ESE's works engine tuner

[speedpro]

Interesting flywheels with the constant thickness webs for reduced friction. Nice row of mallory(?) metal slugs for counterbalance.

[wobbly]

The Asian factories use SCM - 415 forgings, but for one off's then EN 36 or 39B case hardened to 58 - 62Rc is the shit.
Mallory Metal slugs are the go for ballancing, but if you want the real deal, then pay 100,000 USD for a licence, and use Depleted Uranium.

[speedpro]

"Depleted" Uranium is for pussies.

[TZ350]

Whether Frits is on the money I don't know, but this is what he has to say about squish.........

Combustion in an ideal homogeneous air/fuel-mixture has a flame speed of maybe 2 meters per second. So how is it possible that combustion in a 125 cc engine, running at 13000 rpm, is completed within 50 degrees of crankshaft revolution?
The answer is turbulence. Burning lumps of mixture are blown across the combustion chamber and then simultaneously start their own fires in every corner. The blowing is taken care of by the squish effect that pinches mixture (red on the drawing below) from between the piston (yellow) and the outer area of the cylinder head (blue).
There are programs that calculate the squish velocity, and they are all bullshit. Why? Because none of these programs take into account that at high rpm the crankshaft bends, the conrod stretches and the piston moves higher by about 1 % of the crankshaft stroke. And it makes a lot of difference for the squish velocity, whether the minimum distance between piston and head is 0,6 mm or 0,06 mm...
The higher the flame speed, the better is is for power and for the thermal load on the engine. So make your squish gap as narrow as possible: 1 % of the stroke. And do not be afraid that the slightly higher compression ratio will cause detonation; effective squish will do just the opposite.



In days of old the ideal combustion chamber was considered to be a sphere with the spark plug in the center, so that the flame path was as short as possible in all directions. And because that was impractial, the next best thing was a semi-sphere. But that is ancient history; we need turbulence!
Toroidal cylinder heads are shaped so that the inital turbulence, created by the scavenging streams of fresh mixture and still present in the cylinder after the transfer ports have closed, is enhanced as the squish effect moves the mixture towards the spark plug. And after that, the toroidal turbulence takes burning lumps of mixtures from the plug area towards all corners of the combustion chamber.

Frits Overmars



And this is the head Wobbly is designing for my new project, it looks the bizzz, I can't wait to get started .............

[TZ350]

Mallory Metal slugs are the go for ballancing

Where can I get Mallory Metal slugs? is it possible?.........

[TZ350]

.

Check this out for a decent sized exhaust port.

The cylinder is off a ( 360kmh??) racing model aeroplane.



The amazing exhaust port eyebrows are possible as the piston dosen't have a piston ring.

[gatch]

The Asian factories use SCM - 415 forgings, but for one off's then EN 36 or 39B case hardened to 58 - 62Rc is the shit.
Mallory Metal slugs are the go for ballancing, but if you want the real deal, then pay 100,000 USD for a licence, and use Depleted Uranium.

Right so some 4140/4340 would be the go should I do a short stroke crank.

Wikipedia link on mallory metal.

http://en.wikipedia.org/wiki/Mallory_metal

[RMS eng]

Whether Frits is on the money I don't know, but this is what he has to say about squish.........

Combustion in an ideal homogeneous air/fuel-mixture has a flame speed of maybe 2 meters per second. So how is it possible that combustion in a 125 cc engine, running at 13000 rpm, is completed within 50 degrees of crankshaft revolution?
The answer is turbulence. Burning lumps of mixture are blown across the combustion chamber and then simultaneously start their own fires in every corner. The blowing is taken care of by the squish effect that pinches mixture (red on the drawing below) from between the piston (yellow) and the outer area of the cylinder head (blue).
There are programs that calculate the squish velocity, and they are all bullshit. Why? Because none of these programs take into account that at high rpm the crankshaft bends, the conrod stretches and the piston moves higher by about 1 % of the crankshaft stroke. And it makes a lot of difference for the squish velocity, whether the minimum distance between piston and head is 0,6 mm or 0,06 mm...
The higher the flame speed, the better is is for power and for the thermal load on the engine. So make your squish gap as narrow as possible: 1 % of the stroke. And do not be afraid that the slightly higher compression ratio will cause detonation; effective squish will do just the opposite.



In days of old the ideal combustion chamber was considered to be a sphere with the spark plug in the center, so that the flame path was as short as possible in all directions. And because that was impractial, the next best thing was a semi-sphere. But that is ancient history; we need turbulence!
Toroidal cylinder heads are shaped so that the inital turbulence, created by the scavenging streams of fresh mixture and still present in the cylinder after the transfer ports have closed, is enhanced as the squish effect moves the mixture towards the spark plug. And after that, the toroidal turbulence takes burning lumps of mixtures from the plug area towards all corners of the combustion chamber.

Frits Overmars



And this is the head Wobbly is designing for my new project, it looks the bizzz, I can't wait to get started .............

looks like a 2001 RS125 head

[k14]

looks like a 2001 RS125 head

Was just going to say the same thing. I was told that it was only good when running unleaded. But the results I had seemed to say it went pretty good running av gas too.

[Buckets4Me]

looks like a 2001 RS125 head

looks like a casting for a valve cut in half to me ?

[wobbly]

Crank wheels need a ductile core, so all the surfaces that wont be ground need to be painted with a copper based coating to prevent the hardening gas from thru hardening the whole part.
EN39B is the best material and is readily available.Heat treatments ltd can do all the processes including stress relief after rough machining the shape - talk to Adam there if you are going to do a crank.

I have some Mallory slugs in stock.

A true Toroid shape was developed to control deto with unleaded fuel, the processes involved work just as well with better octain fuels.

The zero corner rad was a "secret" for years that I tried for the first time when working with Bartol on his Yamaha and my BSL cylinder layout - well before Thiel and Aprilia got onto it.
But its funny how people make "assumptions" that are usually revealed later as "errors".
A CFD analysis of the Toroid head shows that the mixture ejected from the squish, actually adheres to the vertical wall, around the sharp corner, and rotates anticlockwise - opposite to what Frits shows.
This is why it works even better with a flat top piston.
Who cares though - it works.

I dunno where Frits is getting his info from but the Dellorto with the "Fiat Uno" stepper motor was soon replaced by the stock Keihin solenoid as shown in the pic above.
This was better than the original solenoid in that it can be "pulsed" or PWM controlled by the ECU to vary the fuel flow as needed when the Deto sensor ( on the head - from a Subaru) said bad shit was happening.

[speedpro]

My crankpin was made by heat treatments. machined, heat treated, and ground. Hasn't let go yet but still early days. 20mm ends with a 22mm centre, offset .75mm. Very helpful guys.

[F5 Dave]

So how do they get on with caged bearing offset pins? Yours would be ok as the offset could go another .25 & still slide the bearing straight on, but what about larger offsets? My 500 crank has a 7mm offset & I imagine same size centres & ends. Never really had to think about that before. Non caged rollers would be an option, but bags not load them.

[kel]

I dunno where Frits is getting his info from but the Dellorto with the "Fiat Uno" stepper motor was soon replaced by the stock Keihin solenoid .

Yeah he corrected this in his next post stating the Keihin solenoid replaced the stepper motor and is the same unit as used on the RS125.

[gatch]

Crank wheels need a ductile core, so all the surfaces that wont be ground need to be painted with a copper based coating to prevent the hardening gas from thru hardening the whole part.
EN39B is the best material and is readily available.Heat treatments ltd can do all the processes including stress relief after rough machining the shape - talk to Adam there if you are going to do a crank.

I have some Mallory slugs in stock.

If I do, it'll be a 3 piece..

I should be able to harden/grind everything at work, I think..

Last time I used the tool post grinder I made a guard for it as it didn't have one, the next guy who used it threw the guard out "coz it's for poofts and amateurs", then the cup wheel he had on exploded..