cheapracer wrote:
Wow a lot of misinformation in this thread.
Oil injection does mix with the fuel, it just saves the owner pre-mixing it by hand. I can't recall a production petrol 2 stroke that doesn't need oil to pass the combustion chamber although I know prototypes with isolated primary compression cycles that don't.
only crankcase scavenged engines do this.
cheapracer wrote:
Jimmys (Detroit Diesels) don't have transfer ports, a supercharger positively displaces air direct into the combustion chamber straight through the cylinder wall ports.
thats what i have been thinking about
cheapracer wrote:
500cc GP bikes never passed 200hp on track but I heard a few dyno runs saw just over in perfect test cube conditions.
really? i think this is just a limitation of the crankcase scavenged design. maybe there is simply not enough oil going to the main bearings. any more oil in the mixture and the charge will not burn efficiently enough.
cheapracer wrote:
Some manufacturers have tested 2 strokes mostly modded by The Orbital Engine Company with direct injection but they will never see production. A friend of mine who is a top Ford Engineer handled 3 test cars for Ford Australia driving them around.
lotus has their own design. the others have their own designs too. yamaha calls it e-tec. bombardier licensed it to them i think. or is it evinrude? chrysler all have their hcci engines in 2 stroke. if all of them redesigned an engine from scratch they would use a direct injected 2 stroke using hcci.
the advantage of air blast assisted fuel injection is just too much hype. e-tec uses a voice coil solenoid to inject fuel. others use a more conventional common rail.
cheapracer wrote:
Loop scavenged designs? What do you mean? Loop scavenge has been around since the mid 60's since the advent of pressure wave supercharging (expansion chambers). Literally every one of the millions of common 2 strokes has been a loop scavenge since then and up till this very day.
those are mostly carbureted, crankcase scavenged, crossflow designs. good for the power range and applications they were designed for. no more no less.
cheapracer wrote:
It has been well proven that as the displacement goes up the power advantage of a 2 stroke falls eventually behind a 4 stroke, around a 300cc cylinder is about where they equalize but then the 4 stroke will carry a smaller weight of fuel and be packaged easier due to the lack of expansion chamber. After 300cc, eventually the 2 stroke can't touch the 4 stroke.
not generally true. cargo vessels almost exclusively use 2 stroke diesels in the large tens and hundreds of liters displacement. this is only possible because diesels are direct injected. medium sized 4 strokes are already too complex. how much more for the really huge ones.
cheapracer wrote:
However the small stuff rocks, an 80cc common kids MX bike puts out more hp per litre than an F1 race car.
exactly. if it can be scale up...