V6 v V8 v Diesel

[DocMT]

I'm not gonna debate the physics behind it.. but I can assure you you are wrong here. I've had the 4l V6 in my Tacoma with 32s on it and the 4.7l V8 in two different 4Runners both with 33s. The 4Runners both get better mileage climbing the mountains several times each winter than the V6 Tacoma ever did (which was lighter and had smaller tires). Simple fact that the V8 stays in a more efficient portion of the power-band for the motor than the V6. The V6 was always hunting for gears going up the hills, the V8 for the most part stayed in the gear it was in.

So you can argue all you want, but simple fact is that I've had both motors, and the 4Runner get's better mileage in this situation.

Do some research on how & when an internal combustion engine is at its best and worst efficiency and you'll understand the reason why I'm actually correct.

Bottom line is that large throttle openings (at the lower end of the RPM scale) is where an engine is most efficient. You have to consider three things: combustion efficiency, pumping losses, and internal friction. At the end of the day, a smaller engine working harder is usually more efficient than a larger engine that's not working as hard. Most people have a hard time understand that, but if you do your research the reasons will eventually make sense.

 

[JB.]

Bottom line is that large throttle openings (at the lower end of the RPM scale) is where an engine is most efficient. You have to consider three things: combustion efficiency, pumping losses, and internal friction. At the end of the day, a smaller engine working harder is usually more efficient than a larger engine that's not working as hard. Most people have a hard time understand that, but if you do your research the reasons will eventually make sense.

Sounds like you're throwing a bone to the V8 argument, and don't forget the torque converter. Two 4runners going up the same grade, same speed. V8 is in 4th gear with torque converter locked. V6 is in third, converter unlocked so V8 is running at, what, 800 or so fewer rpms with a direct connection to the wheels while the V6 has the higher revs combined with some converter slip.

 

[DocMT]

Sounds like you're throwing a bone to the V8 argument, and don't forget the torque converter. Two 4runners going up the same grade, same speed. V8 is in 4th gear with torque converter locked. V6 is in third, converter unlocked so V8 is running at, what, 800 or so fewer rpms with a direct connection to the wheels while the V6 has the higher revs combined with some converter slip.

This thread is already a mess, so I'm trying to avoid going into detail about yet another aspect of the debate. So at this point I'll just say that your example would completely depend upon several factors. The transmission in either vehicle could very well be in the same gear and the torque converter may or may not be locked.

 

[JB.]

This thread is already a mess, so I'm trying to avoid going into detail about yet another aspect of the debate. So at this point I'll just say that your example would completely depend upon several factors. The transmission in either vehicle could very well be in the same gear and the torque converter may or may not be locked.

Lots of things "could be". I'm just pointing out a specific, non-rare running state in which the V8 could conceivably be more efficient.

 

[Dlak]

re

I'm forwarding this to Mythbusters.... End of thread!

 

[SP Jon M3]

... At the end of the day, a smaller engine working harder is usually more efficient than a larger engine that's not working as hard. Most people have a hard time understand that, but if you do your research the reasons will eventually make sense.

** See the Top Gear segment where they race a Prius and an M3. The M3 actually gets better gas mileage in the race because they've taken the Prius out of its performance envelope. The M3 is basically lazily strolling around the track while they are thrashing the Prius to get the same work.

Humm..

Do some research on how & when an internal combustion engine is at its best and worst efficiency and you'll understand the reason why I'm actually correct.

Umm.. I've had both engines, and have had them up several times a year to the mountains. I believe I've done enough research, i.e. filling of the gas tank, to know that I am correct.
This is where I'll leave it. But I'll still be :snacker:

 

[DocMT]

Humm..



Umm.. I've had both engines, and have had them up several times a year to the mountains. I believe I've done enough research, i.e. filling of the gas tank, to know that I am correct.
This is where I'll leave it. But I'll still be :snacker:

That's funny because I've also had both engines and I've found the V6 to be more fuel efficient despite working "harder" than the V8.