Is a 4.6 v8 enough in a full size F-150

[buickanddeere]

Um, what you are saying is the exact opposite of what you think you are saying.
Work = Force x Distance
Torque, by definition, is a measurement of work. That's why we are given torque measurements in the unit of Ft-lb
Torque - Wikipedia, the free encyclopedia

Power is the rate at which work is done


Power = Work/time
The common unit of power is the watt.
We are given the power measurements for an engine in horsepower (a unit of power), which is computed based on the torque curve.
This is why horsepower numbers can be misleading.
Power (physics) - Wikipedia, the free encyclopedia

Torque is force and can be stationary or moving. Unless there is motion no work is being accomplished.
Effective HP is the area under the rpm curve from gear shift to gear shift. The engine with an average of 300HP under the curve will perform 1-1/2 times more work than and engine with 200HP average under the curve.
No amount of rear gears will change that.

 

[buickanddeere]

Um, what you are saying is the exact opposite of what you think you are saying.
Work = Force x Distance
Torque, by definition, is a measurement of work. That's why we are given torque measurements in the unit of Ft-lb
Torque - Wikipedia, the free encyclopedia

Power is the rate at which work is done
Power = Work/time
The common unit of power is the watt.
We are given the power measurements for an engine in horsepower (a unit of power), which is computed based on the torque curve.
This is why horsepower numbers can be misleading.
Power (physics) - Wikipedia, the free encyclopedia

Yeah I slipped and put time in there when I should not have.

 

[buickanddeere]

How about 500 lb-ft at 2000 rpms vs 1000 lb-ft at 1000 rpm. Which engine do you prefer? These engines would have the same HP. The higher torque engine would out accelerate the other because acceleration follows the torque curve.

It's get more complex than that.
Four stroke diesels have a short rpm range to accelerate in and torque drops rapidly towards redline. The Two Stroke Detroit had a very flat torque curve. It felt like an unlimited powerhouse right up to redline. It did not however have a torque rise when lugged which make a four stroke "feel" more "powerful". The four stroke was being lugged down to the rpms when the volumetric efficiency improved and the cylinders were filled full and had higher combustion pressure.
Getting back to the engine with the broad torque curve from 2000-5000rpm is always in it's "power band".

 

[merlynr]

My 05 Mustang GT 5 speed was equipped with the 4.6 3V engine and was rated at 300hp and the ecu was governed to not go over 129mph. I hit 105 once and it was still loafing along. People in the know said dynode at about 290 or so hp. The engine was physically large compared to a 302. The car would consistently get 25+ mpg on the hwy and I always thought it would be a good 1/2 ton engine with the right gears. Anyway we traded it for a v6 Edge.

 

[buickanddeere]

How about 500 lb-ft at 2000 rpms vs 1000 lb-ft at 1000 rpm. Which engine do you prefer? These engines would have the same HP. The higher torque engine would out accelerate the other because acceleration follows the torque curve.

1000rpm engine would need more gears and has a narrower power band. The 1000 rpm engine would be fine for HD stationary power to generate power, pump water. plough a field or power a locomotive.
That's what highway tractors have 13 or more gears and so much time is spent shifting.
A highway light vehicle application benefits from the higher speed engine, lower peak torque engine with the wider power band making the same HP.

 

[buickanddeere]

Only when the 245 hp engine is operating at the proper rpm to produce that HP. That is what he was getting at. For another example, I have a souped up 250 cc motorcycle that makes 30 HP at 15,000 rpms but only 8 lb-ft of torque at 2000 rpms vs my Kubota making 30 HP at 2400 rpms and a whopping 55 lb-ft of torque at 2000 rpms. Which would you find easier to get a trailer rolling? Both can get the same work done because they are they same HP. Problem is and as was said, either need to slip the clutch or have some serious gearing on that motorcycle. So i guess i am one of those guys that say torque torque torque for the purposes of this forum.

I'm saying the same thing. Each engine is designed for it's application. The light highway engine falls between the two extreme of your illustration.

 

[HHR]

I've had two 4.6 F150s. The current one (2000 RCLB 4x4 3.55 gears) is pretty gutless and I think our V6 F150 would outrun it to 40 mph. Loaded 2600 pounds of concrete PermaBlock in the back today and the truck downshifted to second on hills where it normally just barely drops to 3rd. 4.10 gears would help a little bit, but the truck just doesn't have torque.
My 1996 4.6L Lincoln Town Car with a 7100 pound GVW Special Service pkg. was a completely different animal. It had factory dual exhaust, a different intake and the heads were different also. That engine was much more responsive and seemed to tow just as well as the 4.6 trucks even though it had higher rear end ratio.

 

[sld]

In the narrow scope of 1/2 ton gas engines, the one with the most area under the dyno TORQUE curve will out accelerate and pull a trailer better.

HP, while a measurement of work, is also just an indicator of what rpm range the power is being made.

You can win an advertising hp war by making peak hp at a very high rpm. That will NOT translate into better towing. Torque rating and at what rpm is what matters.

 

[94BULLITT]

Why can a engine with less torque but similar power pull about the same as one with more torque?

I've had two 4.6 F150s. The current one (2000 RCLB 4x4 3.55 gears) is pretty gutless and I think our V6 F150 would outrun it to 40 mph. Loaded 2600 pounds of concrete PermaBlock in the back today and the truck downshifted to second on hills where it normally just barely drops to 3rd. 4.10 gears would help a little bit, but the truck just doesn't have torque.
My 1996 4.6L Lincoln Town Car with a 7100 pound GVW Special Service pkg. was a completely different animal. It had factory dual exhaust, a different intake and the heads were different also. That engine was much more responsive and seemed to tow just as well as the 4.6 trucks even though it had higher rear end ratio.

Does the 4.6 f-150 have big tires like 265/75r17?

 

[HHR]

Why can a engine with less torque but similar power pull about the same as one with more torque? Does the 4.6 f-150 have big tires like 265/75r17?

255/70r16 which is the stock size.
I think my Town Car had the towing package which gave it a 3.27 ratio.