ESE's works engine tuner

[Flettner]

Same, here you go KTM make This! The A port injection fueling will be super imposed over the normal fueling and largely run off information from the pipe pressure. At low speed no fuel to the A ports, just as our YZ is set up, at low speeds the gas energy exciting the ports is low, this is where short circuiting is worst . As the engine speed gets higher, pipe is working, the A port gas stream has some inertia, less short circuiting, that's when the A port injectors chime in. Should make for excellent harmonization when all injectors are firing.

[husaberg]

Same, here you go KTM make This! The A port injection fueling will be super imposed over the normal fueling and largely run off information from the pipe pressure. At low speed no fuel to the A ports, just as our YZ is set up, at low speeds the gas energy exciting the ports is low, this is where short circuiting is worst . As the engine speed gets higher, pipe is working, the A port gas stream has some inertia, less short circuiting, that's when the A port injectors chime in. Should make for excellent harmonization when all injectors are firing.

Doubling up the injectors therefore using 4 smaller individual injectors, will mean faster injector response which will buy you a lot more time. this should lessen the emissions as well as providing better fuel homogenisation.
Mazda rotaries responded really well to this approach, providing better power, plus far better drivablility in ported applications compared to the ubiquitous webber 48/51 IDA carb

[Norman]

Not a very good picture, I'm afraid...

Thank you very much for posting this article, have been looking for it at home from time to time, over the last 20 years or so, now I can finally put this to rest :-).

[Frits Overmars]

Same, here you go KTM make This! The A port injection fueling will be super imposed over the normal fueling and largely run off information from the pipe pressure. At low speed no fuel to the A ports, just as our YZ is set up, at low speeds the gas energy exciting the ports is low, this is where short circuiting is worst . As the engine speed gets higher, pipe is working, the A port gas stream has some inertia, less short circuiting, that's when the A port injectors chime in. Should make for excellent harmonization when all injectors are firing.

So you decided to let the cat out of the bag. What we need now are injectors that are small enough and fast enough.

[TZ350]

What we need now are injectors that are small enough and fast enough.

I have personally run an Ecotrons small injector at 13,000 rpm in my 125cc two stroke engine ... http://www.ecotrons.com/components/fuel-injectors/

[Flettner]

So you decided to let the cat out of the bag. What we need now are injectors that are small enough and fast enough.

Yes Frits, I decided bugger it, there is nothing in it for anyway as I can't afford to go down the patent track. So if it's on here anyone can use it.

[Nath88]

.
When I followed Nath88's very clever idea about using the return pressure wave at the exhaust port to see when the motor was firing. I ran into a problem, my ECU software averaged the low suction pulse and high plugging pulse and arrived at a lower average for on power open throttle compared to closed throttle. Makes sense when you think about it but I could not figure out how to get the ECU to make sense of it. Basically it needed to reduce fuel when the average pressure was higher and increase fuel when it was lower. This is opposite to the way EFI ECU's think.

That's exactly the problem I'm having now... I've been experimenting with measuring the crankcase pressure instead of exhaust, just after transfers open. Under 25% throttle once on the pipe (7000 up) the pressure is lower than at 0% throttle... then over 25% the pressure starts going up. Which makes sense, the scavenge effect of the pipe drawing against the mostly closed throttle. But as you said, no good for a normal 4 stroke style ECU, it expects a linear input. I should put up some graphs of the data collected. Perhaps if you sampled the pressure before and after the transfers open then take the difference. The ability to write the code specifically for the engine is where KTM has a massive advantage.

At the moment I'm working on modifying the ECU code to capture the highest peak of the exhaust pulse as the port opens. I think this will be a good indicator of how much wave energy has gone into the pipe. So far the best results have been with the exhaust pressure at the powervalve vent. The PV housing was acting as a damper, smoothing the pressure pulse so the ECU could catch the peak easily, signal was a bit too smooth so I'm trying other methods, trying to nail an analog carb feel on throttle transitions. If the code mods don't work out (I'm no programmer), back up plan is to use a 'precision peak hold' circuit on the map sensor, then using the ignition output to reset the circuit at the start of each cycle. You could implement this on your ECU easily enough.

[husaberg]

Cagiva combined a Atac with a PV as well, most of the need to do this i assume disappeared with the introduction of unleaded fuels.

Why would it disappear with the use of unleaded fuels?

Sorry i missed your question, my take on it is.
When the Leaded (Jungle juice or rocket fuel )was banned and replaced with unleaded, the comp ratio were lowered and the 500's suddenly became a lot more user friendly to ride..
Of course at the same times big gains were made with ign mapping as well.
The power delivery was softened so much so, the NSR500 went back to the 180 two up two down crank not long after.
Doohan said they were not even real racing bikes after leaded was banned (or words to that effect)
The GP bikes were able to recoup the initial loss of HP rather quickly.
I am pretty sure the lower comp also allowed more over rev thus effectively widening the powerband, (But not 100% sure) if this was just a technological leap in jetting technology, or just becuse of the different burn characteritics of the lower comp and fuel.
Yamaha experimented with variable comp heads in the Rainey era due to the better effects on acceleration of high comp and better revabilty of low comp.
https://www.kiwibiker.co.nz/forums/s...post1130892885
But in short i don't think the Comp ratio were ever raised again as high as they were in the leaded era.
Maybe Jan Frits or Wob will fill in the gaps or correct me.

[jamathi]

Sorry i missed your question, my take on it is.
When the Leaded (Jungle juice or rocket fuel )was banned and replaced with unleaded, the comp ratio were lowered and the 500's suddenly became a lot more user friendly to ride..
Of course at the same times big gains were made with ign mapping as well.
The power delivery was softened so much so, the NSR500 went back to the 180 two up two down crank not long after.
Doohan said they were not even real racing bikes after leaded was banned (or words to that effect)
The GP bikes were able to recoup the initial loss of HP rather quickly.
I am pretty sure the lower comp also allowed more over rev thus effectively widening the powerband, (But not 100% sure) if this was just a technological leap in jetting technology, or just becuse of the different burn characteritics of the lower comp and fuel.
Yamaha experimented with variable comp heads in the Rainey era due to the better effects on acceleration of high comp and better revabilty of low comp.
https://www.kiwibiker.co.nz/forums/s...post1130892885
But in short i don't think the Comp ratio were ever raised again as high as they were in the leaded era.
Maybe Jan Frits or Wob will fill in the gaps or correct me.

At Aprilia we had more power, more over rev and no power loss at any part of the curve within 4 month's work, with a compression ratio of 1:16, without detonation. No changes to the cylinder were made, but some very serious research
to the cylinder head was very effective-- We were approaching 50HP at the time, 1998, no power jet....

[Frits Overmars]

At the moment I'm working on modifying the ECU code to capture the highest peak of the exhaust pulse as the port opens. I think this will be a good indicator of how much wave energy has gone into the pipe.

Another option would be to look at the highest peak of the exhaust pulse after BDC, i.e. the return pulse. That will be an equally good indicator of how much wave energy has gone into the pipe, and it offers the additional advantage of knowing when this return pulse arrives back at the cylinder. If it's too early, lower the EGT by advancing the ignition timing; if it's too late, retard the ignition timing. That way you'll have a truly intelligent ignition and you can forget about EGT.

When the leaded was banned and replaced with unleaded, the comp ratios were lowered and the 500's suddenly became a lot more user friendly to ride... The GP bikes were able to recoup the initial loss of HP rather quickly.
I am pretty sure the lower comp also allowed more over rev thus effectively widening the powerband, (But not 100% sure) if this was just a technological leap in jetting technology, or just becuse of the different burn characteritics of the lower comp and fuel. But in short i don't think the Comp ratio were ever raised again as high as they were in the leaded era.
Maybe Jan Frits or Wob will fill in the gaps or correct me.

What gaps Husa? You didn't leave much out.
A lower compression ratio forcibly yields a lower expansion ratio; less combustion energy is converted into torque by the time the exhaust opens and more of this energy remains in the exhaust gas in the form of higher pressure and higher temperature. This remaining energy drives the exhaust pulses, improving cylinder filling for the next combustion event, and the next, and the next.... This way a lower compression ratio can lead to higher power.
The lower comp ratio also made engines less sensitive to piston ring groove wear and ignition spark strength, and it helped overrev, so the bikes became easier to ride.
At the end of the lead-area the Aprilias had a compression ratio of 19,5. When lead was banned, this ratio was initially reduced to 14, after which it was gradually raised again. My personal preference would be to try even lower ratios in order to feed the pipe with even more energy.

[husaberg]

At Aprilia we had more power, more over rev and no power loss at any part of the curve within 4 month's work, with a compression ratio of 1:16, without detonation. No changes to the cylinder were made, but some very serious research
to the cylinder head was very effective-- We were approaching 50HP at the time, 1998, no power jet....

What gaps Husa? You didn't leave much out.
A lower compression ratio forcibly yields a lower expansion ratio; less combustion energy is converted into torque by the time the exhaust opens and more of this energy remains in the exhaust gas in the form of higher pressure and higher temperature. This remaining energy drives the exhaust pulses, improving cylinder filling for the next combustion event, and the next, and the next.... This way a lower compression ratio can lead to higher power.
The lower comp ratio also made engines less sensitive to piston ring groove wear and ignition spark strength, and it helped overrev, so the bikes became easier to ride.
At the end of the lead-area the Aprilias had a compression ratio of 19,5. When lead was banned, this ratio was initially reduced to 14, after which it was gradually raised again. My personal preference would be to try even lower ratios in order to feed the pipe with even more energy.

So knowing what you both know now, about how to get more power and disregarding the health and enviromental issues.
Would it still be unleaded or do you think you could get more power again with the leaded and appropriate mods?

[jamathi]

So knowing what you both know now, about how to get more power and disregarding the health and enviromental issues.
Would it still be unleaded or do you think you could get more power again with the leaded and appropriate mods?

I would stick with unleaded I think.
Of course many compression ratios were tried.
1:16 was the best on our dyno.
The teams had different choices, to adjust to the local atmospheric conditions.
And to avoid part-throttle detonation.
Health issues?
When we started using 'unleaded' we were given face masks....and gloves....

[Frits Overmars]

Unleaded, definitely.
The total energy content of a fuel is not dependent on its lead content. Plus, unleaded has a higher flame speed, reducing heat losses and NOx-formation.

Health issues? When we started using 'unleaded' we were given face masks....and gloves....

Ah yes, the infamous Italian 'benzina verde' (green gasoline), the green probably refering to your face color after handling the stuff .

...disregarding the health and enviromental issues...

You mean, like using Avgas? Low-Lead Aviation Gasoline, hah! I never figured out that first 'L'. The stuff contains five times as much lead as leaded car fuel.
They really should have used that L for Low energy content, because even regular pump petrol has a higher specific energy than avgas.
It's only benefit is that is counters detonation in unsound engines. I'd prefer to make those engines healthy instead of paying for poison.

[jamathi]

Unleaded, definitely.
The total energy content of a fuel is not dependent on its lead content. Plus, unleaded had a higher flame speed, reducing heat losses and NOx-forming.

A yes, the infamous Italian 'benzina verde' (green gasoline), the green probably hinting a your face color after handling the stuff .

It was all a stupid game started by Honda in 1982
Apparently they had no other means to raise power....at the time....

[husaberg]

It was all a stupid game started by Honda in 1982
Apparently they had no other means to raise power....at the time....

Pretty sure they introduced toulene into F1 about the same time.
i think their fuel was up to 90% at the peak of the turbo era. i can't recall what the rest was. something heptane i think
I think thats what they prop up modern unleaded fuel with even now (toulene)
To be fair though Shell and Yamaha (harris)were using uneaded about two years prior to the FIM changing the rules to ban leaded

You mean, like using Avgas? Low-Lead Aviation Gasoline, hah! I never figured out that first 'L'. The stuff contains five times as much lead as leaded car fuel.
They really should have used that L for Low energy content, because even regular pump petrol has a higher specific energy than avgas.
It's only benefit is that is counters detonation in unsound engines. I'd prefer to make those engines healthy instead of paying for poison.

while Avgas blue and green might have its issues it is at least very consistant between batches. not to mention available in the backwaters thanks to R22 Robinson Helicopters and dirty old Cessnas