So now lets look at why the way the factory set them up works and is acceptable...
The throttling valve off the pump (normally a 3/4" gate valve on the 3/8" auxiliary water port found on the Berkeley style pump) acts like a FLOW regulator, do not confuse this with pressure, different animal all together.
Because flow is limited, so will the pressure if the system is open on the other end, this is where the debate always gets out of hand. This is the first order of business takes place, this adjustment is crucial for the system to work properly.
Here is the confusing part.... I broke it up into three parts.
1. With OT headers.... The dump line needs to be properly sized, there is a formula I posted in another thread to remain nameless.. here is that formula;
Use 12.8 BTU's per min, per HP (12.8BTU's/min/HP) for gasoline engines.
So, 500 HP X 12.8 btu's X 60 minutes = 384000 BTUH.
Here is a cool little formula.. BTUH= Delta T (F) X GPM X 500 (whereas the 500 is the specific heat of water [1] times the weight of water [8.33#/gal.] times 60 [minutes in an hour]).
So that 500 HP motor needs to cool 348000 BTU's worth of heat (for the most part 1/3 of the heat generated by the fuel).
So lets say you want the motor to run at 130*F.
The lake you mostly run in is approx 60*F.... So now what? well, 348000 = 70*F delta t X GPM X 500... Anyone?
You need approximately 11 GPM of lake water to keep her cool at 500 HP, much less at idle, or 10 HP...
To flow 11 GPM you will need approximately a 3/8" inside diameter dump line at 18 PSI. You can check that here
http://www.tlv.com/global/TI/calculator/water-flow-rate-through-orifice.htmlWhy 18 PSI? the added pressure will keep steam pockets from forming and give the engine the proper range of pressure to get the needed flows between idle and WFO... This can be varied, but 18PSI seems to be the magic number.
So here is the ideal set up.
Balancing valve of your choice (3/4" multi turn gate, 1/2" ball valve, 1/2" globe valve etc.) to a tee to the two ports on the front of the block or to the block drain holes (BBC) after they have been drilled and re tapped to 3/8" FPT, from the t-stat housing (sans stat) to two lines, one line overboard to your properly
side sized through hull fitting, the other line to the header control valve (whether it is manual or a Bassett tee or similar). Done... Yes, that's it.
I do not like to run header water straight from the pump, I like warm water to go to the headers, I feel you have less of a chance of jacking crap up with 120*F+/- water than you do with 50*F+/-.. I may just be goofey that way though. ALL that water needs to convert to steam before it leaves the pipe, with the warm water, it is already more than half way there.
You get the boat in the water with the gate valve open three or four turns, once fired off, rev the engine to appox 1500 RPM (gotta have a good tach for this) this is easier with two people, the boat does not need to be moving, I normally install a Come-A-Long on the front eye of the boat to the trailer for this part. Once the engine is running at 1500, adjust the control valve toward open until the headers begin to mist, then stop, lock down the packing nut (where applicable) and shut down the motor, the procedure is complete.
Typically the boat will run about 150*F to 170*F while idling, then drop to about 120* to 140* while "on it".
Too warm? Larger orifice in the dump line, too cold? (Only worry about this at idle) then drop the dump line size a tad... Just be sure to repeat the procedure for the header cut in point.
Run a tie wrap through the valve to ensure it stays put (either by natural vibration or a long fingered douche bag) and go have fun...
The best part about this system is that there are literally NO moving parts.... What's going to break? What is there to maintain?
The second best part is that your can replace the entire system for about $130 including the control tee....
2. Dry headers.
The same process and piping, but you will need a pressure gauge to get it set up right and that will be done at WFO, not 1500RPM., absolutely no reason you cant put a Bassett tee on the motor, even temporarily to get her dialed in, just don't leave it there open, it will move too much water and be stupid cold. You can fine tune the gat to get the desired temps.... Pressure should not become an issue if the above is followed.
Too tired to do logs right now... maybe later..
Have fun.
Disclaimer; This information was off the top of my head and I just worked a 10 hour day, so there may be some revisions, but I will make those revisions in bold and strike through the boo boos..
GT
