roadster cooling question...

[Roadster943]

Hi, I am new to this...went to Speedweek '02 for vacation, and life as I knew it was over!  Have been building a roadster since then. Hope to have it ready for speed week this year. Have a question on cooling...plan on running a 20 gallon water tank in the rear of the car. Water level will be well above the top of the engine. I am thinking of controling water temp in the engine by turning the waterpump on and off. Will I have any problems with hot spots when the pump is off? The reason I am thinking of doing it this way is that my intake manifold does not have provisions for a thermostat.  Anybody have any thoughts on this? any suggestions appreciated.

[John Burk]

Hi Roadster - It's not hard to rig up a remote thermostat as long as a little water can loop back while the thermostat is closed- Without a thermostat you need to warm 20 gallons to warm the motor and that uses up a lot of the cooling capacity .

[Stan Back]

On our roadster we use a mechanical water pump with a tank in the rear of about the same capacity as you mentioned.  We don't have to remember to turn it on, much less try to control temperature on a run by turning it on and off.  Seems there're better things to be doing.  We restrict the flow after our small capacity pump.  We use a 4-cyl. pump on an 8-cyl. engine and about a 3/4" restrictor.  It all adds up to about 150 pounds over the right rear and the temperature has never exceeded 190.  Hope this gives you some ideas.

[Stan Back]

On our roadster we use a mechanical water pump with a tank in the rear of about the same capacity as you mentioned.  We don't have to remember to turn it on, much less try to control temperature on a run by turning it on and off.  Seems there're better things to be doing.  We restrict the flow after our small capacity pump.  We use a 4-cyl. pump on an 8-cyl. engine and about a 3/4" restrictor.  It all adds up to about 150 pounds over the right rear and the temperature has never exceeded 190.  Hope this gives you some ideas.

[jimmy six]

Before too many comments are made perhaps you should tell us your engine/fuel plans.  Water for weight is usually a good idea but not always. The style and class will help for better responses for the experience you will find here. I even had to add heaters to ensure proper warm up; if your hoping to be impound one morning when it's cold and your fuel motor won't warm up you could be giving that Hp you don't want...Good Luck.

[Glen]

Roadster, you also stated the water would be above the engine, thats about 170 # of up high weight. Two things you might want to consider is baffles to keep the water from sloshing around and mounting it lower. Roadsters  are already top heavy and adding that much to the roadster up high may cause handling problems.

[Roadster943]

thanks for all the replies! A couple of the ideas already sound good...The car is a D gas roadster. 292 cubic inch V-8 Chevy.  As far as the height of the tank, it is a 14in diameter round tank, 30in long, laid horizontally. The top of the tank will be just above the heads of the engine. How much horsepower does a mechanical water pump take to run? I like the idea of running a remote thermostat. I had not thought about running a loop back , thanks. Off to the shop now!

[DallasV]

In our roadster we have a 30 gal water tank in the back of the car. When we run a gas motor we have an in line water pump that runs off the same battery as the tach. We leave the pump off to warm the motor then I click on the pump at about the one mile. When we run a fuel motor we replace the pump with a valve, close the valve to warm the motor then open it for the run and let gravity and heat circulate the water. Or sometimes we just leave the valve closed if we're not getting enough heat with the fuel motor.

[Dave Cox]

We also ran an electric pump with the tank mounted in the rear of the car (to help with the ballasting). A fishing type bait tank pump works very well, and is inexpensive.

[Jim McNaul]

I've seen a pretty neat 12-volt electric water pump used in school busses to move water back to the heaters in the rear of the bus. The're real reliable and long lived.
   Also, I believe the marine suply places have some remote thermostat set ups with constant circulation in the motor, and only introducing cold lake water (ie your coolant tank)gradually as needed.

[bfolkestad]

EMP Stewart has the best 12 volt pump in my opinion. It is 12 vdc brushless with PWM controller.. (this means it will runn like hell and last forever) it also can move 55 gpm..
 
 On another note what is the deal with water tanks? I think glen hit the nail on the head why would you want water higher than the engine (just add the water at the thermostat housing @ the motor or the higest point in the system)
 
 What is a matter with a regular radiator? They work really well. Add a high quality cooling fan (electric high quality) and you will be set..
 
 If you do not think it will work look at a 410 sprinter rad.
 
 I have been out there several times and work on cooling systems for a living, I think the rad is the way to go..
 
 
 Use lead for ballast.it is small and heavy, you can put it where you need it...
 
 I would focus on balance and chassis set up, you should be able to get the car to hook up and go fast..