Living on a prayer
Join Date: Sep 2007
Location: Salem, Oregon
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EGT's, RPM's, and MPG's
Here's my theory - is it full of baloney? I was thinking that i should drive with an eye for maintaining the lowest EGT's. Even if the RPM's are higher with Overdrive off that would mean less fuel is being used.
When I load my camper and head for the hills i weigh at least 11,000 pounds. i noticed when going up hills that i can turn off the Overdrive and let the RPM's go higher, and the EGT's decline quite a bit almost right away.
For example: Overdrive On and a steady highway hill climb makes about 1100 degree EGT's and 2000 RPMs.
If i turn off the Overdrive the RPM's jump up to 2500 when it downshifts, but the EGT's decline down to about 950.
Those are guesstimates since i can't remember the exact numbers from the last trip.
I don't recall seeing the transmission temp change either way.
Which is the wiser way to drive?
Early 99 (7/98) F-350 CC 4X4 AT 7.3L 200K mi - 4" turbo back w/muffler - AFE Stage 2 - PMT1 ECM - DP 40T/DECEL/80E - dual trans coolers - HPX - Fuel CCK - Auto Meter Trans/EGT/Boost - 3.73 - stock tires
Last edited by samiam; 08-23-2010 at 05:00 PM.