Fuel injected 2 strokes?

[wakatoa]

I'm curious about haw these work can anyone enlighten me please.<br /><br />How do fuel injected 2 strokes work?<br />Is the fuel injected directly into the cylinder?<br />How is the crankcase lubricated?<br />And do they have a good reputation for reliability and longevity?

 

[clanton]

Re: Fuel injected 2 strokes?

The fuel is injected directly into the cylinder. The Merc system came from Orbital, and Chrysler car people worked with this system on a 2 stroke engine for a car about 5 years, if I remember correctly it would not meet the automotive emission rules and Chrysler dropped it. I at first thought Ficht was great, but if the EPA stays on marine engines to clean up the emission, I would put my money on the 4 strokes.

 

[trevorcday]

Re: Fuel injected 2 strokes?

By fuel injected 2-strokes I assume you are referring to the direct injection 2-strokes on the market currently aka Optimax, FICHT, and HPDI. These systems inject fuel directly into the cylinder with the injector pulses timed to the engine (this is the real trick vs conventional fuel injection). The FICHT system has been a complete disaster, the main problems being blown-up powerheads resulting from lack of lubrication. The Optimax system has been pretty reliable and has about 5 years or so in the field now. They inject oil directly into the crankcase at the points where it is required (I think Ficht tried to attomize the oil in the incoming air stream). Yamaha has the HPDI system which is relatively unproven (approx. 2 years in the field) but I am sure is good. The experience I have with the Optimax motors is that they behave very well, smoke free operation, 4-stroke like fuel economy, turn-key starts etc. The idea is that they provide 2-stroke performance with 4-stroke like emissions and fuel economy.

 

[bertherr]

Re: Fuel injected 2 strokes?

What happens to the oil that is injected to the bearings & rings in the direct injected two stroke engines? I am most interested in the Yamaha HPDI. Thanks, Bert.

 

[blockbusta]

Re: Fuel injected 2 strokes?

so do the new direct injection motors burn oil?

 

[Silvertip]

Re: Fuel injected 2 strokes?

What is not being discussed here is the Evinrude E-tec series of direct injected engines. These engines are cleaner than most four strokes and burn very little oil if programmed to run XD100 oil. They've been around for several years now and enjoy a great reputation for performance and economy. Early Optimax had just as many disasters as Ficht engines just for the record.

 

[JB]

Re: Fuel injected 2 strokes?

so do the new direct injection motors burn oil?

Yes, but much less than carbed engines. The oil is injected into the crankcase where there is no fuel to wash it away so it needs far less. The air stream passing through does carry some into the cylinder, where it is burned.

 

[Chris1956]

Re: Fuel injected 2 strokes?

I agree with some of what everyone said, but have my own story, based on som tech articles and discussions with a Merc Dealer.

Optimax has a low pressure fuel pump that puts gasoline into an intermediate injection chamber. A blast of high pressure air forces the gasoline into the combustion chamber just before the plug fires. The oil is introduced into the crancase via the intake air stream, at the valve bodies which have the throttle plates. The Merc Dealer advised me that the Optimax motors burn less gasoline than the non-DFI motors, but use about the same amoint of oil. Certainly, I did not expect that answer.

On the FICHT/e-TEC motors, the high pressure fuel pump forces the gasoline directly into the combustion chamber, just before the plug fires. I am not sure of the design of the lubrication system, however it certainly circulates the oil thru the crankcase, likely by spraying it into the incoming intake air, as the Merc and oil injected motorcycles do. From what I understand, the main difference between the FICHT and the e-TEC, is an improved high pressure fuel pump.

 

[4.0l sahara]

Re: Fuel injected 2 strokes?

Watch these two videos about direct injection outboards.

Part 1-http://www.youtube.com/watch?v=viWhxvo6DLk&mode=related&search=

part 2-http://www.youtube.com/watch?v=-Yy5edv3-yU&mode=user&search=

 

[noelm]

Re: Fuel injected 2 strokes?

I guess to really simplify things, the "old" 2 stroke technology used a system of lower crankcase pressure to "suck" a fuel oil mixture into the cylinder to be ignited by the spark plug, this mixture usually went through the crankcase first, thereby lubricating all the bearings and stuff, and then transferred by ports to the cylinder for ignition (by piston movement) an "injected" 2 stroke just uses high pressure to inject straight fuel into the head (kind of like a diesel) and oil is introduced at a metered amount (according to revs and load) at some point in the system some at the intake, some added after, just depends on manufacturer as to where and how, but they all work, they all run very clean, they all CAN cause drama as can anything else.