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Old 02-08-2018, 07:53 PM   #1 (permalink)
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Cooling tunnel for winter driving

Economy performance of gasoline engines dramatically deteriorates during winter time. In my 3 cyl. 5 speed Metro, I am getting about 5.5 mpg overall difference between summer and winter. Engine performance also suffers. I don't have proper measurements for that, but I am regularly climbing the same 6% 5 mile long incline in 4th gear with fully open throttle, and can judge power from the attained speed.

The most important cause of deteriorating winter performance is undoubtedly poor gasoline evaporation at low temperatures. Compared to warm weather, more gasoline enters the engine as liquid film that remains unburnt.

Jacketed intake manifold, heater plate, or warm air from around exhaust collector don't make much difference due to high volume of air flow.

Here is an idea. For winter driving, bypass the radiator with a cooling tunnel made of 3 stacked heater cores whose coolant passages are paralleled to maintain proper coolant flow. Warm engine air is then taken from behind the tunnel.

Thoughts?

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Old 02-08-2018, 09:27 PM   #2 (permalink)
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Yeah some one did a thermostatic WAI with a heater core on here.

My belief is that exhaust heat is better.
It takes about 20 seconds for the exhaust manifold to get hot and it's true waste heat.
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Old 02-09-2018, 02:22 AM   #3 (permalink)
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Quote:
Originally Posted by oil pan 4 View Post
My belief is that exhaust heat is better.
It takes about 20 seconds for the exhaust manifold to get hot and it's true waste heat.
The problem with hot air from exhaust manifold is that small heat exchange surface area on the one hand and huge airflow on the other do not allow efficient heat exchange and appreciable increase in intake air temperature. I tried drawing hot air through a hole in exhaust manifold shield. It accelerated engine warm-up a little bit, but did not improve fuel economy.

Heat from radiator is as true waste heat as that from exhaust.
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Old 02-09-2018, 07:45 AM   #4 (permalink)
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If your grill is blocked, there will be less air flow in to the engine compartment to cool off the exhaust manifold. Wrap something larger around the manifold to suck the air in around.

I've done two Metros where all I did was take a 4" aluminum dryer duct, and cut a slice in the last foot of it and strapped it to the exhaust manifold. Worked great. Much faster warm-up, much smoother and peppier engine. You will notice a bit less power at WOT, mind you.

I did the math, based on the maximum air flow of the metro engine and a rough approximation of the surface area of the exhaust manifold and an typical manifold temperature and wound up with something along the lines of it being able to raise the temperature of that much air by something like 25 degrees centigrade. Most of us don't drive around at WOT, so realistically, it can warm up the air even more...Real world would be different, but the potential is there.

Found my math...31 degrees, based on a temperature difference of 500 degrees, the manifold having ~1 square foot of surface area, and the metro engine running full out...

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