[Fr. Frank]

Don't count out 2-strokes yet.

Mercury has been working with a higher compression version of their 3.0L air-injected (read: supercharged) 2-stroke multi-fuel motor (based upon the Optimax) which, when burning a JP8/Syntroleum blend, has significantly lower emissions than any current 4-stroke V6 outboard, and is comparable in emissions burning any of the kerosene-based fuels, except No.2 diesel, where it lags only slightly when burning summer blends of diesel.

I understand their initial target market is the military and LEO, but still, it sounds promising.

While the test motors are burning seven different fuels: Jet A1, JP5, JP8, JP8/Syntroleum blend, No.2 Diesel, 93 octane gasoline, and paraffin oil (kerosene-alkane oil), I am told the eventual fuel selection will be limited to 3 grades, which will absolutely include JP5, but probably NOT include gasoline, (even though it will still run fine on a 50-50 blend of gas and No.2 diesel, or gas and kerosene).

The engineer I know who works for Mercury says the difficulty isn't getting the motor to run on any of these fuels, it's programming the computer fuel management system to get similar power outputs from the same injectors regardless of the fuel being used. For instance, they've only been able to get 160-165 hp out of the No.2 diesel and about 180 out of the paraffin, but the JP8/Syntroleum and gasoline configurations have given them 220-230 hp before running into either emission or detonation issues.

Evinrude also has a multi-fuel V6 in testing, but I have no information on that.

Oh yeah, Mercury has a 2.6L Verado tuned to 400 hp that has passed the 2500 hour mark :-) That's the equivalent of 150,000 miles for a car.