[SUB-FT86]

Originally Posted by serialk11r

The torque that the engine produces across its rev range is really highly dependent on the engine. Some engines (most Honda engines for example) have 2 cam profiles that they switch between. This can either be done so that you get as much torque as possible everywhere, or you have less torque at lower speeds for better efficiency. A lot of engines however only have one cam profile to work with, that they can usually phase, but it's still only one lift profile. Thus they run out of steam outside their optimal range, which is much narrower than if you have 2 different profiles. A lot of engines are tuned for maximum torque down low, because they pull heavier cars that tend to be driven at lower rpm most of the time.

You might feel a torquey engine more because if the torque peaks at a lower rpm, there is a distinct increase in acceleration that you feel. My mom's 4500 pound Honda Pilot has this "lurch" at around 2500 rpm. It's still pulling slowly, but just not as slowly as before, so it feels faster. I think when people talk about being able to feel engines with a lot of torque, they are talking about higher displacement engines that have torque peak at a low rpm, thus that sensation that the power is "coming on" has some psychological effect.

Torque to weight ratio only applies if the gearing is the same. Gearing tends to be more influenced by horsepower, at least in sports cars. Say they took a car with a 4.5L engine, replaced it with an F1 engine displacing only 2.4L, and swapped the gearbox, and removed the tachometer so you wouldn't know how fast the engine is turning. You'd feel the car going just as fast, despite the huge decrease in torque.

Turbo kinda messes this up because you can create very peaky power at low rpm, and not much improvement to max power. But you can feel a huge amount of acceleration at a lower speed (which takes less energy). A sports car needs more max power, because performance driving happens at higher speeds, so they are designed a bit differently to meet that goal, which can sacrifice some low speed driving characteristics.

Another thing is displacement tends to vary a lot more than rev range. Most cars rev past 5-6000, and street cars don't go past 9000 typically. Meanwhile, displacement varies from 1.3L to a ridiculous 7L on street cars. Thus on a street car, torque almost translates into power because most engines have more or less similar rev limits, but widely varying displacement (which basically determines torque).

This generally happens in high revving 4 cylinder engine vehicles though. A Ferrari 458 italia, Gallardo Lp560 and a Lexus LFA would never sacrifice low,mid and high range. Hell even a high revving 6 cylinder has good torque throughout like a 370Z/Z4M/e46 M3.