2 Stroke 25 Nissan/Tohatsu Cooling System Improvements
 

Guys I'm running a 17X38 Carl Stryon tunnel with 8" Jackplate and I'm trying to improve the cooling system. (Low water pickup not currently option)

I have the lower unit pulled and I was thinking about blocking one or two of the smaller higher ports to allow full suction to the lowest port (the screens).

Looks like I'm pulling air from the higher ports, (the small port on very front of lower unit, and the port directly above the prop)

Any of y'all ever tinker with the cooling system, or have any suggestions?

Plug the bottom one's, hook your pee hose to the top, it takes a few seconds but you know your getting water through all 3 that way , depending on the year that my not be an option??

Andy thx for tip, but I'm not sure I'm following you. I will take a look at motor and try to see what your talking about.

Did you do this to a Nissan/Tohatsu?

No need to block anything. Build a small whale tail out of aluminum to channel the water to your intakes, it will also help greatly with hole shot. I'm not talking about those hideous white monstrosities they sell. Build it something like this, BUT, extend it further forward to catch more water. We built them to extend in front of the gear case. It does not slow boat speed and yet improves hole shot and helps channel cooling water to the intakes. We also bend about 1/2" of the sides 90 degrees down to hold water. The old 2 stroke tohatsus had terrible cooling systems. I'm glad they improved them on the 4 strokes, mine pumps over 20 pounds of pressure.
http://i126.photobucket.com/albums/p...psejy1pbcb.jpg

Thanks For Input
 

CC thanks for your input; been thinking about a whale tale, time to build one.

What changes were made to improve new water pump, and cooling system?

I'm assuming the new LU configuration improved suction to the water pump.

Tohatsu completely redesigned the entire cooling system. It's more like Mercury's cooling system than the old tohatsu's. My 4 stroke will pump right at 23 pounds at 6100 rpm, 4-5 pounds at idle. My old race motors, stock 50hp tohatsu's, would pump 9 pounds at 7400 rpm, about 1/4 pound at idle. I have had this 4 stroke water system completely plugged twice in the year of marsh fishing, not bad.