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Fuel efficiency and gear changes


Chewbacca
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Guys, got a very noob question.

 

Assuming totally no obstructions (this means you are accelerating only. No need to brake or anything):

 

Will it save more fuel to:

 

always shift gear up ASAP

 

or

 

wait for current gear to go past optimal torque (or some other point) before shifting?

 

Or is this car dependant?

 

Thanks....

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rev red line all the way... no issues [laugh] ...

 

I practice 2500 RPM from 1st to 4th & 5th at 2100RPM.

Some practice 3000RPM...

 

But my current car, 3000RPM then it will consider smooth... Because, it is an Auto box [laugh]

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haha difficult to ans u.

 

last time when drive manual at least 3k rpm then change gear. now AT box hence it decides. sometimes in good moon i'll step harder though

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(edited)

To save fuel get to the higest gear as soon as possible

 

without labouring the engine.

 

Smooth acceleration and smooth gear changes also help.

 

If driving manual, match the engine speed to road speed.

 

If changing up release accelerator, if changing down tap the accelerator.

 

So gear changes cannot be felt and your passangers think you are driving an auto.

 

This not only saves fuel, it also saves on wear and tear.

 

:D

Edited by Jamesc
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To save fuel get to the higest gear as soon as possible

 

without labouring the engine.

 

Smooth acceleration and smooth gear changes also help.

 

If driving manual, match the engine speed to road speed.

 

If changing up release accelerator, if changing down tap the accelerator.

 

So gear changes cannot be felt and your passangers think you are driving an auto.

 

This not only saves fuel, it also saves on wear and tear.

 

:D

when changing up, I clutch in moments before I release accelerator...

 

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(edited)

Guys, got a very noob question.

 

Assuming totally no obstructions (this means you are accelerating only. No need to brake or anything):

 

Will it save more fuel to:

 

always shift gear up ASAP

 

or

 

wait for current gear to go past optimal torque (or some other point) before shifting?

 

Or is this car dependant?

 

Thanks....

Assuming no strong headwind, flat paved road withno other vehicle around. Change up as soon as the engine can manage it. But the engine may have higher carbon built-up in the exhaust side after some mileage. I assumed manual transmission gearbox only.

Edited by Good-Carbuyer
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To save fuel get to the higest gear as soon as possible

 

without labouring the engine.

 

Smooth acceleration and smooth gear changes also help.

 

If driving manual, match the engine speed to road speed.

 

If changing up release accelerator, if changing down tap the accelerator.

 

So gear changes cannot be felt and your passangers think you are driving an auto.

 

This not only saves fuel, it also saves on wear and tear.

 

:D

Assume along flat road with manual transmission:

Changing up to higher gears (Example: 1st gear to 2nd gear):-

Release accelerator pedal

Depress clutch pedal

Engage gear selected

Release clutch pedal

Press on accelerate pedal

The car can be travelling as smoothly as the best auto-transmission, with this method

 

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To keep accelerating you will need the power from the engine+gear ratio to deliver a sufficient turning torque to rotate the wheel faster and faster.

To maintain the high speed, you just need to keep the wheel rotating at same rpm.

 

Of course the car designer would have designed the gear ratio at the highest level to supply just sufficient torque to maintain the car speed, taking in account passenger load, air resistance etc.

So most highest gear ratio is still not fuel efficient. Which is why now we have 8-9 speed gear boxes, to further improve the fuel economy during those constant speed situation. When need to overtake or increase speed, the gearbox will drop down to say 5-6 for that extra ommp.

 

 

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Twincharged

If moving off when I am not the first car at the traffic lights or when I am not in a hurry I change at about 2000rpm. This gives me beter FC.

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someyimes i pick up faster but not insanely to cruise speed at 90 & use 6th gear all the way,

 

1 time its around 15.8kml from a fresh reset on fc digits , tuas to changi no jam

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