View Full Version : Wedge Oddities of the TR7 cooling system

05-22-2006, 08:16 AM
Now that my car is up and running, it is time for UPGRADES! And an improved cooling system is top on the list.

Now as I started my planning and plotting, I noted something that seemed rather out of place and that was the plumbing differences between my 76 TR7 and my 80 TR7. Although the expansion tank with the radiator cap were a plus, the problem with the coolant path seems to be a glaring design error. If I have the flow reversed out of the engine, the error seems to be the same.

In this image of my car (above - 80 Spider), the coolant from the engine comes into the radiator (1) from the thermostat housing (3). The expansion tank (4) is attached at the radiator (2).

In this image (above - orange 7), the coolant exits the engine (6) at the thermostat housing and enters the radiator (7). The coolant flows right and down across the radiator and back into the engine (7).

A friend of mine, a NASCAR engineer, took a look at it and here is his 2 cents (actually, it was about a $30 steak).

The way my Spider is set up is inefficient by about 30-40% because the coolant takes to shortest path out of the radiator. (below)

To maximize efficiency, coolant must take the longest path through the radiator. But with the way it is currently set-up, I get coolant back to the engine the fastest way possible, but it is not the coolest it could be. The shorter round-time brings in more thermal energy back to the engine than it needs.

In the second image of this post, the thermal map would look like the image below (radiator pattern 2).

As you can see, the second set-up (second image in post) has the most effecient performing cooling set-up.

Any idea what model year this changed? The second example is an image I pulled off the web somewhere and both seem to be LHD cars.

Anyone made the changeover to the radiator pattern 2? Anyone else notice this?

1980 TR-7 Spider



05-22-2006, 08:20 AM
i thought that there was a baffle between the input and output preventing direct water flow between the input and output ports?