A little history on water injection, a little long but a good read if you're a WWII aircraft fan like me.
War emergency power
From Wikipedia, the free encyclopedia
War Emergency Power (WEP) is an American term for the throttle setting on some World War II military aircraft engines. For use in emergency situations, it produced more than 100% of the engine's normal rated power for a limited amount of time, often about five minutes. [1][2] Similar systems used by non-US forces are now often referred to as WEP as well, although they may not have been at the time.
1 WEP in WWII aircraft 2 Modern times 3 WEP in surface vehicles 4 Boost systems 5 References
WEP in WWII aircraft
Maximum normal power would be limited by a mechanical stop, for instance a wire across the throttle lever slot, but a more forceful push would break the wire allowing extra power. In normal service, the P-51H Mustang was rated at 1,380 hp, but WEP would deliver up to 2,218 hp. [3] In the P-51D Mustang, the model most produced and used during WWII, the WEP increased the HP from 1490 to 1720. The Vought F4U Corsair, not originally equipped for WEP, later boasted a power increase of up to 410 hp (17%) when WEP was engaged. [2] Several methods were used to boost engine power by manufacturers, including water injection and methanol-water injection. Some earlier engines simply allowed the throttle to open wider than normal, allowing more air to flow through the intake. All WEP methods result in greater-than-usual stresses on the engine, and correspond to a reduced engine lifetime. For some airplanes, such as the P-51D, use of WEP required that the engine be inspected for damage before returning to the air. [4] 5 hours use of WEP on the P51D required a complete tear down inspection. [5]
British and Commonwealth aircraft could increase power by increasing the supercharger boost pressure.. [6] This modification was common by the Summer of 1940, with the widespread availability of 100 octane fuel. Raising supercharger boost pressure from 6lb to 12lb increased the Merlin III engine rating to 1310hp, an increase of over 250hp. Pilots had to log the use of emergency boost and were advised not to use it for more than 5 minutes continuously. The German MW50 system methanol-water injection system required additional piping, as well as a storage tank, increasing the aircraft's overall weight. [7] Like other boost techniques, MW50 was restricted by capacity and engine temperatures and could only be used for a limited time. The GM 1 nitrous oxide injection system, also used by the Luftwaffe, provided extreme power benefits of 25 to 30 percent but required cooling on the ground and added significant weight. [7] One of the few German aircraft that could be equipped with both systems, the late war Focke-Wulf Ta 152H high-altitude fighter, could attain a velocity of some 756 km/h (470 mph) with both systems used together, reportedly as Kurt Tank once did in using both boost systems simultaneously when he was flying a Junkers Jumo 213E-powered Ta 152H prototype fitted with both MW 50 and GM-1, to escape a flight of P-51D Mustangs in April 1945.
I haven't done it to either of my Marks, but it's not a horrible idea.
After that, just a little trickle of water down the carb to bust up the carbon is all I ever did.