Todays fleeting thought

redesign a 2 stoke engine with a turbo or supercharger and eliminate the premix or oil injection...  Possible?

I've often wondered about that. What would an engine built like the 71 series Detroits be like? Intake ports at the bottom of the cylinder and exhaust valves.

Wasn't that how Detroit Deisels we all know and love like the 6-71 work?  There have been efforts in the past to do this with gasoline as well.

Yes. That's where early hot rodders got the blowers too. Can you point me to the efforts- would like to see them.

noddaz said:

redesign a 2 stoke engine with a turbo or supercharger and eliminate the premix or oil injection...  Possible?

This is how train and ship engines work.

pres589 (djronnebaum) said:

Wasn't that how Detroit Deisels we all know and love like the 6-71 work?  There have been efforts in the past to do this with gasoline as well.

Oh yeah, forgot about these!  The blower wasn't a supercharger, it was kind of an air mover, taking the place of using the crankcase to force air into the cylinder.

Are you talking about a snowmobile style engine?  I think the issue would be crankshaft lubrication. An old Jimmy diesel has a separation between the crankcase and the area around the cylinders where the air is pushed in. A 2 stroke requiring premix has nothing for oil distribution or storage.  Lubing the turbo with a separate oiling system wouldn't be any big deal.  Crank, not so much.

I'm pretty sure that all 2 cycle diesel engines have closed crank cases and work pretty much like the Detroits.

Yes, and they don't start if the blower isn't functional to some degree.  

There was something in the mid-90's, a company in Europe that tried to create a gas, spark ignited engine that was two-stroke, but I cannot remember the name right now.  I think they built some prototype triples that were installed in cars.  Never made it to series production.

Getting the exhaust out and the new charge in is the thing. I really can't think of a better way. I would like to see a closed crank case 2 cycle engine built from the start as gas. I expect that they wouldn't be as efficient as 4 strokes.

pres589 (djronnebaum) said:

Yes, and they don't start if the blower isn't functional to some degree.  

There was something in the mid-90's, a company in Europe that tried to create a gas, spark ignited engine that was two-stroke, but I cannot remember the name right now.  I think they built some prototype triples that were installed in cars.  Never made it to series production.

Orbital?   Was just reading about them elsewhere.  I thought they were sixes, not threes, but they messed with a lot of stuff.

They ended up inventing a form of direct injection and decided that they were better off engineering fuel injection than whole engines.

Off the top of my head, Stihl makes something like that. 

Edit: Never mind, they make a 4 cycle that uses mixed fuel. 

Toyman01 said:

Off the top of my head, Stihl makes something like that. 

Edit: Never mind, they make a 4 cycle that uses mixed fuel. 

 

Huh?  Doesn't that negate much of the reason why practically all small engines are 4 stroke nowadays?

I mean, I can see the advantage of it, since it would allow the engine to be insensitive to operating angle...

In reply to Knurled. :

They are chasing weight, ie, no oil pump, or oil. And they are chasing torque and efficiency. 4 stroke compared to 2 stroke. 

In reply to pres589 (djronnebaum) :

I think the name was Orbital. edit, knurled beat me to it

On top of Orbital, Chrysler actually has some prototypes rolling around with supercharged two stroke, direct injection, engines.  Could use a standard bottom end, and just have a unique head.

Article from 1991- https://www.chicagotribune.com/g00/news/ct-xpm-1991-11-01-9104080217-story.html?i10c.encReferrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8%3d&i10c.ua=1&i10c.dv=18

and a follow up in 1996 explaining it going away https://www.wardsauto.com/news-analysis/chrysler-says-au-revoir-2-stroke-engine-program

It works, for sure.