>> HP is basically meaningless? Torque is what really matters. And the higher the torque peak then the better it is because the car will accelerate up to that peak.
NO! HP is not meaningless - and a higher torque peak is not necessarily better.
What I like it a "nice fat, flat torque curve".
Basically what doesn't tell the whole story is when they quote a "maximum" HP or torque number. What you really want to know is what the HP and torque look like across the RPM range. Sure you can get a "peaky" engine which produces good HP, but only at a very high RPM, and then you find that it has small torque and low HP at low RPMs. For example a high revving motorcycle engine. The problem with having low HP/low torque at low RPMs is that you can "bog" the car at low RPMs before you get the revs up to the nice power band. This is why a screaming [email protected]
,000rpm 900cc motorcycle engine would not make a good replacement for a [email protected]
1800cc car engine. Sure the motorcycle engine could move the car along (with the same 120hp), but you would have so much trouble getting the engine to pull the car off the line and get it going up to the high RPMs.
Having gobs of low end torque is what you need if you want to pull a heavy load so that you can start off the line without "bogging down". For instance, an engine in a motorhome may only produce 160hp, but it would be something like a monster v8, or a turbodiesel and it would have tons of low RPM torque. If you tried to put a 240hp Honda S2000 motor in there it wouldn't work even though it produces alot more HP (because it has poor low end torque).
Here are some general rules (though not always true):
1> More displacement=more torque (although not necessarily more HP).
2> Higher RPM operation (high redline) can give more HP, but not necessary more torque.
3> Max HP is most important when calculating top speed.
4> Max torque is important when calculating slow speed acceleration and load bearing capability... (For a big heavy car you want torque, for a little sports car you can get by with low torque, high HP).
Comparing extremes you see that people complain that the Honda S2000 & Integra Type-R are a pain to drive slow in stop and go traffic because the engine is yearning for good RPMs and you are working the shifter like crazy. On the other hand a car like the Corvette has a huge V8 (compared to the little Honda inline 4s) and it can grunt along at low RPMs in 5th gear no problem, but some people complain that the corvette is too heavy and doesn't sound as exciting when you are trying to drive on a track at high RPMs.