Difference between Merc EFI & Optimax?

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What are differences between Mercury EFI's & Optimax's?

 

[WillyBWright]

Re: Difference between Merc EFI & Optimax?

The EFIs are very old technology electronically fuel injected conventional 2-strokes, roughly similar to throttle-body EFI in a car. They are no more efficient than carbureted 2-strokes. (Okay, maybe a little better)

The DFI models are fuel-efficient and closer to a sequential multiport fuel injected car.

EFIs have integral alternators, Opti has a belt driven alternator plus a belt driven air compressor.

EFIs mix oil with the fuel. Optis inject the oil directly into the inner workings. Optis use less oil than EFIs. They also require a more expensive and fairly specific oil.

At full throttle, fuel consumption is about the same. It's at low RPMs where Opti excels. Conventional 2-strokes pass about 30% of the fuel straight out of the cylinder without burning at low RPMs. Optis, virtually no waste.

 

[Chris1956]

Re: Difference between Merc EFI & Optimax?

Actually, the Optimax Direct Injection motors differ significantly from "Sequentially Injected Automotive" engines. Direct injection means that the gasoline is injected into the combustion chamber, using high pressure air on the Optimax, and high pressure fuel pump on the E-TEC motors. Sequentially injected automotive engines inject the fuel into the intake manifold, usually next to the intake valve(s). The "sequential" part is that the fuel is injected into the intake manifold, just before the valve opens to draw it in. Non-sequential fuel injection on cars meant that all cylinders received their injections at the same time, reguardless of where the cylinder was in its cycle.