ESE's works engine tuner

[teriks]

Standing in the line of fire of such a degree wheel spinning at 10,000 rpm is a great way of catching an arterial bleeding....

My thoughts too, and that comes from someone used to dealing with cf-props at 30+ krpm. That made me nervous!

[TZ350]

How much of the change in output can you attribute to the ports/ducts and how much to the head shape/commpression ratio ??

I dropped the compression a touch for reliability but I am not sure about the head shape, copying something of Frits's seemed like a good idea at the time.

The port duct changes should have helped reduce short circuiting as the main thrust of the changes were to direct the transfer stream away from the exhaust port at BDC and followed a layout that worked for me before.

I think the problem is with the cleaned up exhaust port and un shroudeding of the side exhaust ports. Same actual timing but I think there is now more effective blowdown time area and the engine is looking for a pipe more suited to peaking at 13-14K rpm than the 12 of the RS pipe I have been using.

It is something I have seen in the EngMod2T simulations too, same ex port timing but increased blowdown from wider or side ex ports and the power curve wants to move up the rev scale.

When I can I will dust Wobblys Parana pipe off and give it another go.

I may have over cooked it on this cylinder with its 203 deg duration exhaust. But if I am right about the effect of the extra blowdown time area from the side ports then that suggests. I could make another one with 190 duration for a broad power spread and enough effective blow down time area from the hand carved side ports for good hp at lower revs. But it wont be happening this week.

[TZ350]

Ok The blue line is where the 3 Ex port cylinder and RS pipe are at now. I dont think the RS pipe suits the new cylinder because the RS pipe wants to peak at only 12K.



The STA's for the 3 Ex port cylinder showing high 30's at the rear wheel is possible for someone who can cut metal into shapes that faithfully replicates the design.



EngMod2T simulation with 83% combustion efficency and Wobs pipe shows that the power will peak around 14K for the 3 Ex cylinder.

There is a nice flat area to the torque curve in the 12.5 to 14.5K area and if I can get a CVT setup to work in that range we could have a rocket ship.

I havnt got my head around everything about CVT's yet but from what I have read and heard from Wax and Frits the amount of rev drop when the throttle is backed off can be controlled by changing the angle and or shape of the slots in the rear pulley sheave.

Speedpro suggested to me that I could fit a sleeve thats been cut with my own slot arrangement to a std pully. Now I could make a pulley sheave with slots curved in such a way that the rpm drop varies depending on the CVT's current ratio or how fast its going. Slow speed low gear (1st 2nd 3rd gear in old gear box talk) the rpm drops more and at high speed high gear high load (4th 5th gear) the rpm is held nearly constant around peak power.

[FastFred]

Ok The blue line is where the 3 Ex port cylinder and RS pipe are at now. I dont think the RS pipe suits the new cylinder

So you didn't get such a great result today but it looks like there is still plenty of promise.

Outright hp has not been all conquering so there has to be a new way of doing it, a fundamental change.

I am looking forward to seeing how the CVT thing develops.

[koba]

i dunno why you reply before reading the entire post.........apple vs apples vs oranges vs kiwifruit

My take on this is:

If 0 was the optimum ammount of inertia for my bike then a standard rotor may be say, 100.

The KX one could be, perhaps, 20.

To little inertia could be had by grinding down the crank wheels or whatever to get a similar ratio to a competition engine, then with the no ignition rotor and just a plate for an ignition pickup perhaps it would be say, -100.

Yes, putting the new ignition on changed at least 3 aspects: rotating mass, nature of the spark and the timing curve BUT knowing the bike well, I can say, with enough certainty to convince my own sceptical mind; the reduction in mass was positive in every aspect.

I can really fell it when coasting with the clutch in and matching engine revs to road speed before releasing the leaver.
(like when one fucks up a shift)

[koba]

Ok The blue line is where the 3 Ex port cylinder and RS pipe are at now.

I'd tap that.

[koba]

...grinding down the crank wheels or whatever...

...and replacing the area with a lighter substitute of the same volume, so as to not affect the primary compression ratio or any airflow characteristics in the crank case...

[Frits Overmars]

...and replacing the area with a lighter substitute of the same volume, so as to not affect the primary compression ratio or any airflow characteristics in the crank case...

Might I suggest a mixture of air and petrol ?
By all means do enlarge the crankcase volume.

[husaberg]

Might I suggest a mixture of air and petrol ?
By all means do enlarge the crankcase volume.

Frits can you clarify something for me. I was attempting to read a forum translated from Dutch the other day.
The post was from Jan. I think it said something along the lines that you were able to obtain an extra .5 hp on( i think the RSA) by either extending the coolant channel either direcly into the transfer septum.or furter into it? Was this a foible of google translate?
because .5 HP is a very dramatic increase for such a highly developed engine?. That certainly would have been beers all around i guess.

[Frits Overmars]

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

[Grumph]

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

That's a tricky bit of patternmaking - which I would not like to try.....

[koba]

I guess that would get more and more important with such high performance engines having the hot ducts and the cold ducts so close over so much area...

[Yow Ling]

That's a tricky bit of patternmaking - which I would not like to try.....

isnt that the same as the cheese in the pizza crust, cant be that hard !

[husaberg]

Jan was talking about coolant passages inside the inner curvatures of the transfer ducts. I have no pictures of those (cutting RSA cylinders in half would be a bit of a costly hobby) but here is a picture of my FOS cylinder with the same coolant ducts.

Dank u wel.
Are you familiar with rapid milk cooling systems.
I guess it would still be easier to do the water galleries on the 2 stroke than the oil galleries in a RC166.
In your cylinder are these formed with a cast in small diameter pipe insert?

[2T Institute]

Yep. Any mass you have to spool up cost you acceleration, and unless you've invested in kinetic energy recovery tech you don't get it back. F1 engines have no flywheel at all, they have enough mass in the crank that it's inertia alone keeps them ticking over at the minimum revs they're required to run at.

Reality doesn't agree, flywheel weights gain a lot of traction and drivability (ask any CR500 owner), with a lot of inertia you don't drop a lot rpm when the throttle is closed under brakes. Getting on the throttle earlier does wonders for acceleration.