Bourke engine viability?

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PMD

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From what I've read, you can get sufficient heat transfer from a moving liner to the outer piston walls via the oil film if the tolerances are close enough.
I guess there is a good precedent in the sleeve valve engines of WWII era, but the loss of oil would not be tolerable in today's emissions environment - even for an aviation engine.
 

Sockmonkey

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I guess there is a good precedent in the sleeve valve engines of WWII era, but the loss of oil would not be tolerable in today's emissions environment - even for an aviation engine.
There are supposedly ways to limit the oil loss to acceptable levels as well, but I'm not sure.
As for the scotch yoke, You could balance it and solve the loading issues with a double crank, but I dunno if the mass would be worth it.

If you were willing to add a little bit of complexity to a standard two-stroke, you could improve the efficiency and and make it run cleaner with an exhaust valve on the cylinder head instead of another set of ports.
 

PMD

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There are supposedly ways to limit the oil loss to acceptable levels as well, but I'm not sure.
As for the scotch yoke, You could balance it and solve the loading issues with a double crank, but I dunno if the mass would be worth it.

If you were willing to add a little bit of complexity to a standard two-stroke, you could improve the efficiency and and make it run cleaner with an exhaust valve on the cylinder head instead of another set of ports.
Of course, that is EXACTLY what Detroit Diesel 2 cycles did: inlet ports at bottom of cylinder and 4x exhaust valves at top to effect uniflow gas path. Also what ever "cathedral" type marine 2 cycle does as well (i.e. THE most efficient ICEs in general use). 2 cycle with piston port oil control has been accomplished (and it is not easy to do) but add the sleeves into the equation NEEDING a full oil film that must surround at least some ports (not sure how you could insert a valve into that design) and the problem would become HUGE.

The point is: there is no need for exotic and complex concepts to have Atkinson-like geometry as one can simply use forced air charging and engine management of direct injection in normal recip 2 cycle designs to give the kinds of power density (and possibly thermodynamic efficiency) needed. There is a LOT of other combustion research that has moved BTE into the 60+ % range (or will in foreseeable future).
 

Aesquire

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The point is: there is no need for exotic and complex concepts to have Atkinson-like geometry as one can simply use forced air charging and engine management of direct injection in normal recip 2 cycle designs to give the kinds of power density (and possibly thermodynamic efficiency) needed.

Yep.
Toyota accepts the lower loss to get the fuel economy. Specifically a 2.5 liter engine that puts out 167 ponies. Others use supercharging to get more power for the displacement. You can't escape the basic "more power needs more fuel", but with slightly higher efficiency you get slightly better economy.

Tiny increments give big savings across a million vehicle fleet. Modern cars also use less piston ring tension to get less internal drag. Accepting high oil consumption.

So check your oil level! A quart loss in 1600 miles is "acceptable", but change intervals of 5000 or more miles means you can run dangerously low if you don't pay attention. And clean oil is needed as hydraulic fluid in the cam timing mechanism. ( dirty oil is a major cause of failure today )

Toyota uses variable cam timing and dual fuel injection to get he Atkinson Cycle working. No fancy cranks or magic.

And the dual fuel injection is both a practical and economy thing... 2 complete, independent fuel injection systems. Direct injection gives better mileage, but causes soot fouling on the intake valves/tract. So they also have port injectors to wash away the soot and provide more fuel at higher throttle settings. The Computer switches automatically to "wash" mode and back while in cruise. ( you can just hear & feel the transition if you pay close attention )
 

Aesquire

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Motorcycles have used Square 4 engines, the Aiel probably the most famous. But that's a 4 stroke.


Here's a start on your journey into....

 

Sockmonkey

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Of course, that is EXACTLY what Detroit Diesel 2 cycles did: inlet ports at bottom of cylinder and 4x exhaust valves at top to effect uniflow gas path. Also what ever "cathedral" type marine 2 cycle does as well (i.e. THE most efficient ICEs in general use). 2 cycle with piston port oil control has been accomplished (and it is not easy to do) but add the sleeves into the equation NEEDING a full oil film that must surround at least some ports (not sure how you could insert a valve into that design) and the problem would become HUGE.

The point is: there is no need for exotic and complex concepts to have Atkinson-like geometry as one can simply use forced air charging and engine management of direct injection in normal recip 2 cycle designs to give the kinds of power density (and possibly thermodynamic efficiency) needed. There is a LOT of other combustion research that has moved BTE into the 60+ % range (or will in foreseeable future).
See, I keep wondering why they don't use the Detroit Diesel configuration for regular gasoline engines and aircraft engines in general. Only needing half as many cylinders is gonna cut the parts count way down even when factoring in the turbo or supercharger forced induction.
 

Niels

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See, I keep wondering why they don't use the Detroit Diesel configuration for regular gasoline engines and aircraft engines in general. Only needing half as many cylinders is gonna cut the parts count way down even when factoring in the turbo or supercharger forced induction.
I have always wondered why mr Wilksch did not try his nice looking three cylinder inverted diesel as spark igniter.
Our mr Battler Briton has an unused example and if I was rich I would try.
 

jedi

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See, I keep wondering why they don't use the Detroit Diesel configuration for regular gasoline engines and aircraft engines in general. Only needing half as many cylinders is gonna cut the parts count way down even when factoring in the turbo or supercharger forced induction.

The 2 cycle Detroit Diesel uses excess air to scavenge the cylinder. In a carbureted gasoline spark ignition engine this would use a fuel air mixture for the excess air and destroy the fuel efficiency and emissions. This would work with a direct fuel injection engine but then you are one small step from a diesel that would requre a higher pressure for the injector pump.

The 2 cycle Detroit Diesels went away when emissions and high mileage fuel efficiency became the driving factor in the trucking industry. Two cycle Diesels are still used in locomotive electromotive rail applications.

 
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PMD

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The 2 cycle Detroit Diesel uses excess air to scavenge the cylinder. In a carbureted gasoline spark ignition engine this would use a fuel air mixture for the excess air and destroy the fuel efficiency and emissions. This would work with a direct fuel injection engine but then you are one small step from a diesel that would requre a higher pressure for the injector pump.

Of course this is EXACTLY what Achates did with their 2.7 litre, 270 HP gasoline fueled, fully emissions compliant demonstrator engine. So important for the SI fanbois to appreciate is the CI is not so fussy on what fuel is used due to lack of aspirated charge.
 
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