Picture of exaust water spill ?

[sunsation288]

Hello every one , i just made 3 run with my new SV27 , and i am very satisfied , and my only concern is ...how much water circulate in my boat ? ....as far i can see , only small amount of water spill at the exaust hole ......have you picture of what we need to have ? , just to help me ...thanks in advance ...and sorry for my bad english :huh: .....and if i am not clear ...feel free to ask
Regards
Christian

[ReddyWatts]

Does this photo help?

[sunsation288]

Thanks Reddy , your always ready to help :thumbup1: , mine is a brushless , i can see output on your nitro , nitro and brushless have the same water pickup ? , i am presently away from my home , (at work :bounce: ) and check for the pickup tonight
Thanks again
Christian

[ReddyWatts]

We are between the kids baseball and football seasons. Have some time to help.

[sunsation288]

I definitely not enought water coming out , the picture i found from Darin Jordan boat have more output than mine
Thanks i will dig in tomorow morning
Regards

[Doby]

Quite often, the rudder water pickups are not the greatest. Sometimes drilling out the hole helps. A lot of people disconnect them in favor of a pickup attached to the transom. Thats what I did with mine and it shoots out a good 1&1/2 feet from the side.

Of course that opens up another topic of discussion,,,is more water flow better or worse??? I say the more the better!

[HarryK]

Hey guys,
Regarding the flow rate debate. This site has the flow rate formula and explanation for it. I've drilled through the rudder and slotted the other side of the rudder with a dremel. Temps never out of the teens with pond water temp in the 70's. http://www.overclockers.com/articles599/ -- Harry

[blakybob]

If you have your rudder angled too far back (positive) or too far in (negative) it will have an effect on how much water the rudder intake picks up. Is your rudder sitting straight up and down?

Blake

[Electro]

Hello, i had the same problem with mines but the only thing was that the water was clogged from the factory and no water would come out and i installed a water pickup on the rear and wow what a difference,

[kck741]

flip the stock water jacket around on the motor you will see a diffeRANCE

[sewerpit]

hows this added larger water outlet and ose waterjacket
http://i476.photobucket.com/albums/rr127/sewerpit/th_s2-1.jpg (http://s476.photobucket.com/albums/rr127/sewerpit/?action=view&current=s2-1.jpg)

[Fluid]

It is a common misconception that the water has to spray out under high pressure and volume to cool the motor and ESC. This is simply not true - not my fault, it's physics. Water has a high specific heat (means it takes time to heat up = takes time to take heat away from the source) which makes it a so-so medium for removing heat - but we have no choice. Push the water too rapidly through the motor and ESC and cooling will be worse than if the water moves more slowly. This is even more the case if you are using old-skool "cooling coils" instead of a water jacket where water comes into direct contact with the motor housing. Bottom line - as long as you have a steady stream of water exiting the boat you'll be fine. It should not shoot out like a firehose.

Our motors and ESCs do not generate nearly as much heat as a nitro or gas motor does so they are easier to cool. Good BL motors are ~90% efficient, while gas motors are ~50% efficient. What is not used for turning the prop is turned into heat, so for equal outputs in horsepower the gas motor generates almost twice as much heat....


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[ReddyWatts]

You do not need high pressure in a boat cooling system, but the more flow the better.

The effect of velocity on heat transfer for water in a tube is shown in Figure 23-3.

[ReddyWatts]

Simple test for you to see heat transfer between metal and water increase with water flow.

Fill two pans of water half full. Place both burners on high and time both for five minutes. Continually stir one to simulate a higher flow rate of water against metal and stir the other, once a minute. Check start temp and end temp with with your infrared temp guns.

Results:

Pan water (slow water flow) start temp 68.5 F, final temp145F after five minutes

Pan water (faster water flow) start temp 68.0F, final temp 170F after five minutes.

Faster moving water against the metal has a better heat transfer rate, so increasing the water flow will increase cooling of the motor and controller.

[Fluid]

Actually Ready, in your non-applicable "test" the water heated faster because all you did was to increase the movement of water across the heating surface (augmenting convection), demonstrating that water has a relatively low rate of heat transfer. All it proves is that some movement is required - which no one disputes anyway. Your "test" does not simulate what happens in our boats - unless you cool your motor with a pan of water.

Without knowing the tube diameter or the delta across the tube surface, the chart is meaningless and possibly misleading.

You can believe whatever you want of course, but myself - along with thousands of other thermodynamics-based engineers - have several centuries of science on our side. I'm just trying to help here - don't shoot the messenger. I'll keep quiet if it makes you happy. :zip-up:

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[ReddyWatts]

Ok, but I believe the facts, not rhetoric.

[planezero]

Knowing the theory is nice (link (http://en.wikipedia.org/wiki/Heat_transfer_coefficient)), but nothing beats a real test.
Obviously dT would be greater and dt would be smaller with a higher flow, but thats all meaningless without real figures for dT.

Do three two minute runs...average the end temps of both your motor & esc.
Then restrict the flow slighlty with a paperclip anywere on the tubing and do the same...
I'd love to do this test but my SV is still smashed up :cursing: