It's been tried before, but to work, the intake valve has to remain closed to prevent the compression load. In addition, the injector lives in the intake manifold passage and not in the cylinder. If you shut off an injector the cylinder will still be getting a small amount of fuel from the other cylinders and will tend to fire in a too lean condition. If fuel economy is the order of the day, then diesel is the answer for a heavy car. A volvo diesel wagon will get 28-30 mpg if you can stand the lack of acceleration and hill climbing ability. I also had a friend that tried removing 2 pistons from a Chevy v8, using a cut-off connecting rod bottom end as a spacer and oil stopper. The engine ran but all but left the car due to vibration. Major disaster with good intentions. Probably the best of all worlds would be to use a 4 cylinder industrial diesel engine with a lot of boost from a turbo. Moody did this back in the 70's and got 45+ mpg, but was shut down by the engine manufacturer (Perkins 4-108) because they didn't want to dance with our illustrious EPA. Hopefully gas prices will stay high and spurn development of modern diesels again. Plain physics-higher compression yields higher efficiency...enough ranting.

Reminds me of those horribly designed Caddilac machines from the 80's that would run on 4, 6, or 8 cylinders depending on the load. What a hunk of crap! If you love your "classic Volvo" as you call them, and you want it to last forever as an example of good sense, taste, and refinement (ha!) then don't succumb to the fashions and trends of the day. This gasoline nonsense, although quite a shock right now, will soon pass over much like it had in the 60's 70's 80's and early 90's. A change of the socio-political landscape should cure it. Your "classic Volvo" won't be much of a classic if you convert the drivetrain in an reactionary attempt to keep up with the times. It would make as much sense as affixing 22" chrome wheels with spinners (Dubs) on an Amazon.

The engines that do this are designed for the feature and have valve trains that adapt to eliminate compression on the cylinders that drop out. just cutting the fuel would still leave you dragging 2 holes against the compression. Pull 2 plug wires and see how the car runs. I'ts a good idea, but sadly it won't work on our primitive red blocks.
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Dave Shannon
Spring Valley, California
'67 1800s
'73 1800ES
'88-240
my pages