Ford 3.31 or 3.55?
I am looking at Ford F350 diesel. I see there are two gear ratios to choose from. A 3.31 or a 3.55. I see they both are rated at 14,000lbs. What would be the differents between the two. Are advantage ...
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Maybe some 6.7L owners can chime in with specifics but IMO there isn't enough of a spread between 3.31 & 3.55 to worry much about it.
In theory, the 3.31 will offer slightly better fuel economy while the 3.55 will provide slightly more power. Key word, slightly...7% difference between 3.31 and 3.55.
My 2 cents: gearing is more of a factor with gas engines than diesels. My 5.4L V8 in a heavy crew cab 4x4 3/4ton benefitted from changing to 4.30 gearing-- those extra RPM put the engine closer to its prime powerband.
Diesels make so much torque at lower engine speeds that gearing is less of a factor; not a non-factor, as deeper gears still bring a bit more torque to the table, but there does come a point where it's logical to ask if more is necessary.
In theory, the 3.31 will offer slightly better fuel economy while the 3.55 will provide slightly more power. Key word, slightly...7% difference between 3.31 and 3.55.
My 2 cents: gearing is more of a factor with gas engines than diesels. My 5.4L V8 in a heavy crew cab 4x4 3/4ton benefitted from changing to 4.30 gearing-- those extra RPM put the engine closer to its prime powerband.
Diesels make so much torque at lower engine speeds that gearing is less of a factor; not a non-factor, as deeper gears still bring a bit more torque to the table, but there does come a point where it's logical to ask if more is necessary.
