How to increase power and torque at higher RPM range on Sakae 21 14-cylinder radial engine?

Question by MuscleCarInTheLandOfHondas: How to increase power and torque at higher RPM range on Sakae 21 14-cylinder radial engine?
this is for a story i am working on, (an alternate universe i created).

A fighter pilot working on his Zero fighter is tinkling with his engine wants to increase engine power and torque at combat settings (ie 2000 RPM, max 2700, output at stock is 1,150HP). The trouble is, he can’t use “aftermarket” parts as this will cost a lot of time and his squadron is in a constant state of readiness.

the 14 cylinder engine has individual cylinder heads made of lightweight material and the exhaust pipes are individually connected to the ports and directed to the rear, protruding just a little from the rear of the engine cowling. there is no obvious flywheel, the crankshaft directly connected to the propeller.

it is fuel injected, the air intake occupying a large crescent-shaped hole in front of the cowling. camshaft isn’t a shaft but a disc (radial engines have disc-cams)

question 1
would altering the fuel mixture (more fuel) add power?

2
would cooling the fuel delivery system (increase fuel density) do the same?

3
adding extra alcohol to the fuel mixture ( different from methanol injection to prevent detonation at high RPM) “increase” power/torque output?

4
altering the exhaust pipes’ contours slightly to allow better expulsion of exhaust gas?

exceptions –
cannot remove material to lighten rotating assembly.
alloy prop unavailable….
port/polish too risky, material at cylinder head too thin to gouge out or shave
installation of extra equipment will hamper agility and the pilot doesn’t want that

Best answer:

Answer by Ben T
1. Getting the optimum Air:Fuel ratio will help (usually peak power is between found between 12.5:1 and 13.5:1)
2. Fuel injection is already under pressure cooling won’t do anything.
3. I’m not familiar with the engine, but increasing RON (research octane number) will increase power, but the motor should be tuned.
4. Absolutely, but looking like it will flow better is a long way from actually flowing better.

I’d be looking at regrinding the cam if you can (although I guess it’s probably already optimal), better ignition components and getting timing dead on, but really by the sound of it there won’t be allot he can do, just make sure it’s in good tune.

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