Husky developing DI 2T ?

[AlexMember]

Yeah good point. Not sure about that.
They could utilise a special type of 2T oil that does contain something (fuel) to encourage it to transfer and eventually be consumed but I think that defeats the purpose of reducing emissions.
Why could they not run a wet sump of 2T (or really, even 4T oil)? The oil would need to reduce it’s misting so it doesn’t transfer so easy. The cylinder walls need a thin coating of oil for the piston … dripping into the transfer ports ….urgh. Who knows. They need to do without transfer ports, run a wet sump and just force the air in the side intake port like a 2T diesel supercharger style!

[Steve WyethMember]

It’s a tricky one isn’t it? Going to a wet sump on the face of it seems the obvious way to go but then how to you get the air into the cylinder now that you don’t have any transfer ports?

I don’t think having the air at atmospheric pressure going through reeds directly into the cylider would work as there isn’t suffiecint tarnsfer time/volume to get the required amount of air in there. An option would be a turbo or supercharger but that adds weight and bulk and is not practical for a dirtbike.

The system works in the current 2t applications as the piston downstroke pressuriszes the crank case forcing the air (and fuel) into the chamber via the transfer ports. Without this forcing of air I don’t think it would work so well. This is even more obvious given that the reed/intake port would need to be covered by the piston upon ignition as the reeds won’t take the pressure from the combustion cycle.

The other way to do it is introduce some sort of intake in the head with a valve that opens to allow the air in. Sound familiar?? Now that you have these wonderful valves what will operate them? We’ll have to add a cam and cam chain to drive the valves open and closed.

That’s a wicked idea, I should patent that, the idea might just take off Maybe they could look at an electrically operated solenoid inlet valve system, again, weight penalties would be realised in a bigger electrical system though.

[Steve WyethMember]

Iva wrote:

That is correct Axel, the bottom end will be lubricated by direct sprays onto the bearings, reading down the article it states this, but will they spray engine oil (a loss system) or will they spray 2St fuel oil mix on the bearings? I’d sort of lean towards the latter to keep it slightly lower tech on the spray system in which case do we then need an expansion chamber to burn the unburnt fuel…?
F’d if I know, I’m only a scientist, not an engineer! :huh:

Why would you bother with fuel in the crankcase if it’s being injected directly in the head? Not having the fuel in the crankcase will provide better lubrication as the oil is doing the lubing and it’s not dliuted with fuel.

Here’s another thought, wouldn’t having a gallery through the centre of the crank/conrod be an idea to pump oil upto the little end bearing…….

[AlexMember]

Well yes you could but can you imagine the manufacturing process to do that??? Most expensive crank in the world.
Remember that currently there are a couple of simple holes in the top of the rod to let lube get to the little end bearing. Realistically there might not be a great need for lube up there too you know.
Regarding a valve, yes there are working 2T devices that have an intake valve. I’m pretty sure they are still force fed air as there is no way to “draw” air in.

[Steve WyethMember]

You mean a ‘trapping valve’ motor? Champo was always talking about building one, never happened. Easier said than done I guess, I know all about that

I dodn’t think the manufacturing process needs to be much harder to allow for a gallery in either.

Lotus have a pretty schmick looking design, see here

[Scott SouthwellMember]

If I remember correctly Ossa Di 2T has two injectors. Would it be possible to have one injector feeding oil into the bottom end with the air and lubricating as per normal with only the fuel being direct injected into the combustion chamber?

[Scott SouthwellMember]

Maybe something like this. The key could be how little oil is actually required to lubricate a 2T. At present with premix a lot of the oil is wasted. (The techy bit starts at about 1.20)

[drewMember]

virtually no 2T smoke or smell… no 2T smell? what’s the point of that?

i would have thought just going to EFI through the case would have cleaned up emissions if sprayed when the exhaust port was closed but still on the intake stroke.

other than that the ski-do would be much simpler than an oil pump/ wet crank 2T…. right?

the e-tec is a similar set up to the omnivore.

ski doo please make us a 300cc version of your e-tec.. twin cylinders is fine.. well by me anyway .

[AlexMember]

That Skidoo motor is essentially the same as we have been discussing.
Injected fuel. Crankcase air induction with transfer ports. 2T oil delivered to the crank (and the powervalve which is odd). What happens to all the oil? My guess is they are loosing some to misting and splashing in the crankcase and burning it (“Virtually no 2T smell…”). They might be using “better” big end bearings that require less lubrication rendering wet sump overkill?
They might even have a drain/pickup below the crank so with the force of the compression stroke any residual oil gets pushed back into the 2T reservoir?

[alanMember]

old barsteds like me may not buy these new wiz bang two strokes if they make them .like how yo can buy a new bike thats as flash as they where when we where young spose its called a mid life crisses

[Gary NewnhamMember]

Good luck with the Lotus thingy.
Outboards have solved all the problems already and use an oil feed pump with multiple lines to various bearings and sprays onto cylinder walls.
These things produce up to 350HP regularly and meet current emissions regs.
They use a direct injection oil , thinner than normal 2T and usually synthetic.
Ralph Sarich experimented with direct injected 2T many years ago and it is to him we owe the DI technology.
However they also run an air pump to assist with atomisation from the injector, not sure why.

[Steve WyethMember]

gazza55 wrote:

However they also run an air pump to assist with atomisation from the injector, not sure why.

I’m 99% sure it’s because the fuel pressure isn’t high enough to achieve sufficient mechanical atomisation. For this to happen fuel rail pressures need to be circa 30 Bar.

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