Dirttracker18

It's all about the weight difference!

I noticed a significant difference going to bigger and heavier tires. When I switch back to my smaller and lighter winter tires I get a lot of power back.

Don't discount the difference weight makes vs power. In racing I am happy if I can find 10# to take off my car. A difference in hundreds of pounds exists between the F150 and F250. Add about 500# of weight to the F150 in the bed and then drive the two of them

Edit:

Base curb weight of the F250 in SCREW 4x4 in 2005 is 6321#
Base curb weight of the F150 in SCREW 4x4 in 2005 is 5577#

Difference between them is 744# assuming they are identically dressed, plus the add ons you mentioned earlier. Could be close to 1000# difference when it is all said and done.

That is significant!

650NutKase

My vote is on this. Gearing can make a world of difference off the line. The extra weight of the 250 is also a big factor.

WarSurfer

Pretty standard equation for calculating weight reduction benefit is 100lbs=~10rwhp

So a 1000lb delta is equivalent to a ~100rwhp delta.

The OP stated they have the same gearing. There may be some issues with one needing new plugs/wires, etc but in this instance weight is the primary cause of delta in acceleration.

FordBoy05

Forgot to mention previous owner said the truck was tuned. I'm not so sure I believe this. The truck just seems more responsive, a lot more power and firmer shifts. Is there any way to tell if the truck is tuned?