EFI for a gasoline generator set.

[karley12345]

I'm working on designing and developing a fuel injected gasoline gen set for a hybrid vehicle. EFI is not something that is usually used in case of I.C.'s used for gen sets.
I'm considering various pr'o and cons exclusive of cost.

Theoretically it should provide more power and better fuel economy. But by how much considering this is a constant load, constant rpm operation?

What sensors to use?

Direct Injection vs mpfi?

[speedbeek]

Going to fuel injection will give you better performance. How much better will depend on the engine and implementation. In general, 10-20% more power can be obtained and 10% better fuel economy. Again this is general and can be better or not as good. What you will find with EFI is better dynamic performance in the form of consistancy. Engine start would be a significant improvement as well as performance over different temperatures/air densities. Even for your constant speed application, this should hold.

DI will take significant redesign of an engine head to implement and have more costly electronics, but that was not the question. I think DI also needs higher voltage and pressures so those may be constraints to work with. EFI using an alpha-N may be a good place to start. You could easily optimize for your operating point using an electronic carburetor strategy. Then you could easily expand to speed density when the time is right, adding a MAP and temperature sensor.

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[karley12345]

When you mean an electronic carb, do you mean a carb with an electronically controlled throttle?

[speedbeek]

The Alpha-N engine control strategy (for EFI) is often refered to as an electronic carburetor. It basically works like a carburetor where throttle position alone determines how much fuel to deliver. Not to be confused with e-carb which is where you take a carbureted engine with CDI box, keep the CDI box and do a port fuel injection- so stand alone/separate fuel and ignition systems. Maybe that is where you want to start so you do not have to handle ignition, just depends on your goals and experience. Electronic throttle would be independant of engine control strategy, but has a significant impact to the system, good and bad. Mostly good since your software strategy can take control of its own destiny and prevent crazy load transients. Obviously you then need more CPU power to handle the communications and thinking.