ESE's works engine tuner

[Condyn]

B port short side radius below BDC on these 1974 Yamaha GYT cylinders with the roofs axial way up. Why? I am completely confused on this one. By the way the elevator shaft phrase was coined by the great Kevin Cameron!

[wobbly]

Teriks - OK so here is the beginning of the project.
Baseline engine ( black sim ) is 31cc piston port on unleaded race gas , and the simulation is very close to the actual power curve supplied by the customer - who has his own dyno.
The initial stage of the project is to use existing engine parts that have proven to be reliable at 20,000, including a reed block from a Tiger King.
So a long stroke crank , with a new En39B billet much longer rod , with existing piston/bearings etc puts the new engine at 34.8cc ( 35cc being the class limit )
This is still very oversquare , always a bad idea , but this begins proof of concept for the EngMod optimised porting/pipe /new carb etc and the beginings of heading toward
what I consider as SOTA for bmep and piston speed.
Here is the result - the cases and cylinder are being designed in SolidWorks as we speak , and the Ti pipe is at the laser cutter already.

[wobbly]

Porttiming - the pops are blowback thru the carb , coming from either the ignition rev limiter or simply the carb going way rich well past the peak power rpm.

[porttiming124]

ok thank you wobbly

[peewee]

https://youtu.be/oJcnaM-hB8Q

Zundapp crankcase, std. Derbi cilinder modified. Build in a Dutch shed by 2 brothers.

Lots of hours spend though...


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that seems like a mighty sophisticated shed. in america the shed has only a lawn mower with a garden hose and a few shovels

[Muhr]

Yes it will be interesting to follow!

I myself spends Saturday night trying to master magic of super polish ...
And borrowed a 3d printer for carbon fiber / nylon. has managed to print the first part to the 50cc engine
Has also managed to cut some parts yesterday for manufacturing a connecting rod for the engine

Tried to make the rotor cover in Carbon nylon, would work if I make a disc against the rotary valve I think. (Also has one to be cast in aluminum)
Polishing was also quite ok, enough for a surface treatment.
Someone who has some tips on companies that are good at surface treatments such as "DLC".

[teriks]

Teriks - OK so here is the beginning of the project.
Baseline engine ( black sim ) is 31cc piston port on unleaded race gas , and the simulation is very close to the actual power curve supplied by the customer - who has his own dyno.
The initial stage of the project is to use existing engine parts that have proven to be reliable at 20,000, including a reed block from a Tiger King.
So a long stroke crank , with a new En39B billet much longer rod , with existing piston/bearings etc puts the new engine at 34.8cc ( 35cc being the class limit )
This is still very oversquare , always a bad idea , but this begins proof of concept for the EngMod optimised porting/pipe /new carb etc and the beginings of heading toward
what I consider as SOTA for bmep and piston speed.
Here is the result - the cases and cylinder are being designed in SolidWorks as we speak , and the Ti pipe is at the laser cutter already.

Wow, that standard engine is for sure how to flatten the curve... not always a good thing.
Id guess you'll get very close to your sim results. Even the 6.5 sim matches the limited data I have quite ok, after a bit of reduction of CE.

[teriks]

Tried to make the rotor cover in Carbon nylon, would work if I make a disc against the rotary valve I think. (Also has one to be cast in aluminum)
Polishing was also quite ok, enough for a surface treatment.
Someone who has some tips on companies that are good at surface treatments such as "DLC".

You sure are getting things done

I have had some stuff done at Ionbond: https://www.ionbond.com/about-ionbon...ations/sweden/
Youd have buy thru a company though, but given the waterjets etc Id guess that wont be a problem for you.

[Tim Knopper]

https://youtu.be/oJcnaM-hB8Q

Zundapp crankcase, std. Derbi cilinder modified. Build in a Dutch shed by 2 brothers.

Lots of hours spend though...


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The real numbers are 23 hp reed engine and 23 rotery engine official on dynoday every end of the year

[wobbly]

Condyn - nearly all the two stroke Jap engines from that period had the scavenging pattern as you describe with the B port up at around 45*, and its floor below BDC.
And there have been many examples of the boost port short turn lowered below BDC over the years , as they are angled up at 55+ - usually with a 1/2 moon concave curve , its something I have been meaning to try on a modern cylinder
for ages , but hard to rectify if its a fail.
The modern scavenging pattern reverses the axials , with the A port up at 25* + and the B at 15*- and I spent hours , years ago welding and epoxying up LC type ports to do exactly that.

[katinas]

Wob, Condyn, maybe this in theme. Quite by accident on Husqvarna TC65/85, we noticed that by rounding A and B the floor edges, up to r-3 mm, the power increased. I can’t say exactly why, but probably it helps mix flow back to transfers through the piston cutouts, after TDC and until the moment when A and B closed. With many others small modification on latest TC 85, all ended 12 hp at 7000rpm and rise without spots to 36.47 hp at 11756 rpm. from wheel.

[Muhr]

You sure are getting things done

I have had some stuff done at Ionbond: https://www.ionbond.com/about-ionbon...ations/sweden/
Youd have buy thru a company though, but given the waterjets etc Id guess that wont be a problem for you.

Thanks! I have heard some mixed experiences from them.

Wob, Condyn, maybe this in theme. Quite by accident on Husqvarna TC65/85, we noticed that by rounding A and B the floor edges, up to r-3 mm, the power increased. I can’t say exactly why, but probably it helps mix flow back to transfers through the piston cutouts, after TDC and until the moment when A and B closed. With many others small modification on latest TC 85, all ended 12 hp at 7000rpm and rise without spots to 36.47 hp at 11756 rpm. from wheel.

It is impressive!

36.47 hp at 11756 rpm It is 22nm at peak hp.

[teriks]

Thanks! I have heard some mixed experiences from them.

I have had mixed experiences too.
The crank pins on the MB40 was more miss than hit, but IMO thats mostly due to the loads and base material.
-I had a batch of shafts that were too soft and wore out way too fast, so tried to save some with dlc.

If I ever finish my own cases, Im trying shafts in "Uddeholm Vancron SuperClean", should negate the need of coatings.
Shafts are finished, but still a long way to go before I have running engines.

[Niels Abildgaard]

Wob, Condyn, maybe this in theme. Quite by accident on Husqvarna TC65/85, we noticed that by rounding A and B the floor edges, up to r-3 mm, the power increased. I can’t say exactly why, but probably it helps mix flow back to transfers through the piston cutouts, after TDC and until the moment when A and B closed. With many others small modification on latest TC 85, all ended 12 hp at 7000rpm and rise without spots to 36.47 hp at 11756 rpm. from wheel.

If the ultimate power of a two stroke is limited by port areas,as I think it is, we can rate these 36.47hp from a 85ccm with 52 from a RA125.

52*(85/125)**,6666=39.25 to be compared with Katinas 36.47.
Considering that the 85ccm has relative higher thermal losses it is awfull impressive for a private run project..

[Frits Overmars]

...on Husqvarna TC65/85 we noticed that by rounding A and B the floor edges, up to r-3 mm, the power increased. I can’t say exactly why, but probably it helps mix flow back to transfers through the piston cutouts, after TDC and until the moment when A and B closed.

Katinas, I think I understand your message, but I am not 100% sure. Are you talking about rounding off the inner edges at the bottom of the cylinder bore, as in the Aprilia picture below, or are you talking about the floors of the transfer ducts where they enter the cylinder above the piston?