ESE's works engine tuner

[breezy]

No ... its an optical illusion, its a small black mark left by the power valve, looks much deeper than it actually is.

TZ350, are you sure.... sticking in some bleed holes between the transfers and exhaust port to divert any burnt gases trying to back flow down the transfers to be pulled into the exhaust port?

[Frits Overmars]

Would making an engine detonate by-design be the way to get around the fixed burn-rate limitations and allow sky-high rpm levels?

It seems that way.

Wouldn't you have to light off the detonation in a closely-timed manner, something other than, say, a glow-plug, and if so, how (microwave ignition?)

A glow plug is the worst ignition starter I can think of. It gives more ignition advance when you need less.
Microwave ignition doesn't ring a bell. Is it akin to plasma ignition?

How do you build a lightweight aluminum engine that will live under shocks that will break up, among other things, the ceramic insulator on a sparkplug, which is a pretty hardy substance?

By making sure that this rapid combustion does not start too soon.

might the answer to this also be the answer to how rotating/reciprocating parts aren't flying apart at the sky-high rpms?

I don't see a direct connection yet.

I get that HCCI is an auto-ignition process, as in diesels.

I wish it were that simple. In a diesel you can stipulate the beginning of injection which in turn starts the combustion. With HCCI things are not so straightforward.

does the combustion chamber shape dictate where the charge ignites, or does it all ignite at once, and if so, is that detonation?

It's supposed to ignite simultaneously all over the combustion chamber and that is very close to detonation, so it's important that this ignition does not happen too early in the cycle.

Seems to me if flame fronts "collide" the only thing that happens is that the fuel has all been burned and the fires go out. Yes? No?

Yes.

[Frits Overmars]

When rygerizing ones engine, will it be possible to do the performance mod only, whilst maintaining conventional lubrication of the crank by mixture, Frits?

Not really. It could be done but it wouldn't make sense.

[Frits Overmars]

Frits, all those holes around the top of the cylinder, just water jacket? i just had to ask...

Nope. Eight of the holes are coolant passages; the other eight are threaded; it's where the head studs go .

[Frits Overmars]

Maybe the Ryger has a hot spot in the head or maybe the whole head is a hot spot so once it is hot enough it lights the mixture just like an RC engine does. RC engines do rev awfully high.

Don't be misguided by rpm numbers. Look at the piston speed; then those RC engines are nothing special.

[Frits Overmars]

Above I tried to answer a couple of your questions. Not every question got answered but some of those unanswered questions were so good that I could not risk answering them .

[Tunisti]

Speaking generally, if there would be somewhat homogenous mix of exhaust gases and fresh mixture, would it change the combustion characteristics into "softer" state: giving the charge some stability when it comes to the beginning of the (HCCI) combustion. In other words: if detonation would occurr in some random point in the mixture, it wouldn´t be able to proceed in the mixture, since there would be these "shock wave dampening burnt gas lumps" all around the mixture evenly? This ofcource with the assumption, that detonation would be "pressure ignition" caused by violent shock waves causing rapid pressure raises in so called "intersections".

If that´d be true, then the pressure and temperature of mixture could be able to reach to the optimum circumtances for HCCI combustion, even though there would occur some punctate detonations (which would be "stalled" away)?

I´ve also though that in this situation, where exhaust gases would be intentionally mixed with fresh charge, there could be two options:
1)The exhaust gases would be mixed in "late state of time". Meaning that the fresh mixture would already be in the cylinder, and there would be no pure charge density losses, when (hot/cold) exhaust gases would be mixed in. The mixing could be done ie. with pipe´s pressure wave.
2) The exhaust gases would be mixed in the charge, before the scavenging begins. In this case it´d be good, that no more charge would be flowing in to the area where the charge is held, since adding exhaust gas to the mixture rises the pressure of the mixture. (Simply by "raw" pressure or by heating the charge -> higher pressure). Normal EGR type solution would be bad, since the density of the incoming charge would be lower... Maybe the mixed exhaust gases could be either "hot or cold", depending on the need of scavenging pressure and HCCI conditions. Maybe some type of valve/piston skirt control bethween the exhaust duct and "the area where the charge is held".

Somebody also talked about Ryger and variable compression ratio. Since the cylinder head is conventional and the picture of the cylinder´s deck/bore shows that the bore cannot move in relation to cylinder, there could be still at least one option. Let´s think things differently (in the way of "real life" combustion parametres): let´s say that compression ratio=pressure of the non ignited charge at TDC. This would lead us into that conclusion, that if there would be less pressure in the cylinder when the exhaust closes, there would be lower compression ratio. In order to have less pressure in the same volume, you either need lower temperature or less gas. Since temperature is hard to control, we´re left with the amount of gas. You could ofcourse restrict the air flow (=lower the inlet duct pressure) by giving less throttle. This would cause "lower compression ratio" and lot´s of pumping losses. How about if we changed the volume of "the area where the charge is held"? There would be no pumping losses, but the "compression ratio" would be decreased, since the scavenging pressure would be lower - thus the pressure in the cylinder being lower too at the time when the exhaust port closes.

I almost hope that Frits wouldn´t say anything.

[Leed]

given the short rod length: 90mm
and emissions and premix reduction
seem to point to the separated crankcase, long piston
if the rings don't touch the piston... do the 'rings' seal a rod or linkage instead... does the piston float from a small sacrificial blowby stream
have scaled the image based on the plan view of the head... I was wondering if the gudgeon stayed completely below the 'spacer' plate
it does not, and there could be be a second rod involved for the piston at TDC

...move along nothing to see, sorry to waste peoples time

[MotleyCrue]

Thinking some more maybe retarding the timing to a crazy amount would just force a ton of heat into the exhaust residual for the next cycle and after a few cycles combustion would just happen all on its own or at least very fast, some amount after TDC. The more it was retarded the quicker the heat would come in and the sooner the engine would go from a dog to fantastic. Maybe thats why on the video the engine sounds odd then all of a sudden hits full song. I think I'll go with that.

Running extra lean or extra rich might help get this going too, I'm thinking lean.

Running the timing a bit late adds heat to the exhaust and would normally be the wrong thing to do until high in the revs and overrev. Retarding the timing even more than that might seem crazy at first glance but even at the lower revs ultra retarded timing would work because once the HCCI kicked in combustion would be fast and efficient and the exhaust temperature would drop down to a decent value that wouldnt hurt anything.

This could be self stabilizing/regulating, if the exhaust temperature dropped too much due to the HCCI, the HCCI would be lost and the engine would again run with ultra retarded regular combustion quickly heating things back up then the HCCI would automatically kick in again. All this could happen in a fraction of a second, but with the right design the flip flopping between HCCI and ultra retarded regular combustion would not happen and the engine once on HCCI would just stay there.

[peewee]

anyone heard of mirror bore coating ? i wonder how it compares to nikisil

http://www.nissan-global.com/EN/TECH...e_coating.html

http://blogs.youwheel.com/2014/05/30...-bore-coating/

[2T Institute]

Ryger idea, see if this will work. Weld a piston on top of a piston to create a chamber. Put 6 windows in the upper piston skirt. 5 windows for the transfer ports and 1 window to the exhaust. Now all that's left is to figure out the size and timing of all the windows, the size, length and volume of the exhaust duct, and the volume of the upper chamber. The exhaust pulses pump this chamber. Maybe some one already posted this idea and I missed it.

I'm guessing the Ryger piston is very long, say 90 mm with the wrist pin near the bottom, and sealed off right above the wrist pin boss to create a separate chamber inside the upper piston.

Think your onto something here.

[Flettner]

i expect you have already spun this crank set up with something attached externally?, obviously not under load. how did it go? (you may have posted these findings previously, sorry to ask again ) in reality i expect if its good enough for 17500-20000 rpm it would be job done

Yes it's been spun up in the milling machine, only to approx 3000, it did shake, there will need to be a ballance shaft as the crankshaft has not much bob weight on it. Thankfully plenty of room for that.
I have two cylinders lined up for this bottom end (still in the pattern shop). One I've started to show off on bucket foundry and one thats not (not yet anyway). First one is just a wacky idea, second one is a little more serious (still probably just as wacky )
In the mean time I'm trying to get the sleeve engine to make some noise

[husaberg]

Ryger idea, see if this will work. Weld a piston on top of a piston to create a chamber. Put 6 windows in the upper piston skirt. 5 windows for the transfer ports and 1 window to the exhaust. Now all that's left is to figure out the size and timing of all the windows, the size, length and volume of the exhaust duct, and the volume of the upper chamber. The exhaust pulses pump this chamber. Maybe some one already posted this idea and I missed it.

.

Yip...........................

[ken seeber]

Frits,
Just a simple naïve question. Would the Ryger technology be applicable to a 4 stroke engine?

[MotleyCrue]

Ryger idea, see if this will work. Weld a piston on top of a piston to create a chamber. Put 6 windows in the upper piston skirt. 5 windows for the transfer ports and 1 window to the exhaust. Now all that's left is to figure out the size and timing of all the windows, the size, length and volume of the exhaust duct, and the volume of the upper chamber. The exhaust pulses pump this chamber. Maybe some one already posted this idea and I missed it.

I'm guessing the Ryger piston is very long, say 90 mm with the wrist pin near the bottom, and sealed off right above the wrist pin boss to create a separate chamber inside the upper piston.

A few pages back Frits implied, though did not flat out state, that if we looked in the exhaust port and ran the piston from top to bottom we wouldn't see anything unusual. I think we would see some of what you described above looking in the exhaust port and that would be unusual.