Torque vs. horsepower revisited

[Gen1GT]

There was a massive discussion about torque vs horsepower a few years back, but a recent review in Road and Track reminded me of the differences. My contention has always been that all other things being equal, horsepower beats torque every time. R&D does a quick write-up on the BMW 335d, which has 265 horsepower and a whopping 425lb-ft of torque. The BMW 335i has 300 horsepower and 300lb-ft of torque.

The 335i has 35 more horsepower but 125 fewer lb-ft of torque. That's a fair advantage in horsepower, but a ridiculous disadvantage in torque. Proponents of the torque theory would believe that a 125lb-ft torque advantage would allow the 335d easily smoke the 335i, yet the 0-60 for the 335d is 6 seconds and the 335i is 5 seconds.

Just like 1.8T Jettas always beat TDI Jettas, I hope it lays to rest what really matters when it comes to making a car go fast.

[thekid]

Torque is for towing! :D

[kevcol74]

What about the weight of both cars? There are alot more factors to consider than pure HP and torque numbers.

[Logan]

Torque is also for pulling up stumps or for pulling walls down.
:)

[kevcol74]

My first car was a 1965 Oldsmobile Dynamic88 Convertible (yep, rare and HUGE!) Had a 425 ci Rocket, factory rated 375HP, 495 ft lb of torque... car also weighed almost 5000lbs! I called it the "house hauler", could have pulled a house with all that torque! The car was literally 6'6"wide and 18' long (we measured it! lol) The thing with the torque, it didn't matter if it was me alone in the car, or me and 7 buddies (yes, we fit 8 in semi-comfortable), it accelerated the same. You could not feel a loss of power with more weight in the car. And it was no slouch, a P5 wouldn't stand a chance, a MSP might have one! lol

[991.8l]

Just like 1.8T Jettas always beat TDI Jettas, I hope it lays to rest what really matters when it comes to making a car go fast.

Don't 1.8T Jettas have a lot more HP than TDI Jettas? I don't get how that proves your point?

My mazda protege has 120lbs of torque (122hp), but a civic SiR has 111lbs of torque but (160hp) the pro even in 5-speed will not out-run a civic SiR.... so having more torque is not the only answer..power to weight ratio, gearing, and HP are also key factors.

[starscream]

Hrm... simple solution. Get more of both! and then get stickers...things with stickers are always faster!

Type R = 200 hp remember that.. the sticker alone increases your speed and your **** size!

But really... i always figured torque is to get you out from a stop, HP is longer sustaining in the sense of once your going. Its simple physics that its easier to move something in motion rather then from a dead stop. I could be wrong, but thats how i understood it. Hence why big rigs have crazzzzyyyyy torque but shit for HP, They can haul shit but not go fast with it. Also weight and gearing DO make a HUGE difference. a the MSP can do amazing things against bigger cars...but on a straightaway it gets killed for lack of a 6th gear.

[2003 Mazdaspeed]

Does both 335 have the same gear ratio?

[Nutella]

^ shouldnt since the diesel operates in a completely different rpm range (very narrow).

btw, HP = Torque X RPM, so they cant really be compared as apples to apples. They are different.

You can have gobs of torque but if you cant deliver it fast enough, you cant accelerate fast enough. e.g. big rig diesel, torque is VERY high, rpm is pretty low, so it takes forever to get up to speed.

Torque is more a measurement of 'twisting force'
HP is the rate of transfer of energy (power). How 'fast' you can 'twist' the shaft with that force 'torque'. makes sense I hope.

[starscream]

How 'fast' you can 'twist' the shaft with that force 'torque'. makes sense I hope.

mmm makes complete sense.... fist...twist... shaft.. right! lol

[kevcol74]

Can someone explain "Torque" to the Honda Engineers? :P

[CulRidr]

Don't 1.8T Jettas have a lot more HP than TDI Jettas? I don't get how that proves your point? That IS his point... HP > torque
The 1.8T has a lot of HP (more then the TDI) and the TDI has a lot of torque (more then the 1.8T)...

[evil_y2k_twin]

What i think is - torque gets you started, but the horsepower is what gets you to the end.

[991.8l]

That IS his point... HP > torque
The 1.8T has a lot of HP (more then the TDI) and the TDI has a lot of torque (more then the 1.8T)...

my bad read that wrong... thought he was saying torque > hp in going fast. :p

[kevcol74]

That IS his point... HP > torque
The 1.8T has a lot of HP (more then the TDI) and the TDI has a lot of torque (more then the 1.8T)...

Not true. My 86 Mustang GT was all stock, 200 HP, 375 ft lbs. Put it beside a Honda Prelude (97-01), and I will eat it for lunch, top and bottom end. (trust me, I did many times) And the Mustang is MUCH heavier.

Y? Factory in gearing and loads of torque.

[991.8l]

Not true. My 86 Mustang GT was all stock, 200 HP, 375 ft lbs. Put it beside a Honda Prelude (97-01), and I will eat it for lunch, top and bottom end. (trust me, I did many times) And the Mustang is MUCH heavier.

Y? Factory in gearing and loads of torque.

The mustang makes 200hp a lot quicker than a prelude does... remember thats peak HP... so the prelude is only making 200hp at 6000+RPM... where the mustang makes it at say 3500RPM.

Low/Mid range power = quicker off the line...

high-end power = higher top speed.

[CulRidr]

How much HP in the Prelude?
And his point was for 2 comparable cars (TDI VS 1.8T fits the bill)...you're comparing 2 different cars with loads of factors playing in it, either for or against "the winner" (weight, gearing, traction, powerband, etc, etc...)

[kevcol74]

The mustang makes 200hp a lot quicker than a prelude does... remember thats peak HP... so the prelude is only making 200hp at 6000+RPM... where the mustang makes it at say 3500RPM.

Actually its 5500 rpms... :p

It hits max torque around 3250.... great for shifting!!! Provided your tranny doesn't grind:mad: I needed a newer tranny in that thing! lol

[cruisinblackp5]

The mustang makes 200hp a lot quicker than a prelude does... remember thats peak HP... so the prelude is only making 200hp at 6000+RPM... where the mustang makes it at say 3500RPM.

Low/Mid range power = quicker off the line...

high-end power = higher top speed.


Wow, that made my head hurt with how many things are wrong there.

How is hp related at all to top speed? Other than over coming drag

[Demetron]

Just that...overcoming drag. You have more available power to overcome "terminal" velocity.

[kevcol74]

Just that...overcoming drag. You have more available power to overcome "terminal" velocity.

Can't remember, was that a good movie? :woot:

[991.8l]

Can't remember, was that a good movie? :woot:

isn't that only when you're falling? :p

[991.8l]

How is hp related at all to top speed? Other than over coming drag

What would factor into top speed then? Gearing is very important I know.. but some cars hit top speed in 4th vs 5/6 cruising gears. I would think the more power a motor can make uptop near its highest RPM the larger tolerance for max-speed.

If two cars made 200 hp... one at 8000RPM (red-line) and one at 5500 but then dropped off to more like 130hp at red-line... would that first car not be able to reach higher speeds?

[starscream]

If two cars made 200 hp... one at 8000RPM (red-line) and one at 5500 but then dropped off to more like 130hp at red-line... would that first car not be able to reach higher speeds?

Not necessarily. Depends on gearing.... if both have a gear ratio in 4th at 1:1 then yes the 8000 would have a higher top speed because all things equal, it has a HIGHER RPM to get higher sorta speak (since gearing is equal). However if the ratios between the 5500RPM and the 8000RPM are different, its hard to say without having those gear ratios there...I think... LOL

[991.8l]

I think this helps me to understand it better:

http://craig.backfire.ca/pages/autos/drag#accel

At very low speeds, the effects of aerodynamic drag are minimal. At the same time, the engine can exert a very large force at low speeds, meaning that the acceleration force will be high. At higher speeds, the drag builds up, and the engine's force decreases. Eventually, the drag force and engine force will become equal, leaving no force left for acceleration. It is at this speed that the car is said to have reached its drag-limited top speed.


So far in this article, I have assumed that a car can put out its peak power no matter what speed it is travelling. In real life, this is not the case because a car's engine does not always operate at peak power. Therefore, a car's top speed may be much lower than expected. Generally, a car with many transmission gears to choose from will be able to approach its theoretical top speed, while a car with very few gears could be way off, because the engine will be nowhere near its power peak.
Some cars, especially very old performance cars, do not hit their aerodynamic top speed, but rather run out of gears. If a car hits its redline in top gear before reaching its drag-limited top speed, the car is said to have a gear-limited top speed. This is not very common in modern cars, which have many transmission gears, and axle gearing configured for fuel economy.
A car will always have a top speed equal to its gear-limited top speed, or its drag-limited top speed, whichever is lower.


There are many things that will prevent a car from reaching it's theoretical top speed. Below is an incomplete list.

Friction between the road and the tires. Power used to build momentum in the wheels and other moving parts.
Instability at high speeds. Lack of a suitable facility (hills, etc).
Wind.
The law.Conclusion

Aerodynamic drag is a significant factor in a car's ability to accelerate. At very high speeds, the ratio of the engine's power output to the body's drag becomes more important than the power-to-weight ratio, which is important at lower speeds where drag is not significant. Assuming that the car has suitable gearing, the only way to increase the top speed would be to improve the aerodynamics, or add power. In ideal conditions, the weight of a vehicle has almost no effect on top speed, only the time it takes to get there.

[kevcol74]

Unless Jackson has invaded under the hood of the Prelude, I'll put my money on the Mustang any day...lol
By rights, yes the Prelude "should" have a higher top speed, afterall, the 86 Mustang is very much like trying to push a brick through the air.... The lude is much more aerodynamic = less drag. However, where it counts to me, stop and go or 1/4 mile, the lude's got nothin!
:P

[991.8l]

You have to give credit to honda though to pull 200hp out of a 1.8L 2.0L, and 2.2L motor. They design their motors to run like fuel sippers at low RPM and sports cars at high RPM... make great daily drivers, and racers on the weekend.

[kevcol74]

You have to give credit to honda though to pull 200hp out of a 1.8L 2.0L, and 2.2L motor.

Yes, I do respect getting such numbers from such small displacement engines... And the lude has th H22A... 2.2L... :P

Engine advancement has come a long way in the last 20 years, more power from less displacement and better fuel economy.... So much for the sating from the 60's Musclecar era.." There is no replacement for Displacement!"
I'd still take a 1969 Mustang Boss 302 against anything.... within reason....lol

[991.8l]

Ya the Prelude was actually one of the most torquey cars honda made at the time.. hence the 2.2L... id still prefer a Type R 1.8L making 195Hp. Less displacement also improves on handling.

[kevcol74]

Ya the Prelude was actually one of the most torquey cars honda made at the time.. hence the 2.2L... id still prefer a Type R 1.8L making 195Hp. Less displacement also improves on handling.

You really are stuck on those Hondas eh? lol

[starscream]

I commend Honda on making some pretty nice engines. But i think theres alot of other engines out there that rank higher if not better then a good amount of the honda engines. Honda also has a heavy marketing beast behind them...that makes a big difference as well as the aftermarket community. Honda's got tons of support especially the B-Series and now K-Series motors.

[991.8l]

They do 4cylinders real well... they are still behind the pack on V6 motors though... I've been waiting for their DOHC VTEC V6 motor... but constantly the SOHC J-Series design continues to be used... it just gets larger and larger 3.0 -> 3.2 -> 3.5 -> 3.7

[starscream]

They do 4cylinders real well... they are still behind the pack on V6 motors though... I've been waiting for their DOHC VTEC V6 motor... but constantly the SOHC J-Series design continues to be used... it just gets larger and larger 3.0 -> 3.2 -> 3.5 -> 3.7

4cylinders is about all they do well. I mean they got some good stuff.. like the F20 outta the s2000 is a nice motor. but yeah their v6 and up is lacking. I mean to an extent it not super needed because of the "green" market. But still... If they put heavy RnD into it like they did on there 4bangers it would be awesome.

Dont get my wrong i love my Honda Odyssey with VCM but still, i do find rare times it lacks in power.

[991.8l]

Dont get my wrong i love my Honda Odyssey with VCM but still, i do find rare times it lacks in power.

Nice! the only mini-van you'd ever catch me in... and in comparison one of the most powerful available out there... even to the domestics.

[starscream]

Nice! the only mini-van you'd ever catch me in... and in comparison one of the most powerful available out there... even to the domestics.

True.. and most loaded too. I got the Touring model, complete with running boards, skirt, navi...seriously the 9yards on it.. Bah but yeah end
/treadjack!

[midnightblue97lx]

You didn't mention throttle response.
Or the fact that it was diesel vs. Gas.
Try that with 2 cars with gas engine, or 2 with diesel engines .One with 265 horsepower and 425lb-ft of torque. And the other with 300 horsepower and 300lb-ft of torque. Make sure they weigh similar, and have the same or similar gearing.
THen get back to me.

[Gen1GT]

You didn't mention throttle response.
Or the fact that it was diesel vs. Gas.
Try that with 2 cars with gas engine, or 2 with diesel engines .One with 265 horsepower and 425lb-ft of torque. And the other with 300 horsepower and 300lb-ft of torque. Make sure they weigh similar, and have the same or similar gearing.
THen get back to me.

Sorry, I thought it was general knowledge that the 335d was a diesel, so I didn't state it.

These two cars are the closest you can get to an apples to apples comparison in the arguement of torque vs horsepower. They're obviously not geared the same, because one makes power right up to 7000 RPM, and one makes power up to 4000 RPM (barely). Throttle response doesn't matter in a drag race, only road racing where you're on and off the throttle a lot.

Everyone seems to have a good grasp of the difference between torque and horsepower, although they're not that different. Nutella nailed it; horsepower is a function of how quickly you can create torque. More horsepower means you're creating torque faster. Period. Everything in the world is rated by its horsepower, not its torque; industrial electric motors, engines of all sorts etc...

You could take an F20A (and the S2000 transmission, 240hp) and slap it in an older 5.0 Mustang with 225hp, and the Mustang would then be faster (don't anyone get on me about Mustangs...I've beaten them in my Protege). It wouldn't be faster to 60 feet, but it would be faster after that. You can make as much torque as you want with ANY engine by using gearing. Put that F20A into a truck with 10 speed transmission, with ultra-low final drive, and you'd be suprised at it's ability to haul. It's just not practical to rev an engine to redline for every shift; not very practical or economical.

I think the US could learn a lot from the Germans in how to build a diesel. You could slap that 335d engine in any American truck, and haul just as well, but it would be smooth, quiet and better on gas.

[DuRWooD]

To think of it simply, torque is the force with which the engine turns, horsepower is that torque pushing to increase RPM. So obviously a higher horsepower engine will be faster, and a torqy engine will be less affected by mass.

Say a 1000 hp engine with 1ft lb of torque, it could push the engine with 1ft lb at a very high rpm, where as a 1 hp engine with 1000 ft lbs wouldn't be able to turn very fast, but would hold it's low RPM very easily.

[tiwing]

Maybe in a pure drag race comparing diesel and non diesel varietes of near identical displacement, the d will lose every time. But in the case of BMW (and VW), I imagine the d was not built with 0-60 in mind. Fuel economy and a good solid feeling of power was likely more important. I'd probably buy the diesel version simply because it will still be a fun car (though not quite as fast) and for the vast majority of miles driven, handling and fun would be equal with the diesel costing less to run. that's why we bought a TDI golf instead of the 1.8T... (though the suspension needs some work.... but whatever)

[starscream]

but what about area under the curve? lol

[cruisinblackp5]

Overall fun factor, HP can take a seat any day for me. Id rather have the tq to get going from a stop and feel my chest pushed back into the seat then have to rev the shit out of it a few times between lights. Perhaps a driving prefference.

[kevcol74]

Overall fun factor, HP can take a seat any day for me. Id rather have the tq to get going from a stop and feel my chest pushed back into the seat then have to rev the shit out of it a few times between lights. Perhaps a driving prefference.

+1 I like the feeling, and reaction from passengers when they get pinned back to their seats... HP doesn't do that, torque does.... HP just keeps them there if you have the right set-up, like cruisinblack's stang would!

[starscream]

HP just keeps them there if you have the right set-up, like cruisinblack's stang would!

I heard my tricycle has more HP then cruinsblack's stang... its not supercharged but it is bean-charged. Boost aint constant tho, gotta keep eating those beans while i peddle

[midnightblue97lx]

Maybe, I'd still like to see a comparison of power curves.

[cruisinblackp5]

To you I have this to say

http://www.grafixpressions.com/prev/fwd_sucks_prv.gif

[kevcol74]

Maybe, I'd still like to see a comparison of power curves.

That will depend on the octane levels used... and if someone ate their wheaties that morning!

[Gen1GT]

but what about area under the curve? lol

That's why this topic has so much grey area. There are so many factors to how a car drives, and it's such a dynamic state; you are never at one RPM unless you're cruising. So the fact that you have to speed through an RPM range completely affects the nature of a car.

If you had a great CVT with gear ratios variable from 1000:1 to 0.75:1, to get best acceleration, you would hold RPM at peak power, and the transmission would give all the torque you could handle and more at low RPM.

I love using the S2000 as an example, because it's such a screamer. It makes 152 lb-ft at the RPM it makes peak power, 8300 RPM and 240 horsepower. With its stock total gearing in 1st gear (4.1 final drive, and 3.12 first gear) of 12.79:1, it's making 1944 lb-ft of torque. Sounds like a lot, but it's not, really.

For comparison, an older 5.0 Mustang makes 215 horsepower at 4200 RPM, which is 269 lb-ft. A quick net search gave me a 1st gear of 3.35:1 and final drive of 3.08 (although I'm sure both numbers vary from year to year and version of the Mustang), giving us 10.32:1. Torque at 4200 RPM at the shafts is now 2776.08 lb-ft.

That's why torque feels fast. And because it's higher gearing, you spend more time running through one particular gear. If the S2000 had 18.26:1 total gearing, it would have the same torque at the axle of 2776 lb-ft, but the time in that gear would last a split second, and only get you to 35 km/h. On the other hand, what if you used a CVT with ratios variable from 20:1 to 0.75:1? You would start out with 3000 lb-ft and 240 horsepower constant, decreasing torque with infinite variability right up til gear or drag limited top speed.

In the end, it doesn't matter that the Mustang makes more torque, because the S2000 makes it faster. Take a big strong guy, and have him move cinder blocks. He may be able to move 2 blocks at once, but takes 1 minute to move them. Take a fast little guy, who can only move 1 at a time, but can do 3 in one minute. You're getting more work done and at a faster rate with the little guy, even though the big guy can move more at once.

[kevcol74]

Dude, you totally missed the pun in that line!!

And I take it you just compared the S2000 to a 1985 Mustang GT with the optional 3.08 rear end... Or was it the 84.5 GT350 with the 3.08? Atleast it was stick you compared, the auto had tbi with 210 HP... :P Or maybe a 94 GT? You have to be more specific, but regardless you compared to the old push rod V8...Either way, you are comparing old Ford tech to newer Honda tech... now compare bang for the buck with similar years.... S2000 will get crushed by the Mustang.... ;)

[starscream]

Dude, you totally missed the pun in that line!!

And I take it you just compared the S2000 to a 1985 Mustang GT with the optional 3.08 rear end... Or was it the 84.5 GT350 with the 3.08? Atleast it was stick you compared, the auto had tbi with 210 HP... :P Or maybe a 94 GT? You have to be more specific, but regardless you compared to the old push rod V8...Either way, you are comparing old Ford tech to newer Honda tech... now compare bang for the buck with similar years.... S2000 will get crushed by the Mustang.... ;)

You need to lay off the mustang smack ;) LOL

[kevcol74]

You need to lay off the mustang smack ;) LOL

But its sooooo good!!!! :woot: Its full of good nutrients, like testosterone.....

[evil_y2k_twin]

5.0 with 373 gears is fun!

[pnfnj]

Overall fun factor, HP can take a seat any day for me. Id rather have the tq to get going from a stop and feel my chest pushed back into the seat then have to rev the shit out of it a few times between lights. Perhaps a driving prefference.
agreed...i love having tons of TQ. over HP.
nothing beats a 75ft. burnout :)

[pnfnj]

5.0 with 373 gears is fun!
my truck has 5.9L and 3.93 gears...hehehe

[Gen1GT]

My Protege has 3.307 1st gear and 4.105 final drive...but it needs it, and good thing it reves to 7000+, cause you can wind out 13.575:1 pretty damn fast.

And Mark, FWD technically does suck when it comes to racing, but c'mon, you drive the worst RWD chassis being built today! :p