Originally Posted by Jeremy2792
Now, which action takes more gas?
-Driving in a high gear, but giving the engine full throttle?
-Driving in a low gear, but giving the engine little throttle, resulting in high RPM's.
So which burns more gas? Pedal to the floor, or high RPM's?
I have to disagree with the higher RPM less throttle using more fuel.
Fuel use is directly related to load place on an engine, Particuarly in an EFI controlled engine, Higher the load=low vacum=higher injector pulse width.(pulse width is also controlled by throttle position, TPS sensor)
At higher RPM with little throttle, yes the injector must cycle more than at a lower RPM, but the pulse width is much lower. (I am assuming just cruising, and not a WOT blast. )
So if you are going 40 mph in say first gear the RPMs are at ,say 8000 and the throttle is only open a fraction. High vacumn and very little fuel is needed to maintain this. But Go the same speed in 6th gear with the RPMs very low and the throttle wide or almost wide open is going to create low or no vacumn (higher load) with will raise the injector pulse width and use more fuel.
Here are a couple other examples.
*Copied from another site*
1- How Engines Use Gas
When you press your
gas pedal, your gas consumption goes up, right? Many people believe
the gas pedal is connected to the fuel pump somehow, but this is
technically incorrect. Instead, the gas pedal simply opens a valve
called the throttle. All this valve does is to allow air into the
engine. The more open it is, the more air enters. So, the term "gas
pedal" is really a misnomer...it's more of an "air pedal". Anyhow, as
the air entering your engine changes, sensors pick up this info on the
fly and adjust your engine gas intake electronically. In older cars,
this was done through a carburator, a rather ingenious device. This
means simply - the further you push your gas pedal down, the more gas
you burn. It does not matter what gear you're in; how fast your
engine is revving, or really anything else. Gas pedal goes down; gas
cunsumption goes up.
#2
Any engine is at its most efficient, when its RPM is HIGH, and
the load on it is LOW. When you are in a high gear, the load on the
engine is greater, and a slight up hill can easily reduce the RPM,
meaning that there is a greater load on the engine. By shifting down a
gear at that moment, you will effectively reduce the load on the
engine, and the RPM is able to come backup. Yet you have not pressed
the accelerator down any further, thus your fuel (energy) consumption
is still constant.