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> Higher gears require fewer revs on the highway, leading to improved gas mileage. He seems to be suffering from the common misunderstanding that higher revs =
by sacrosancty 4y ago
> Higher gears require fewer revs on the highway, leading to improved gas mileage.
He seems to be suffering from the common misunderstanding that higher revs = higher fuel consumption. Those extra gears aren't at the top end to reduce torque at high speed (what?), they're spread more uniformly to keep the engine operating in an efficient or powerful region.
- rightbyte 4y ago> misunderstanding that higher revs = higher fuel consumption That is a good approximation. Each revolution has to do a somewhat fixed amount of work due to resistance. However too low revs will mess up milage too due to bad combustion.
- euroderf 4y agoA question tho. A manual transmission makes engine braking possible. But I never quite understood whether engine braking actually does suck a lot more gas thru the carb. In other words, when your foot is off the gas but there is high airflow thru the carb, does it draw gas ?
- lagadu 4y agoFor cars with carburetors, yes it does use a little fuel because some air will get sucked into the engine. Fuel injected cars use none because they simply don't activate the injectors if you're not pressing the gas pedal.
- rightbyte 4y agoModern cars use injection systems and usually cut of injection when you request no torque (unless the motor need to keep idle rpm to not die). Note that engine braking is possible with automatic too.
- sacrosancty 4y agoResistance in the engine isn't a major source of power loss. RPM should be whatever is optimal for the power output. You don't reduce highway fuel consumption more and more by using a higher and higher gear because then the engine is running below its optimal rpm for efficiency.