Tq. vs. Hp explained

So basically in order to Find a significant Hp gain, you must Possess more Torque times basic RPM power.
 
That the whole idea behind NA tuning. If you can't make more torque, make the torque you have more often. A car with more horsepower will always out accelerate a car with more torque, all other things being equal ie a car with 150hp 120lb-ft will out accelerate a car with 120hp and 150lb-ft.
 
not necessarily...and this is radically theoretical, but gearing plays a huge part of it...if both cars had long gearing, the torque car would win...if both cars had short gearing, the high hp car would win...
 
I have to disagree with you on that one. If the gearing is taller, the car with more torque will run out of breath in 1st gear long before the car with more horsepower, assuming both engines have powerbands typical of a torque or hp dominent engine. The car with torque will beat the other car in perhaps the first 60', but it wouldn't be close after that. A perfect example is comparing a 2000 Jetta 1.8T(the one with 150hp and 155lb-ft) to the 2004 Jetta TDI with 110hp and 185lb-ft. The 1.8T does the 0-60 in 7.7 and the TDI takes over 10.5 seconds. Not even close even though the TDI has 30 more lb-ft.
 
Great points...

This will be difficult for me to persuade you into towards my opinion on this..mostly because I suck at explanations, and there is no true way to prove my points...but I will try...

first of all...it totally depends on how different the gearing is betwen the runs...In all honesty, I feel that a the first two combinations you mentioned in the same car will run a 1/4 extremely close to each other...there is not nearly enough of a difference between the high hp car and high torque car...

But the gearing thing...torque is multiplied by gearing, so with shorter gears, you have more torque to the wheels...hp is not, since its a rate based on time...But lets make this easier...say you have two engines...on makes 200lb/ft of torque at 3500rpm, and makes 100bhp at 7000rpm, which is the redline (not a very likely combo, I know)...and another engine making 100lb/ft at 3500rpm and 200bhp @ 7000rpm...and both have a close ratio 6 speed gear box...

Now in order for large amounts of torque (force of rotation) to do any work, you need to have very long gearing...the long gearing allows the car to accelerate down the road...with very close gearing, like say short enough to only get 20mph out of first gear (not uncommon for some extremely close racing boxes)...you get...wheel spin...and thats it...the torque to the wheels is so great that nothing happens in the form of acceleration until the next gear...then you accelerate through second ok, and third ok...but remember the powerband, at the time that you are shifting after first gear, the car is not dropping back into its torque band...you are slow...

At the same time, this is an ideal box for a high hp/low torque engine...the close ratio allows first to be eaten up fast, despite small amounts of lowend torque...then the engine is making lots hp, and to do work with torque at a high rate, you need short gearing...so the car continues to accelerate hard through every gear...

Now the other way around would be with an extremely long gear box...one in which you could pull 40mph out of first...the low torque car would use this lower gearing affectively to do considerable acceleration with a much slower climb in rpm...that is what torque needs...torque is instantaneous, the longer the engine holds that rpm, the more work it does...with long gearing, the engine stays on 3500rpm longer...so it accelerates longer...and being that the gearing is spread out, every shift change brings the car back down into that torque zone, and continues to accelerate hard...

on the other hand, the high hp car could do nothing with this gearbox...and barely get rolling, because it was relying on high torque multiplication through the short gearbox to make up for its small torque output...not only that, but after first gear, the revs would drop well out of the power band...it is misleading to put a certain hp at a certain rpm...because to do work, at least in automotive instances, needs to sweep through a band of high power...so when you have short gearing, the car can continuously plow through its powerband...and still accelerate...but without the gearing, and without the properly matched rev falls after each shift, it has trouble...

These are two extremes...which is why I said theoretical...but because of this variable, I can't say that a high hp car will always beat a high torque car...
 
I don't like the VW comparison...the 1.8t's were underrated in the first place (which helps your point even more), but the TDI has a 2000rpm less powerband because of its diesal nature...and they do not have the same gearing...

My example would be between say a WRC rally car... which has AWD and about 400-lb/ft of torque, and around 286bhp (tiny turbo's)...as of a few years ago...the rules, as always, have changed since then...

and the second car would be say a Ferrari 360, which is around 276lb/ft and 400bhp...The weights are off between the two cars...but not by a whole lot...the only thing the WRC car truely has at acceleration advangtage is the off the line benefit of AWD...the ferrari can run 0-60 in around 4 flat...with 1/4 times in the low 12's...the ferrari is closely geared, and the WRC cars are moderately longer...and WRC cars of that time can run 1/4 times in the low 11's, with 0-60's in the low to mid 3 second range...

which is close, don't get me wrong...I am only arguing that it is not HP vs. Torque...its gearing that makes the difference...most high hp cars are faster than high torque low hp cars...but I am saying that it is not simply the hp that makes them faster...its proper gearing...you could make a high hp car with low torque extremely slow by giving it long gearing...and vice versa...
 
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kooldino vs. turfburn I think it went on for a couple of weeks.
 
haha who won?

I am not arguing with Josh about it...I just feel there is more to it than simply hp vs torque...and that a high hp car will always win...
 
It's hard for me to make my point without some dyno charts and gear ratios to explain it, but I'll do my best.

Jamie, when you say longer, I think you're meaning taller gearing. We'll use the same engine's you mentioned:

A: 100hp@7000RPM , 200lb-ft@3500RPM

B: 200hp@7000RPM, 100lb-ft@3500RPM

Tall gearing would be something in the region of: 1st-3.00:1, 2nd 1.4:1 with a 3.5:1 final drive. This makes 10.5 total gearing in 1st and 4.9 in second. With the first car, you'd have 2100lb-ft at 3500RPM at the axles, and 787lb-ft at 7000RPM(10070005252). In second you would have 980lb-ft at peak and 367lb-ft 7000RPM. This obviously means you'd want to shift well before 7000RPM where total torque is less than it would be at peak in second gear.

The second car would make 1050lb-ft at 3500RPM and 1575lb-ft at 7000RPM in first, and 490lb-ft at 3500 and 735lb-ft at 7000RPM in second. I would guess the two car's torque would cross near that magic RPM of 5252, where car B would start to gain on car A. Car A would need to shift around 6000RPM to keep in the torque zone, but car B could probably rev to 8000RPM or more taking advantage of gearing. It would have to be making 93lb-ft or less for car A(which is now in second gear) to start pulling harder again, but probably wouldn't happen til past 8000RPM. By this point, car A's powerband is falling again. Car B could shift at 8000RPM and would drop right into 5000RPM where it's quickly building power again.

After the first 60 feet it would be car A constantly trying to catch car B, but would have to keep shifting to keep the engine spinning near peak torque and it would fall flat on it's face.

You example of WRC cars doesn't really apply either. The FIA limits their power levels, so teams build for a huge powerband. Because they can't build for power, they increase VE at all RPM, which is why they have so much torque. You can't compare it to an F360 because they are totally different drivetrains. If you put the WRC engine in the F360, it would be slower because it can't take advantage of gearing. If you put the F360 engine in a WRC car it would be faster.

I don't think there is one example of a car with more torque and less horsepower being faster than a car with more horsepower and less torque.
 
Again, good points...and I will get back in the morning...as for the driving habits though, I mentioned 7k being the redline...so that you couldn't rev over that to take advantage of the where the revs fall after each shift...which isn't uncommon for a high hp car to make most of its power right on the rev-limiter...
 
also as for possibly one example...at least they are so close it completely depends on driver...

A 04 BMW 330i without the performance package...225bhp, and 214 lb/ft of torque...

vs.

an 05 RX-8...238bhp and 156lb/ft of torque...

the RX-8 is nearly 400lbs lighter...and the BMW has DoubleVanos that makes the area under the curve near Everest's (at least compared to the RX-8's.)..which overall...is truely the most important part in the first place

but according to Motor trend, which may not be the best place for mag racing...the RX-8 did a 14.87, with a 6.3 O-60...while the heavier german did it in 14.70 with a 6.12...

both are RWD...both have 6 speed manual boxes that take advantage of each engines particular powerband...and the lower hp, higher torque car wins...despite its extra heft...

a bad example at best...but it may hold...
 
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yeah...I overlooked the most obvious part about this entire discussion...something which turfburn pointed out well...its a blend of both that is important for automotive engines...and not peak numbers...but area under the curve that matters for acceleration....

figure a racing engine with a curve shaped with a near perpidicular slope towards the hp peak...and has barely any power or torque anywhere else...it could have a 9000rpm 500bhp peak...but big deal...and then you have a 300bhp V-8 with 300lb/ft of torque...and a huge broad flat power and torque band in 6500rpm...the car with more area under the curve would win...period...

and also, Ferrari and BMW started having major succes around the late 90's when they began giving engines additional lower rpm torque...and backed off of the peak hp race that Jag and Merc where involved in...the Ferrari F2001 had about 40 less hp than some of its competition...but went with about 25lb/ft more torque...and was easily passing people out of turns and the like...but the advantage in out of corner acceleration was there...by gaining torque, and only lowering their peak output...they were still gaining area under the curve, which made for a faster race car...
 
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I've always said that a nice long power band and average horsepower are what accelerates you. My speaking of a car with more horsepower will always out accelerate a car with more torque is a complete generalization, but it still pretty much holds true. You can't use the BMW as an example, because it still has more horsepower than torque, although your point of a massive powerband is correct. Although the race between the BMW and RX-8 would be completely driver dependant.


Horsepower is a generic term to describe torque/time regardless of gearing. It's what allows us to compare one car to another. You can't compare one car's torque rating to another's without knowing the RPM it occurs at and what the gearing is, which is way too complicated. And you're right of course, peak power doesn't mean squat. But I still hold strong on the point that making torque twice as fast is just as good as making twice the torque. And there are so many examples of cars with more horsepower that will out accelerate a car with more torque. And to make more torque, you just need shorter gearing.
 
Ok here is what I have noticed personally. Im not knocking any brand or one so dont take it that way.

I have run several cars. Wheight makes a difference as well.

Stock WRX: Of the line he got me untill I hit 7500 rpm, when he shifted to 2nd I still has 1500 rpm in my sweet spot. After 1/4 mile I had 1 1/2 car lenghth and was just shifting into 3rd.

Modded MSP running 9psi : We pulled together and then he was getting away from me. Then same as the WRX, he had to shift. After that I past him and was pullin away fast.

My car dyno's at 211whp with 153lbs of tourque N/A. The tourque the other guys had got them out faster, but my HP at high RPMs (9000) got them in the end.

Now I did get my ass spanked by an MSP with a shitoad of mods, and a modded WRX as well. But thats a different story.
 
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