ESE's works engine tuner

[Grumph]

Thanks for the information everybody. Thanks for the trabbie pics Frits, I'd never seen the internal layout. I note that the discs are larger diameter than the crankshaft. Makes for a bit more complicated casting - but if you're going to produce them in the numbers they did, it would be worth it.

Will - you may be familiar with the Alpha journal type rotary valve which is a truly horrible device. You'd think that this type of internal disc would be preferable, they must have known about it but chose the journal type.....WHY ?

[TZ350]

page 1700 .....

By the way, you should know that Albert Einstein distinguished four kinds of people:
dumb + lazy: harmless
dumb + diligent: disastrous
smart + diligent: not much better than dumb + diligent
smart + lazy: the only useful kind; those are the ones who seek efficient solutions.

US Chrome, good buggers, both 7075 rods have been hard chromed at minimal cost. Because they are keen to help out with the projects (and I guess ultimately would like to do more paid chroming for me in the future).

But odd that they will not send the components back to NZ, they can only sent within the US? No problem I'm getting the parts sent to the guy that makes the Gyro rotor blades for me in Florida, so they will be sent out to NZ in due course in a box of rotors, hopefully shortly. This will have to be sorted in the future if I'm going to get more done. Anyone needing 7075 parts hard chroming?

Katinas first test ride of the Ryger he built.

https://www.youtube.com/watch?v=ckOw-Cp7wH8

https://www.youtube.com/watch?v=L-0AH79mY2E

Is Viton the preferred material for O-rings used to seal liquid cooled heads?

Viton is the material of choice for the inner ring where it seals the chamber to the cylinder top.
But around the outside where it seals only water ,normal O rings are fine.

I have been made aware of the dangers of Viton when heated or burned as in fan belts on burnt cars being dangerous.

Attachment 329720

Lengthening the exhaust duct and cool it very well is one of the things I regret not having tried! I had the idea in 2007, but did not try it because I was planning to retire... Almost certainly it will give e good power improvement!

The idea floated about lengthening the Ex duct and increasing the cooling in this area is exactly what i will be advocating for the new kart engine design. Along with a shape change to include the Aux duct ears right down to the header joint and water having access into the back of the bolt on spigot.

Attachment 329719

Edit - here is the optimum duct geometry as I have found in EngMod.

Turbo:-

Some further reading for TZ he might need to reverse engineer it a bit for his application.
http://www.spartgsxrspecials.com/tur...and%20dont.htm

Vannik or anyone that knows stuff, I don't have your software so don't know this, if combustion does not happen, what happens to the air velocity in the combustion chamber at / after TDC? Does the rapid turbulence in the combustion chamber stop and reverse at some stage, as the squish starts to open up again? Or does it keep going but just slow down a bit?

The turbulence is caused by the breakdown of the main flow. Because of the viscosity (in effect the internal friction of the fluid) the main flow progressively break down into ever smaller eddies and if left long enough all the main flow and all the eddies will stop. The main flow is from the transfer port loop and a stronger better directed flow with more kinetic energy can generate a lot of turbulence before it stops. If you have weak flow by the time combustion happens you need the extra flow from the squish to generate extra turbulence to get good combustion.

On the other side if you have strong flow and thus good turbulence the extra turbulence can speed up the combustion too much and you loose power but mostly overrev. This explains why engines do not always behave the same to squish changes. Good engines use squish to minimize end gas to stop detonation while poor engines use squish to add turbulence.

So to answer the question: Turbulence cannot reverse, it is a one way street after creation. The bulk flow with the squish opening will loop slower and slower, both because of the increase in volume and because it keeps generating turbulence until it completely stops.

Detonation.

This started te be a problem when 50cc engines started giving more than 17HP, around 1975.
At the time I thought this was a limit on engine power.
Nikasil plated cylinders were very prone to detonation.
Because of the rounded off edge at the top.
At Minarelli/Garelli I solved this problem by sticking the cylinder head insert 3mm into the cylinder.
A good solution, used for many years.
But at Aprilia we found an even better solution: plate the first 5 mm around the bore at
the top of the cylinder.
Later this was machined to a very sharp corner, and this eliminated completely the unnecessary
'dead room' at the top of the cylinder, it also gave 0,3HP more.....
A little bit of still remaining detonation was eliminated by modifying the inner wall of the
transfer ducts, cooling the piston.
But part-throttle detonation remained a problem.....
Which we never had on the dyno!
On the photo you see a piston after a 54HP run...
As long as you keep the throttle wide open a 2 stroke doesn't brake down!

When modifying a cylinder measuring duct sizes is not easy, especially in the curves!
You can see our solution to this problem on the photo....
Round 'sensors' fitted to a piece of welding rod!
We had them from 7-7,25- 7,5 and so on until 28mm.
Behind the cylinder, in the wooden block.

Detonation.

This started te be a problem when 50cc engines started giving more than 17HP, around 1975.
At the time I thought this was a limit on engine power.
Nikasil plated cylinders were very prone to detonation.
Because of the rounded off edge at the top.
At Minarelli/Garelli I solved this problem by sticking the cylinder head insert 3mm into the cylinder.
A good solution, used for many years.
But at Aprilia we found an even better solution: plate the first 5 mm around the bore at
the top of the cylinder.
Later this was machined to a very sharp corner, and this eliminated completely the unnecessary
'dead room' at the top of the cylinder, it also gave 0,3HP more.....
A little bit of still remaining detonation was eliminated by modifying the inner wall of the
transfer ducts, cooling the piston.
But part-throttle detonation remained a problem.....
Which we never had on the dyno!
On the photo you see a piston after a 54HP run...
As long as you keep the throttle wide open a 2 stroke doesn't brake down!

The Aprilia RSW was a ROTAX design.
Later Aprilia made their own engines, but closely followed the original ROTAX design.
Except some small details.
Now they could say everything was 'made in Italy'
Which had financial 'advantages' for certain people!
Who could now take a bribe from the suppliers......as is usual in Italy.
So I am certainly not the 'father' of the Aprilia engines!

I was responsible for cylinder development, starting with 46,5HP and ending with 54HP.
Later, when working at DERBI, I had the idea of making the RSA engine, and made the first sketches.
The actual design was, of course, done on a computer by a professional designer.
Although it won several world championships I don't consider it a big success...

Aprilia always used AGIP fuels and oils for dyno testing
102 octane.
We were given face masks and special gloves, which we never needed for the 130 octane fuel.....

When modifying a cylinder measuring duct sizes is not easy, especially in the curves!
You can see our solution to this problem on the photo....
Round 'sensors' fitted to a piece of welding rod!
We had them from 7-7,25- 7,5 and so on until 28mm.
Behind the cylinder, in the wooden block.

Pistons:


We had cast and forged pistons.
Cast pistons gave slightly more HP, but sometimes cracked.
0,8mm piston rings gave more HP than 1mm rings.
As the auxiliaries and transfers overlapped each other a certain power los was caused by this.
So closing the pin hole in the piston was tried.
There were many solutions that were tested, but they all caused some trouble.
In the end the best, and most reliable, solution was welding then closed.
This was very well done by PANKL in Austria, and never caused any trouble!

Do you mind me asking why do you think cast pistons made more hp than forged?

Because forged pistons had a tendency to 'bend' their top inwards.

Transfer ducts.

Many transfer ducts with small differences were tried.
We found more power by enlarging the A-port in the direction of the exhaust.
Only the lower half, but it was important to give the A-duct an inclination away from the exhaust!
The ducts were very conical, the smallest point being the port.
In and outside walls of the ducts had a constant radius from top to bottom.
The flow remained attached to the inside radius and so cooled the piston and eliminated detonation.
Flow bench testing and the Jante type testing proved useless for power improvement.
Giving the rear side of the B-duct an inclination versus the middle of the cylinder gave a big improvemet

[oldjohnno]

Lots of photos of the Alpha (and the disc valved Centuri twin) here: http://www.villiers.info/Alpha/

[WilDun]

I was always under the impression that the Alpha also used discs. (and I see that I was correct) but hadn't studied the earlier single.
So which came first? the MZ (Trabant) twin or the Alpha twin? - anyway it doesn't matter, it's a very tidy layout - they should have done that with the Ariel Arrow!

TZ, is your Ariel Arrow still languishing under the bench?

[Frits Overmars]

Thanks for the trabbie pics Frits, I'd never seen the internal layout. I note that the discs are larger diameter than the crankshaft. Makes for a bit more complicated casting.

Nah; you can't cast decent disc recesses like that anyway; they'll always need some final processing.
I suppose the simplest approach would be to cast those cases 'full' and then dip in a cutter blade.

[WilDun]

Nah; you can't cast decent disc recesses like that anyway; they'll always need some final processing.
I suppose the simplest approach would be to cast those cases 'full' and then dip in a cutter blade.

Yes, that would be the best way to do it - I always found over the years that machining cast "pockets" like that was really a pain in the arse and often very difficult to get a smooth even finish - much easier to machine areas like that from solid!

Just as a matter of interest, the Trabant engine has been used successfully in some light aircraft.

[Grumph]

Nah; you can't cast decent disc recesses like that anyway; they'll always need some final processing.
I suppose the simplest approach would be to cast those cases 'full' and then dip in a cutter blade.

True. Given the stories about the Trabbie bodyshells, I was pleasantly surprised to see the quality of the castings - and the level of finish too.

[Frits Overmars]

Just as a matter of interest, the Trabant engine has been used successfully in some light aircraft.

I didn't know that. And I'm interested. Got any pictures Will?

Given the stories about the Trabbie bodyshells, I was pleasantly surprised to see the quality of the castings - and the level of finish too.

Not everything in the DDR was of 'Russian' quality. Trabbi castings were allright, as were Simson castings. MZ street bike castings were not great, MZ racing cylinder castings were horrible.
By the way, if the East-Germans describe something as Russian, you'd better steer away from it. It's their summary of ponderous, clumsy, rude, churlish, inane and dumb. Not much love lost there....

[WilDun]

I didn't know that. And I'm interested. Got any pictures Will?

Not everything in the DDR was of 'Russian' quality.
By the way, if the East-Germans describe something as Russian, you'd better steer away from it. . Not much love lost there....

Ha ha, used to be a joke here "when does a Skoda look good? ..... "when it's parked next to a Lada". ...... But then a while back the Americans got a nasty surprise when they found that their fighter aircraft were not as good as the Russian ones - and they very quickly had to do something about it!

Yes quite a while ago I saw a video of a light aircraft fitted with a Trabant engine but I'll have to find it. - performed well!

[tjbw]

Yes, that would be the best way to do it - I always found over the years that machining cast "pockets" like that was really a pain in the arse and often very difficult to get a smooth even finish - much easier to machine areas like that from solid!

...

Agreed, though those deep grooves would still be tricky (for me) even from solid, in fact I'd be inclined to redesign the crankcase, making the central section an insert.

[WilDun]

Agreed, though those deep grooves would still be tricky (for me) even from solid, in fact I'd be inclined to redesign the crankcase, making the central section an insert.

Yes, was just now thinking along those lines myself, however a production machine set up to do that specific job would be a much cheaper option than an insert (ie in a factory which churns them out!).

FRITS, here are a few links :-

http://www.lightsportaircraftpilot.c...entalaircraft/

https://www.pilotmix.com/sd-1-minisport

http://www.youtube.com/watch?v=u2R7VznSGVw

https://en.wikipedia.org/wiki/Air-cooled_engine

[tjbw]

...

It surprised me that nobody commented on the red circles in Husabergs Cyclemaster picture, showing the engine's most interesting part: the governor.
It was a spring-loaded vane that gradually closed the inlet opening in the disc as the revs went up. Removing the vane gave the little engine a second wind.
Attachment 329476

...

Might there be some merit in something similar, that adjusts the inlet timing depending on rpm?

[WilDun]

Might there be some merit in something similar, that adjusts the inlet timing depending on rpm?

I think Flettner is already working on some form of controlled variable disc timing and knowing him, he's probably got it just about sussed by now!
BTW, I don't remember there being any timing adjuster on the Cyclemaster I owned.

[tjbw]

I think Flettner is already working on some form of controlled variable disc timing and knowing him, he's probably got it just about sussed by now!
BTW, I don't remember there being any timing adjuster on the Cyclemaster I owned.

It's hard to see on the photo, but it's a vane that actually closes the inlet port as rpm increases, don't think it changes the timing. Perhaps some kind of performance limiter was required in some markets.

[wobbly]

Flettner has had a variable disc valve timing setup for ages, a moving insert that changes the closing timing with an Ignitech controlled PV servo motor.