ESE's works engine tuner

[wobbly]

In jetskis we used a much too big stinger to increase the low and mid power, then pumped water into the stinger to squeeze down the effective outlet area
Best power was at 3 psi at full noise, and this was set by a jet under the water solenoid.

[F5 Dave]

What silicon or similar will standup to petrol and oil in a 2 stroke crank case? I have blanking plates I want to seal in.

Yamabond, which is pretty much 3Bond 1215. Most bike shops or gasket places will have it. Std fare for Suzukis & Yams which don't have centre gaskets.

[F5 Dave]

In jetskis we used a much too big stinger to increase the low and mid power, then pumped water into the stinger to squeeze down the effective outlet area
Best power was at 3 psi at full noise, and this was set by a jet under the water solenoid.

That's brilliant. . . But why does too large a stinger increase bottom end?

[wobbly]

I know it seems counter intuitive, but at low speed where the pipes tuned length is too short,the power will come up if you reduce the effects
of the return wave coming back way too early.
Thus by reducing the pressure in the pipe you ameliorate the bad effects by killing how well the pipe system works.
High pressure in the pipe increases the effectiveness of the wave action, so to reduce this additional "performance" at low rpm,you open up the stinger diameter.
Less bad matching of port timing and pipe length = more power.

[F5 Dave]

oh, ok I'd just assumed there was an optimum for output/heat as always chasing top end. So this has a noticeable difference on mid/low?

Pity its not the other way around or I can imagine some simple RAVE type valves on the stingers. So a 2ndry ATAC further down the pipe to release pressure, would have to have some muffling. Too complex I guess.

[wobbly]

On the big bore ski it was around 35% increase in power at the bottom of the used powerband.

[Drew]

Pity its not the other way around or I can imagine some simple RAVE type valves on the stingers. So a 2ndry ATAC further down the pipe to release pressure, would have to have some muffling. Too complex I guess.

What does it matter what way round the equation is? If you can increase/decrease the stinger size relative to the revs, the rest is just timing.

[wobbly]

A servo driven by the Ignitech would be the go to progressively throttle down the stinger related to rpm.
Ignitech do a stand alone servo driver that has TPS as well for a 3D map.

[F5 Dave]

What does it matter what way round the equation is? If you can increase/decrease the stinger size relative to the revs, the rest is just timing.

It matters because a simple pressure operated arrangement is, well simple.



Servo option does make sense though. That is huge boost increase, I wonder why it hasn't been applied more often?

Edit, a butterfly arrangement could be a robust easy to seal & make arrangement once you've worked out the area it occupies.

[Drew]

It matters because a simple pressure operated arrangement is, well simple.



Servo option does make sense though. That is huge boost increase, I wonder why it hasn't been applied more often?

Edit, a butterfly arrangement could be a robust easy to seal & make arrangement once you've worked out the area it occupies.

I see the pressure driven solution to be harder to set up, of the two basic options. But I get what you meant now.

Something to look into for you guys running dribblers though.

Yours is already very quiet, I noted at the track the other day dave. Why that is?

[TZ350]

The mid chamber bleed re visited .....

Model aero engine carburetor, about 9mm bore.

Attachment 279495Attachment 279496

I have been having trouble with detonation in over rev and I hope to cure it by bleeding some of the pipe pressure off when the engine is running in the detonation zone.

Sometimes stingers/mufflers have been attached here at the fattest point on the pipe because the pressure wave is at its lowest amplitude and quietest so I guess I can bleed pressure of from here without upsetting things and being to noisy.

Might get a chance to try it out in a day or two.

Deto in the Over Rev Zone.

Attachment 279979

The mid chamber bleed.

Attachment 279980

Tried it open and closed, Red open, Blue closed. The big surprise was how quiet it was when open, hardly any more noise at all, certainly wouldn't need any sort of mufler.

Actually I tried it lots to see if I could join the two curves and if it would kill the high rpm deto. But it was difficult to coordinate by hand and the runs were all over the place. Although the results were good enough to make me very interested in developing a proper ATAC Valve.

Attachment 279978

Kel gave me a hand to try and figure out where this top end deto is coming from.

I tried to take pictures when the Red light flashed, but all I got was a lot of unfocused blurry photos.

Although I could see the Red light flashing, in all of the shots the green light obscured the Red deto one.



At the end of the runs the engine went into auto ignition and ran on, in the clip you can just see Kel pull in the clutch and thumb the kill button but the engine still ran on for a bit.

The mid chamber bleed re visited as it might be useful for some low end boost......

In jetskis we used a much too big stinger to increase the low and mid power, then pumped water into the stinger to squeeze down the effective outlet area
Best power was at 3 psi at full noise, and this was set by a jet under the water solenoid.

A servo driven by the Ignitech would be the go to progressively throttle down the stinger related to rpm.
Ignitech do a stand alone servo driver that has TPS as well for a 3D map.

That's brilliant. . . But why does too large a stinger increase bottom end?

I know it seems counter intuitive, but at low speed where the pipes tuned length is too short,the power will come up if you reduce the effects of the return wave coming back way too early.

Thus by reducing the pressure in the pipe you ameliorate the bad effects by killing how well the pipe system works.

High pressure in the pipe increases the effectiveness of the wave action, so to reduce this additional "performance" at low rpm,you open up the stinger diameter.

Less bad matching of port timing and pipe length = more power.

On the big bore ski it was around 35% increase in power at the bottom of the used powerband.

Servo option does make sense though. That is huge boost increase, I wonder why it hasn't been applied more often?

Ok the mid pipe bleed didn't work for me as a detonation suppressant but it did show a useful low end boost. The interesting thing was that there was very little noise from it.



Red line is the bleed in the open position, Blue is closed.



And there was those who scorned me for trying this .......

I will re visit this again, maybe with a bleed system like Frits suggested.

Attachment 279498

Frits proposed this bleed system, thought I should at least give something like it a try.......

[F5 Dave]

. . .

Yours is already very quiet, I noted at the track the other day dave. Why that is?

It was a bit noisy, so I spent some money & got Damon to make a new sleeve which has a reversal at the end of the muffler made in light ally after the original muffler.

Its made in larger di pipe- it removes sound energy without causing a restriction as there is a little volume for the original to spill into. When I've tested this setup before I've noticed no diff on the dyno.

[TZ350]

OK ... got the EFI wired up and the Laptop talking to it, things looked OK and the TPS was ranged correctly.
Then the USB/Serial communications stopped?????? ...... Ohooowell another day tomorrow.

[F5 Dave]

Must admit I forgot about the bleed valve. Wonder it's affect vs capacity as implied? Only issue is noise more of a constraint in larger cylinders with bigger stingers.

[SwePatrick]

In jetskis we used a much too big stinger to increase the low and mid power, then pumped water into the stinger to squeeze down the effective outlet area
Best power was at 3 psi at full noise, and this was set by a jet under the water solenoid.

Very kind of you to share the info. great thanks.
I tuned the engine to exactly that before your answer, nice to know i´m on the correct ballpark and playing my game

I got 132cc and an 28.5mm stinger and reached these 3psi at about 10500rpm.
And keeps steady all the way to the top at 13000rpm.
Then it 'chokes' out at about 4-5psi

The most amount on GP racers hp output with reeds(wheel hp)
Does somebody know those numbers?

Kind regards
Patrick