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Quote:
ORIGINAL: HankL
Gearing
A vehicle that is either overgeared or undergeared will lose MPG at highway
cruise. In city driving gearing doesn't matter nearly as much as not having
a 'heavy foot.'
An engine is numerically overgeared if it is not cruising at about 60-75% open
throttle.
An engine is numerically undergeared if it is trying to cruise in the 'Power
Enrichment' zone above about 80% throtttle where the PCM computer
greatly enriches the air to fuel ratio.
For the same reason anyone who presses the accelerator down all the way near
the floor whether they are driving in the city, highway, climbing a hill, or pulling a
trailer is going to get about 25% worse MPG than someone who presses right up to
about 70% throttle but never goes over it.
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I find this interesting HANK... I’m willing to bet you did not realize this information is on a NON-overdrive vehicle.... If it’s not then it’s REAL bad advice for a vehicle with a .67 overdrive ...like those who own 3rd Gen Rams... I just returned from a road test where I monitored the throttle % and RPM’s... and it was no where close to your 60%-70% throttle opening....
The FACT is at 65MPH on flat ground with 4.56's & (SHORT) 29.75” Tall tires my throttle opening is 13.5%@2631RPMs (At this exact same speed/RPM I was able to get 20+MPG average of 2400 miles from DFW Texas to Deltona Florida and back) at 70MPH it was 15%@2744RPM's ....No where close to Hanks suggested 60-70%... I’ll have pictures up soon of the SAFC-II readings. Now I don’t doubt that if I had Overdrive off that I would have been WELL over those throttle % openings... So I can only assume his information is accurate for NON-overdrive vehicles.
So Hank, since we are part of a 3rd Gen Ram community … do you have any suggestions that pertain specifically to 3rd Gen Ram owners through your own personal experience with your very own 3rd Gen Ram? I don’t think you do because you don’t have one. So how can you offer suggestions and WORSE tell people like myself that my experiences with the 3rd Gen Ram are not accurate when you don’t even own one!
SPEED SAFE, AIR RAM