ESE's works engine tuner

[WilDun]

is "TDC" in the diagram related to just one crank or is it the smallest volume based on the phasing of the cranks? seems like as displayed it's off the transfer crank in one and the exhaust crank in the other.

Guess it could be considered "TDC Dwell"!

As for plugging duration, why not simply call it LP or SP (Long Plug or Short Plug) - perhaps expressed as a percentage?

[OopsClunkThud]

how about using plugging duration but get more specific about if it's "exhaust plugging duration" vs "transfer plugging duration" positive value is exhaust, negative is transfer.

[Muciek]

Guys, I'm tired of making cones for pipes by hand (hammering them on pipes and other stuff..) , maybe someone got some drawings for the slip roll ?

[Flettner]

My boat OP engine ran 6 degrees exhaust lead.
Most outings with no tuned pipe just a Rotax aircraft engine muffler and a four into one collector. At one point I built four tuned pipes, all this successfully did was wreak the gear drive, my home cobbled gears couldn't live with the extra torque. The exhaust pistons also suffered, as I had expected might happen.
I was worried I wouldn't have enough time for the reverse plug when the chambers were fitted so hence only six degrees exhaust lead, for an engine with tuned pipes I don't think you should go much more.
Reguarding the exhaust piston thermal issue. My engine had four carburetors, two feed exhaust crankcases, two feed transfer cases. As a transfer carburetor and an exhaust carburetor combined to fill one cylinder I made the exhauat carburetor 66% fuel and the transfer carburetor 33% useing the extra fuel to help cool the exhaust piston.
My new OP has the exhaust case 100% fuel and the transfer case air only. Some cylinder filling advantages can be had like this, an air buffer, done properly.

[wobbly]

JFN2 - as I have said several times before , you are tuning completely in the dark if you dont do the measuring and calculate the inlet piston ports actual power capability.
Now JanBros spreadsheet calculator is available you dont even have to buy EngMod just to see what the STA numbers look like.
I was really surprised a while ago when doing the numbers on a new CPI Banshee cylinder design.
It had such good inlet time area the huge Boyesen ports were not actually needed at all , untill the cylinder was theoretically capable of making over 120 Crank Hp.
As I was shooting for just over 100 CHp , I thought I would test the codes accuracy at that level of tune .
I filled the Boyesen ports with epoxy and did a dyno session to get the ignition and jetting on the money , then simply knocked out the epoxy filler.
Initially it made 102 Hp , with the Boyesens open it lost 4Hp.
Case closed.

[F5 Dave]

. . . .
Case closed.

Ohh Dad joke.

Was the inlet same as my 496 would be? I'm at 99 now in Road spec 10k peak, 35mm carbs.

[Frits Overmars]

Naming of porting events.

Since starting to look at opposed piston engines where the phasing of the crankshafts are possible I have run into a nomenclature problem.....Negative plugging duration where the exhaust port closes before the transfer ports.... So what do we call this "negative plugging duration"?

Neels, how about

TRAFEX - transfer after exhaust
TRAFEC - transfer after exhaust closure

Or, when no transfer is involved:

CHAFEX - charging after exhaust
CHAFEC - charging after exhaust closure

Take your pick

[Vannik]

is "TDC" in the diagram related to just one crank or is it the smallest volume based on the phasing of the cranks? seems like as displayed it's off the transfer crank in one and the exhaust crank in the other.

I use the exhaust piston crankshaft as the master. And a positive phase angle is by how much the exhaust piston crankshaft leads the transfer / inlet crankshaft.

Somewhere in between the TDC values for the two crankshafts is the smallest volume and the effective TDC. If both crankshafts have the same stroke this effective TDC is halfway between the two. The result of all this is you have to find a new optimum timing value, for now I just add half the phase angle to the timing value specified for zero phase angle.

[Vannik]

Neels, how about

TRAFEX - transfer after exhaust
TRAFEC - transfer after exhaust closure

Or, when no transfer is involved:

CHAFEX - charging after exhaust
CHAFEC - charging after exhaust closure

Take your pick

Frits, you are giving me an idea, negative plugging duration will only work with some sort of blower, turbo or super, so what about "Charging duration"?

[Frits Overmars]

Frits, you are giving me an idea, negative plugging duration will only work with some sort of blower, turbo or super, so what about "Charging duration"?

It's always a pleasure to hear that I've contributed to an idea, but in this case I hesitate to take any credit.
Doesn't 'charging duration' cover the whole cylinder filling phase, rather than just the phase after exhaust closure?
If you'd call it 'supercharging duration', then yes, I think that would cover it. But we need short words if we want to make them stick.
SUDU? (That reminds me of Sudoku, the kind of puzzle that I use to take my mind off more serious matters ).

[Vannik]

Boost Charging Duration?

[andreas]

Trailing transfer?

[JanBros]

Why don't we call it Voldemort ?

after "the phase who must/can not be named" ?

[WilDun]

Why don't we call it Voldemort ?

after "the phase who must/can not be named" ?

He was that enigmatic wizard of a tuner, who could do just about anything with two strokes (ie of his magic wand) ...... wasn't he? -

Thread is getting sillier by the minute!

[Muhr]

Hi everyone I have my "forgotten" little 50cc project that has been around for a few years. have now decided to make a shifted engine and when I still do, I thought I would use a balance shaft. And if I still make a balance shaft, I can just as well make it a rear mounted rotary valv. Has started scraping together some stuff, including a gearbox gears for balance shaft and a clutch.
Now to the question, are there any guys that have been rebuilt to dry-clutch that i can get some inspiration from on smart solutions?

Edit: Perhaps the easiest thing is to steal gears and cage mounts from a kz (unfortunately, the gears are a little longer)