Beat the Heat

Keeping things cool under the hood of a hot air-cooled ride

Story & Photos by Jim Youngs

While production cars benefit from countless hours of engineering to address insulation issues, that’s not the case with most replicas and project cars. You typically start with a fiberglass shell and a bare chassis, and then you’re on your own when it comes to controlling high temperatures.

Fortunately, the aftermarket offers a number of heat-control products, and that’s just what I needed for my Porsche RSK Spyder replica. I’d already been advised by the manufacturer, Thunder Ranch, that I would have to address some heat issues in the engine bay. That’s because the turbocharged engine, a 2,110 cc modified Volkswagen Type 1, sits in a rather tiny engine bay, with the turbo sitting just inches below the fiberglass cover. All the extra exhaust tubing in the bay radiates even more heat, exacerbating the problem.

The Design Engineering Inc. heat protection products installed were Fire Sleeve, Titanium Protect-a-Boots, Heat Shrouds and Titanium exhaust wrap.

So how does one reduce the underhood temps on an air-cooled engine? I had already installed a few heat-control items, such as a large-capacity oil pan and full-flow oiling (to improve distribution from the stock setup, which isn’t sufficient for higher horsepower levels). I also added an oil thermostat and a Derale 96-row oil cooler with an electric fan and thermostat. What more could I do?

Fire Sleeve is used to protect the fuel line and is very simple to install. Cut the sleeve to the proper length, as you would any hose, and slip the sleeve over the hose. With the included Fire Tape, wrap the hose ends and clamp the hose back in place.

I received some pointers here from the guys at Design Engineering Inc. (DEI), a firm specializing in “thermal tuning.” Based on their recommendations, I ordered their Titanium exhaust wrap, aluminized Heat Shroud, Fire Sleeve and Titanium Protect-a-Boots. These items have a wide range of applications and would be ideal for most any project car. The exhaust wrap alone is said to reduce underhood temperatures by 50% and can withstand 1,800 degrees F.

Since one of the oil lines from the cooler is close to the exhaust pipes in two spots, adding Heat Shroud made good sense. One benefit of this product is you don’t have to remove lines or wiring to install it. Take good measurements, cut the piece to length and wrap the shroud over the line you want protected. Last, fasten it with the hook-and-loop closure. For extra security, we tie-wrapped the bundle as well.

The Titanium Protect-a-Boots were the simplest DEI products to install. It was simply a matter of slipping the wide end of the boot over the spark plug boot then pulling it back to expose the end of the boot.

The Heat Shroud is a high-temp fiberglass fabric bonded to an aluminized material with hook-and-loop closure. Designed to reflect heat from wiring and hoses, it can fit on diameters ranging from a half-inch up to 1.25 inches and can be easily cut to length.

The Titanium exhaust wrap is easier to work with after soaking it in water for a few minutes. Design Engineering Inc.’s online product installation guides provide a lot of information on how to measure the wrap for your particular project. That’s especially helpful if you’ve got tight header clearances, as in our application.

Start the exhaust wrap by securing it with the Design Engineering Inc. stainless locking ties. Then continue to wrap the pipes with about a quarter-inch overlap. Keeping the wrap tight is the goal as you go along. DEI suggests starting the header wrap at the exhaust port and taking your time. The tighter the wrap, the better the hold and less chance of a loose or irregular fit. After you have all the wrapping done, run the engine up to operating temperature to create a baking effect. Some smoking of the pipes is normal and will subside after several days. It’s advised not to try to clean the wrap with high-pressure water or air. Instead, use a wet shop cloth to remove dirt and debris.

Fire Sleeve is an iron oxide, silicone-coated fiberglass sheathing that provides protection up to 2,000 degrees F for insulating hoses, wires, fuel lines and more. It comes in 3/8-, 5/8- and 1-inch inside diameter kits with finishing tape for seams and sleeve ends. Protect-a-Boots slip over spark plug wires to provide 1,200 degree F protection.

As projects go, installing these DEI products is rather simple and straightforward. DEI also offers other products aimed at any number of insulation and heat issues, such as Boom Mat heat and sound control kits, air tube covers, mats and other types of sleeves and shielding. So what have you got to lose? Just some excess heat!