Water injection questions from the Quincy Forum

[iwanajohnson]

alright guys, relatively new to high performance outboards. I was wondering if anyone woudl take the time to help out someone like me. I don't think It will be a problem because everyone on this site is extremely nice and helpful nomater what your boating experience that's Why I love this site so much. I was wondering if anyone could explane to me this water injection and how it worked. I've personally never heard of it but had kind of been thinking about something similar. I was thinking If I could test the weight vs. gain ratio, somehow get a tank of iced down or cold water and put in the boat, that way it would be able to be circulated around the engine to keep it cooler. was wondering if this would impact me in any way as far as positive or negative. I'm primarily goning to be drag racing so It's all about 1280ft. could someone tell me about this water injection and tell me if my idea's off or anygood. Also I deal with only 2 & 3 hold OMC motors, maily the 56ci tripple. was wondering if anyone had ever thought of filling in the spark holes on a tripple, having it drilled and threaded for 2 plugs, and running 6 spark plugs on a tripple with 6 coils, a mod 50 front and wicked port and exhaust work done. am I crazy or a genius. someone help me out.

[Mark75H]

Water injection is pretty simple. In a tuned pipe the length of the pipe AND the speed of the sound waves are critically designed and built for a specific motor RPM. The pipe only increases power in a narrow rpm range ... maybe 1 thousand rpm on either side of the optimum. So if the pipe is built to give best increase power at 7,000, it works somewhat at 6,000 and 8,000, but is usless at 5,000 and 10,000 rpms. 10,000 rpm probably doesn't matter that much, but going thru the turns, the motor rpm probably does go to 5,000 or lower. Two things can be done to make the pipe work at lower rpm, the pipe can be longer .... or you can cool the exhaust down and slow down the sound wave to make the pipe work at a lower rpm.

Variable length expansion chambers are very popular on racing outboards, water injection is less popular, but has been used. Variable length is harder to set up on megaphone tuned exhaust, so water injection is usually tried instead on megaphones.

[Tim Chance]

For iwannajohnson, here are some facts and opinions from my experience racing. 1. A redundant system with two ignitions. I think if that was a good idea that when I picked my new B Flathead up at 5th and State in Quincy, Illinois O.F.Christner would have had 4 spark plugs screwed into the cylinder head not two. 2. Running ice-cold water through the motor doesn't seem right to me. I think the motor runs best at high temperature when all the parts heat up and fit the best. Just cool it so it doesn't get so hot it sticks. 3. Water injection: Sam told you why and how it works. My experience is that I ran Ross Gibson's B Runabout (Desilva/Looper) with water injection a lot. He had a water tank, a battery, a pump and a door bell button by the throttle that you would push with your pinkey finger to activate it. Only problem was that Ross had bigger hands than me and I really had to stretch to reach it. It helped punch out of the corner but if I stayed on too long the motor would flatten out and lose power. This was with megaphones. I also tried it on my Konig with expansion chambers, but it didn't help that much and was a lot easier to just slide the pipes. Hope this adds a little bit.

[Neil_M50D2]

The water injection into pipes is to cool the exhaust gasses thereby making the pipe look longer to the engine. (the speed of sound is slower in cooler air than hot air) Extending the pipe or injecting water out of the turn brings the pipe more into tune as a longer length is required at lower RPM.

We primarily used water injection coming off the beach just when the prop grabs a full load and the RPM goes from 13000 RPM to maybe 8000 RPM. Water-cooling the gases keeps the engine from loading with fuel at that low RPM. Once up and running we slide the pipe as needed out of the turns. The only other time water injection was nice is slow down without loading the engine. First slide the pipe back, still going too fast, injecting water will slow it a little more. Whereas, backing off the throttle tended to load the engine with fuel and suddenly poof, it shuts down. Pro racing, two speeds on and off.

Neil Bass

[Tim Chance]

. Pro racing, two speeds on and off.

Neil Bass[/QUOTE]

Neil, I agree. I would tell newcomers: "It's not a throttle it's a switch."

[franka]

Water injection is used in automotive racing. It's sprayed into the intake tract and it cools the intake charge so that the charge shrinks, becomes more dense, allowing more air and fuel to be injested each intake stroke. It works continuously and at all operating rpms very well.

It's also used in supercharged engines for the above reasons but also to prevent detonation.

Where in the Quincy was it injected? From the above posts it sounds like the exhaust stack. But I would not be surprised if it was in the intake tract and served the same function, to make the intake charge denser.

This is a great forum.

[Tim Chance]

Water injection is used in automotive racing. It's sprayed into the intake tract and it cools the intake charge so that the charge shrinks, becomes more dense, allowing more air and fuel to be injested each intake stroke. It works continuously and at all operating rpms very well.

It's also used in supercharged engines for the above reasons but also to prevent detonation.

Where in the Quincy was it injected? From the above posts it sounds like the exhaust stack. But I would not be surprised if it was in the intake tract and served the same function, to make the intake charge denser.

This is a great forum.

Go the the Quincy Looper Pictures thread and look at the 2nd and 3rd photos that are of Bill Ela'a A motor. Bill only drove Ruanbouts and I drove that motor on a Hydro many-many times. The one photo from the rear shows fittings and hoses just in front of the springs on the exhaust elbows. That is the water injection. As a note I don't think Bill ever had the late model wide sweeping pipes on his A. About 1972 - 73, I sold Bill my B Quincy and my 13' Krier Runabout. I think those pipes must have come from my B. Incidentally Bill blew my old runabout over backwards at the Nationals in Hinton, WV, broke his arm and retired from the sport. I stood on shore and watched it blow over. Bill had never repainted and the boat still carried my number (Y-200) and it was a weird feeling. Another story about Bill and numbers in the late '60's Bill had put his numbers on with tape. Finally Charlotte Queen told him if he didn't paint his numbers she would disqualify him. Next race comes along and I say to Bill "You're gonna get disqualified, Charlotte said you had to paint your numbers."
Bill shook his head and grinned, and said "I painted the tape!."

[franka]

Yes I see them. Thanks for the heads up on that.

Certainly someone, somewhere along the line must have tried water injection on the intake side. Has anyone seen or heard of that on an outboard? Seems almost anything anyone can think of has been tried at one time or another.

Thanks again.

[Tim Chance]

Yes I see them. Thanks for the heads up on that.

Certainly someone, somewhere along the line must have tried water injection on the intake side. Has anyone seen or heard of that on an outboard? Seems almost anything anyone can think of has been tried at one time or another.

Thanks again.

Yeah, I've tried that a time or two too. It's called the roostertail from the guy in front of you. Most times the motor quits. Seriously, I have never heard of anyone using water injection on the intake side of a racing outboard. That doesn't mean it's never been tried, just that I've never heard of it.

[Mark75H]

I doubt water injection into the intake tract would be a good idea on a 2 stroke ... water and bearings are not a good mix.

Alcohol fueled 2 strokes do get some of the same effect, esp since more alcohol is used than gas for correct mixture strength