Effect of AFR on Economy

When Andre said, "... the best fuel economy is achieved... between 1.03 and 1.05 Lambda", is he referring to all N/A cars or this implies for FI vehicles as well?

Thanks

It should apply for all engines -the aim is to get as much useful energy out of each unit of fuel as practical. What is sometimes overlooked is the engine isn't technically running on the fuel, but using the fuel to heat the gases in the combustion chamber - the gases being primarily the ~78% nitrogen in the air and the combustion gases, primarily CO2 and H2O. The heating increasing the pressure of the gases which then push on the piston.

Some may even give best economy in the 1.1 to 1.15 range, or leaner, especially if direct fuel injection and/or lean burn engine designs are/is used.

Some dyno's can monitor fuel usage and give a read-out on the power/torque Vs fuel usage, which is sometimes useful.

If you're experimenting on the road, keep an eye on the lambda values as you try leaner mixtures, it should be gradually and consistently increasing and any irregularities or jumps may indicate a lean misfire, which will kill economy more than slightly enriching it again to get ride of it.

Thanks Gord!

Respect