20V Blacktop Swap – Cooling System
By Eric Southers
Another one of the main fabrication hurdles with the swap (but one of the easiest and funnest!) is routing the coolant system lines. Luckily, the input & output of the water system is on the exhaust side of the engine.
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Instead of trying to find rubber hose of the exact shape, I purchased some 1-1/4″ 0D 6061 Aluminum pipe from a local supplier for the straight runs. It was cheap and very easy to work with.
The engine-radiator line was easy to fabricate. If you notice closely I reused a line from the 16V engine as well as one from the 20V clip.
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The radiator-engine line was more complicated since I needed to incorporate the filler neck. Also, I am not using the stock MR2 oil cooler, so I don’t need to route the line over the exhaust manifold. (if you do use the oil cooler, just mount the filler neck over the manifold.) I ran the line over to the driver’s side of the car, straight up to near the fuse box and then back over into the thermostat housing. For the elbows I just purchased 2 proper sized hoses that each had two 90 degree bends. Then just made up some brackets to hold the pipe to the firewall. I attached the filler neck to the firewall as well.
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The heater core lines are a lot easier since you just use flexible rubber hose. I forget the diameter I used, but it’s the same as the 16V lines. I used the same bracket that was on the tranny to hold the lines in place. You can sorta make them out in the below pic:
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