The great torque/HP debate

[Motor Daddy]

Believe me, I'm a "RPM" preacher. That is what this is all about.

I don't need torque to calculate HP. HP is 550 lb-ft of WORK per second. I can calculate torque from work. It's easy:

work per minute/33,000=HP
No torque required.

If I lift 200 lbs 165 feet (directly away from the center of the Earth), and it takes me exactly one minute, the HP=1

If I lifted it with a rope and shaft, and the shaft revolved at a constant rotational velocity, and the shaft revolved 5252 times in that minute, the torque was exactly 1 lb-ft. No torque required to measure HP, and no dyno required to measure torque!

[bc]

Motor Daddy, maybe I misread your statement but are you saying that the smaller engine will always win even if both engines are setup right no matter the scenario or is this limited to just the scenario you posted earlier.

[Motor Daddy]

Motor Daddy, maybe I misread your statement but are you saying that the smaller engine will always win even if both engines are setup right no matter the scenario or is this limited to just the scenario you posted earlier.

Limited to this scenario. The ALWAYS refers to this example, as in, the 455 is not capable of beating the 400, regardless of the gear or MPH.

[kurt454]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

[Motor Daddy]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

If you look at my example, the 400 has a greater torque at the wheels at every MPH even though the engine has a lower torque curve. That means it has the capability to carry a heavier load at every MPH vs the 455.

The ONLY thing the 455 has going for it is some "streetability" factors.

[Wolfplace]

Believe me, I'm a "RPM" preacher. That is what this is all about.

I don't need torque to calculate HP. HP is 550 lb-ft of WORK per second. I can calculate torque from work. It's easy:

work per minute/33,000=HP
No torque required.

If I lift 200 lbs 165 feet (directly away from the center of the Earth), and it takes me exactly one minute, the HP=1

If I lifted it with a rope and shaft, and the shaft revolved at a constant rotational velocity, and the shaft revolved 5252 times in that minute, the torque was exactly 1 lb-ft. No torque required to measure HP, and no dyno required to measure torque!

=
I give up
This is why I do not normally get into these kinds of discussions
Before I go I will repeat this one more time as we are talking about engine here not a rope on a string

HP IS NOT MEASURED ON A DYNO IT IS CALCULATED FROM TORQUE & RPM
If you raise either HP goes up
How is this different from what you stated above?
Unless I am mistaken RPM is time based,,

[Motor Daddy]

Believe me, I'm a "RPM" preacher. That is what this is all about.

I don't need torque to calculate HP. HP is 550 lb-ft of WORK per second. I can calculate torque from work. It's easy:

work per minute/33,000=HP
No torque required.

If I lift 200 lbs 165 feet (directly away from the center of the Earth), and it takes me exactly one minute, the HP=1

If I lifted it with a rope and shaft, and the shaft revolved at a constant rotational velocity, and the shaft revolved 5252 times in that minute, the torque was exactly 1 lb-ft. No torque required to measure HP, and no dyno required to measure torque!

=
I give up
This is why I do not normally get into these kinds of discussions
Before I go I will repeat this one more time as we are talking about engine here not a rope on a string

HP IS NOT MEASURED ON A DYNO IT IS CALCULATED FROM TORQUE & RPM
If you raise either HP goes up
How is this different from what you stated above?
Unless I am mistaken RPM is time based,,

A dyno is a device to apply a load to an engine and find out how much WORK the engine is actually doing per time interval while calculating the acceleration of that load.

Here's one for you:

If the acceleration is zero, how much power does the dyno register?

Ps, you would have a zero acceleration at WOT at say 5,000 RPM when the engine is not increasing or decreasing RPM. Why would it be at WOT and not increasing RPM? Because it is loaded to the MAX, and it is doing its MAXIMUM WORK at that RPM, which means its maximum HP at that 5,000 RPM at WOT.

[Stan Weiss]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

So the millions of diesel trucks on the road have it wrong.

[Motor Daddy]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

So the millions of diesel trucks on the road have it wrong.

No, they are built for durability. How durable would a 500 HP 302 be in a Kenworth, and how long would it last running at the peak power RPM?

[kurt454]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

If you look at my example, the 400 has a greater torque at the wheels at every MPH even though the engine has a lower torque curve. That means it has the capability to carry a heavier load at every MPH vs the 455.

The ONLY thing the 455 has going for it is some "streetability" factors.

No. In a towing application, the 455 can match gear for gear with the 400. Peak torque trumps in a towing application, since a tow truck is not concerned with over-gearing for the dragstrip.

[Motor Daddy]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

If you look at my example, the 400 has a greater torque at the wheels at every MPH even though the engine has a lower torque curve. That means it has the capability to carry a heavier load at every MPH vs the 455.

The ONLY thing the 455 has going for it is some "streetability" factors.

No. In a towing application, the 455 can match gear for gear with the 400. Peak torque trumps in a towing application, since a tow truck is not concerned with over-gearing for the dragstrip.

Why would I match gear for gear with a larger engine?

That would be foolish of me since the smaller engine makes its peak power at a higher RPM and I wouldn't be taking full advantage of that peak power through the use of gearing to obtain the maximum amount of torque at the wheels per MPH.

[kurt454]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

If you look at my example, the 400 has a greater torque at the wheels at every MPH even though the engine has a lower torque curve. That means it has the capability to carry a heavier load at every MPH vs the 455.

The ONLY thing the 455 has going for it is some "streetability" factors.

No. In a towing application, the 455 can match gear for gear with the 400. Peak torque trumps in a towing application, since a tow truck is not concerned with over-gearing for the dragstrip.

Why would I match gear for gear with a larger engine?

That would be foolish of me since the smaller engine makes its peak power at a higher RPM and I wouldn't be taking full advantage of that peak power through the use of gearing to obtain the maximum amount of torque at the wheels per MPH.

Big difference between towing and racing. This is where you are mistaken. You can multiply the GREATER TORQUE of the 455 just as far as the 400. The 455 will pull a heavier trailer.

[Motor Daddy]

The higher HP engine will be quicker/faster at the dragstrip because it can run deeper gears to multiply it's torque.

It is like comparing a naturally aspirated 350 diesel against a n/a 350 gasoline engine. The diesel will have excellent torque at very low rpms due to it's high compression efficiency. It will pull a heavier load in a truck before 'bogging down' than the gas 350. The gas burner will most likely have less peak torque, but a higher peak HP at a higher rpm. Geared properly, the gas engine runs faster at the strip.

I see horsepower as the ability to gain speed.

Actually it's a myth that the higher torque engine will be better at pulling heavier loads.

If you look at my example, the 400 has a greater torque at the wheels at every MPH even though the engine has a lower torque curve. That means it has the capability to carry a heavier load at every MPH vs the 455.

The ONLY thing the 455 has going for it is some "streetability" factors.

No. In a towing application, the 455 can match gear for gear with the 400. Peak torque trumps in a towing application, since a tow truck is not concerned with over-gearing for the dragstrip.

Why would I match gear for gear with a larger engine?

That would be foolish of me since the smaller engine makes its peak power at a higher RPM and I wouldn't be taking full advantage of that peak power through the use of gearing to obtain the maximum amount of torque at the wheels per MPH.

Big difference between towing and racing. This is where you are mistaken. You can multiply the GREATER TORQUE of the 455 just as far as the 400. The 455 will pull a heavier trailer.

Use the two engines in my example and show me mathematically how the 455 can pull a heavier trailer than the 400 when the 400 is geared proportionally numerically higher than the 455.

[allblowdup]

I gotta chime in cuse this looks like fun. The millions of trucks out there do have it wrong,well sorta. The reason that diesels had greater pulling power long ago was because they were huge in displacement. They were way bigger than there gas counterparts. Today the reason that even the smaller ones pull so great is because of a little thing called 20psi of boost . If we could get a comparable gas engine to run and survive for hundres of thousands of miles at 20psi of boost then it would surely out pull the diesel of today. In the future diesels will probably become even more popular because they do not have some of the design limitaions that gas engines have. Torque is great but hp will always win. You can have all the torque you want but if it is not moving then you do not get anywhere. HP is the rate of work being done and more you have the faster it gets done. Sorry guys for busting in but I just had to.

[kurt454]

You using two different gear ratios in your two engines. Equalize the gearing between the two engines and the 455 dominates.

Towing is not a contest of acceleration over a broad rpm range. It is brute force(aka Torque) being applied at a fixed speed.

The 455 in your OP has a 511 ft-lbs of peak torque. Your 400 is showing a peak of 465. With EQUALIZED GEARING the 455 can pull a heavier load. Big engines are not just for durability.