Motor Cooling Jacket Water Flow

[Mike W]

I just received my new motor and jacket and was surprised to see no central flow divider to ensure complete circulation. The entire volume inside is open and water can simply flow in the inlet, across the top, and out the outlet. The majority of the volume of water within the jacket will remain stagnant and accumulate heat. Are they all like this?

Has anyone added a central divider of some sort with a small flow bypass on the bottom and opposite the nipples? My first thought is a slice of PVC tubing with an ID slightly greater than the motor OD after you cut a small section out sufficient to allow it to be compressed and epoxied into the jacket. That cut would then create the flow bypass opposite the nipples.

[TRUCKPULL]

Mike

The water outlet should be placed at the top (or highest spot on the motor when installed)
This will insure that the jacket is full when running.

Larry

[grsboats]

Larry is correct no need to worry about!
Gill

[martin]

Yes keep the outlet @ the 12 o-clock position, also @ the end of the motor where the wires exit the motor. This places the outlet @ the highest point further.

[Mike W]

Consensus is it doesn't matter, but it still bothered me enough to try to correct. I found a perfect bottle to use for a divider. The small upper port allows some flow for air and the large bottom port should direct most of the flow down. This would have to improve cooling.

Cooling Jacket.jpg

[fweasel]

For all the time I spent in chem labs, I've never seen a water jacket with any type of internal workings. It was always fill and the bottom, exit at the top, flow against gravity.

[Shooter]

It might not be practical for our application (i.e. It works good enough as-is), but I do believe your concerns are valid. We used to cool motors (much larger than these) on test rigs and found that an open volume was not that efficient. Spiral grooves forcing the water around the jacket seem to work best. They limit the stagnant water and 'hot spots'. You are absolutely right, the water will follow the path of least resistance, so if your outlet is right next to the inlet, then you are not getting nearly the cooling you could be.

IMO, the best would be a slip fit diameter jacket with tightly wound spiral grooves on the ID. Water still in direct contact with the can, but forced to travel around.

[Shooter]

Here you go!!

https://m.youtube.com/watch?v=tpp1BfCT3as

[martin]

I have some of the Hobbyking purple water jackets that are a close fit on its id to the motor can with a spiral groove running the length of the jacket. On a 50mm long jacket the pitch of the grooves 9 spiral grooves over the 50mm length jacket. I have no idea if they cool any better than the normal type jackets.

[rol243]

There are several different brand names of Glow r/c marine engines that do have special milling work done to the inner sections of there cylinder head cooling heads, not just in and out like we use with our cooling cans.

[grsboats]

Martin I saw no significant difference in cooling my motors too.
Gill