Ted B. wrote:
>>>Best I can come up with at the moment is that the engine in my current
>>>car
>>>is a Mitsubishi "4g64" 2.4L inline 4. -Dave
>>
>>Really I was just curious if there was anything magical about 40% or
>>redline, or if that happened to coincide with the torque peak, which
>>I've always heard was a good approximation of where the BSFC map is
>>most favorable even under part throttle conditions. Having a nasty
>>Real Job(tm) I can't be looking for that info just at the moment
>>
>>nate
>>
>
>
> Well, I found some numbers for the Nissan 3.5L V6 (aka Maxima) engine. This
> engine has been one of the best automotive engines in the world for several
> years, so I think it's a good "example" to use.
>
> Redline is 8000, so maximum fuel efficiency should be about 3200RPM, for
> that particular Otto Cycle engine (8000 X .4). Peak horsepower is 265 at
> 5800RPM and peak torque is 255 at 4400RPM. Nissan does use variable valve
> timing, but this would tend to favor lower RPMs, as higher RPMs don't need
> the valve timing trick to produce more power or torque.
>
> SO, peak fuel efficiency RPM for that particular Otto Cycle engine seems to
> be below -both- the horsepower and torque peaks, which makes sense. You
> don't need MAXIMUM horsepower or torque to keep a car moving, but more
> torque will be helpful for acceleration.
>
> Now I want to hear from Nissan Maxima 3.5L owners . . . what speed (MPH) is
> equivalent to 3200RPM engine speed in your Nissan Maxima in top gear (O/D
> enabled, if it's an automatic)?

It is well over 80 mph, and, with my 2 recent speeding tickets, I never
cruise at that speed.


If you pay attention to RPM or MPH, have
> you noticed an increase in fuel efficiency at that speed??? Since it's an
> Otto Cycle engine with an 8000RPM redline, it should be most fuel efficient
> around 3200RPM (8000 X .4). IS IT most fuel-efficient near 3200 RPM? -Dave

I dont have hard data, but no way it is most efficient at that kind of cruising
speed.