Is it horsepower or torque that determines how well a truck is going to pull a load or trailer? Lets say an 08 Silverado has a 4.8L with 295hp and 305ft-lbs and an 08 F150 4.6L has 248hp with 295ft-lbs. Is there going to be a noticeable difference in pulling a trailer with the same weight (Lets say a 6,000lb trailer)?

 

I believe that it's both.

Torque is the guts to get the load rolling from a stop.
Horsepower is what it takes to keep things rolling at higher speeds.

The 300 straight six was a great example of this.
You could get rolling just fine and stay with some v8's from a stop, but once you got on the highway, you could barely hold 55-60 mph, especially on a hill.....

The 300 had lots of torque, but not a whole lot of HP.

I just experienced this on a trip to Florida with my "new" truck.

My old truck is a 91 F250 with a 7.5L (460).
My camper is about 3000, 3500 loaded, and I could run 70-75 mph easily and use the O/D.
My new truck is a 97 F150 4.6L.
With a similar weight trailer, maybe a bit lighter, but the same frontal area, I could only run with the O/D off, and could barely hold 65 with out either coming out of TC lock, or downshifting.

The rearend ratio was the same for both trucks, 3.55.
The tire diameter was pretty close I think on both trucks, 235/85/16 vs 265/70/17.

I love that the 97 looks pretty and is not a rusty working girl like the 91.
But sometimes I sure miss that big block.

The 91 would run at about 2000 rpms in O/D at 70-75 mph and get around 11mpg, towing or not. (My all time high MPG of 12.5 was towing 3500 with another 900-1000 in the bed....go figure)

The 97 ran at 2500-3000 at 65-70 mph and I got 7.5mpg on the Florida trip.

I guess there truly is "No replacement for Displacement".

 

yea i agree with the above post, i had the 300 striaghtsix, but like u said great off the line, sucky on interstate and higher speeds, but if you dont have torque, you dont have anything IMO, you notice why the 4.6 has almost 300 ft lbs, its a small motor but torquey so it can pull pretty well in a half ton truck

 

(torque x engine speed) / 5252 = horsepower, where torque is in lb-ft and engine speed is in RPM.

Take the peak torque and related RPM - can figure the horsepower at that engine speed - should be less than the peak horsepower rating given. Take the peak horsepower and related RPM - can figure the torque available at that engine speed - should be less than the peak torque rating given. Just another degree of difficulty and confusion toward figuring out the best-us answer.

Rated torque and horsepower are posted at specific engine speeds. Don't think that most would want to operate at the peak horsepower RPM for extended periods. Look at the rice-burners - most have what seems to be disproportionate horsepower for their given engine size - but holy crap - look at the RPM where this max horsepower is rated - talk about a ring-tinging, wound-up-tight, sing-songing motor - what they lack in torque, they make up with speed!

Transmission and axle ratios, along with tire size determine what road speeds are possible at given engine torque and horsepower peaks.

Suggest one goal would be to size ratios and tire sizes appropriately so that the engine is operating near the engine peak torque speed at the desired road speed. But then have to look at the horsepower available at that engine speed - and hope that it's enough to pull the load up whatever hills (gravity) and overcome wind and friction (bearing/driveline) resistances.

Torque is 'oomph' - if you can't pull a load with the engine at this peak rated RPM - then you just ain't gonna pull it in that gear. If you can pull it, then the horsepower available at that engine speed will determine how fast you're going to accelerate.

Horsepower is energy - essentially the engine speed where one will pull the mostest total pound-miles-per-hour in a given gear.

For the original question - suggest the Chevy will be able to pull the load 'better', although at an engine speed that may be uncomfortable, and one may have to run in a lower gear to meet the basic torque requirement.

Keep in mind that most pickups have the aerodynamic properties of a brick wall - and that wind resistance increases exponentially with speed - so that a 10% increase in speed may require a 15-20% increase in the horsepower required to push air out of the way.

Sure, this is confusing - difficult to give specific answers without considering all the data - tranny gear ratios, axle gear ratios, tire sizes, aerodynamic resistances of the truck and the trailer, etc. But agree with the general rule - no replacement for displacement - although gear ratios and tires can help close the gap.

 

They both matter equally in my opinion... but the engine is the least of the worries nowadays compared to the frame, suspension, traction etc.

 

My I6 does fine pulling my 10' box trailer. No problems keeping speed, starting from a stop, or anything else. I even use overdrive with no problems. But above torque or horsepower, BRAKES are most important.

 

I pulled a UHAUL tandem trailer helping someone move&this thing was loaded up.My 05 F150 STX with the 3.55 rear 4.6 liter engine pulled it flawlessly.She held up the speed pretty good.I would have liked the 5.4 liter engine but I dont pull a trailer for a living.Some guys on this thing do&require a larger engine....Pete

 

HP is a mathematical derivative of torque. Without torque you don't have HP. Overcoming wind resistance will require torque not HP. The reason the I6 dies at highway speed is because it has run out of torque at the rpm required to maintain highway speed. Both trucks will pull the load but without knowing what the final gear ratios are and what the torque curves are you cannot tell which truck will pull better. On paper the Silverado has more torque but at what rpm? The 4.6 is allegedly designed to have 90% of its torque available at 2000rpm. Not sure of the Silverado.


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