"How to Tune your Cooling"
How important is the amount of water cooling delivered to the engine?
Over the years, I have heard many people talk about whether to restrict the amount of water through the engine for cooling. I have seen HUGE HP gains on the dyno by regulating the amount of water delivered to the engine.
I have developed a system that I use for ALL my boats and it seems to work well for me. I use the premise that there MUST be enough water run through the engine to perform 2 functions.
1. Enough water must run across the head to prevent the engine from getting HOTTER AND HOTTER AND HOTTER! If there is not enough water to prevent a continually increasing amount of heat, the engine will quickly "melt down". There must be at least an amount of water run through the engine to equal the increasing amount of heat generated by the work the engine is doing.
2. Here's how I tune the cooling! I run the boat around the course EXACTLY as I would run it in its most demanding race (Tight on the buoys at full throttle). I first set the mixture control so it is perfect on the straightaway. Now, if the engine picks up speed in the turns, this indicates that it is getting hotter and becoming lean in in the turns. I have TOO MUCH cooling. When the boat straightens out for the straightaway and the load decreases, the engine cools off and it goes rich. I will have to keep the needle rich enough not to "sag" the engine in the turns and it will be to rich in the straightaway. If I restrict the cooling, AND richen the needle a little, it will run through the turns hard, AND will run at the SAME lean/rich setting on the SAW. I keep changing the water flow until I get consistent running on the course. It is MOST IMPORTANT to keep the needle rich enough to run through the turns hard and come out of the turns hard.
With the MANY type boats being raced (Hydros, Monos, World Endurance Racers, Gas, etc.) the logical question is: Does this fit all the boats? Definitely! However: there will be differences in the amount of water required to satisfy #1. The testing procedure to "tweak" the water is the same for all. You may have to regulate the water to the engine and have full water to the pipe coupler, etc. The engine is the component that requires regulation.
What is the easiest way to restrict your water?
A needle valve works very well during the tuning phase, and use a flow meter to see where you are. You can then place a fixed orifice in the water line or you can place an adjustable metering collar around the line. I make a collar out of nylon with a nylon screw that goes around the water line(kind of like a Du-Bro Collar that we use for other applications). This collar pinches the water line when you screw in the nylon screw. It makes an infinitely adjustable device, that will allow quick and easy adjustment, like a needle assembly.
Until Next Month..........