1000cc two stroke

[speedpro]

I wonder if anyone's ever built a two stroke Lanchester engine?

Horizontally opposed, piston heads facing each other, with the combustion space between them, and a crank at each end . Would have to be big bang firing but the induction and exhaust should work OK. And that would be a BIG bang.

Something like that has been built from scratch by a guy Neil Hintz. 2 crankshafts, 4 pistons. It was built as a uniflow engine with both crankcases at one end feeding one cylinder and the crankcases at the other end feeding the other cylinder. Various guises were tried, 2 or 4 carbs, 2 or 4 expansion chambers. Originally built as a bucket engine the first one had brushcutter conrods and would do about 20,000rpm (very short stroke per piston). Later versions were full size 500cc and were used to power a microlight. In each cylinder one piston controlled the transfer ports and the other controlled the exhaust ports. The last engine had smaller exhaust side pistons and there was some differance in the phasing of the pistons in each cylinder.

[Ixion]

If you used a third crankshaft to couple the cranks, you could use that to drive a charging cylinder, like the NSU/Puch split singles.

[speedpro]

If you used a third crankshaft to couple the cranks, you could use that to drive a charging cylinder, like the NSU/Puch split singles.

Trouble with that is that then the cranks are both rotating in the same direction and we have a torque reaction problem.

The concept is good, BMW have a pivoting balancer thing along those lines in one of their new 650(?)cc bikes I think.

[Ixion]

No, if you cross the conrods from the power cranks to the comon crank, the power cranks (ie the ones with pistons) can turn in opposite directions. That's exactly how Dr Fred did it, back in nineteen hundred and diddly. Does mean very long conrods for the connectors, though, which might be a problem with modern day revs.

I think I better get another beer mat, this design is getting complex.

[Mr. Peanut]

Rods, cranks, seals, special pistons...

Bah.

Build a rotary and be done with it.

[Ixion]

Booorrrriinnng.

And they don't go ringa-dinga-ding. Do they, huh ? Huh? Huh?

[FilthyLuka]

Well, reading through the thread (and scribbling down notes something vicious) im starting to get enthusiastic about the project more and more.

So far:

Staying with v-twin. Why? No idea, seems like a good idea... Although my brain seems to be imagining a square twin...

For the crank, seeing as the need to be isolated, im thinking go with the twin, counter rotating cranks joined by gears, going to the gearbox/clutch

So, the crankcase would be effectively be two crankcases joined back to front. Both cylinders would be vertical, but bolted into the same crank case, like an inline engine but the other way, longditudinal if you will. Obviously the bores would be independant of each other, carbs in between the two. The cranks would be two CR500 cranks, running with a bit out of the (random side) right hand side crank case (the section that the crank comes out of will need to be sealed, so the crank doesn't de-pressurize). So, if you took the left crank case cover of, you would see two gears mashing together This would be the two cranks.

Do you guys reckon it would be a wise idea to have a set of gears joining the cranks on each side? Or would that just be un-neccesary?

Also, if the gears were running together, there would need to be lubricated. Simplest way to do this is for the gears to have their own sealed chamber on the right hand side of the crank case where one would dump in oil for lubricating purposes. Something tells me that running the gears that would be joining the cranks together un-lubricated would be a bad idea.

The reason i want to keep the gears out side of the main crank case is so that keeping the two chambers of the crank case separate becomes a lot simpler. No gear needs to go in between the two, so each cylinder would have its own pressurized crank, assuring it get the optimal shot of fuel/oil/air mixture every cycle. (I never liked sharing as a child, i might reflect this in the engine design).

If the twin crank idea goes through, the bike will say "VTWIN" on the side just to piss pixie off...

And for some reason the picture of Honda's oval piston featured in the NR-750 keeps coming to mind, one piston, two con-rods, two spark plugs, two intake/exhaust ports... Could be fun to make something that utilizes this design, but too much of a pain in the arse making pistons :S

[pete376403]

I wonder if anyone's ever built a two stroke Lanchester engine?

Horizontally opposed, piston heads facing each other, with the combustion space between them, and a crank at each end . Would have to be big bang firing but the induction and exhaust should work OK. And that would be a BIG bang.

You're describing either the Commer TS3 truck engine (3 cyl, 6 piston, 12 con rods and two big rocker shafts. design originally borrowed from Dornier (IIRC) bomber engine of WWII
Or, two strokes taken to taken to the extreme, the Napier Deltic, used originally in british motor torpedo boats then locomotives, and then in the "nasty" class boats used in Vietnam

[DEATH_INC.]

Well, reading through the thread (and scribbling down notes something vicious) im starting to get enthusiastic about the project more and more.

So far:

Staying with v-twin. Why? No idea, seems like a good idea... Although my brain seems to be imagining a square twin...

For the crank, seeing as the need to be isolated, im thinking go with the twin, counter rotating cranks joined by gears, going to the gearbox/clutch

So, the crankcase would be effectively be two crankcases joined back to front. Both cylinders would be vertical, but bolted into the same crank case, like an inline engine but the other way, longditudinal if you will. Obviously the bores would be independant of each other, carbs in between the two. The cranks would be two CR500 cranks, running with a bit out of the (random side) right hand side crank case (the section that the crank comes out of will need to be sealed, so the crank doesn't de-pressurize). So, if you took the left crank case cover of, you would see two gears mashing together This would be the two cranks.

Do you guys reckon it would be a wise idea to have a set of gears joining the cranks on each side? Or would that just be un-neccesary?

Also, if the gears were running together, there would need to be lubricated. Simplest way to do this is for the gears to have their own sealed chamber on the right hand side of the crank case where one would dump in oil for lubricating purposes. Something tells me that running the gears that would be joining the cranks together un-lubricated would be a bad idea.

The reason i want to keep the gears out side of the main crank case is so that keeping the two chambers of the crank case separate becomes a lot simpler. No gear needs to go in between the two, so each cylinder would have its own pressurized crank, assuring it get the optimal shot of fuel/oil/air mixture every cycle. (I never liked sharing as a child, i might reflect this in the engine design).

If the twin crank idea goes through, the bike will say "VTWIN" on the side just to piss pixie off...

And for some reason the picture of Honda's oval piston featured in the NR-750 keeps coming to mind, one piston, two con-rods, two spark plugs, two intake/exhaust ports... Could be fun to make something that utilizes this design, but too much of a pain in the arse making pistons :S

Righto, twin cranks then. If you start off with something similar to the CR engine( just as an example to give you the idea), lay the front cylinder forward a bit, then mount the rear crank above the front gearbox shaft ( won't be too tall, no cams 'n shit ) and gear them both straight onto the clutch primary drive(or maybe through an idler). Don't need to be counter rotating if they're in line. Keeps it compact and simple. Oil will of course then come from the gearbox to feed these gears, as per normal. No need for a second set of gears on the other side. I would probably reverse the rear cylinder and piston so that the exhaust comes out the rear or it could be messy, and then you can run both carbs in the middle of the V (out the side anyhoo) with 90 deg manifolds. You MUST keep the crankcases completely separate unless you run both pistons up and down together or it won't work. This is basically how the RZ500 and KR250 are made (prolly others too, but I haven't seen them myself) so is an already proven design.
Get into it

[DEATH_INC.]

You're describing either the Commer TS3 truck engine (3 cyl, 6 piston, 12 con rods and two big rocker shafts. design originally borrowed from Dornier (IIRC) bomber engine of WWII
Or, two strokes taken to taken to the extreme, the Napier Deltic, used originally in british motor torpedo boats then locomotives, and then in the "nasty" class boats used in Vietnam

The problem with this idea for a bike engine is you spread the COG to wide, and add more heavy bits too. Mass centralization and lightness is where it's at.

[Ixion]

You're describing either the Commer TS3 truck engine (3 cyl, 6 piston, 12 con rods and two big rocker shafts. design originally borrowed from Dornier (IIRC) bomber engine of WWII
Or, two strokes taken to taken to the extreme, the Napier Deltic, used originally in british motor torpedo boats then locomotives, and then in the "nasty" class boats used in Vietnam

Them was diesels, but, was they not. Diesel is easier. Didn't the Deltic use sleeve valvves. Mr Motu is the expert on the Deltic.

[Motu]

No,I'm a TS3 man.I used to have a Johnson outboard that was a flat twin 2 stroke.Had to be a big bang because that's the only way they can run.....but I always wondered how that arrangement would work with a lot more capacity....and in a bike of course.Two CR500 top ends,double crankcase induction with reed valves...it'd need a special crank,but that's child's play to these young engineers.

[cowpoos]

No,I'm a TS3 man.I used to have a Johnson outboard that was a flat twin 2 stroke.Had to be a big bang because that's the only way they can run.....but I always wondered how that arrangement would work with a lot more capacity....and in a bike of course.Two CR500 top ends,double crankcase induction with reed valves...it'd need a special crank,but that's child's play to these young engineers.

Do you know who made the super charged 10 or 12 rotary cyclinder air cooled two stroke?? was an air craft engine of course!!

[speedpro]

Rotary cylinder or radial??

[cowpoos]

Rotary cylinder or radial??

errr...radial... woops!