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Howdy,

I'm a long time DIY car guy who's always been into mileage. For the past few decades I've done many of the simpler things you guys mention. A quick and possibly stupid question for you folks. Is heated intake air preferable to cooler intake air for mileage purposes? I realize hotter air will be less dense, thus requiring less fuel, which may or may not require a greater throttle opening. I'm mainly thinking about a carbureted vehicle, not only during warmup, but after as well.

One other thing. I'm a traffic signal technician by trade. In other words, I'm the guy who knows a whole bunch about how and why traffic signals do what they do. Would there be an appropriate way to submit an overview of info on how signals do their thing, or should I just put it in a post like this one? When you understand how they work, you can make driving decisions to use less fuel.

Thanks.

I just sent you a PM. I like the idea.

Sounds like an article I would like to read.

cold air is for power, warm air is for MPGs.

Yes to all of that! Using warm air in the intake tract will increase MPG in part by reducing the "pumping losses" that your engine experiences trying to suck air past an almost-closed throttle valve. Since, as you note, the warm air is less dense than cold air, you do indeed have to open the throttle further. That means less of the engine's power goes to pulling the air past that throttle valve, which allows you to accelerate while using slightly less fuel. :)

In a carbureted car, you get a second helpful effect: Warm air helps fuel evaporate better than cold air does. Liquid gasoline burns pretty poorly, while gasoline vapor burns quite well. So you can get the same power (to accelerate the car, or just tootle along at a steady speed) using less fuel, because you're burning what's there better. This matters the most when the engine is cold, but it still should make some difference even when the engine is up to operating temps.

So yeah, a warm-air intake is a Good Thing for FE.

Oh, and please post up the traffic light article! I'd love to know the hows and whys!!

-soD

Thanks for the warm air confirmation. I'll get the traffic signal info to Larry in a few days.