# fuel consumption - gear - rpm relation

I'm wondering how does the rpm on different gear affects mileage. I'm not even sure it affects at all.

Let's say on a 6 gear, 15000 rpm motorcycle engine system. My questions are

1. Will 6k rpm on first gear and 6k rpm in 6 gear consume same amount of fuel?
2. Same rpm, same gear one on a straight road, one is climbing uphill, will these consume same amount of feel?

The speeds will vary considerably in such configurations, feels like the consumption will be same, but when I think about it there are differences, hence I'm confused.

• Imagine another example. a) Car going 50 km/h on a straight road, 3rd gear, 1900 rpm. b) Car going 50 km/h on a straight road, 3rd gear, 1900 rpm, hauling 20 t trailer :) Don't you feel that when going downhill you have to release gas (even letting go completely, using engine as brake) vs. going uphill when you almost hit the pedal to the floor :)
– Mark
Commented Feb 17, 2017 at 10:16
• Or let's say you are on 5th gear and trying to take off, no matter the rpm it will need much more fuel than on the 1st gear because it will require much more power(throttle). Right? Commented Feb 17, 2017 at 10:31
• Keep in mind that your consumption will be based on your throttle position not the RPM but even then you will travel less distance in lower gear. Meaning you will have less efficiency. Just in case if you were wondering about fuel efficiency but forgot to mention in your question :) Commented Feb 17, 2017 at 10:45
• Actually yes, the fuel efficiency matters invoked this question on my mind. So original version of my concern was "is higher gear always better for fuel efficiency?". By looking at these answers and commments, I can say not always. Being on the right gear is the right choice for the fuel efficiency. Commented Feb 17, 2017 at 11:11

## 1 Answer

It depends on how far you need the throttle open in each of your described situations to maintain the 6000 RPM. If the throttle is in the same position in both situations, then the same amount of fuel will be used per revolution. If one situation requires a more open throttle, then more fuel will be used per revolution.

• so this means, same amount of fuel does not always spin the engine for same amount, it's up to the power we need out of the engine. Right? Commented Feb 17, 2017 at 10:29
• That is right. If you rev the engine in neutral, very little fuel will be require to take it up to 6000RPM. You will only need to open the throttle a tiny amount. Commented Feb 17, 2017 at 10:48