Someone raved and raved the other day saying it's all in da torque. All this wheel torque per ton mumbo-jumbo.

I torque my rims to 85 ft-lbs, a very easy concept to comprehend. Force times lever.

If torque is so material in acceleration, how come a 2k2 M3 has only 6.5% more torque (262@4900) than a 2k2 Maxima, weighs 2.9% more (3415), yet reaches 60 about 2 to 2.3 seconds faster (4.8 sec)? TORQUE?

Or is it really HP (333 vs. 255)? Cause lets face it, Celicas and RS-X's are great sports cars, but they have no torque. Yet they are not slow nor are they cheap. I say it's HP, not torque. Semis can have 400 hp and 1100 ft-lbs of torque, and slow as molasses. I say torque is needed to sustain speed as a load is applied. It's not gonna catapult your car 0-60 in 4.8.

 

HP = (torque X RPM)/5252 . So basically, an engine with alot of torque that can reach high RPM's will produce the most HP. ( high compression engines like those in a celica gts and RSX type S can reach high RPMs) Cars with a small amount of torque that can reach high RPMs are still able to produce a good deal of HP.

 

Don't look at torque or HP values at one RPM...

It's more like how much torque/HP can be sustained throughout a wide RPM range... A nice flat torque band will still probably kill another car with a "reasonably" higher peak torque at only a narrow band...

You know that saying/feeling "running out of steam"?

 

wow, im so confused

 

I understand.. think about it this way... HP is how fast you hit the wall... TQ is how far through the wall you go.



Honestly, I am talking from my little knowledge I have, TQ is what you need for pull off the line FROM low rpm. For example how much TQ you have determines what if any load you can tow.

I know that might seem odd, but that is the easiest way to put it for me. Thus getting from the dead stop into the HP rpm range quicker, in turn going faster and maintaing that pull when you shift into the next gear

Also comparing a M3 to a maxima is not the same.. BMW rate the motor very LOW

my best guess

 

Torque gets you going, HP keeps you moving. That's the simplest explanation i can give.

To elaborate however, have you ever driven a diesel engine? They're known mostly for their torque rather than HP. From a stop they can really haul *ss. But once they get going you feel like you're not really getting anywhere fast. The car is moving for sure but you just don't feel the pull on higher rpm's any longer.

To give a twist on my first statement:

Torque makes your car quick, Horspower makes it fast.

 

I'll try to make this as simple as I can or I'll start confusing myself

The M3 is faster because it can accelerate longer in each gear (ie it sustains the torque curve longer). When you add up this extra acceleration in each gear, you've got a faster car overall. A good example is the LS1 vs the LT1. When the LS1 first came out, people swore it was slower than the LT1 because the LT1 packed a mean low rpm punch. However, you get that LS1 out on the highway above 60mph and it would walk an LT1 quite easily. Looking at the power curves of the LS1 vs the LT1, you'd see a much flatter and broader torque curve that held on much longer in the LS1. This is what gave the LS1 it's "legs".

THE BEST EXAMPLE IS THE MEVI. The VI really doesn't make that much more peak power, instead it allows the torque curve to hold on much longer. Even though your motor isn't producing that much more peak power, the car is much quicker and faster because of the added useable rpm.

Diesels make HUGE torque, but they have very short powerbands. The diesel "feels" fast off the line, but the sensation of speed is quickly over due to the very short powerband. A diesel's powerband is ~800rpms long. A fast car's powerband is usually 2500-3000rpms long. That's a huge difference in terms of acceleration.

Always look at the midrange torque curves because that's where you spend most of your time accelerating. Pay little attention to the ultimate peak numbers. Assuming the same car, a motor that makes 200hp@7000rpms with 150ft/lbs@6000rpms will never accelerate as hard as a motor that makes 190hp@7000 with 180ft/lbs@4000rpms.


Dave

 

Torque is ultimately what accelerates the car...torque at the wheels, that is. A car's acceleration curve will follow the shape of the torque curve.

However, HP is ultimately what determines how quickly a car can accelerate under most circumstances.

Why?

Gearing.

Take two cars with the same weight, layout, etc...assume it's the same car except for the engine. Both make 200 ftlbs but one 200 HP and the other 300 HP. The car with 300 HP will accelerate faster, assuming the gearing of the 300 HP car is shorter/more aggressive.

Why?

Torque AT THE WHEELS is equal to engine torque multiplied by the overall gear ratio (overall GR is final drive ratio times the particular gear ratio). The car with 300 HP makes more torque at the wheels. Not only can it therefore accelerate quicker, but typically the gearing will be such that the car can maintain the acceleration in the lower gears longer, delaying the shift to a higher gear which then cuts the torque at the wheels and drops acceleration.

If you do the torque-at-wheels calcs, an S2000 with a "measly" 2.0L engine can accelerate just as hard (in terms of G's) as a modified N/A 4th gen Maxima but can also stay in lower gears longer. The overall result in faster acceleration than a 4th gen.

If you look at it, HP/weight ratio is the best indicator of how quickly a car can accelerate.

This all assumes the the torque curve of the two engines is relatively flat. I won't get into this much, but it should be pretty apparent that if a car has "holes" in the torque curve, it won't accelerate overall as quickly as a car that maintains it's torque over a broader range.

 

Variable valve timing, variable cam, or variable intake runner systems or something. A lot of the cars that have these systems make relatively little torque. Take the 360 Modena. A V8 of any size should be able to make more that 270-something lb-ft of torque, right? I remembered that it had a variable intake runner system, perhaps valve timing, too.
The M3 is another example. It only makes something like 269lb-ft, but it has the Double Vanos infinitely variable valve timing.
Of course, there's all the Hondas, too. I won't bother talking about any of them.
The weird thing is, I was surprised at one certain car that made more torque than the M3 and the Modena. The Lancer Evolution VII. Even though it's just a turbo 4-banger, it makes over 280lb-ft of torque.

But with all this RPM talk, it turns out I was right, but for the wrong reason.

 

The simplest thing i was ever told is: HP makes your car go fast - Torque makes your car feel fast...

HP is what gets the numbers you see for cars, while torque is what pushes you back in the seat and makes a car 'fun' to drive.

 

Dosen't get any simplier than that!

 

Engine Torque doesnt matter at all, a car can make 50ftlbs of torque and with the right gearing still put more to the ground than a car with 150ftlbs. It's simple, how can u make a 4th gen maxima go faster, give it shorter gears all throughout even final drive, the result, gears that multiply more torque to the ground, therefore making the car accelerate much faster, but because each gear is so much shorter, the top speed per gear is lower, for example if top speed in 1st gear was originally 40mph, then with a very short gear it might be 30mph. With a very close ratio transmission with very short gears, u can offset the low torque output of the engine, by having greater multipliers to put teh torque to the ground. Now the only problem with that is that each gear now ends much sooner, 40mph vs 30mph in my example. How do u offset this? easy, just stay in that specific gear longer, meaning higher redline, 40mph in 1st gear u are at redline lets say 6000rpm, now with the short gears you are at 30mph @ 6000rpm in 1st gear, now if u could rev until u were at 40mph, it would be something like, 40mph @ 8000rpm, at which point, u have gotten more torque to the ground with shorter gearing.....and by increasing redline, u dont have gears that end too abruptly.

This is where those high revving motors shine, civic si, integra type R, S2000, Celica GTS, RSX Type S etc... they have relatively low engine torque, but their gearing allows them to put a significant amount to the ground, and let them rev high enough so that their gears still have teh same top speeds per gear that most other cars do or similar range. The reason that the M3 is so much faster than the 2002 Maxima, is almost exactly this reason, it has similar torque, and it revs much higher, it can have shorter gearing and still have normal like speeds in gears, use a larger torque multiplier for more revs. Theres also the fact that the torque curve of these cars are generally better. Since HP is derived from torque, if u want high end HP u want to keep ur torque curve as flat as possible, bc having the same amount of torque at a higher rpm translates to far more hp. Like others have stated, 200ftlbs of torque at 4000rpm yileds less hp than 200ftlbs of torque at 8000rpm.