Hi,
The UK-based 8th Air Force P47s that were using water injection were having major problems, so P&W sent over Bill Closs.
Just before Bill Closs departed, Frank Walker (who reported to Bill) discovered that isopropyl alcohol was unsatisfactory. Bill discovered, when in the UK, that the P47s were using isopropyl.
The mixure was changed to ethanol and methanol, mixed with 50% water, and the problems vanished.
P&W called water injection ADI, for Anti-Detonation Injection. All military R2800 engines that had ADI were given a "W" suffix (ie R2800-8W), but the civilian engines never had this suffix, even if they were fitted with ADI (ie R2800-CB16). Furthermore, engines that were not ADI were often retro-fitted with ADI in the field.
ADI was initially tried on a Wright R-1430 engine by T. E. Tillinghouse (before he left Wright to go to P&W) in 1934. It raised the power from 500 to 768hp.
The ADI flow rate varied to how much power was being developed.
2400HP - ADI flow rate of 9.2lbs per minute
2500HP - ADI flow rate of 11.5lbs per minute
1900HP (in high blower) - ADI flow rate of 7.8lbs per minute.
The above information came from "R-2800 Pratt Whitney's Dependable Masterpiece" by Graham White. It is a wonderful book.
river