Higher horse power is not a factor for fuel economy

Another gross oversimplification of the concept. Torque is twisting force, horsepower is twisting force and speed. If you have two engines making the same torque, but engine A is making the torque at twice the rpm, it is putting twice the torque on the wheels due to gearing. It is also making twice the horsepower.

 

My god man, you need a Haney tune. Get all that extra crap turned off in the ECM and let it breathe.

 

It was explained to me that torque is the ability to do work and HP the work accomplished.
Just a thought!

 

Torque is turning a bolt to say a 100 lb/ft. Horsepower is how many bolts you can tighten to that spec in a given amount of time.

 

Formulas that apply to this thread.

When hp is known...HPx5252÷rpm=torque value.

When torque is nown....torquexrpm÷5252=HP.

Notice that you divide by rpm to get torque values and multiply by rpm to get HP values.

Torque is a force used to rotate around a fixed point of rotation, like a shaft.

HP is work over time. HP does not have to be around a point of rotation. Torque does.

 

Torque is how fast you can reach top speed befor you run out of horsepower. How fast your top speed is depends on horsepower.

Your crusing along on a flat stretch and hit a hill... You start slowing down because you don't have the horsepower to maintain the same speed going up th hill. If you stop on the hill and start again it's the torque that will bring you back up to speed. Up untill the point you run out of horsepower.

It's usually a trade-off between one or the other. Top-end low-end power/to que. Only so much of each to go around. What gains you torque usually decreases hp. Visa versa.

/necro

 

If you take two identical trucks with identical weights, identical drivelines and physically identical engines, but one is programmed as an econo engine that makes 450 hp and 1650 ft/lbs of torque and the other is a performance engine with 550 hp and 1850 ft/lbs of torque and they are driven the exact same way at the same speed, there should be very little or no difference in fuel economy.
Way to test this, put the higher hp truck behind the low hp truck and have it follow the low hp truck from point A to point B without passing it.
The torque doesn't really matter because both trucks will use the same amount of hp to do the same job, at cruise speed full torque is not required but is available, same with hp.
If 200 hp is needed to keep the lesser truck rolling at highway speed, then the other truck only needs 200 hp to do the same work and there should be no difference in fuel economy unless the more powerful truck gets out there and starts using that extra 100 hp.
I used to get great fuel mileage when I followed slower and less powerful trucks.

 

Personally, I see it this way.

If you need to accelerate your loads faster, you need more HP. In any application, be it commercial or competition, HP = Acceleration.

If you need to MAINTAIN a certain speed, Torque becomes more important. The vast majority of vehicles hold their cruise speed at the same RPM and so the more torque you have, the easier it is to maintain a given speed.

If you have low HP, it'll take longer to accelerate because your torque runs out too quickly and you have to shift sooner than appropriate.

If you have low torque, your cruising speed will be slower because you need to run a couple gears lower to generate adequate torque.

 

This zombie thread is 5 years old.

Your fuel economy depends entirely on your cruising speed. Aerodynamic drag is the primary factor, and it increases as a square of your cruising speed. Double your cruising speed, and you increase your aerodynamic drag times 4. Triple it, and you increase it by 9 times.

 

Not adequate torque, you will never have adequate torque out of a #### engine. You are referring to what is called mechanical advantage in gearing if you get low enough.