just a little more power
Hi all, We have an 2015, F350, 6.2,srw, crew cab, 4x4. We tow a Flagstaff 2020 529RLKS, uvw 9631 lbs. We live in California, so just about anywhere you go, you go over a hill, mountain. I would like ...
Forum Discussion
mkirsch wrote:parker.rowe wrote:
I'm not sure why people think the rear gear ratio only changes rpm/mph.
It increases torque multiplication to the rear wheels. It will tow more easily in all gears. It may allow towing one gear higher than usual
If the truck is in fact a 3.73 truck, it will make a difference going to 4.30's. Ford didn't offer that option for fun.
Yes, it will increase cruise RPM in 6th by 2-300 rpm. Might loose 1mpg unloaded. But as Fish stated you may gain mpg towing.
You know WHY it "tow more easily in all gears?"
Because the engine is running at a higher RPM at all speeds!
The engine produces more HP at higher RPMs, up to the peak of the power curve.
People think "gear ratio only changes rpm/mph" because that is precisely what it does.
If you were doing 60MPH at 2000RPM with stock 3.73 gears, you will need to rev the engine to 2305RPM to maintain 60MPH with 4.30 gears, or you will only be doing 52MPH at 2000RPM.
You still have torque multiplication happening.
For easy math, lets say you have an engine with a nice flat torque curve.
100ft lbs at both 2000 and 2300rpm.
Running in direct (1:1), also to make the math easier.
100ft lbs x 1 x 3.73 = 373 ft lbs
100 ft lbs x 1 x 4.30 = 430 ft lbs
The main benefit is not that it puts you at a different rpm closer to the torque peak...it is that you increase the torque multiplication in every gear.
