Header tank size

Joel K

Supporter
Hi everyone,

Looking to lay out the engine compartment and wondering what is the ideal size Header Tank. Also, given the correct size of header tank is an additional reservoir/recovery tank really necessary?

Appreciate any help on this topic.

Thanks,

Joel
 

Ken Roberts

Supporter
Here is a good explanation on how to calculate the size http://blog.cantonracingproducts.com/blog/calculating-expansion-tank-size-requirements

Unfortunately the SLC just doesn’t have a big enough area to mount the correct size expansion tank (18% of capacity) so a recovery tank would be a good addition. I would recommend 1.5 qt minimum for the expansion tank. A quick visual check of the coolant level in both tanks is best but since both tanks will more than likely be aluminum, sight gauges should be added.

You might want to add a second bung near the top of the expansion tank. Most tanks only have one bung at that location. One for the radiator air bleed and the second for the engine air bleed.

The expansion tank will bloat slightly when hot. Take that into account when designing the mount. Round tanks will bloat less.

Most drag strips and tracks require the coolant overflow to be captured. The Dorman plastic tank that comes with the car is strictly a expansion tank and just pukes the overflow over the side of the tank.

If you live in one of the warmer southern States than I would definitely add a recovery tank. If you are using the fans that came with the kit and/or aren’t using a well designed shroud than I definitely would recommend a recovery tank.

If you are the type to want the best of the best than look for a expansion tank that has special chambers to help deaerate the coolant.

If your expansion tank is sized to be about 18% of your coolant capacity and your radiator size and fan performance are top notch than you might not need a recovery tank. Many OEM cars do not use them.
 
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Howard Jones

Supporter
1 Gallon is plenty for an expansion tank. That is 231 Cubic inches. 10 inches tall X 8 inches wide X 3 inches thick equals 240 cubic inches or slightly more than a gallon. Those are the rough dimensions of my tank. I made it to fit the spot so I had to make a couple out of cardboard and then calculate the volume until I had what I wanted.

My SLC fills from dry with 3 3/4 to 4 gallons so that is about right at roughly 20% of total coolant capacity. Good one Ken. I was going to try and remember how I arrived at that 20% number, I bet I got it from Canton..........you saved me some time going through notes. Thanks.

On overflow tanks or recovery tanks....... They are not the same thing. I have an overflow tank and all it does is contain any coolant that gets pumped out of the port below the radiator cap. It is vented to the atmosphere so will overflow if completely filled. The overflow line from it exits the car at the rear to keep coolant off the rear tires. Most racing rule books require one and even without a racing rule requirement, they should be installed on a car that sees track work. Recovery tanks will be sealed and also contain overflow from the expansion tank/radiator cap vent port, however, since it is pressurized from the coolant system it will pump expelled coolant back into the system when the main coolant system cools down thus "recovering" the coolant,

The former is better suited in a track car as they get a lot of inspection between sessions and a coolant problem is quickly recognized and corrected as well as having the overflow tank drained. The latter is used on most production cars and is best suited on a streetcar where coolant loss might be missed until overheating occurs.

How big? Mine is made from 4-inch diameter aluminum tubing 10 inches long or about 125 cubic inches more or less. Call it about half the expansion tank volume. Once the car has been run a few times any excessive coolant has been puked out and drained off and it should remain dry thereafter. That is what I really use it for. To set optimum coolant level in the expansion tank at full hot as well as a container of last resort to avoid putting down fluid on the track.
 

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I've used a Canton 1.25qt expansion tank for over a decade without any issues.

I run the puke hose from the cap vent into a small generic Summit canister for the overflow (fill from bottom, empty from top if it overflows).
 
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