In the world of building modified cars, you have to be willing to think outside the box to make different parts jive when building a car. Whether it's notching the frame to lower a vehicle, rolling the fenders to fit oversized wheels/tires, or fitting an upgraded radiator to cool that larger engine you stuffed under the hood, you have to be ready to modify and customize things to make it all work correctly.
This is the case especially when building small cars with larger or higher horsepower engines, where space is at a premium. I've always come up against issues finding a radiator that was just the right size that fits nicely, and cools the car better than the stock radiator did. There are a lot of large aluminum radiators for sale out there on Ebay and other sites to fit street rods and muscle cars, but the smaller ones to fit the space I needed are slim to none. Even the ones that are close to the right size, usually don't have the outlets in the correct place. Luckily we had a couple large aluminum radiators suited for small block Chevy V8's laying around and after eyeballing them, I decided to try cutting them up and building a radiator to suit my needs. It's only metal right?!
I started by cutting the end tanks off the core at the welds, Once these were off I could cut the core down to the height I needed. The core is basically (in this case) made up of rows of thin aluminum tubing that are connected by fine metal fins and then housed at each end by base plates. Once I broke it down to the basics like this, it was pretty easy to see what needed to be done to cut the core down to a more suitable height for the Volkswagens I was building. I first marked and cut the base plates on each end between two coils (the thin metal tubing that the coolant flows through). This got me to the height I needed, and I then began cutting and sectioning the end tanks to the size I needed and moved the outlets to where I needed them. Some sort of tape here comes in handy and helps hold it all together to give you an idea of what it will look like and even allows you to do an initial test fit. Remember it's a lot easier to change the radiator layout when it's held together with tape rather than weld!
With everything taped up it all seems a lot more doable.. just weld each seam up, pressure test, and mount it in the car right? Well in this case.. not exactly. By moving both outlets over to the same side, I needed to convert it to a dual pass radiator. Originally the coolant came in one port and had to travel across the radiator through the coils to the other outlet and back into the engine, but now the coolant would take the easiest path and straight down through the other outlet. So to make a "dual pass" radiator I needed to add a plate below the top inlet that blocks the water from flowing straight out the bottom port and instead through the coils, thus lowering the coolant temperatures. I cut a piece of aluminum plate to size, then sanded it with a belt disc sander until it was a tight fit with a slight bevel. I then used the Eastwood TIG 200 to weld the cap to the endtanks. Before I laid the final weld sealing the two halves of the end tank together, I took some high temp, waterproof epoxy and sealed the edges around where the plate sat near the coils. Using epoxy avoided putting any unnecessary heat into the coils and sealed the plate from leaking.
With the radiator now converted to a dual-pass, I welded the rest of the endcaps onto the core and added my outlets and overflow port as needed. I did a basic pressure test by capping off all of the outlets, spraying the seams of the radiator with soapy water, then applying around 20psi with an air nozzle off of the compressor through the overflow outlet. Any air bubbles that popped up I cleaned and rewelded the area. With all of the leaks fixed, I was ready to install the radiator and fill the cooling system.
The verdict is in, both radiators I built hold more coolant, dissipate the heat better, and overall keep the engine temperatures lower, giving me a huge piece of mind when cruising during the summer. The cost of a custom one-off radiator to fit my exact needs would have cost me close to what a new TIG 200 retails for, so once again tackling a project like this helped me save money and get some more time under the helmet with the TIG 200.