What is important, (and most people realize this by now) is that to fly a plane (or drive c ar, or roll a boulder up a hill) at a certain speed, it requires a certain amount of POWER (energy/time) to be available. It is not important how the power is made. If you decide to use a propeller, it is important to keep the rpm of the propeller resonably low, so in order to go said speed, you'll have to be making the required POWER at a certain propeller RPM. Ignoring losses in any gearboxes, it's irrelevant what speed the engine turns, as long as you can supply the PROP the right amount of power at an rpm you can use.
If a particular auto conversion works or doesn't work better than lycoming, a continental or a merlin it is just because there's is one or more aspect of that design that makes it unsuitable. I'm of the opinion that there are relatively few auto engines in the 200hp range that are significantly light, cheap and simple enough to make sense in an airplane. Move up in the power range and a 400 hp LS with a good PSRU and a well sorted cooling system might behave really similarly to a 400 hp lyc, but it will probably cost (ignoring development costs) WAY less.
To maintain a given speed, we all know that thurst has to equal drag. Put another way, the power used by the airplane going through the air (drag force X speed) must equal the rate of work done by the prop on the air.
People on car forums always have the same argument: torque versus power. It is AVAILABLE power that determines how fast you go or how fast you accelerate. An engine capable of 1000hp is no good if you're running it in a condition where it won't make that much power. For the power to be AVAILABLE you have to be able to operate the engine at a condition (fuel flow, timing, rpm, etc) that allows it to make the amount of power you need to accomplish your goal (a particular speed, acceleration, a climb rate, etc).
If a particular auto conversion works or doesn't work better than lycoming, a continental or a merlin it is just because there's is one or more aspect of that design that makes it unsuitable. I'm of the opinion that there are relatively few auto engines in the 200hp range that are significantly light, cheap and simple enough to make sense in an airplane. Move up in the power range and a 400 hp LS with a good PSRU and a well sorted cooling system might behave really similarly to a 400 hp lyc, but it will probably cost (ignoring development costs) WAY less.
To maintain a given speed, we all know that thurst has to equal drag. Put another way, the power used by the airplane going through the air (drag force X speed) must equal the rate of work done by the prop on the air.
People on car forums always have the same argument: torque versus power. It is AVAILABLE power that determines how fast you go or how fast you accelerate. An engine capable of 1000hp is no good if you're running it in a condition where it won't make that much power. For the power to be AVAILABLE you have to be able to operate the engine at a condition (fuel flow, timing, rpm, etc) that allows it to make the amount of power you need to accomplish your goal (a particular speed, acceleration, a climb rate, etc).
