Wet sump 2 stroke?

Does it exist? a 2 stroke that does it's thing without getting the crank case involved?

Yes they do exist but generaly very big with HUGE supper chargers and direct injection.

2 stroke diesels are the first that comes to mind.

Some of the new weed wacker engines are built this way now.

look at old Detroit Diesels. It's why buses don't sound right anymore.

Rotary?

44Dwarf wrote: Yes they do exist but generaly very big with HUGE supper chargers and direct injection.

Back in school, I got to see the prototype two stroke from Chrysler- pretty decent sized blower on that one.

Was that the Orbital Engineering motor?

The problem with a wet sump two stroke is the crankcase is essentially another combustion chamber without a spark plug. As the piston travels downward, it compresses the fuel air mix in the crankcase and forces it through the transfer ports into the 'real' combustion chamber up top. Problem is, if there's lubricating oil etc in the crankcase it too becomes part of the fuel/air charge. So there's the reason for the ginormous blowers, they have to take the place of the olde tyme simple design.

Yeah, in a normal-crankcased 2-stroke, the supercharger is for forced induction in the sense that, without it, air wouldn't move in at all. It doesn't provide boost in the traditional sense. (Not until you pull it off of the GMC engine, change out the 45 degree gears for 30-degree, and stick it on a V8, anyway )

It's kind of a neat concept. Air goes in through ports in the bottom-ish of the cylinder, exhaust goes out through valves in the head.

Regards "normal" 2-strokes, ever had one of those Mercury V6 outboard motors apart? They're... interesting. It's a shame that they're so expensive, and designed around having a limitless supply of ~75 degree water. A 200hp model would rattle around inside a 12A-shaped hole.

Jensenman wrote: Was that the Orbital Engineering motor? The problem with a wet sump two stroke is the crankcase is essentially another combustion chamber without a spark plug. As the piston travels downward, it compresses the fuel air mix in the crankcase and forces it through the transfer ports into the 'real' combustion chamber up top. Problem is, if there's lubricating oil etc in the crankcase it too becomes part of the fuel/air charge. So there's the reason for the ginormous blowers, they have to take the place of the olde tyme simple design.

No, while it used Orbital's injectors, Chrysler wanted to use their own block. So the blower was the substitute for the crank...

Odd to see a two stroke wiht poppet valves, that's for sure. But I also know it didn't get very far.

(only related to the two stroke part- we (F) had our own two stroke, too- direct injection, dry "ish" sump. It was in an early 90's Fiesta- it actually drove really funny- no real engine braking. But outside of the one car, it didn't get very far.... And I'm trying to work with the University of Idaho on a DI project- they are one of the very few in the Clean Snowmobile SAE competition who is using a two stroke DI enigne- it's almost making the Yellowstone requirements w/o cats. Although to me that says a lot about the yellowstone requirements.... )

Eric

Yeah, Yellowstone's requirements have been the subject of much debate in the off roading world. I'm sorta glad to see that kind of thing, it's made possible engines like the turbocharged and supercharged 4 strokes Honda and SeaDoo use in their PWC's. Come to think of it, one of those would make for a really cool A Mod car powerplant...

Jensenman wrote: Yeah, Yellowstone's requirements have been the subject of much debate in the off roading world. I'm sorta glad to see that kind of thing, it's made possible engines like the turbocharged and supercharged 4 strokes Honda and SeaDoo use in their PWC's. Come to think of it, one of those would make for a really cool A Mod car powerplant...

http://students.sae.org/competitions/snowmobile/

(Go VANDALS!)

Many old diesels are two-stroke wet sump. Since there is nothing to generate intake force, they require a supercharger of some sort. They were mostly ditched because of emissions, but they made nice power for their displacement