ESE's works engine tuner

[Niels Abildgaard]

Our computerized testing program was fully automatic and very precise.
There was, of course, automatic compensation for temperature, humidity and air pressure.
You could choose the cooling water temperature you wanted, and it was kept constant.
Also the dyno room was air conditioned, with constant temperature and humidity.
You could be sure that if you saw a 0,1HP gain that it was 100% true!!
And I repeated every modification at least 3 times....

That set up must have cost a lot.
Did Aprilia get the money back?
What would the optimum 125 ccm look like?
The 250 would have been two of these one a single V2 throw crankcase and one fuel inlet of course

[jamathi]

Sometimes riders complained about not being able to change gear.
With their 'spark interruption' system.
So I had a button fitted to my desk so that I could interrupt the ignition.
At certain revs the engine kept running without a spark!!!
The power did not change, and there was no detonation......

[ken seeber]

The power did not change, and there was no detonation......

HCCI surely. I assume this was mainly observed at full throttle, however did you ever gradually close the throttle under this HCCI condition to see at what point it cut out? . It'd be good to know what rpm range this might have occurred., but again I would probably think that you were only concentrating in the max power range where the engine was being used on the bike.

[Haufen]

HCCI surely. I assume this was mainly observed at full throttle, however did you ever gradually close the throttle under this HCCI condition to see at what point it cut out? . It'd be good to know what rpm range this might have occurred., but again I would probably think that you were only concentrating in the max power range where the engine was being used on the bike.

Please excuse me for being a smart ass here, but without further investigation there is absolutely no evidence that this was a) homogeneous and b) triggered by compression alone. What's wrong with some old fashioned ordinary pre-ignition? I would regard pre-ignition as far more likely in this case, especially as the EGT did not seem to be affected (I guess riders would have complained about engines suddenly hitting a rev wall due to a too cold EGT).

Did you notice a change in EGT when the engines were runing independent of the spark plug, Jan?

[tjbw]

That set up must have cost a lot.
Did Aprilia get the money back?

Won multiple world championships, value: priceless, well almost

[Niels Abildgaard]

Won multiple world championships, value: priceless, well almost

Exactly.
I once talked to a man who made kart engines for a living and it was winning on saturdays or no sales next week.
How much did the journey from 46 to 54 cost and how much did it sell? Just round millions (not Lira please)?

[Flettner]

Vannik, thank you, it all makes sense.

[ken seeber]

Please excuse me for being a smart ass here, but without further investigation there is absolutely no evidence that this was a) homogeneous and b) triggered by compression alone. What's wrong with some old fashioned ordinary pre-ignition? I would regard pre-ignition as far more likely in this case, especially as the EGT did not seem to be affected (I guess riders would have complained about engines suddenly hitting a rev wall due to a too cold EGT).

Did you notice a change in EGT when the engines were runing independent of the spark plug, Jan?

You’re absolutely right, as HCCI is a form of pre-ignition. HCCI, by definition is a compression ignition phenomenon that can occur under a certain set of conditions (mainly lean from my understanding which is not what a high performance 2 stroke would be using), but it is certainly a form of pre-ignition, ie combustion commencing prior to the spark within the plug. Classic pre-ignition, well in my mind, is caused by something within the combustion chamber envelope being hot enough to initiate ignition. Typical causes being a spark plug earth electrode, carbon or an overly hot exh valve. Combustion temps and pressures can rise prematurely, worsening the initial cause, and then can lead to detonation. To me, it’s hard to imagine that a well cooled and internally clean engine such as the Aprilia 125 test engine would provide such conditions for classic pre-ignition.
How would you find out? Probably through using cylinder pressure transducers, quartz windows & high speed cameras, exhaust analysis etc. Maybe a change in EGT as you are suggesting. What would you suggest the change would be? Maybe there was engine damage after such conditions were experienced?

[husaberg]

Sometimes riders complained about not being able to change gear.
With their 'spark interruption' system.
So I had a button fitted to my desk so that I could interrupt the ignition.
At certain revs the engine kept running without a spark!!!
The power did not change, and there was no detonation......

Jan i beleive that is the third form of ignition
1 Spark ignition
2 Compression ignition
3 ARC (Activated Radical Combustion) now called HCCI

Please excuse me for being a smart ass here, but without further investigation there is absolutely no evidence that this was a) homogeneous and b) triggered by compression alone. What's wrong with some old fashioned ordinary pre-ignition? I would regard pre-ignition as far more likely in this case, especially as the EGT did not seem to be affected (I guess riders would have complained about engines suddenly hitting a rev wall due to a too cold EGT).

Did you notice a change in EGT when the engines were runing independent of the spark plug, Jan?

You’re absolutely right, as HCCI is a form of pre-ignition. HCCI, by definition is a compression ignition phenomenon that can occur under a certain set of conditions (mainly lean from my understanding which is not what a high performance 2 stroke would be using), but it is certainly a form of pre-ignition, ie combustion commencing prior to the spark within the plug. Classic pre-ignition, well in my mind, is caused by something within the combustion chamber envelope being hot enough to initiate ignition. Typical causes being a spark plug earth electrode, carbon or an overly hot exh valve. Combustion temps and pressures can rise prematurely, worsening the initial cause, and then can lead to detonation. To me, it’s hard to imagine that a well cooled and internally clean engine such as the Aprilia 125 test engine would provide such conditions for classic pre-ignition.
How would you find out? Probably through using cylinder pressure transducers, quartz windows & high speed cameras, exhaust analysis etc. Maybe a change in EGT as you are suggesting. What would you suggest the change would be? Maybe there was engine damage after such conditions were experienced?

Honda readies Activated Radical Combustion two-… engine for production motorcycle
Honda has been researching and developing the Activated Radical Combustion (ARC) two-… engine for several years. As a showcase of the engine’s viability and durability in the most arduous conditions, Honda’s RD Asaka Center successfully raced the experimental EXP-2, 440-cm 3. single-cylinder, off-road motorcycle in the gruelling Granada-Dakar Rally in 1995, the event that covered 8000 km of mostly desert terrains and in which the two-… had been thought to be at a disadvantage for its inherent gas-guzzling trait. The EXP-2 placed fifth overall in the motorcycle category, proving its worth in this most arduous test of machines and riders.
Honda is now readying a production dual-purpose (on- and off-road) motorcycle employing the ARC technology. With the ARC, Honda is applying a third combustion process to the piston-compression, internal combustion engine. The first and second piston-compression, internal combustion engine types are, of course, the spark-ignited gasoline (and alternative fuels) engine and the compression-ignition diesel.
Honda observes that the burning of gasoline in an engine is not a simple, procedural process; mix fuel with air, add ignition source, bang, and let the process take its effect. It is chemically more complex, with a large number of intermediate chemical reactions. In essence, asserts Honda, combustion begins with an initiating reaction that forms highly reactive intermediate molecules, or activated radicals, from the stable fuel and air of the incoming charge.
Propagating reactions continue with various molecules reacting with these active radicals. These propagating reactions from both additional reactant molecules and more active radicals to continue the combustion process, which goes on as long as it unleashes enough energy to continue the chain.
The ARC phenomenon was observed by many owners of two-…-powered motorcycles, generators, and other products, whose engines would continue running after the electrical ignition was shut off. This auto-ignition was generally attributed to a pre-ignition caused by hot spots in the combustion chamber, and engineers’ attention was focused on eliminating it. Honda pays due homage to the researchers who had earlier discovered the role of active radicals in the auto-ignition phenomenon: Yakov Zoldvitch in the 1930s, and more recently notable efforts by Toyota’s Masaaki Noguchi and his team (The Toyota-Nippon-Soken combustion, SAE 790840), and Shigeru Ohnishi of the Nippon Clean Engine Research Institutes who had actually constructed a stationary engine for generators on the active radical principle in the late 1970s.
In 1992, Honda started a small research project, under the direction chief engineer Minoru Matsuda, to determine if this auto-ignition process could practically solve the irregular combustion problem for two-… engines. The team, led by Yoichi Ishibashi, made surprisingly rapid and fruitful progress. While Ohnishi had earlier broadened the engine’s auto-ignition range by throttling the flow of fresh charge from the crankcase into the cylinder (usual two-… breathing practices), this was not sufficient for a mobile power plant.
Honda engineers determined that, for any given engine load, the most important variables controlling the occurrence of the auto-ignition process were the temperature of the residual gas and the pressure remaining in the cylinder when the exhaust port was closed. That last value, explains Honda, pressure at exhaust closing, or PEC, could be readily regulated by a very simple mechanical design, a movable valve to throttle flow at the exhaust port, and thus retain higher pressures in the cylinder.
For a vehicle engine, the ARC auto-ignition process could not be the sole source of ignition over the engine operating range. So in the Honda ARC application, spark ignition is still employed at very lowest load conditions, such as at idling, for which there was so little incoming charge that sufficient temperatures could not be maintained, and at high loads for which there was too little residual charge and too little heat from the charge. The ARC could operate from roughly 5% of peak load to 60%, but it is most efficient from about 6 to 22% load, almost exactly the range at which irregular combustion causes the most problems in a conventional spark-ignited two-… engine.
The EXP-2 experimental motorcycle’s 402-cm 3 capacity was chosen to compete in the Granada-Dakar rally against a horde of large-displacement four-… competitors. Honda took its own NX4780 Vee-twin four-… offroader, whose performance and fuel consumption characteristics were placed under scrutiny, whereupon the EXP-2’s specifications were determined. The EXP-2 employed an exotic PGM-FI fuel injection system, hitherto reserved to Honda’s Grand Prix racers.
The fuel injection was chosen for the computer’s ability to be readily brought in to control the exhaust valve operation, not because it was essential for fuel feed.
The production-prototype ARC engine is a liquid-cooled, single-cylinder 250-cm 3 unit breathing from a conventional side-draft carburetor. The electronic control unit controls the stainless-steel ARC (exhaust port control) valve which is actuated by an electric servo motor, ignition change-over between spark-ignition and ARC-auto-ignition, and carburetor idling and slow-jet. The ECU is fed with various information including transmission gear position, engine rpm, coolant temperature, and throttle opening angle.
Honda claims the following improvements with the ARC:
Fuel economy improvement: 27% improvement on Honda’s own real-life operating mode; 29% improvement at a steady 60 km/h
Reduction of hydrocarbon emission by 50%
Market improvement in driveability.

click on the attachments three times

Another intersting thing Cameron says is the peak cylinder pressure occurs arround 11-15 degrees after TDC
He also says that combustion is symetrical ie if it starts at 18 Degrees BTDC it finishes arround 18 Degrees ATDC.
during the 15 degrees on either side of TDC the piston is of course pretty much motionless ,depending of course on the stroke and conrod length.

[jamathi]

HCCI surely. I assume this was mainly observed at full throttle, however did you ever gradually close the throttle under this HCCI condition to see at what point it cut out? . It'd be good to know what rpm range this might have occurred., but again I would probably think that you were only concentrating in the max power range where the engine was being used on the bike.

Yes, I think it was HCCI
Auto-ignition by a too hot spark plug had quite a different effect!
That always ended with a seized engine....
HCCI caused no damage at all, the engine ran very well.
It happened with max. power carburation, and around and above max power.
I did very few experiments with it, which now I regret!
The test without spark was only done to find out where the gear change problem came from....

There was also part-throttle auto ignition which caused a lot of damage to piston and head!
Incredibly strong detonation!

[jamathi]

A complete dyno room cost maybe half a million Euro.
They are using them to test 4 stroke engines now!
We had 3 dyno rooms for 2stroke racing development

[jamathi]

That set up must have cost a lot.
Did Aprilia get the money back?
What would the optimum 125 ccm look like?
The 250 would have been two of these one a single V2 throw crankcase and one fuel inlet of course

This was the 250.

[Niels Abildgaard]

Hello Jan

Thank You for the Test beds picture.
I had not realised that there was and is an Aprilia before and after Your two strokes.
It is was not important at any rate.
My pictures show the ultimate two stroke configuration.
Ligth,even pull ,simple and nobody can claim that it will not work yet.

[Haufen]

You’re absolutely right, as HCCI is a form of pre-ignition. HCCI, by definition is a compression ignition phenomenon that can occur under a certain set of conditions (mainly lean from my understanding which is not what a high performance 2 stroke would be using), but it is certainly a form of pre-ignition, ie combustion commencing prior to the spark within the plug. Classic pre-ignition, well in my mind, is caused by something within the combustion chamber envelope being hot enough to initiate ignition. Typical causes being a spark plug earth electrode, carbon or an overly hot exh valve. Combustion temps and pressures can rise prematurely, worsening the initial cause, and then can lead to detonation.

I agree if you switch pre-ignition with auto-ignition in your first sentence. (sorry, I am doing it again but it is also difficult for me to find the right line to differentiate as english is not my first language)

In the wide range of auto-ignition, which also covers pre-ignition and HCCI, the latter is only a very rare and exotic special case, whereas there are many other forms of auto-ignition which can be triggered by different things do not necessarily lead to engine damage.
For me, saying "it was HCCI because the engine ran without a spark plug and without damage" is like saying "it must have been beer, because it was definitely not wine".

Also, I don't know of any reference in literature having achieved HCCI in rich condition and at a corresponding BMEP (15+ bar 2stroke, 30+ bar 4-stroke). Does not mean that this is not possible, but could be that other things are more likely.

To me, it’s hard to imagine that a well cooled and internally clean engine such as the Aprilia 125 test engine would provide such conditions for classic pre-ignition.
How would you find out? Probably through using cylinder pressure transducers, quartz windows & high speed cameras, exhaust analysis etc. Maybe a change in EGT as you are suggesting. What would you suggest the change would be? Maybe there was engine damage after such conditions were experienced?

I am quite sure any 2-stroke can be brought to the point where pre-ignition is likely to take over, just squeeze the exhaust pipe outlet more and more. And of course you push for the limit in racing. What this does, is that it increases EGR ratio which could then trigger auto-ignition. But ignition in such a scenario would probably not become homogeneous, rather initiated from the exhaust port side as this is the hotter side.

I guess you could find out with pressure indication and become quite sure, but to be really really sure that all the mixture is burning homogeneously and commencing the burn at the same time some optical measurement would be necessary.

With pressure indication, the zig-zag knocking signal after tdc should become smaller and smaller until it disappears, also the burn should become much faster and thus the pressure signal would become narrower and higher with no more bump on the left side (assuming there was one in the first place).
I would love to throw some high tech lab equipment at a RSA engine and then stay there for a couple of months or so for sure, who would not. As for now, the destiny of lottery has not answered to my prayers unfortunately

With HCCI the EGT would become lower, as the burn would be faster and thus there would be more time for the charge to cool. I would expect to see at least 50deg C lower EGT. So we have less energy for the pipe to work with and after peak we are switching suddenly a longer pipe? You don't want that in a racing two-stroke. Also, power should increase with faster combustion and if not, positive and negative work gained by faster combution would be the same, which would be another rare coincidence.

[jamathi]

At Aprilia we never had any high tech equipment, just an EGT sensor.
Nothing else was needed for finding more power!