Sizing of coolant/water lines.

[lsrjunkie]

I'm currently building the cooling system for my Jimmy six in Hank. The two big questions I have are; 1. What is the nominal size for the water lines? I plan on using an electric water pump in line with a 20 gal water tank. 2. What flow rate should I look for in a pump?

FYI, I am thinking that -16 should be plenty large and I was looking at approx. 60 gph for the pump. The water lines will be about six or eight feet between the engine and the tank.

I'm hoping to make around 400-425hp, 320CID and I'm shooting for the 175mph mark.

[RichFox]

My GMC used two -10 lines from a 9 gallon tank and two Jabsco 12 volt bilge pumps. Unblown it worked fine. It takes a long time to warm up 9 gallons let alone 20.

[lsrjunkie]

Thanks Rich! So the next question is, do you think what I'm planning is overkill?

[BobDcuda]

RichFox, how long are the runs to your tank?

[Sumner]

The other option is the rad-in-a-tank.....

http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20hooley-construction-2013-13.html


...  We really like that since we have gone to it.  We run water from our old tank to it but others just have the rad. in a tank with all the water.  The nice thing is that your motor runs with a pressurized system like is normal to the rad.  Also you can pretty much build heat in the motor and the water in the radiator without heating the water in the tank much depending on how you do it.

If you had the rad. in a tank back in the car then you would want hard lines from it forward to the engine compartment past the driver.

I'm going with the rad-in-a-tank for the lakester,

[RichFox]

RichFox, how long are the runs to your tank?

Roughly 90 inches. Maybe a little longer on the Vega. I used Airoquipt Stratoflex hose with the pumps mounted on the tank.

[RichFox]

Thanks Rich! So the next question is, do you think what I'm planning is overkill?

You don't have to fill the tank all the way if you decide it is better with 6 or 7 gallons..

[Rex Schimmer]

Lsrjunkie,
If you are looking at 400 hp you should have about 40 gpm (in your post you say 60 gph, but I am sure you meant 60 gpm) so if you have a "real" 60 gpm you should be good. The -16 lines should be fine, if you are going with a water tank I would suggest using some sort of pressure vessel so that you can run the cooling system at 17-25 psi pressure as it has a huge effect on keeping your engine cool. If you go the "radiator in the tank" method remember that water to water coolers are 7-10 times more efficient that water to air so you don't need a very big radiator but you must provide a pumping system to move the tank water through the radiator to be efficient. As far as warming up the engine I highly recommend using the BMW 320I three way thermostat from around the 1983-4 year. This thermostat will circulate the water in the engine through the engine, not back to your tank, until the water is warm and then it will modulate the water from the tank to the engine to maintain its setting temperature. Also remember that electric water pumps don't like to make pressure so any kind of restriction greatly reduces their flow.

Rex

[BobDcuda]

Rex, I'm running about 250 HP in my F/CPRO slant six motor. I want to replace all mechanical water pump (crank driven) with an electric pump.  Are you saying that 25 gpm will be adequate for my application?  I was looking at the Dedenbear WP3 model that is rated at about 23 gpm. 

I was planning to use -12 inlet to a blanking plate to cover where the OEM pump would have been, and OEM hose from the thermostat housing back to the radiator.

[Rex Schimmer]

Bob,
Yes 25 gpm should be good for 250 hp (Stu VanDyne water flow rule: 10 gpm/100 hp) but I have never seen an electric water pump that will flow at its rated flow if you add resistance to the outlet, like a radiator and an engine block. I would be very cautious when selecting an electric pump. All of the "standard" electric pumps are centrifugal type pumps and they are manufactured with lost of clearance so once any restriction is applied to the outlet the flow rate drops substantially. I would not buy an electric pump unless the manufacture can supply a pump map that shows out put flow rate vs. out let pressure . A good racing water pump will have close internal clearances and will continue to produce rated flow or near rated flow even with 10-15 psi of outlet pressure. Rich Fox used the Jabsco flexible impeller pump on his car and they will easily make 15-20 psi at full flow as they are very low leakage. I have one on the torch cooler for my TIG welder that is at least 45 years old and it makes 15-20 psi all day long.

Rex

[Richard 2]

Stewart components  http://www.stewartcomponents.com/#     906-789-2816   Makes some nice inline water pumps.
Richard

[rouse]

The Stewart site is now under construction, so shopping is out on line, you have to call.

About the hose sizing; take a look at your flow rate in GPM and make sure the velocity stays at a reasonable speed. There are standard charts for flow velocity through a given "pipe size", I'd double check that before spending money on a guess. A good clue would be the stock sizing, more power and longer length hoses shouldn't be smaller.

Rouse

[BobDcuda]

Great input - thank you guys. 

[Sumner]

The inline pump on the Stude is a Meziere 35 gpm pump and worked fine when cooling the motor direct (very low pressurized system) and now used to pump water through the rad-in-a-box where we have the high pressure on the engine/radiator side.  The engine was never dynoed but blown gas and we think between 800 and 850.  This was with a 30 gallon tank.

The pressurized system, as Rex said, is more efficient at cooling but if you go that way and don't use the rad-in-a-box you have to be extremely careful as the forces on the inside of the coolant tank can get extreme.  I would use nothing other than a round tank and do some careful pressure testing outside the car above the pressures that will be in the system,

Sum

[lsrjunkie]

Thanks for the info guys! As always, it is greatly appreciated!

Sum, any sort of pressure vessel is something that I treat with great respect. I've been around a few that have failed, and it is nothing short of terrifying!