HP vs Torque, JUST FOR YOU JAMES!

Turk

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Taken from another board...

Inspired by dred's thread on torque, HP and work, a buddy and I got into a discussion about how people frequently misunderstand torque and gearing. For some reason, we found ourselves looking up dyno charts for various cars and came across one for the E90/E92 M3, which looked basically flat at 260ft-lbs from 3,000 RPM to 8,100 RPM. Given how fast the car is, I figured it had to be geared pretty short. And it is. But what's shocking is how much torque the car puts to the wheels, particularly in first gear.

Below are plots of wheel torque for the E90/92 M3 (peak torque 260-ish-something) and C5 Z06 (peak torque 400ish) versus MPH for the first four gears, assuming shifts at redline. The M3 puts almost 50% more torque to the wheels than the Z06 at low speeds... and the cars are pretty evenly matched after that.

The other plot is torque to the wheels versus MPH for the gears over the entire usable RPM range.

Of course this all discounts weight. But if you convert torque to thrust and divide that by the weight of the car, the M3 still wins in first gear (even with a 600lb weight disadvantage). That's the third plot.

The long and short of it is that most people would probably not describe the M3's engine as torquey (at least when compared to a big 2-valve pushrod V8). But engine torque is pretty irrelevant. Torque to the wheels is really what matters, and in this case the M3 is very impressive.

Maybe this isn't interesting to you guys, but I was bored waiting for a teleconference to start late last night...
 
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Turk

Turk

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So as we see here James, the M3 puts down more thrust through first gear, and almost equal thrust through all other gears eventhough it has 110 less torque than z06. Why do you think this is? THINK!!!
 

Mook

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oh god not this shit again :rofl:
 
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Turk

Turk

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Proof is in the pudding mook. I just noticed too, that this guy used the M3s wheel torque of 265 and the z06s fly wheel torque to measure the torque through the gears. If we used the M3s flywheel torque of 295, the M3 is putting more power to the ground through every single gear when compared to the z06.
 

Mook

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i'm not talking about proof...just talking about the thread in general. seems we have the same debate once a month
 

James

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Oops, I hurt his feewings again. :dunno:
 
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Turk

Turk

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Oops, I hurt his feewings again. :dunno:
It's just too fun proving you wrong with real statistics. Like about how North Korea doesn't matter and why HP is more important than torque.
 

OffshoreDrilling

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Horsepower isnt even a measured value, its calculated through an equation relating to two variables.... Torque and RPM.

Obviously you can change the equation to solve for each of the variables, but that is not how a Dyno calculates it. A dyno measures torque and RPM then calculates horsepower.

The reason your car makes so much horsepower, and has relatively little torque is because it revs so high. Your peak TQ is somwhere around 8300RPM. Obviously multiplying by 8300 versus 6500, or about there for the zo6 peak torque RPM, is going to get you a bigger number. The motors make power in different places. high TQ X lower RPM or low tq X high RPM.

Take a look at the horsepower equation, then look at the what the x and y axis are labeled on the graph you posted. Looks a lot like the equation doesnt it? (mph could be changed to RPM easily enough by knowing the tire circumference) Find a graph with the horsepower on the y axis versus MPH. Ive got a feeling it would look a lot different. :hsugh:

The Z06 is a long ways out in quarter mile times from the M3... Not to poke fun at you turk, but Ive never seen a ZO6 at the track NOT hit 12s. Whats your best run so far, somewhere in the 13s while modded?

Your argument doesnt make any sense to me that HP is more important than torque. Seems to me from everything Ive read, that you are unknowingly arguing the M has better gearing. :dunno:
 

ktraver97ss

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This may be true, but if you cant shift properly its all irrelevent.......hehehe
 

bluzohh6

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God I wish Justin would just come on here and end this argument once and for all
 

Fish

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So someone with an M that has more "thrust" then a Z06 should run 12s?
 

OffshoreDrilling

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Power to weight ratio fish. Since horsepower is more important, BMW put more padding in the seats and added 600lbs to the car. That way when the M3 gets walked by the inferior pushrod powered Z06, their drivers asses wont hurt so bad.
 

OffshoreDrilling

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How about you race my truck Turk, you have the power weight ratio advantage.
 

Fish

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Power to weight ratio fish. Since horsepower is more important, BMW put more padding in the seats and added 600lbs to the car. That way when the M3 gets walked by the inferior pushrod powered Z06, their drivers asses wont hurt so bad.
According to the chart Turk put up along side the banter in the quotes, the weight didnt matter. The M still has more "thrust". :hs:
 

OffshoreDrilling

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It has more thrust but the weight is why its slower. Even if you take off .1/every 100lbs its still not close to the Z06 times.
 

L36 SS

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Power to weight ratio fish. Since horsepower is more important, BMW put more padding in the seats and added 600lbs to the car. That way when the M3 gets walked by the inferior pushrod powered Z06, their drivers asses wont hurt so bad.
:rofl:
 

Fish

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We both understand this Jared, but Turk doesnt. I guess I should have put my posts in italics for being sarcastic. :mamoru:
 

Fish

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All I have are croquet mallets. :( Can I come?
 

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