Date: 10 Feb 1999 18:49:19 -0700 From: klaus <klausnopsamsion.xmission.com> Subject: Re: SAAB 9-5 or Charysler 300M ?
In alt.autos.saab Eoin <bulwnklnopsambee_emm.net> wrote: > I agree with all of that, except the thing about torque vs hp. > Remember that torque and power are related, but that power is the > thing that moves the vehicle down the road (field? path? rocks?). > Torque can be freely exchanged for speed (meaning that the output > shaft of a transmission can be spinning at a given speed and have a > certain amount of torque available, or spinning much slower with > higher torque, but the power is the same). Nope. There's impedance involved there. What you want is a flat torque curve and high low end torque. If you have a high HP and peaky torque speed curve (like a turbo or motorcycle), as you climb a hill, you will either spin the wheels, or lose torque (which is what takes you up the hill) and your engine will stall, or you have to shift down, which has its own set of problems like hitting that torque curve just right again. Torque can not be "freely exchanged for speed" unless you have a zero impedance system, i.e., a perfectly flat torque speed curve. Why do you think big bore, short stroke engines are so popular for off raod trucks and you'll rarely see a turbo, except for diesels? > So the torque curves of 2 > different powerplants are meaningful only in that they can be > translated into power curves which will then allow a meaningful > comparison between the two. Well, having driven many 4x4s off road, and owning two presently, I'll take my Landcruiser FJ40 over any of them because it has a low rpm, short stroke, big bore straight 6. It'll beat the crap out of my Tahoe with a V8 that's huge. Well.. on a steep hill climb where traction is an issue. The low end torque is amazing (it'll start from a standstill in all four gears). The smaller trucks like the Nissans and Toyotas are really tough to get up long steep hills because they are so peaky. And coming down backwards is not an option. Neither is turning around. -klaus
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