[sser2]

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?