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Old 12-17-2011, 01:03 AM   #12 (permalink)
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Originally Posted by meelis11 View Post
Anyone has good examples to show how to set up exhaust heat exchanger?
Basically you need to wrap copper pipe around exhaust and coolant flows through that spiral? How many wraps around exhaust?
How much is it possible to make warmup time quicker?

That autospeed idea seems really good to use it as heat battery - to preserve waste heat that in the morning you get engine warm sooner.

I'd be wary of adding any weight to my car, but an exhaust heat exchanger sounds like a great idea, if you could overcome some practical problems. I'd be interested in how Toyota overcame some of them - specifically, you don't want the exhaust heat exchange to be part of the cooling loop once the engine is up to temperature... however, simply changing how the thermostat functions (instead switching from exhaust heat exchanger to radiator loop once up to temperature) would not work, as the liquid in that part of the loop would quickly reach astronomical temperatures. Instead, you would need to somehow decouple the heat exchanger from the exhaust at some point.
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