2stroke/4stroke hybrid

Well i run into this article describing a new type of hybrid design engine and i though you guys might like it


http://www.popsci.com/popsci/bown/2003/article/0,18881,537079,00.html

Well this proves which stroke cycle is the superior design - the 4-strokers are stealing design features of 2-strokers! But they still have to have those valves, they should just quit cold turkey and switch all the way over. J/K :biggrin:

awww, I was all excited when you said it was a 2-stroke / 4-stroke hybrid... then it turned out to be a fuel-lubricated 4-stroke. There have been rotary engines doing the same thing for at least 20 years, probably longer.

As far as inverted operation goes, four-stroke aerobatic engines have handled that problem just fine for more than half a century... the question that the "hybrid" above addresses is "how do you lube an invertible 4-stroke while keeping the cost comparable to a (cheap cheap) 2-stroke?"

On the (perhaps more interesting) topic of hybrid power cycles:

I've seen one "switch-mode" two/four stroke engine design, which was designed to run as a four stroke most of the time (for driveability and emissions), but could switch to two-stroke mode for short bursts of power. I can't remember whether it always used poppet valves for intake and exhaust, or if it had a sleeve valve (or similar) to switch the intake for 2-stroke operation. I can't comment on any specifics about the design or mfr, but I can point you to another (conceptually similar) engine concept here (below) which operates as a 2-stroke all the time, but uses a rotating valve to maintain control of intake/exhaust timing.

http://www.memagazine.org/backissues/nov02/departments/tech_focus/techfocus1.html
(see "breath in, breath out" about halfway down)

Fuel lubrication is also one of the reason of the shorter life of a twostroke engine.

this is just a concept engine, its described as a monostroke engine, it combines the 2 and 4 struke concepts, quite interesting. the model may confuise you at first so i will give a brief explanation, the air enters under the piston and is compressed, whe the piston is at bdc a side port transfer chamber is opened allowing the air from below into the combustion chamber at the same time blowing out the ehaust gasses
www.bourke-engine.com/VLB/