Okay everyone I have a unique problem, and you will probably ask why I'm posting here.
Because it involves the ls3.
I have a friend of mine using a crate ls3 as the motor on a giant hydraulic pump. He is running at about 4-4500 rpm constant and he has started having some cooling "problems" he says that he is running at about 205 after about 10 minutes

He has a custom Ron Davis radiator (it's the biggest thing I've ever seen)
The biggest cfm fans he can get, with good shrouds
Stock water pump
And everything is static so there isn't much air flowing except what the fans are pulling.
It isn't enclosed so there is ambient air around it. (Think T bucket kind of engine bay, nice and breezy)

So in going back and forth with him the opinion I have given is that
1 the motor isn't really too hot
2 there might be air in the system (as a week or so ago he was running at about 178°)

And he wants to look at putting a electric water pump on there
I'm thinking it might not have enough flow for the motor spinning at 4K
He was looking at a 50GPH one.

If there is any information I've left out just ask for it. (I'm sure I have left out something important.
I just got home after a looong day at work and I'm only 1/3 awake.
But a friend is a friend and I want to help him out.


Thanks all.

 

Hello,
Any engine talk is fun for me. There is an LS forum that might better help and receive this question more amicably.

Firstly, 205 degrees isnt bad for an LS motor but if you are used to Fords I suppose it is concerning. Notice if the engine runs at 205 degrees regardless of ambient temps or load/speed etc. Then if it does the system is fine and maybe just the thermostat is keeping temps in that range.

If the engine is highly sensitive to ambient temps or is running much hotter depending upon these factors then you may wind up with issues when the motor is being pushed and you need it most. Or in hot temps etc. In other words if this thing hangs at 205 degrees no matter what then the cooling capacity is fine.

Checking online to see what engineers consider when designing stand still power would be helpful.

There are 2 great electric water pumps available now and others that arent so great but if the motor is not doing much idling or low speed work then I cant see the benifit. One electric pump even has an automatic variable speed control and stand alone controller.
The variable speed pump i mention is not mounted on the engine so you could even mount a second radiator and an auxilliary cooling system.
I run a meziere on the street and have put over 100k miles on meziere electric water pumps without any issues.

It seems you already know that the electric pumps outperform mechanical oem pumps at low speed and idle.
If he engine is cycling from idle to full load to idle constantly then the electric pump may help as well. Under load the coolant heats up quickly and pulling from idle to 4k rpm maybe that extra flow down low in the rpm range will help.
As for worrying about coolant flow at steady state high rpm, the oem pump may just do a better job than electic as you also seem to consider.
Meziere makes a mechanical pump that may outflow the oem mechanical down low and up top....not sure but why not check it out. An extra 5 or 10 gpm may show some improvement or it may not.

Oil cooling and sump capacity also should be considered as a way to stabilize engine temps. Coolant alone is only one part of the equation.

Thermostat....perhaps a 160 degree thermostat may help. If running a 180 or 190 degree then allow a window of 10 degrees above that in normal operation.
Maybe stand still applications use a different thermostat. GM may even have literature for LS motor in this application, what operating temps to shoot for and how to acheive these goals, coolant capacity etc.

I bet a nice large air to oil cooler with fan, with a dual spin on filter assembly such as for diesels or industrial motors will work nicely to increase capacity cool things down too. I dont know what cooler the crate motor comes with, if any.

Here is a link to one of the pump setups i mentioned.
http://www.hotrod.com/articles/davie...ic-water-pump/
With this setup maybe you dont even need a thermostat?

Now if i could only solve my own cooling issues on my e force C6 z then that would be a feat.

 

The cooling system normal temps run anywhere betwen 190 F-210 F as set by GM. If there is air in the system, that will impede proper water flow for sure.
I would get worried if it started running consistently at 220F or higher.
At that point, a bigger cooling pump might be the order of the day.

 

(more than likely) Here's his problem. There probably arent any other hoses connected to the water pump other than the 2 large radiator hoses...
The system as designed by GM needs those 2 smaller hoses connected to a heater core and a reservoir they are critical as to how the system circulates coolant.
If those are not connected. remove the thermostat and pick up a 21 or 22 mm freeze plug from your local Oriellys,Autozone, wherever.
Drill a 1/2" to 5/8' hole in the freezeplug and install it into the deep recess of the waterpump.
That'll solve your cooling issue.
I had the same trouble in my sandrail ,block would overheat but radiator was stone cold. doing the freeze plug trick solved my issue.

 

Wow, Az, you sure know how to get out and have fun.