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There was a Flying Wing on show at the Gravenhurst Boat Races. It reminder me of the late 60's and early seventies when Mercury Raced the 1250 and 1350 Stacker models. They took an idea used in the Spitfire planes in WW2 and added water injection into the exhaust pipes. At first they were only letting the factory racers run it. Racers who never attended a race where the factory boys raced never knew of the mod and never added it to their motors. They missed out. IT WORKED! Racers hit a button to inject the water coming out of the turns. It gained the boat extra noticeable punch.
Here is an example of a 1250BP stacker with the water injection:
https://s-media-cache-ak0.pinimg.com/73 ... be4956.jpg

HAVE THE DRAG RACERS TRIED THIS IDEA??

Hi Don,

Sorry I did not read your post sooner or I would have responded sooner. When you use straight megaphone pipes, the engine is tuned to a specific rpm range. In the case of the Merc in the pic, that range is roughly 6000- 8500 rpm. I know, I designed and installed a system on my 1250 BP Stacker in 1970. As you know, there are two ways to change the tuned rpm. First, change tuner length; longer for punch, shorter for top end rpm's. Secondly, change the medium the sound waves travel through The water injection when activated causes the pressure or sound wavefront to travel thru steam rather than dry hot air. Hence, the change in tune. The activation rpm was at roughly 3800-5800rpm, at which point a foot switch activated a solenoid, taking engine manifold water and injecting it to the pipe elbows. At 6000 rpm you would release foot switch to go back to high rpm tune at 6000-8500 rpm. It worked awesome. It was tricky activating the footswitch, trimming the motor, and operating the foot throttle, all at specific rpm's. My next step was to have a circuit designed to use in conjunction with my tach, to automatically activate the footswitch circuit. I blew the boat over at 100mph in Michigan, and promised my wife I would not race anymore. So much for that project! Remind me next time I see you, to show you pics of the boat on my hone.

I forgot to mention that with todays internally tuned engines, the concept would not be any where near as effective, if at all. Hope that answers your question.

It's cool, on a merc 2.5 it doesn't work. Tried it dyno’d it and scraped it

Works on a Yamaha GPR1200...picks up a couple hundred rpm

Fun Facts...

I have pics of a DBR OMC from circa 2007-2009 Jasper with what looks like a water injection system on it. What's the best way to post pics these days with Photobucket being NFG ?

Cool idea, but I suspect your time is better spent really dialing in your fuel and ignition curves as opposed to sending water into the exhaust (Rob correct me if I'm wrong).

Matt

Tinypic still works..

G2

Yes he does, but you really need a pipe for it to work......... Specifically the 2.5 Merc has an exhaust problem and slowing down or producing more back pressure doesn't apply well to it.