[hayden55]

I have found that for large v6 engines of the american style. (3.0-4.X L) anywhere from 1200-2700 RPM are within a couple % of peak BSFC.
I really tested this out on the Ranger when I only had 1,2, and 5th. I would drive anywhere from 1st to 2700 RPM at 90% load, 2nd to 3000 RPM at 90% load, then shift to 5th and hit about 1075 RPM at 30 mph and continue increasing speed at 90% load to 45 mph. (28" tire and 3.73s) Then I would just stay in 5th and cruise around at 45 mph since that is the speed limit here. A little pulse and glide with EOC and what not, DWB up to stop signs. I did note that you get charging issues doing that and wouldn't dare use the starter. I actually had a tank of cruising around town at 25 mpg for about 100 miles on a stock 1996 Ford Ranger 3.0 5 speed with EGR issues, vaccum leaks, and more sensor issues. Been working on getting the transmission back in it now that Quarantine has hit and I have more free time. It has been one hell of a pain in the ass!

*I think skip shift is the way to go on these bigger non 4 cylinder engines. Going gear to gear at 90% load on the bigger stuff is a little too brisk for me versus how slow the old 96 civic was at doing it.