The F1M Forums

As I understand it, in the left side pod there are two oil coolers. One for the engine and one for the gear box. Two versions of mounting them them. Hasegawa has the late type (from Germany) while Tamiya has both versions. Tamiya has no tubes to connect them while Hasegawa has tubes for the lower but not the top oil cooler. It look like Hasegawa got the shape right while Tamiya goofed.

In the Right side pod is the radiator for the water. I have found pictures of three types. Tamiya and Hasegawa has different types.
The prototype has the tubes mounted on the left side of the radiator. This is not in the kits. It was later changed on the car.
Tamiya has the tubes mounted diagonally which seems to be right for a 1978 season car. They made the top plate with two rows of five holes were it should be a single row of four holes. The prototype had 2x5 holes.
While Hasegawa has both tubes at the bottom of the radiator. I've seen this on pictures of some of the restored cars running now and it seem to be the configuration on the 1979 season cars. It doesn't have the top plate with holes either and that is also a 1979 feature. The etch plate from Hasegawa contain the four hole plate.
Can anyone confirm or correct these speculations of mine?

It's been five years since I posted this. Has anything come to light during this time?

I also found a picture of 2x 4 holes to add to the confusion.

The other thing that is important to consider is the flow path of the coolant tubes within the radiator core. Orientation of the tubes(and cooling fins) can have an impact on cooling efficiency, coolant drag within the radiator( power loss), as well as air drag and downforce. It would seem in these various combinations that Lotus was experimenting with the impact of different configurations. As an example, the third photo suggests a longitudinal matrix tube path: in on the bottom right, up across at a header and down and out on the left. Other references indicate that the top photo had lateral oriented cooling matrix tubes. You have to see more detailed photos of the other radiators to verify their specific coolant paths.