Quote:
Originally Posted by richard in NC
HP versus Torque has been a hotly debated topic on most boards I've ever been on. Bottom line is you need both but more important is the whole torque and HP curve.
One way to look at it is torque is what gives you acceleration but HP is the enabler of that torque. In any given gear, the acceleration rate (G's) matches the torque curve, of course except for traction limitations at lower geers/speeds and aerodynamic drag issues at higher speeds. To see this (in any car) in 2nd gear at 1500 RPMs, accelerate all the way to redline. In the Z4 35i, you'll get a constant equal push all the way to 5500 RPMs and it trails off after that.
However, a car with more high RPM HP will out accelerate a car with lesser HP, as long as gearing allows it to stay at those high RPMs. But note, at those RPMs, the torque is higher as well than the torque of the lesser HP car.
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It's all good info, Richard, but please know where I'm coming from on it and why I stress torque instead of horsepower.
I sense what most ppl want to know is what affects their z4 as a daily driver. There are plenty of tek talk over on the M3 and 3Series forums if people want it, but you'll notice we typically don't go down that road.
The analogy that works for me in the torque vs horsepower debate is the difference between the n54 and the M3 V8 s65. IMO, the n54 sort of represents the "everyman's" performance engine. It's got gobs of smooth buttery torque, but less horsepower than the "racer's" alternative, the M3's s65. The M3's engine is fantastic IMO, it's got more liters of displacement, more horsepower, but less torque. But given the choice, I would take the n54 over the s65 anyday for a couple of reasons, the primary of which is its torque.
From a practical point of view, when you read the M3 forum there's plenty of e90/e92/e93 M3 1st time owners second guessing their purchase because of one simple fact: They were under the misimpression that buying a car with 400+ horsepower would be a fun daily driver/street racer. The fact is, unless you're prepared to rev that engine hard and keep it in the upper RPM/horsepower band, the 3800 lb M3 is sluggish. But that's not required with an n54 - it pours out plenty of torque right off idle.
Here's another thing: a couple of my 70's era muscle cars have engine displacements approaching 7 liters. Give a European 7 liters to play with and they'd go crazy
, but my old v8 just lumbers along, with not much horsepower but with lots torque! They're a blast to drive - in a straight line.
Thanks Richard, cheers.