Infidel
01-11-2008, 06:47 PM
This question is largely answered incorrectly and I have to correct people often, so here is the answer for a 5spd or manual tranny:
When driving down a steep hill, the safest and proper way to do it is to let the engine do the breaking, Example: I put the car in a lower gear so that the engine revs are high, but not red lining. Foot off the accelerator. Usually this will enable me to not have to use the breaks until they are needed. This is the safest way to do this.
I am bringing this up because I've been asked to go to a higher gear because the passenger thought I was wasting gas. This person knows tons about cars, but he was wrong, and here is why.
1. the brakes will over heat and stop functioning eventually. aka bad for brakes.
2. because there is negative load, the injectors duty cycle is effectively zero.
3. Idling actually wastes more gas than if I was at negative load at 6000 RPM.
What are your thoughts?
When driving down a steep hill, the safest and proper way to do it is to let the engine do the breaking, Example: I put the car in a lower gear so that the engine revs are high, but not red lining. Foot off the accelerator. Usually this will enable me to not have to use the breaks until they are needed. This is the safest way to do this.
I am bringing this up because I've been asked to go to a higher gear because the passenger thought I was wasting gas. This person knows tons about cars, but he was wrong, and here is why.
1. the brakes will over heat and stop functioning eventually. aka bad for brakes.
2. because there is negative load, the injectors duty cycle is effectively zero.
3. Idling actually wastes more gas than if I was at negative load at 6000 RPM.
What are your thoughts?