Oh, certainly, agreed. But just how do you throttle an engine running on HCCI ? I'm sure Neil would love any pointers you may have observed first hand...Originally Posted by Frits Overmars
Low personal B.M.E.P.
Oh, certainly, agreed. But just how do you throttle an engine running on HCCI ? I'm sure Neil would love any pointers you may have observed first hand...
Forum whore
Starve it. Of both air and fuel. And make sure there are no puddles of any combustible liquid anywhere in the engine; Neil experienced that first hand.
Forum whore
Gee, I turn the computer off for a few days and I miss out on all the good stuff
I thought I wrote it on this thread, perhaps not, but all you would need to do to get HCCI in a turbo engine is trap back some exhaust gas either don't allow all the hot exhaust out or via turbo control (high back pressure) (and cam timing) push some exhaust gas back in on the induction stroke. With the super ECU controled turbo's now I'm sure this would be possible, I guess via a knock sensors and/or cylinder pressure tansducers. But yes, not a full throttle thing I don't think?
HCCI can be tripped off by either just high comp or lower comp and recycled trapped exhaust gases, I think this is the true traditional way.
Drew, thank you, knocked at the door, no one home, so uplifted the DT, will do the job nicely.
Lucky find number two, made a bit of a cock up on the sleeve engine, the drawings are a little obscure on this, (what #%&^&* drawings) so it would seem the 250T twostrke clutch won't fit. But as luck as luck would have it, a 250F clutch almost fits (my machine shop says it will) so now I can go ahead and build the clutch case pattern, including the water pump. It's been a good weekend.
Ta
No stress man. 24 box was excessive for a rooted lump of scrap, will have to hook you up if we ever get our bucket chair to a track and we meet..
Drew, thank you, knocked at the door, no one home, so uplifted the DT, will do the job nicely.
Forum whore
Ha HA, almost drank them myself. The engine will be fit for purpose, thanks again.
I am down in Wellington from time to time and I would like to go out to the Kitoki? track and have a look one race weekend. Must keep an eye on the dates.
Low personal B.M.E.P.
You did mention exhaust gas triggering HCCI back a bit. I assumed you were referring to it in uniflow cylinders as the only reference I'd seen was Irving referring to one of Phil Vincent's experiments. Apparently the port layout was such that a spiral column of hot gas remained in the cylinder to ignite the incoming charge. Unexpected and awkward....Gee, I turn the computer off for a few days and I miss out on all the good stuff
I thought I wrote it on this thread, perhaps not, but all you would need to do to get HCCI in a turbo engine is trap back some exhaust gas either don't allow all the hot exhaust out or via turbo control (high back pressure) (and cam timing) push some exhaust gas back in on the induction stroke. With the super ECU controled turbo's now I'm sure this would be possible, I guess via a knock sensors and/or cylinder pressure tansducers. But yes, not a full throttle thing I don't think?
HCCI can be tripped off by either just high comp or lower comp and recycled trapped exhaust gases, I think this is the true traditional way.
still basking in the glory..
https://www.researchgate.net/publica...CI_Combustion:Gee, I turn the computer off for a few days and I miss out on all the good stuff
I thought I wrote it on this thread, perhaps not, but all you would need to do to get HCCI in a turbo engine is trap back some exhaust gas either don't allow all the hot exhaust out or via turbo control (high back pressure) (and cam timing) push some exhaust gas back in on the induction stroke. With the super ECU controled turbo's now I'm sure this would be possible, I guess via a knock sensors and/or cylinder pressure tansducers. But yes, not a full throttle thing I don't think?
HCCI can be tripped off by either just high comp or lower comp and recycled trapped exhaust gases, I think this is the true traditional way.
Drew, thank you, knocked at the door, no one home, so uplifted the DT, will do the job nicely.
Lucky find number two, made a bit of a cock up on the sleeve engine, the drawings are a little obscure on this, (what #%&^&* drawings
four stoke engine i think but si ( spark ignition ) used to initiate hcci.. maybe some rubbish blowdown to contaminate new charge and spark energy to initiate hcci... reading through it says that spark energy doesnt start a flame front in heavily erg charge , only cause heat to help start hcci. my apology's if this has already been posted
Hardcore Biker
More slider action: Had a happy morning making swarf doing some manual mill rotary table machining out of crankcase mouth. Had to cos the vertical CNC is tied up on a big job (= survival).
External engine assy is getting there, and as you see it, it is actually devoid of the sliding cylinder waiting on O ring groove machining. Every time you do something, you realize there are lots of other things to be done. Designing on the move I say.
Hardcore Biker
One thing I didn’t post yesterday was some more work on the cylinder head insert. When the cylinder is at its highest, corresponding to max power setting, the insert will be well buried into the liner. From the pic, imaging that the liner is 10 mm from the main top face of the insert. In this situation, the cooling wouldn’t be great directly behind the combustion chamber.
So, to improve the situation, there are a series of vertical flutes outside the plug body area. The pic shows the basic coolant path, which is split into two symmetrical paths, one each side of the insert. What is not shown is how this flow is controlled. This will be done by a 3D printed flow guide, this will contain and direct the flow around the insert. Bit of Solidworks coming up next.
Hardcore Biker
more details on F1technical.net
Forum whore
That's an M14 plug, isn't it? Switching to an M10 plug might give you room for coolant bores between the plug thread and the three bolts that hold the insert to the head cover.there are a series of vertical flutes outside the plug body area. The pic shows the basic coolant path, which is split into two symmetrical paths, one each side of the insert. What is not shown is how this flow is controlled. This will be done by a 3D printed flow guide, this will contain and direct the flow around the insert.
Here are some pics (granted, from much simpler inserts) that may tickle your brain.
L-Plate Rider
Just a last comment to the F1 technology: I don't really think that they are running HCCI since they are all fighting against the knock limit. Sometimes they hit the limit followed by immediate engine failure seen from every manufacturer. I think to run HCCI with good power and the traditional control systems they have (no variable compression, no variable valve lift and timing) the engine need to be undestructible.
I think they run the stated before Prechamber Ignition. Mahle has his own interpretation, but Mercedes at least should use a system similar to this:
It's a conventional sparkplug with a added finger cap and holes in it. The counterpart is the piston shape. You have a normal DI main injection and short before TDC you inject a little fuel in the piston cavity. When the Finger cap meets the puddle it get squished inside the sparkplug as a well ignitable mixture. The ignition produces a high pressure in the "prechamber" which shoots the flamefront across the main chamber and makes a fast and complete combustion, mixture quality independent.
In theory....
More information can be found in here: https://www.dbu.de/OPAC/ab/DBU-Absch...t-AZ-22203.pdf
It is written in german, but the pictures alone tell a good story.
Maybe we can use somewhat of it for two strokes...but with the needs of a pipe we don't want a constantly fast combustion. Right..?
Forum whore
Not necessarily. If you can control HCCI so it doesn't happen before TDC, it won't destroy the engine. And the F1 boys do have several control options.
Their compression ratio may be fixed but their compression pressure isn't. And they are also free to play with exhaust gas recirculation.
We always want a fast combustion; it will limit heat losses and NOx-forming. For two-stroke exhaust pipes we may also want exhaust gas that hasn't already lost all of its energy in the expansion phase, but we can easily control that, as we are doing right now, by delaying the start of combustion....but with the needs of a pipe we don't want a constantly fast combustion. Right..?
Fast combustion will have the added advantage that we can ignite even later, making sure that we won't have any combustion pressure on the piston before TDC.
Forum whore
Dragged the old Bighorn out to do a Vinduro yeaterday, new piston, battery, clean out the fuel system as it has been sitting a while, changed back to the trail bike gearbox (close ratio not needed) widened the exhaust port and reshaped a bit (from what I've learn't on ESE) and WOW we have an engine that's just too much. Thankfully the EFI and variable rotary valve housing make it sooo rideable in the low rpm's, it's a tractor and a road racer all in one, love those straight forest roads! I haven't had so much fun in a long time
Hardcore Biker
Hi Neil this is probably the wrong place for this but I don't keep up with the ESE thread. What happened to the Ryger. Dose it work? has it won anything?
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