Throttle Position During Acceleration and its effect on FE

[omgwtfbyobbq]

The relationship depends on how much pumping/friction losses are wrt to your engine. If you know what engine's in your car, find the BSFC map and you'll have all you need to know. Unless you have a drive by wire system... And in that case, you are teh scr3w3d. Anyway BSFC maps show you just how efficiently your engine is operating at a certain load/rpm. For instance, when I'm cruising at 55mph in my (moms) 92 V6/auto Camry (dotted lines I think) , my BSFC is greater than 500g/kwh because I'm using very little hp/torque compared to what the engine is capable of. Larger displacement engines have to pump more air at a given power/torque level, and suffer from a decrease in efficiency as a result.



Specifically, my engine is operating at ~16% efficiency when cruising at ~55mph. So even though at near full throttle, from ~1.7-3k rpm, my engine is running at ~32% efficiency, most of the time it's running at, or around, or less than half of that. Ideally I can probably get around 60mpg since I get ~30+mpg@55mph, but due to CA drivers and auto transmission, I probably won't see that. Anyway, pulsing and gliding, codfishing, whatever you want to call minimizing pumping losses, works. The driver can maximize how much it works, and determine what their optimum FE is for a given P&G cycle/conditions provided they have the BSFC maps for their vehicle, or spend enough time experimenting.