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SL-C Manual: Cooling System

Radiator Fan Mounting

There are a variety of methods you can use to attach the fans to the radiator. Following are photos & diagrams showing examples of fan mounting methods.

Also check that the fan blade orientation is correct for drawing air through the radiator.

Although all of these pictures do not show a shroud, using one is recommended. You can fabricate a custom shroud from aluminum, fiberglass or another composite material. Fans are much more efficient with a shroud, which is why every production car has them. If your car is always moving fast enough to cause enough air to go through the radiator, you don’t need a shroud. All other applications should have shrouded fans, particularly those with air conditioning, as this alone increases condenser efficiency dramatically.
Even race cars need shrouds, for when they must stop, but continue to have their engines running.


One thing to remember when mounting the fans- do not mount them with cable ties or Ty-wraps! If you are using a shroud as you should, this won’t be a problem, as the fans will mount to the shroud. The reasons for this are twofold: first, the fans should be off the core in the shroud so that the effectiveness of the fan is maximized. And second, because the manufacturer of the radiators will void any warranty on the radiator if there is evidence of fans being attached to the core with ty-wraps or any other through-core attachment method. Although this is a common approach, you should avoid it if only to be sure to keep your radiator warranty intact. When these kinds of fan attachments are in your fan packaging, they are provided by the fan manufacturer not the radiator manufacturer!

Radiator Mounting

Mounting the radiator in rubber isolation mounts reduces the likelihood of eventual cracking and leaking. One simple method of doing this is to enlarge the mounting holes in either radiator mounting flanges or chassis front extension. Then insert grommets into these enlarged holes and run the mounting bolts through the grommets to complete the insulated mounting.

If you do rubber-mount the radiator, install a dedicated ground strap to ground the radiator to the chassis. Failure to ground the radiator will eventually cause corrosion and radiator leaks, in addition to possible clogging.

Coolant Pipes

The SL-C ships with a set of 1.5” diameter straight stainless steel tubes. These are intended to be combined with builder-provided silicone elbows and couplers to transport coolant between the radiator and engine. If you use these, be sure to use the appropriate clamps for silicone hose such as the ones that can be found here. The use of the incorrect heater-hose type of hose clamp can damage the silicone and cause leaks. Superlite also sells fabricated stainless coolant tubes that are essentially one piece per side made from several pieces of stainless tube including bends welded together into one piece. This option reduces the number of hose connections dramatically thus reducing the risk of leakage.

Check the wiki here for a discussion and more details about choices.

Whatever option you choose concerning coolant pipes, they should be mounted away from the chassis using standoffs and padded P-clamps (also called Edelmann clamps) or a similar approach. You can use standoffs directly under the mounting point for P-clamps. The standoff lengths should be in the 10mm – 20mm range depending on insulation requirements.

You should insulate the coolant pipes where they run underneath the body cabin section. In this area, you may need 20mm standoffs due to the thickness of the insulation. You can insulate the pipes with hot water pipe foam available at home improvement stores like Lowes or Home Depot.

The diagram below shows where the cabin section of the body needs to be cut out for the coolant tubes to pass underneath. The area in question is just behind the rear edge of the front wheels. The perspective is from the front of the SL-C cab; the outer vertical lines are the sides of the SL-C; the step at the top left and right of the respective diagrams is the step where the front shell closes.

Be sure to make covers for this area after the coolant tubes are done. Failure to do so will leak air and water into the side of the body under the doors. It's also a pathway for insects and rodents to get into the cockpit. You make cover for this area by wrapping the area with clear packing tape, and applying a mix of resin and fiberglass cloth. Trim the excess at the green stage (when the resin is still soft enough to cut easily, but hard enough to keep it's shape), remove when fully cured and install with screws after the packing tape is removed.

Drivers Side

Passenger Side

Looking from the front of the body

Header and Overflow Tanks

Here is a diagram of a typical cooling system for a front-engine LS-powered car. This picture is from an off-road site, and so some of the detail doesn't directly apply to our mid-engine cars, but the overall plan is essentially correct for an LS engine. Other engines may need a different plumbing setup. If you are running steam vents, plumb them to the expansion tank, not to the radiator as shown here.

You must use a header tank (called a “pressure bottle” in the diagram). A header tank makes it easy to fill the system with coolant and makes it easy to bleed air out of the system. Air in the system causes overheating, and can damage the engine due to detonation when hot spots near the combustion chamber overheat due to local boiling or air bubbles.

It is also recommended to run an overflow (recovery) tank. An overflow tank is designed to catch coolant that is expelled from the cooling system when the engine is warming up. As temperature increases, the coolant expands and the excess coolant is pushed past the cap seal into the overflow tank. When the system cools, the coolant contracts and the coolant from the overflow tank is drawn back into the header tank. When the system is cold the overflow tank will be close to empty, at the minimum mark. When the system is hot the overflow tank will be at the maximum mark. For this recovery system to operate correctly you need to run a recovery type radiator cap.

Custom tanks can be built that take into consideration the shape of the body above the engine. Several builders have taken this approach and the 01 race car has a similar design. In the following picture, you can see the custom header tank one builder has fabricated and mounted in the upper left of the body over the engine.

Note that it follows the curvature of the body, and allows the owner to easily fill the tank just by opening the rear shell. This header tank has a provision for an overflow tank. 

As shown above, be sure to mount the header tank as high as possible in the car in order provide maximum air-bleeding action.