Norm,One aircraft which used water injection was the Focke Wulf TA 152 which used both the MW50 (methanol (antifreeze)/water/oil (anti corrosion), and GM1 Nitrous oxide system. It was arguably the fastest aircraft in service in WWII, although it had no effect on the war. The MW50 system was used at lower altitudes for climbing and to break contact by many different aircraft. There is a famous story about Kurt Tanke outrunning 2 Mustangs using MW50 in an unarmed TA152. The GM1 was used at altitude for short periods. The effect in both cases was to increase charge density and BMEP by injection into the supercharger intake. Given that aircraft have adjustable mixture, multi speed superchargers, and constant speed propellers, monitored manifold pressure, EGT, etc, adding water to them would be simpler than on an engine which changed speed constantly. I suppose that with computerized injection it would be possible especially if the engine was made from ceramic. I did play around with one of the kits which dripped water into the intake back in the 70s, and do not remember any positive effect--regardless of what they said in Popular Mechanics. In any case the MW50 could only be used for 2-10 minute periods with at least a 5 minute period in between. If it was used there would also be an inspection needed as it shortened the life of the engine. Given that some of the motocross engines have a life expectancy in minutes that might not be a consideration. One of the major reasons that MW50 was used by the Germans was that they used only 87 octane (heptane) fuel. I would imagine that detonation was more of a problem for them than for the US where everything ran on 100 octane high lead (isooctane). The US had "war emergency power" settings that would use the higher supercharger settings that the isooctane allowed. The Mustang had a water injection system on some early planes(probably because the Germans used it.) The pilot would have to break safety wire to use the power--the engine life would be greatly shortened, and need an inspection before flight. Repeated use would shorten engine life to 5 hours. The Brittish's need to be able to "kick the tire, light the fire, and the last one up is a sissy," precluded a lot of the fanciness in the US and German aircraft. The Spitfire could be in flight in minutes vs a P38 which took a half hour. Interestingly, the Douglas MD80 series aircraft have a wired out quadrant on the throttles which allow overboost past normal takeoff thrust (bore scope inspection required). The Pratt and Whitney J57 used water injected from rakes in the intake to boost charge density and EPR to allow heavily loaded aircraft to make sufficient takeoff thrust. B52s and KC135s used this system and were very impressive to watch take off. I am sure there are Youtube videos out there.Except for something special like F1 racing I really do not think that water injection has much practical use. Considering that 700 HP is available from a production Chrysler car it seems like they have things covered.Now that I am all warmed up, I can re-write my accident report :-/.......Cheers,Doug
---In
DSN_KLR650@yahoogroups.com, wrote :
#ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 blockquote.ygrps-yiv-3170481ygrps-yiv-634383186cite {margin-left:5px;margin-right:0px;padding-left:10px;padding-right:0px;border-left:1px solid #cccccc;} #ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 blockquote.ygrps-yiv-3170481ygrps-yiv-634383186cite2 {margin-left:5px;margin-right:0px;padding-left:10px;padding-right:0px;border-left:1px solid #cccccc;margin-top:3px;padding-top:0px;} #ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 .ygrps-yiv-3170481ygrps-yiv-634383186plain pre, #ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 .ygrps-yiv-3170481ygrps-yiv-634383186plain tt {font-family:monospace;font-size:100%;font-weight:normal;font-style:normal;} #ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 a img {border:0px;}#ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 {font-family:Tahoma;font-size:12pt;} #ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 .ygrps-yiv-3170481ygrps-yiv-634383186plain pre, #ygrps-yiv-3170481 #ygrps-yiv-3170481ygrps-yiv-634383186 .ygrps-yiv-3170481ygrps-yiv-634383186plain tt {font-family:Tahoma;font-size:12pt;}I was reading on some of the water and alcohol injection systems used on aircraft during WW2 & got into thread on Thumpertalk in which an engineering student was discussing water injection as an application to a MX 2 stroke. As have most tuners, I've played with intake water injection a bit but have not done anything with injection of water into the exhaust. One problem in longer term use, ignoring the control problems, was erosion of intake parts so we quit playing. Tried one system on a gasoline powered combine with erosion issues starting to show. Or other effects "eating" the surfaces. Has anyone played with that? Part of the effect in injecting water into the exhaust would be the cooling effect which would lower back pressure. The calculations as to decrease in exhaust gas volume due to the heat absorption from the water phase change, versus the expansion due to the water's phase change expansion is too involved for my lazy brain. I'm not speculating as to whether it would be practical to install such a system onto a general use KLR but simply interested. Anyone?
