NetHeads, After years of threatening to do it, I finally got around to installing water injection on my plane, and test flew it today.
I ran water injection on my 2110cc Karmann Ghia back in the late 70's when I lived in the desert, to tame the detonation caused by the 9.9:1 compression ratio (lots of long stories in that sentence). It was only activated above certain throttle settings using an adjustable vacuum switch, squirting water down the throats of twin Weber 40IDF carbs, and worked quite well. What I didn't realize is that water injection also "steam cleans" piston tops and combustion chambers, because when I pulled the heads to lower the compression, the chambers and piston tops looked like new! I don't have detonation problems with the latest incarnation of my 2180cc airplane engine, especially since I dropped the compression ratio to 8.1:1 so I could run 93 octane auto fuel on the hottest summer days, but I do like the idea of keeping the chambers and pistons squeaky clean and deposit free. So I found a "windshield washer kit" on ebay for $12 that uses a pliable plastic bag for the reservoir, allowing me to easily fasten it to my engine mount in an area that is otherwise quite tight on space. I can report today that running the injection at near wide open throttle is barely perceptible, indicated only by a 20-30 rpm drop in RPM, and it makes the engine run slightly leaner, according to the mixture meter. I installed the push-button switch that came with the kit, but only used a pint or so of water in two minutes of operation, so I'll probably install a toggle switch so I can run it for 10 minutes to empty the bag and do some serious cleaning. I welded primer port fittings into the intake manifold for each cylinder (total of four), with a standard .020" diameter primer nozzle installed in each cylinder's inlet manifold runner for the primer system. Since the engine starts without priming in the summer, I simply disconnected the fuel line and slipped the plastic tubing into the tee that goes to each side. Works like a charm. I was concerned about the primer nozzles sucking water out of the bag at high vacuum (idle), so I also bought a $10 "pneumatic" 12V solenoid (a Keurig coffee maker replacement part) from ebay so water only flows when I want it to. Although this likely falls under the heading of "stuff you don't need", I like the idea of having clean combustion chambers and piston tops, and a quick way to quell detonation should it ever happen with this low compression ratio. Obviously, this won't work in freezing temperatures, but it's not needed for detonation in the winter anyway. See enclosed photo for my rather shoddy (but temporary) installation, but it does work fine this way. As you can see, real estate is limited, so a normal hard plastic reservoir wouldn't fit. All electrical connections are insulated and there's a fuse and a breaker in the line also. See http://www.n56ml.com/ghia2.jpg for a picture of the Ghia (still got it), and see the water injection "installation" photo below this message as an attachment. -- Mark Langford ML at N56ML.com http://www.n56ml.com -------------- next part -------------- A non-text attachment was scrubbed... Name: injection-setup.JPG Type: image/jpeg Size: 84421 bytes Desc: not available URL: <http://list.krnet.org/mailman/private/krnet_list.krnet.org/attachments/20160730/7b650e1d/attachment.JPG>
