[noir_lord]

I used diesel as historically cc for cc they have lagged behind petrol engines (though that has largely ended).

The turbo is irrelevant though, the IC has a turbo, they work and are reliable the rotating engine doesn't but that doesn't rule out a basis for comparison.

It comes down to fuel efficiency, emissions, maintenance and cost and I can't see this engine winning (for cars).

[iaw]

The turbo is not irrelevant because it has a direct impact on the ratio of power delivery / fuel consumption due to the recaptured energy from exhaust gasses. The volumetric efficiency (ratio of cylinder pressure pre-compression to atmospheric pressure) of engines with turbo-chargers is almost always >1 while the volumetric efficiency of naturally aspirated engines is always (excluding rare high-performance vehicles in specific ranges of operation) <1.

I don't have time to do more thorough research right now, but the Ford Duratec 30 series of engines [1] is roughly comparable in both displacement and cylinder count and produces between 200 and 240 HP depending on configuration which puts this engine slightly ahead of normal engines from a performance perspective (smaller form factor and lighter).

Is there any apples to apples comparison that you can find that actually makes this development look substantially inferior? I get that you used a diesel because historically that gave the ICE an advantage but with modern diesel technology and forced induction they aren't the same animal.

[1] http://en.wikipedia.org/wiki/Ford_Duratec_V6_engine#3.0_L

Edit: changed 'pre-combustion' to 'pre-compression' for clarity on volumetric efficiency definition.

[noir_lord]

In this context it is irrelevant since my comparison was purely one of power output against displacement.

The Turbo allows a given displacement to output more power for a given displacement, indeed volvo have 2 litre putting out 450hp (uses staged turbo's one of which is electrically driven), I wasnt comparing the nearest ICE equivalent to the rotary.