ESE's works engine tuner

[breezy]

Been thinking about HCCI a bit more. Seem that it is a part load thing only. One thought, say if you wanted 20 hp (under HCCI control because of the low emission and fuel consumption benefits) and your engine was 20 hp, then no go. Then give the engine to the WWW (Wobbly’s Wonderful World) and it comes back with 40 hp. So, could you then run the engine at its 20 hp part load point and then expect HCCI to kick in? Not likely.
After talking further to some ex Orbital cronies, it is clear that HCCI just needs temperature. In a 2 stroke, this can be accomplished with high levels of retained exh gas. In a 4 stroke, similarly using high levels of EGR. But, to get more power, amongst other things, the WWW crew strive to trap more fresh mixture in the cylinder at the time of exh port closure. The problem is that this is cool, not conducive for HCCI.
Dunno where this is going, but maybe HCCI could be promoted at higher load by being able to increase the gas temp after EPC. The big risk here is deto. Could be that Fletto’s auxiliary piston, that is phased early in the compression stroke, might be the go initiate HCCI prior to the conventional spark timing.

picture of typical erg system,

[TZ350]

Page 1560 ......

http://www.highwaymanbikes.com/the-h...ge-road-racer/

http://www.highwaymanbikes.com/desig...acing-chassis/

Not a Bucket but very interesting Vintage race bike build.

[Muciek]

Guys does anyone had luck using RGV carbs without solenoids? I wanted to use 34mm one in 125 engine, engine starts very well runs for about 2 minutes reaction for throttle is excellent but when the engine gets into working temperature it fouls a plug and You had to clean a sparkplug because engine dies. I have blocked air solenoids, it's weird and I don't know why it happens.

[Frits Overmars]

picture of typical erg system

That's a typical foul-stroke EGR system you are showing, Breezy.
Two-stroke EGR can be much simpler: just one exhaust port without auxiliaries. And then EGR does not mean Exhaust Gas Recirculation but Exhaust Gas Retention.

[breezy]

That's a typical foul-stroke EGR system you are showing, Breezy.
Two-stroke EGR can be much simpler: just one exhaust port without auxiliaries. And then EGR does not mean Exhaust Gas Recycling but Exhaust Gas Retention.

yes Frits, its a foul stroke diagram, but it shows a EGR set up, giving an inkling to the process .

so your picture shows a cylinder, single exhaust port... is the gas retained in the port itself? doesn’t this occur in 2 strokes already? how would you control the amount of heated gas and temp required to be fed back into the cylinder?

[Frits Overmars]

... your picture shows a cylinder, single exhaust port... is the gas retained in the port itself? doesn’t this occur in 2 strokes already? how would you control the amount of heated gas and temp required to be fed back into the cylinder?

The exhaust gas is not fed back into the cylinder; it never leaves the cylinder because we make sure that there is not enough blowdown time.area to get rid of it all.
That is why I emphasized the absence of auxiliary exhaust ports that would otherwise increase the blowdown time.area. And yes, this occurs in two-strokes already.
The best-known control mechanism is the exhaust power valve used in the Honda Activated Radical combustion engine.

But once you have established HCCI, you can also control it via the mixture strength. With HCCI you can make the mixture as lean as you wish and the fact that very lean mixtures are no longer spark-ignitable doesn't matter because they will still be compression-ignited as in a diesel.

[jamathi]

PS, if the jetting and ignition are perfect with a correctly set squish and you keep on getting a hot spot in front of the exhaust, then most likely
the stinger is too small and or there is insufficient cooling of the Exhaust duct.
I cured this in the KZ10 engines by allowing water thru slots right up to, and into the back of the bolt on flange spigot.

This picture makes me very happy Wobbly!
At Aprilia I was thinking about lengthening the exhaust duct 1 cm and then cool it very well.
It was in 2007.
This was not done because I retired.
Thank you for having the same idea, now I know it would have worked!

We were having a lot of deto problems in part throttle corners, about 30% throttle.
Is this also a problem in karting?
Because of this we could not use best power carburation on-track
And the gear-shifter would not work at high rpm, because the engine continued running without spark.
Probably HCCI
I had a switch fitted to the dyno, around 1999 to check this.
This was done because the riders complained about gear shifting problems, above all the 250's
The engine kept running without spark....
And without detonation.
So it looks like there was HCCI at full throttle, but not on small throttle openings.
The riders refused to chance gear in the 'old-fashioned' way.
But when Rossi went to the Honda 500/4 he had to do just this...

A problem I sometimes had on the dyno was that the engine sometimes would refuse to rev above 13000-13500
You could hear it coming, from the exhaust noise
Then it suddenly stopped running at all.
To resolve this I had to make a radius at the auxiliary ports, or make them inclined towards the main, so it looked like insufficient blowdown
But this usually cost some power....
Our exhaust ducts were CNC machined, and all cylinders flow tested.
Some cylinders had this problem, others did not.
I never really understood why this happened.

Once a mechanic brought back a spark plug from a race, the mass electrode had broken off.
But the engine had finished the race....
So I tried it on the dyno, and was amazed about how much more power there was!
That is until the ignition coil failed at around 13000....

[wobbly]

Having the duct 1cm length extension on the Aprilia would have made it exactly the length I have found works best ie 1.5X bore.
And in most engines this is way too short - as is the duct exit area way too big.
Using these length and cooling ideas, along with making the floor of the duct,going into the spigot, co-linear,with all of the oval to round transition angle in the roof
would have put your RSA close to 60 Hp.
All way to late now of course, but thanks to your help Jan , I will be able to use / test these and many more ideas with Franco at TM.

Here is the next idea i will be testing soon in the KZ10 , using an old Boyesen offset reed cage originally designed for a KTM.
I will be using " proper " reed petals, but from the testing I have done before on Jetski world champ engines this should be worth a couple of Hp in a 125

[peewee]

i present to you guys my machine shop. chinese drill press borrowed from the neighbor. . got the pins in and ill attempt to weld the hole tomorow without melting off the edge of the piston

[peewee]

hey wob is that asymmetric valve for a engine that has a sharp kink at the carb/reed block like yami twins ?

[jamathi]

Wobbly

For CNC machining the exhaust duct we had separate programs for upside, downside and auxiliary ducts.
So we could 'mix' them.
First the auxiliaries were straight, later I made them slightly curved, which was a bit better.
This reduced exhaust duct volume a little bit.
I also had a cylinder cast with a much higher underside of the exhaust duct.
Just as high as the top of the transfer ports.
Only the top was CNC finished.
My intention was to see how high the underside could be made without losing power.
And to see if just the blowdown flow area would be sufficient!
But when I decided to retire I understood that the cylinder would not be plated before I left.
So it became machined with the 'normal' programme.
I still regret not having been able to do this test!
Raising the exhaust port underside 1,5mm and making it narrower at the sides had already given good results.

[teriks]

My intention was to see how high the underside could be made without losing power.
And to see if just the blowdown flow area would be sufficient!
But when I decided to retire I understood that the cylinder would not be plated before I left.
So it became machined with the 'normal' programme.
I still regret not having been able to do this test!
Raising the exhaust port underside 1,5mm and making it narrower at the sides had already given good results.

How about, when you have raised the exhaust floor enough to loose power, you add a nice radius to promote flow, while maintaining the small duct area.
In a way that could give a good hint if the (potential) gains comes from the reduced area or the potentially reduced short circuiting.

[SwePatrick]

About HCCI ignition(i think)
I have built a new engine(not fully complete yet)
Test started it this weekend.

It´s an Kawasaki KX250 downstroked to 211.9cc(due to regulations in swedish dragracing)
However, i was so eager to hear the engine spin even though the pipe isn´t ready yet.
So i started it anyway.
And note, the exhaustvalves wasn´t in place, the guillotine therefor left a big hole downwards in exhaustport(no lid on either)

Engine started nicely but started to rev out of control almost directly.
Tried to stop it, pulled the cord to the stop button, nothing happened.
Placed hand onto the carburetor, nothing happened.
With hand still on carb and full throttle engine lowered the speed.
Had to shut off fuel to get it to stop.

Later, put back all exhaustports and started engine with no other adjustment.
It ran nicely on idle.

Quite interesting experiance

I figure the exhaustpulses drew fresh air into cylinder through guillotineport.
And even though i had hand on carb it still drew fuel enough to get a burnable mixture.
But, interesting is that what i think it almost directly triggered HCCI.

Rgds.

Got the pipe from my friend today.
No silencer yet, so turn speakers down
It distorts sound quite a bit as is.
But, a vid from today, just hade to rev some, to get positive vibes

Click on link(should be working, it´s public):
https://www.facebook.com/patrick.wet...4096572449475/

Kx250 -96 downstroked to 61.1mm stroke from 72mm
Maico 490 rod 137mm long.
Ported 200/138/138/138
Ported boyesen radvalve, redirected flow a bit so it aim´s for my big boyesenports in cylinder, and ported it to 42mm.
Keihin PWM 40mm
Own design on head, torus design, 15-1 compressionratio 0.8mm static squishclearence.

Later on, i will redesign radvavle some more and use a 44-46mm carb
Pipe is just a test to get a baseline, simple design in a simple program(but with some experiances included)

Rgds.

[shnaggs]

Here is the next idea i will be testing soon in the KZ10 , using an old Boyesen offset reed cage originally designed for a KTM.
I will be using " proper " reed petals, but from the testing I have done before on Jetski world champ engines this should be worth a couple of Hp in a 125

Wobbly, what does the offset reed cage provide? Wouldn't the one side of the valve be vary close to the inner runner, causing some shrouding and lack of flow?

[philou]

I tried assymetric reed valves to correct the inclination of the conduit for large shit minarelli am6 with very good results.