ShinerBock wrote:
4x4ord wrote:
There are times it would be advisable to manually shift or lock out gears I’m not arguing that. I am saying that revving an engine higher under light loads with the idea of increasing fuel economy is foolish. No one in their right mind is going to make it a habit of locking out overdrive gears to increase their fuel economy,
I never said to revving to 1,800 rpm is a good idea under light load. In fact I said the opposite that under light loads it is best to be at the lowest rpm and higher gear possible. The 1,800 sweet spot only comes into play when you are moderately to heavily loaded, towing something with high wind resistance(like an RV), and/or going up grades.
Also, 5th gear is still overdrive on both my Ram and your Ford so you are not taking out all of your overdrive gears, just one of them. I also have 3.42 gears which puts me exactly at 1,800 in 5th at 65 mph while 6th puts me below 1,400 at the same speed.
I guess we agree then.
When you look at the BSFC map that you posted you can see that the rpm and load you selected are for one very specific circumstance. If you start pulling a little harder the transmission is going to automatically shift down a gear. If you start pulling slightly lighter you will be getting better fuel economy in the higher gear. Towing a trailer down the road is a constantly changing load so the actual load might seldom be at the average. Even if you have a BSFC map for your engine, unless you are constantly watching your instantaneous fuel consumption and are able to calculate in your head how your mpg converts to engine torque and rpm, you will have an impossible task of knowing which gear is most fuel efficient. I'm saying it is best to keep it simple and just let "Drive" with "tow haul" do the thinking for you. The basic principle is throttle down and gear up for better fuel economy. If we find ourselves on a road where the transmission is constantly up shifting only to end up in too high of gear where it needs to recover with a downshift then I know we would agree it's time to lock out 6th.
