[elhigh]

Hey saand, a few thoughts:

I've seen this tried a few times, esp. with VW engines cut down to two-cyl opposed units, that was especially to fight the unbalance problem. It didn't double the mileage. Mileage did increase, but only because the incredibly underpowered engine was pushing a custom super lightweight car.

If you're going to run on just two cylinders, run on the middle two. I think that will reduce shaft whip along the crank vs. trying to fire the outside two. It separates the firing to every 360 degrees for a nice even beat. And the two adjacent hot cylinders help keep each other warm for better combustion.

I don't think there are many advantages to be found in removing the pistons in the disconnected cylinders. Obviously there are frictional losses, but leaving them in place means you can have your full engine output at a moment's notice - perhaps literally if you simply interrupt the injector controls with a dash mounted switch. Don't bother with cutting down the cam lobes either, for the same reason.

Weight reduction is key. Drag reduction is key. The more load you can take off the engine, the closer you can get to an optimum level of power output with your minimized engine.

But what everybody else is saying is also true. Your engine was built to work properly as a four banger. All the parts are intended to work together; taking a few parts out of the loop like this throws everything off. You may see some improvement after all's said and done. But once you've got the vehicle weight down to the minimum, and changed your driving habits to the thriftiest you can make them, hook the two cylinders back up. See if the mileage changes.