Who Knows the Most Efficient Intake Air Temperature?

[HannabilRox]

Any expert out there know what the ideal Intake Air Temperature is for the 3 cylinder 1.0L Metro motor?

At what air temperature does the motor run most efficiently with it's ideal air / fuel mixture?

If the ECU senses cold air ( say 40 degrees F ) does the fuel injection run leaner or richer than if the ECU senses warmer air ( say 80 degrees F )?

[hot_sd]

I don’t think there is such a temperature. Did someone tell you that. As far as I’m aware to get complete combustion air and fuel have to be mixed something like 14.7 to 1. This is the ratio that gets the most complete combustion of the fuel and maximum energy. If the air gets warmer, its density will reduce and the ECM should also decrease the fuel to maintain this ratio. So as the air gets colder or warmer the air/fuel mixture should be neither too rich or too lean. If the fuel flow is not adjusted correctly and this ratio is not maintained then the mixture will become rich or lean. The ratio is what determines whether it is rich or lean.

In general colder and more airflow will give the highest power but your fuel economy will probably go down. Turbos, superchargers and intercoolers all use this principle to increase engine output.

[91Caprice9c1]

Hot_sd is spot on here. Colder air = richer mixture, hotter air = leaner mixture again, as hot said, because of density. The ECM must have a good idea of the actual intake air temperature in order to provide the best running conditions for the motor, in accordance with the environment it is in. Tampering with this will not improve performance/fuel economy. Gasoline engines do run stronger in cold weather, because the denser air can be mixted with more fuel, giving a larger explosion in the combustion chamber.

Originally Posted by hot_sd

In general colder and more airflow will give the highest power but your fuel economy will probably go down. Turbos, superchargers and intercoolers all use this principle to increase engine output.

That's right. Turbo chargers, superchargers and nitrous all aim to increase the amount of oxygen in an engine, which is matched by a proportional amount of fuel in order to increase combustion pressure.

-MechanicMatt