Endre (Andy) Bujtas

This is what the radiators look like from the back side. The cooling fans used are Perma-Cool Model 19114 14 inch electric fans. They push the most air of all the electric fans I examined (2950 cfm) and were the most inexpensive too.

I received my 2 Ron Davis aluminum racing radiators and built a frame to support them. The frame is open on the sides to allow for thermal expansion of the radiators. Each radiator has a core size of 14 x 14 inches and are of a 2-pass design with 2 - 1 inch cooling channels. Each radiator, by themselves, can supply about 65% of the cooling of the the 406 engine. Mounted on the radiator frames are the oil cooler and A/C condenser. The oil cooler is a Fluidyne model ZR-1 and will be mounted on the left (driver) side next to the oil filtration system. The A/C condenser is a high flow/cross flow aluminum unit from Vintage Air. This unit will be mounted on the right (passenger) side near the A/C compressor. Recall that these radiators will be mounted in front of the rear wheels.

Right Side Radiator

This picture shows what the right side radiator assembly looks like. The A/C condenser is of a high-flow high-efficiency parallel-flow design from Vintage Air. I'm currently working on the plumbing of the A/C system.

Radiator Support Frame

This shows the right side frame used to support the radiator/fan assemblies. It is designed to allow thermal expansion of the aluminum radiator. The frame is designed to be at the same height and location of the lower side body ducts. The frame also supports the Perma-Cool high-flow electric fans. Not seen are the thermal switches to control the fans. Each leg of the coolant "rams head" have a thermal switch to control their respective fan when the temperature reaches 220F and shuts the fan off at 170F.

AC Condenser

This picture shows the completed radiator/AC Condenser plumbing. I made all the AC lines myself, including the stainless steel lines you see in the picture. All the parts were purchased from Vintage Air.

Trans Cooling Opening

This picture shows how the transmission oil cooler fits with the body installed. Everything fits fine. The area around the cut-out was re-inforced with steel prior to cutting. I also noticed that IFG bonded a 1/2 inch square steel tube in the area around the rear trunk lid weather strip area and the tail light reflector housing. This also allowed me to weld my frame to the body - aside from bonding the frame to the fiberglass. The frame also acts as an anchor point for my new rear grille. I purchased an aluminum grill from CRP to replace the heavy steel grill from IFG. The difference in weight is significant, but the CRP grill needs to be modified since it is longer than the IFG grill. Hmm! This begs the question: why are 2 cars, which are supposed to replicate the real car, so different in the grill dimensions?

Coolant Expansion Tank

As some of you know, building a car has some trial and error aspects. My coolant expansion tank is one example. This is the third revision to the location of this tank. The previous revision had the tank mounted on the body. This prevented me from completing the cooling system and test-running the engine. So, I made a new bracket so that the expansion tank is now part of the chassis.

Air Tunnel

This picture shows the completed air tunnel for the radiators. Air gets directed from the side lower vents and is forced into the radiators. The tunnel is made from a thin 16 ga steel frame. I used aluminum door screen material to form the shape, then glassed-in the shape with fiberglass cloth. This makes it very stiff - aluminum screen bonded with fiberglass resin and cloth. The insulation you see is to keep the side fuel tanks as cool as possible.

Here is a generic issue with any build that uses the rear lower vents for the radiators. The reason is the long distance the coolant must travel to get to the radiators and the pressure drops across 2 radiators in series (what most people are doing) - not to mention the pipe losses as a result of the long distances the coolant must travel to and from the pump. In addition, the stock belt-driven water pump is not very efficient and really doesn't push the coolant too quickly through the system. Remember, the pump was designed primarily for a system with the radiator right there in front of it. And since the stock pump suction port is above the bottom of the radiator, the Net Positive Suction Head (NPSH) is reduced and likely to cause the pump to cavitate – further reducing its efficiency.

To minimize the losses I designed my coolant system with the radiators at each side - taking air from the lower side ducts. The hot outlet is split and goes almost directly to the respective L/R radiator. And each of my 2-core (with 1 inch channels) aluminum radiators were designed to handle 60% of the 406's heat load. However, unlike most radiators, mine are of the cross-flow type. That is, when the hot coolant enters the top it doesn't go down the core, but to the side. Then the coolant goes to the water box at the opposite side and reverses direction. Therefore, my flow is from side to side instead of top to bottom. I'm also using a remote electric water pump that is placed well below the bottom of the radiators. The suction head (NPSH) is good and there is little (if any) pump cavitation.

Now I found out later (after building my system) that Lamborghini can get away with having the radiators in the back since their coolant pump is right there in the back - recall the front of the engine faces the rear of the car. And they do split the system so that each radiator cools independently - a parallel system with short flow paths. I did notice, in one of my pictures, their version of the "rams head". So I assumed they have a parallel coolant system as well.

For individuals with a V8 facing the front and who want to have their radiators in the back, I recommend using a high flow remote electric water pump instead of the stock belt-driven pump. Aside from the cooling issue, using a remote electric water pump also allows the builder to move the engine closer to the firewall, thus providing greater alignment of the rear wheel hubs to the transaxle (for Porsche systems anyway).

As for making the "rams-head":
It is pretty easy to make. I used 2 1.5 inch aluminized 90 degree exhaust elbows from JC Whitney for the legs of the rams head.

For the flange I used 2 1/4 inch thick exhaust flanges from Headers by Ed in Minnesota (?). One flange already contained the 2 inch hole, while the other was a blank flange. I got an extra blank flange for pressure testing the finished rams head.

Next I located the center of the blank flange and scribed a 2 inch circle. The idea is to match the location (center) of the 2 inch hole/flange to the blank flange. Since I'm using 1.5 inch pipe for the legs, I marked the 2 centers on the centerline. The idea is to fit 2 1.5 inch diameter pipes into a single 2 inch diameter hole. The centers are located about 1/4 inch from the 2 inch scribed hole center. I then cut 2 1.5 inch holes in the flange (at the centers) using a 1.5 inch bimetallic hole saw. You can get these at any hardware store (Milwaukee or Dewalt). Bimetallic hole saws are meant to cut through steel. Don't use a regular wood hole saw.

With the blank flange cut, I welded the cut flange to the flange with the 2 inch hole along the outer edge to form a single 1/2 (approx) flange. The welds were ground to the flange shape for appearance.

Now that the flange was made, it's time to make the rams head legs. The height of the rams head is up to you, but I cut mine (each leg to be joined) to about where the 90 degree bend ended and the straight section began. You can check where you want to make the cut by slipping the cut flange (before you welded it to the other flange) over one of the 90 pipes.

Then you must cut about 1/4 inch along each side edge to be joined. I used my chop saw to cut off the section. The cut will look U-shaped. I cleaned the recently cut edges on a disk sander to get rid of the burrs, etc. Fit the 2 legs together into the 2 holes in the flange. Don't weld the legs to the flange yet, but weld the legs together first before welding to the flange. To get them straight and aligned, I used a piece of 2 x 2 inch angle iron and clamped the pieces together before welding. Weld the 2 legs together on the outside. To properly seal the inside seam, I brazed the inside surface with an Oxy-Mapp gas torch.

With the 2 pieces together, fit into flange and weld the inside surface. This will also complete the welding of the 2 flanges as well. You can also weld the outside surface as well. Then grind the inside weld in order to blend the weld to form a 2 inch to 2 1.5 inch transition. I used a 3/4 or 1 inch drum sander in my air angle grinder. To true the flange (flat gasket or o-ring) surface, I sanded it on my small table belt sander. This ensures that the mating surface is flat and not warped.

Once finished, I air tested it for leaks. I used 2 rubber stoppers (from a hardware store) and clamped them together into the 2 legs. Air was entered at the blank flange, which gets bolted to the rams head flange. I drilled and tapped for a pipe fitting to attach an air hose. I pressurized the rams head to about 120 psi and used soapy water to check for leaks. Brazing the inside really helps prevent leaks.