still be there, the ring need some movement in piston 'radially' this can cause havoc when piston is 'rocking' around bottom dead centre.
Maybe a little bit less problem yes, but it will autochamfer the exhaustport quite quickly

[SwePatrick]

Quick question guys, i have searched but no luck.

The ralation between stiff reedpetals and crankcase volume.

Bigger volume - needs stiffer blades?

Or is it the other way around.

Rgds
Patrick

[wobbly]

Bigger case requires softer petals.
Its diminishing returns theory , the positive effects of having a bigger case get slowly erroded away by the fact that
the soft petals loose control and flutter with uncontrolled modes in the mid range.
A big case and soft petals work well at very high rpm , but in this case as you go bigger or softer the mid power gets Much worse.

[SwePatrick]

Thanks Wob.

I have actually made the case smaller this year as i had HUGE volume before, never measured, but now i have 1.3-1
I was lacking some midrange grunt before, that?s why i changed the volume.

So i?ll have to use stiffer ones now, thanks again.

[wobbly]

1.3 seems to be the approx limit.
But in any case , I have found that the best power comes from soft main petals and adding backups to control the modal flutter.
Here are some recent tests on making the mains softer , and using different backups top and bottom

[TZ350]

A big case and soft petals work well at very high rpm , but in this case as you go bigger or softer the mid power gets Much worse.

EngMod indicates a definite difference for reed and rotary valve case volumes.

It will be interesting to see if my "rotary valve" engine with its very big case volume will show a performance advantage that couldn't be realized if it was a reed valve inlet.

[Flettner]

So remind me the reason twin Rotary Valve is not a good idea? Or was it and just not tried much in practice. Was it Exact Weld (?) had a twin RV system?
Or are we best to just have a 'sliding door' that changes the crank case volume from a little bit to a lot as the pipe does its job.

[husaberg]

So remind me the reason twin Rotary Valve is not a good idea? Or was it and just not tried much in practice. Was it Exact Weld (?) had a twin RV system?
Or are we best to just have a 'sliding door' that changes the crank case volume from a little bit to a lot as the pipe does its job.

Jan said it wanted to try it and a dutch crowd made some very nice CNC crankcases to try it.
But i think the money ran out.

The first RSA engine was made at Derbi, it was meant to be able to beat Aprilia.
The Derbi reed valve engine gave 47,5HP when I arrived there in 2004.
So obviously something new had to be made.
But it was improved to 49.5HP, mainly through better inlet flow and better crankcase cooling.
It's electric water pump proved insufficient, so it was not used on the RSA.

The 250RSA had side inlet, so it used RSW cylinders, all tested and developed on a 125 RSW single.
It simply was a normal 250 with the gearbox output shaft in a higher position, and therefore the crankshaft rotation had to be reversed.

The 125 RSA/Derbi was a completely different engine, with the inlet valve on the rear.
This was done after flow bench tests showed that the RSW inlet flow was very much disturbed by the connecting rod, it seemed logical at the time!
Later we realized that the RSA inlet flow collided with the cylinder wall at the opposite side.
So there was very little gain....
Fins directing the inlet flow versus the transfer tunnels would have helped I now think!

In 2006 a special RSA cylinder was made with the cylinder bolts in a different position.
It had also better cooling of the exhaust duct and small cooling canals through the inside wall of the
transfer ducts, which improved power by 0,5HP!

So I finally came upon the idea of using a disc valve on each side, as already had been done by Exactweld.
But I decided to retire, a Dutch friend made some crankcases, but never finished the work.
So I still wonder how it would have gone....

The 70HP I mentioned for the 500 was, of course, on a single cylinder.
The engine used for those tests was a 500 engine, with only 1 crankshaft fitted.
Testing on 2 cylinders is more complicated and inconvenient.

Derbi was owned by the Piaggio group, which owns several Italian makes.
At the beginning of 2005 Piaggio bought Aprilia.
So they decided to close the Derbi racing workshop and I had to return to Aprilia, which I did in 2006.

The piston melting with a bigger than 39mm carburetor was probably caused by a weak spot just before maximum torque.
Because no powerjet was used at the time....

I first tried it on a 50 cc in 1074: more power.
Going from 80 to 85
Then at Aprilia in 1996: more power.
Without varying the crankcase volume.
We went from 112 to 113 and 115, later 118 was tried, still better.
For the RSA we had to lengthen the connecting rod from 115 to 120 to improve inlet flow: more power.
It is mainly due to piston friction I think.
NSU already found this in 1953, piston friction was the main source of friction in their 250 4-stroke engine.
It may be different for a reed valve engine, I have not much experience with these.
But the piston friction loss will, of course, be the same in a reed valve engine.

Of course at BDC there is no difference as you have to adjust the cylinder height!
Maybe it is interesting that with a longer connecting rod I could use higher transfer ports on my 50.
Getting still more power!

The crankcase volume also changes, of course, unless you change the position of the piston pin in the piston, as we did at Aprilia
This can be better or worse....
You can change your crankcase volume in many ways.
But always keep in mind that flow is more important than volume.....
On rotary valve engines I found the bigger the better, within reason of course....
The Aprilia engines had very narrow crank wheels, (16mm) so a very big crankcase volume. About 660cc in TDC
A big crankcase volume makes very long inlet timings necessary.
And big carburetors.

This is probably the reason why reed-valve engines need a smaller crankcase volume.
The reeds 'decide' for themselves when to open...
They need some depression.
And because maximum inlet flow is probably determined by the reed block, big carburetors won't work on a reed-valve engine.
They just slow down the flow in the carburetor, making for a difficult carburetor adjustment.

So I think that a rotary valve engine will always give about 3-4 HP more (125cc) than a reed valve engine.
Because of its unrestricted inlet flow and less pumping losses.

[Flettner]

Thank you Glen. All I need to know.

[husaberg]

Thank you Glen. All I need to know.

If you talk to Frits he might be able to tell you if there is amny of thoose cases still about or if the file still exists seeing you have the CNC
those molds you have can make a cylinder suitable for testing.

[SwePatrick]

1.3 seems to be the approx limit.
But in any case , I have found that the best power comes from soft main petals and adding backups to control the modal flutter.
Here are some recent tests on making the mains softer , and using different backups top and bottom

Yes, i'm using 'backups' to finetune the blades, it was late yesterday after a full day of headscratching of where my power was(dynoday)
I'll try to stiffen it up today to see if it?s the answer.
I'm missing the last 500-600rpm, pipe is tuned for 13200, but now i stuck at 12600.
It has produced 69hp at 13200rpm with this pipe before, and now 56hp at 12600.
I recon i won't gain all back to 69hp, but 63-65hp might happen if it could rev past 12600 and produce power all the way, but with more torque than before due to better crankcase.