Oddball engines and prototypes

[WilDun]

Michael Moore just posted these images of this engine on the ESE thread:

Now we can see that it's a four stroke, with reed valve controlled crankcase compression, feeding an inlet poppet valve via another reed valve!

That layout was used successfully in the YS (Japanese) model aircraft engines - this gave them a distinct advantage over your average four stroke in that field! but I guess that in bikes etc. the burning of oil in the fuel would not go down well!

[Grumph]

That layout was used successfully in the YS (Japanese) model aircraft engines - this gave them a distinct advantage over your average four stroke in that field! but I guess that in bikes etc. the burning of oil in the fuel would not go down well!

That Maico appears to be based on the 490 - which is of course a 2 stroke. A bit of smoke from a motocrosser isn't a problem...I'd be surprised if that layout ever approached the 490's HP figures - torque maybe, but no one I know has ever complained about a 490's lack of that....

[Niels Abildgaard]

That layout was used successfully in the YS (Japanese) model aircraft engines - this gave them a distinct advantage over your average four stroke in that field! but I guess that in bikes etc. the burning of oil in the fuel would not go down well!

Mr Diesel tried the scheme before 1900.His engine was a single cylinder crosshead type so it was easy to arrange

[husaberg]

In re alternate charging systems:

Michael Moore just posted these images of this engine on the ESE thread:

Now we can see that it's a four stroke, with reed valve controlled crankcase compression, feeding an inlet poppet valve via another reed valve!

That Maico appears to be based on the 490 - which is of course a 2 stroke. A bit of smoke from a motocrosser isn't a problem...I'd be surprised if that layout ever approached the 490's HP figures - torque maybe, but no one I know has ever complained about a 490's lack of that....

Reminds me of this?
http://www.kiwibiker.co.nz/forums/sh...post1130803792

Ellwood Hybrid – Single Cylinder Reed Valve Intercooled 4 Stroke Engine
Attachment 306648


Attachment 306647
John Ellwood, who built this engine, says hybrid engines working on this principle began back in 1915. John got the idea to build one back in 1994 and he's been working on the constantly evolving project ever since.

The first Ellwood Hybrid was based on a Godden engine, commonly found in speedway motorcycles, he's also built one with a Jawa engine. The first one was converted in a pretty straightforward manner, as John describes it:

“
A hacksaw, drill and file were enough to slaughter the speedway engine. A bit of rubber pipe, two reed valves from an RD 350, a seal on the crankcase and a carb from a Rotax converted a relic into a Hybrid.

He has both a 500cc version which he says puts out an estimated 50 hp and a 1300cc version doing somewhere around 150 hp. The 1300 is all handcrafted and it's fuel injected and water cooled with 4 crankcase mounted reed valves, a belt driven rotary cross head valve, an intercooler and 15:1 compression.
Attachment 306649
Ellwood Hybrid reed valve locations on crankcaseJohn has been racing the 500cc version and plans to race the 1300 in Supermono racing in the U.K. so it must run pretty well. I just think it's an interesting combination of 2 and 4 stroke technology.

John has done a lot of work without the resources of any expensive engine building facilities. I wonder how this would run if really refined and, with the right equipment, it would be much easier to determine how much extra power this setup actually provides. Definitely different.

John adds: "...here in Sweden we're having a flying kilometer race at the end of March, Bonneville Salt Flats style - only we do it on ice. I've entered the black 500 Hybrid, and will put on the laughing gas tube, to get a bit extra boost." I checked out the ice racing website and got a chuckle, there's a note, "Don't bring any salt."
http://thekneeslider.com/ellwood-hyb...stroke-engine/
http://ellwoodhybrid.webs.com/

[WilDun]

One thing (drawback?) about the single cylinder version is that there has to be a holding chamber with non return valves to store the first pulse.
If it were a twin cylinder, either a boxer twin or a 360 deg parallel twin (both having alternate firing cylinders of course) then no storage chamber with valves is required as there are effectively two under piston pulses combined making one supercharge (so to speak) which will go straight to the inlet valve on whichever cylinder is on the inlet stroke.
So a supercharge is produced on each stroke, feeding each cylinder on alternate strokes. - clear as mud?

[ken seeber]

As we know, the concept isn’t new, I think Husqvarna also did it ages ago. The difference here is that old mate routed the mixture thru the cam/valve gear to provide lubrication, whereas, I think, the others used the cam chain to carry the oil up to lubricate the top end, independent of the mixture.
What’s been achieved? Possibly a bit more power than the equivalent 4 stroke, but with the additional complexity of reed valves, an isolated crankcase, presumably a split crank with ball/roller bearings, external ducting & oil in/with the fuel.
I reckon the opposite is the way to go. Only if.

[Frits Overmars]

What’s been achieved? Possibly a bit more power than the equivalent 4 stroke.

You're very kind, sir. I'd rather compare it with the two-stroke engine it was based on, which definitely had a good deal more power.
How shall we call this? Castration by cams and valves?

[WilDun]

How shall we call this? Castration by cams and valves?

Not really, the opposite in fact! - castration removes the "offending?" parts, this adds to them!

[Yow Ling]

Not really, the opposite in fact! - castration removes the "offending?" parts, this adds to them!

Castration removes the urge

[Frits Overmars]

Castration removes the urge

That's the way I meant it, Yow Ling .

[Pursang]

Complicating a simple concept...or, simplifying a complex one?
Best, and/or worst, of both worlds.



Needs electronic/hydraulic (computer controlled) valve control, variable exhaust geometry, open mind.
Pressurised intake charge would help too.

Cheers, Daryl.

[Pursang]

Here is a commercial example of the crankcase supercharging process.
http://www.shindaiwa-tools.co.uk/index.php?id=141

A lot of work to go to if it is only a 'marketing' advantage (though worse things have been done).

Cheers, Daryl

[WilDun]

Here is a commercial example of the crankcase supercharging process.
A lot of work to go to if it is only a 'marketing' advantage (though worse things have been done).

Cheers, Daryl

Daryl, Don't get the top post! - Is there something missing? or have I become completely befuddled?
-
UPDATE : yes, definitely confused I think! - I actually do remember an Italian kart engine ( from memory, AMI or something like that)) which used that principle but don't think it could be switched to four stroke mode (guess half speed camshaft required for four stroke)

Most of the manufacturers have now got four stroke models, I have a 25cc Honda which doesn't use crankcase charging but in order to be able to use it in all positions it has a lube system where the oil is whipped up into a mist in a separate tank and is then circulated through the crankcase by the pumping action of the piston, up through the belt tunnel to the OHC setup, then back down into the tank again.
All very interesting, but I can't see that there is any benefit over a two stroke and it's more complicated - haven't seen much evidence of any of those little fourstrokes dominating the market either!

[WristTwister]

[ken seeber]

Daryl, Don't get the top post! - Is there something missing? or have I become completely befuddled?

I think that all the manufacturers have now got four stroke models, I have a 25cc Honda which doesn't use crankcase charging but in order to be able to use it in all positions it has a lube system where the oil is whipped up into a mist in a separate tank and is then circulated through the crankcase by the pumping action of the piston, up through the belt tunnel to the OHC setup, then back down into the tank again.
All very interesting, but I can't see that there is any benefit over a two stroke and it's more complicated - haven't seen much evidence of any of those little fourstrokes dominating the market either!

Sadly Will, the thing operates on a 4 stroke cycle (and how dare you for ever buying one....), and they fundamentally don't have the short circuiting fuel scavenging losses of a 2 stroke. Over your Honda, they require no oil changes, hence disposal. In fact, that is one of the arguments for crank case scavenged 2 strokes, that the oil is disposed in the best possible way, combustion.

Still, some one had better get a move on to get the clean 2 stroke thing going before electricity takes over. It's all nice making more power and listening to the sexual arousal of a developed 2 stroke, working thru EngMod etc , knowing where the RAD is, and hours on the dyno, but if there is no place to run it, then it's all over.