HP vs Torque

[mich800]

For the horsepower does not matter it is torque that accelerates debate.

Video

[Jarlaxle]

Chuck_thehammer wrote:
first engine with overhead valve 1904 Buick
first engine with overhead camshaft 1956 SCCA race car.

what other major internal engine change in the past 100 years..

OHC engines go back to about 1910.

[wilber1]

myredracer wrote:

wilber1 wrote:
I had a 124 sedan with the 1600 twin cam. Body was a bit of a tin can but the mechanicals (engine, transmission, brakes etc) were pretty sweet for their time.

Interesting! Not many in these parts that would know about that stuff. The 1600 must have really made it go and been fun to wind the sn*t out of. The bodies on the Fiats of that era were def. not a strong point. My Abarth 1300 has a factory modified 124 pushrod engine and am building a custom 1600cc engine for it (c/w dual Webers). The Fiat engines & mechanicals of the 60s were pretty interesting & unique.

It would be fun to play with today. Tune it up, hang a couple of DCOE's and a good exhaust system on it. They weren't much to look at but with a great little power train, a good suspension and 4 wheel disc brakes they would be a good platform to play around with. Kind of wish I still had it along with the 65 and 68 Mini Cooper's we owned.

[myredracer]

wilber1 wrote:
I had a 124 sedan with the 1600 twin cam. Body was a bit of a tin can but the mechanicals (engine, transmission, brakes etc) were pretty sweet for their time.

Interesting! Not many in these parts that would know about that stuff. The 1600 must have really made it go and been fun to wind the sn*t out of. The bodies on the Fiats of that era were def. not a strong point. My Abarth 1300 has a factory modified 124 pushrod engine and am building a custom 1600cc engine for it (c/w dual Webers). The Fiat engines & mechanicals of the 60s were pretty interesting & unique.

[wilber1]

myredracer wrote:

wilber1 wrote:
Could be. I know the Fiat 124 Spyder that came out in 66 had belt driven DHOC's.

After moving from Ferrari, Aurelio Lampredi designed the 124 twin cam, based on an existing SOHC Fiat block. The belt-driven engine was extremely successful and had a long 30 year production run including use in race cars. Competitors like Alfa had chain driven DOHC engines which were more complex and harder to work on. Anyway, longtime Fiat enthusiast here... Have a couple of 60s Fiat Abarth projects in the garage. Both engines will produce substantially more HP & torque than original. Small bore engines are fun to work on to squeeze the most HP & torque out of them. 🙂

I had a 124 sedan with the 1600 twin cam. Body was a bit of a tin can but the mechanicals (engine, transmission, brakes etc) were pretty sweet for their time.

[Chuck_thehammer]

myredracer wrote:

wilber1 wrote:
Could be. I know the Fiat 124 Spyder that came out in 66 had belt driven DHOC's.

After moving from Ferrari, Aurelio Lampredi designed the 124 twin cam, based on an existing SOHC Fiat block. The belt-driven engine was extremely successful and had a long 30 year production run including use in race cars. Competitors like Alfa had chain driven DOHC engines which were more complex and harder to work on. Anyway, longtime Fiat enthusiast here... Have a couple of 60s Fiat Abarth projects in the garage. Both engines will produce substantially more HP & torque than original. Small bore engines are fun to work on to squeeze the most HP & torque out of them. 🙂

as are 1,200cc 4 cylinder DOHC motorcycle engines...
life at 11,000 rpms are fun..

even retired OLD guys like rpm's.

[myredracer]

wilber1 wrote:
Could be. I know the Fiat 124 Spyder that came out in 66 had belt driven DHOC's.

After moving from Ferrari, Aurelio Lampredi designed the 124 twin cam, based on an existing SOHC Fiat block. The belt-driven engine was extremely successful and had a long 30 year production run including use in race cars. Competitors like Alfa had chain driven DOHC engines which were more complex and harder to work on. Anyway, longtime Fiat enthusiast here... Have a couple of 60s Fiat Abarth projects in the garage. Both engines will produce substantially more HP & torque than original. Small bore engines are fun to work on to squeeze the most HP & torque out of them. 🙂

[noteven]

Will a 600hp 1850 lbs-ft rating ISX accelerate 80,000lbs quicker than a 475hp 1850lbs-ft rating ISX?

Yes.

[wilber1]

burningman wrote:

wilber1 wrote:

RCMAN46 wrote:

4x4ord wrote:
Torque and horsepower ratings together help to explain the power curve of an engine They are both valuable numbers.

If a gasoline engine with 440 hp at 5800 rpm and a peak torque of 465 lb ft at 3400 rpm was stuck in a f350 with a rear end gear ratio of 7.1:1 it could be expected to pull identical to a 440 hp Powerstroke diesel installed a similar truck with 3.55 gears.

I would agree only if the gasoline engine was turbo charged or if they are only operated at sea level.

440 HP at the flywheel is 440 HP at the flywheel. If the gearing allows an engine to make that much, it doesn't matter. HP is a measure of work being done.

I think what he was getting at was the non-turbo engine’s performance is measured at sea level and will decrease at altitude, giving it a disadvantage out in the real world.

Both lose power at altitude, the turbo just loses less but that is a turbo vs non turbo thing, not a diesel vs gas thing. 440 hp is 440 hp regardless of the altitude.

[LVJJJ]

I towed for years with a 292 6 cylinder engine in a 1965 Chevy Van. It's a stroked 250 and has tons of torque. Chevy used it in wreckers until the big block v-8 was developed.

It gets the rig moving nice and quietly smooth right up to 60, but then it runs out of horse power, so usually keep it at 55. Now I tow with a 350 in a Suburban and it has to build up rpms and scream to get things moving. We can go faster once we get going but I sure miss the low end power of the old 6. Been thinking of turbo charging it, which would take care of the horsepower problem.

[burningman]

wilber1 wrote:

RCMAN46 wrote:

4x4ord wrote:
Torque and horsepower ratings together help to explain the power curve of an engine They are both valuable numbers.

If a gasoline engine with 440 hp at 5800 rpm and a peak torque of 465 lb ft at 3400 rpm was stuck in a f350 with a rear end gear ratio of 7.1:1 it could be expected to pull identical to a 440 hp Powerstroke diesel installed a similar truck with 3.55 gears.

I would agree only if the gasoline engine was turbo charged or if they are only operated at sea level.

440 HP at the flywheel is 440 HP at the flywheel. If the gearing allows an engine to make that much, it doesn't matter. HP is a measure of work being done.

I think what he was getting at was the non-turbo engine’s performance is measured at sea level and will decrease at altitude, giving it a disadvantage out in the real world.

[ShinerBock]

To me, there are two difference types of power numbers. Peak power and usable power. What good is 400 peak hp if it is at such a high 5,000+ rpm that the only gear you could actually be able to use 100% of it with the torque converter locked at a reasonable road speed is 2nd gear? This is the case with most gas N/A truck engines. After third gear, you will never even come close to reaching that high of a road speed to get to the rpms to hit peak power with the TC locked. If the TC is not locked then you are not getting 100% of the engines power to the wheels depending on how efficient your torque converter is. This makes that peak power useless unless I was using my truck for racing.

In contrast, my diesel will hit its peak horsepower at 2,800 rpm in multiple gears and at reasonable speeds with the torque converter locked. It will hit peak horsepower in 2nd at 46 mph, 3rd at 59 mph, and in 4th at 81. This makes that peak horsepower more usable for towing and passing situations.

[wilber1]

RCMAN46 wrote:

4x4ord wrote:
Torque and horsepower ratings together help to explain the power curve of an engine They are both valuable numbers.

If a gasoline engine with 440 hp at 5800 rpm and a peak torque of 465 lb ft at 3400 rpm was stuck in a f350 with a rear end gear ratio of 7.1:1 it could be expected to pull identical to a 440 hp Powerstroke diesel installed a similar truck with 3.55 gears.

I would agree only if the gasoline engine was turbo charged or if they are only operated at sea level.

440 HP at the flywheel is 440 HP at the flywheel. If the gearing allows an engine to make that much, it doesn't matter. HP is a measure of work being done.

[wilber1]

myredracer wrote:
The guy in the video seems like a kid fresh out of mechanical engineering school regurgitating his book learning. 🙂 Kinda like I would have been at that age. He actually has a decent video on why engines don't need exhaust back pressure.

wilber1 wrote:
Overhead cams go back before WW1. A 1912 Peugeot race car which won the French Grand Prix was the first DOHC engine. Several WW1 aircraft engines used overhead cams.

I believe it was actually Fiat that developed the first DOHC engine in 1912 followed by Peugot in 1913 and Alfa in 1914. I think it was Fiat that was also the first or one of the first to use belt driven overhead cams.

Could be. I know the Fiat 124 Spyder that came out in 66 had belt driven DHOC's.

[RCMAN46]

4x4ord wrote:
Torque and horsepower ratings together help to explain the power curve of an engine They are both valuable numbers.

If a gasoline engine with 440 hp at 5800 rpm and a peak torque of 465 lb ft at 3400 rpm was stuck in a f350 with a rear end gear ratio of 7.1:1 it could be expected to pull identical to a 440 hp Powerstroke diesel installed a similar truck with 3.55 gears.

I would agree only if the gasoline engine was turbo charged or if they are only operated at sea level.