[GMAs]

Well... their are benifits to cooling by liquid.. notice I didn't say water... and they are a thighter more compact engine but, you stil need some air around it.. for the exhaust cooling and the crankcase... Oil and cyc and head temps could be controled by thermostats and the temp of the engine would be a lot lower than what it is now... so the variations in expansion of the metals would be more controlled.. and thus prone to less cracking... clearances would be tighter and engines should last a heck of a lot longer... and the heating of the interior would be simplified to the point of a controlled enviroment throughout the range of power. No baffels and sealing of the engine is required. And if the compression ratio was held to what it is now... a cleaner burning cheeper fuel could be used as preignition and detonation would be less likely to occur... also the engines could be shoved up in hp to take advantage of more even cooling and thus less cyc cracking and problems. More streamlined aircraft... and I am sure that getting rid of the top air intake would give us some speed increase....

Then their are the downsides....

Metal corrosion being exposed to liquids for cooling... leaking coolant... expansion of coolant and the additions of a water pump and plumbing. a engine that weights more...more expensive to convert and make changes in existing airframes.

Lets see did I leave anything out... G.M> GMAs