Hannibal wrote:
4x4ord wrote:
Kind of..... Saying "higher HP puts more torque to the drive wheels and pulls the grade faster." is not really accurate because HP needs to be geared to do what your asking of it. If a 500 HP tractor is capable of putting 600,000 lb ft of torque to the rear axle in low gear but has a top speed of 20 mph it obviously isn't going to be much of a match against a 396 HP Duramax towing a 10,000 lb RV up a 6% grade.
Or if you are comparing two fairly similar pickups to each other, such as was the case when Pickuptrucks.com faced off the Ford against the Duramax and Ram. The lower horsepower and lower torque Duramax pulled its trailer up the Eisenhower pass and sat and waited for nearly 2 minutes for the F350 to finally catch up. there was all sorts of speculation as to why...things like Ford's turbo couldn't spin fast enough at the high altitude of the test (and that could have played a role) but GM conducted the test; The goal was to exploit Ford's weaknesses so if high altitude was going to exploit the turbo let's pick the Eisenhower pass. Then the GM engineers looked at the gear ratios on that new Ford 6r140 and noticed how it is programed to be kind of lazy. The 6r140 will not downshift from 4th to 3rd until the engine rpm drops below 1900 rpm. They knew the slope of the hill they would choose, all they had to do was select a weight for the trucks to hook on to that would pull that poor little Ford down to just above 1900 rpm and it would struggle up the hill in 4th gear where that mighty new 400 HP Powerstroke was only producing 280 HP.
Anyway if you want a simple statement to make regarding horsepower you might be able to get away with saying something like; "Given the right gears Horsepower trumps Torque every time" But going by the actual definition of the words Horsepower and Torque are measuring entirely different things.
I think we're agreeing on the subject. Just coming at it from different angles. Peak HP numbers matter but you have to have gears matched to the engine to allow it to reach peak HP at the speed you want it too. I like the 3.73 rear gears with gas or diesel as it put my Cummins Rams just under peak hp on the grades at 60mph in direct and the gas V8 just under it's peak hp in 2nd or third with the Torqshift 5spd. I'm sure the new transmissions change everything but it still has to be geared to match the engine's power band at the speed you intend to run. Otherwise you'll be lacking horsepower.
For whatever reasons the Ford wasn't able to produce the necessary hp to run with the GM, it was still horsepower that it was lacking. That was pretty clever of GM to calculate a way to exploit the Ford's weakness. My 5.4L F250 is a little on the lazy side too. In tow/haul mode, full throttle launch will shift to the next gear at around 4400rpm rather than it's 5k rpm peak hp. Still enough hp for our lightweight 5th wheel.
I don't discount torque at all. It's the measure of an engine's strength. Higher torque means more hp at lower rpm and usually a stronger built engine overall with the exception of one that only uses 4 bolts per cylinder in it's heads. A high torque, low hp engine will likely be as strong as an ox. And just about as fast.
We are definitely on the same page. I guess I should say that my story about the GM engineers is only that....a story. I would like to call it my theory but in reality it's just my guess.
