Originally Posted by 360view
I find it is much, much better
to talk about MPH per 1000 rpm
instead of differential gear ratios.

If you are turning 2000 rpm at 80 mph
your ratio is 40 MPH per 1000 rpm,
etc

Doing it this way combines tire size, overdrive ratios, and differential gear ratios.

In highway driving there is considerable fuel economy improvement up to a ratio of 40 MPH per 1000 rpm,
slower improvement above 40.


I like this thought... but I like to take it another step and figure displacement per mile. Right now I am a hair over 2000@60mph. so about the same displacement per mile as if I had a 159 CID engine running 4000@60mph. if I slow it to 1500@60mph it is like the 159 running at 3000RPM at 60mph witch is close to what my neon was running in displacement per mile with tiny tires and no OD 122 CID at just over 3000 RPM, so actually I would still be slightly more displacement per mile so I don't think it is un doable, I know it is a truck but not a very big or heavy one at all by todays standards. The long term plan is to do some stuff to increase the low end TQ like zero deck the pistons and take about .030 off the heads and better spray pattern injectors... maybe a bely pan and some other aero tweaks.

I am not causing global warming, I am just trying to hold off a impending Ice Age!