Why are there two different I-6 motors listed
 

for the f-series trucks? I was looking at some info on the 1991 f-150 and it listed 150HP and 145 HP under engines.....anybody know why? Is one for towing? Maybe more torque?

what are you looking at :confused:

If you're looking at the EPA's fuel economy database, e.g. at fueleconomy.gov, it's because two different variations on that engine were offered. Different torque bands or emissions specs are good guesses.

KBB.....

how do you know which is which by looking at them? My brother thinks he has the 145 and I think I have the 150 but not sure. His revs WAAY quicker but doesn't have the torque mine does.

Both are wrong as there were three different 4.9 I6 motors.

4.9 L I6 1987–91 165 hp (123 kW) 275 lb·ft (373 N·m) EFI
4.9 L I6 1992–93 145 hp (108 kW) 265 lb·ft (359 N·m)
4.9 L I6 1994–96 150 hp (110 kW) 260 lb·ft (350 N·m)

Being a 1991 you should have the 165hp unless the truck was one of the last off the line and they used the 92 motor.

Try https://www.fleet.ford.com/maintenan...ls/default.asp and see if it will give you the engine details.

manufacture date is 3/91, so it seems I got the "big" one....that might explain the different behaviors of the two motors. Almost like a gas vs diesel. His is very snappy and quick and mine feels heavier but is not lacking in the torque dept. It can get moving in a hurry if I am willing to sacrifice some fuel.

What about just the regular old california vs US version?

I know lots of things are made 49 state legal, and then they have some extra cats/emissions equipment for the ones sold in Cali.

If it "feels" like that much difference, his probably has higher ratio axle(s).

He is running a 2.65? and I am running a 3.55.

I just noticed on the door are the remains of a large decal that had "construction" in it. Looks like they tried to sand it off? That would explain why the engine runs so good. I don't know why I never noticed it before. The ford FLEET lookup does not match the label in the truck. The FLEET lookup says it has a GVWR of 10,000 lbs and the door says 6600. The wheel bases are also different. Should I go by what Ford says or the sticker? I know this thing will pull anything and will carry a full cord of wood with no problem.