All you EVER feel is torque, actually, but that's a little deceiving, because how hard it FEELS like you're accelerating is based on HP, not torque. That's because the torque number, on it's own, means NOTHING. In order to really know anything, you have to know the RPM at which that Tq is being produced because that tells you basically how often you are producing that tq... essentially, Horsepower.
The reason a Torquey car feels faster at low RPM is because it's making more Horsepower. Let's say your Si is making 100 ft-lb of tq @ 2000rpm. Well, all else being equal, a car making 200 ft-lb of tq @ 2000rpm is going to feel roughly TWICE as fast. Why? Because it's making that torque at the same rate, but it's making TWICE as much as you each time. Make sense? Let's put it into the HP equation...
HP = (TQ*RPM)/5252
HP (Civic) = (100*2000)/5252 = 38 hp
HP (Other) = (200*2000)/5252 = 72 hp
Surprise... it's DOUBLE!
Now, let's say you're still making that 100 ft-lb of torque, but now you're @ 6000rpm, and the other guy is still @ 2000rpm. He's STILL making TWICE as much torque, but you're making your tq 3 times as often as he is... so let's see what happens.
HP (Civic) = (100*6000)/5252 = 114 hp
HP (Other) = (200*2000)/5252 = 72 hp
All else being equal, guess who's faster? I'll give you a hint... NOT the guy making more Torque. Know why? He's not making it nearly as often as you are. I have to explain this to people who think "Torque is EVERYTHING" all the time. Fact is, Torque means NOTHING without knowing how often you're making that torque... aka RPM. On the other hand, people with high RPM engines like to think that RPM means everything. Sorry, it doesn't, either. RPM means NOTHING without knowing how much Torque you're producing every time. So, to make it easy on everyone, we've got a special unit that combines BOTH Torque and RPM... Horsepower.
So, all you TECHNICALLY "feel" is torque, but just as important as the torque number is how many times you "feel" it.
TONS of torque even with low RPM = good HP = "Feels Fast"
TONS of RPM even with low torque = good HP = "Feels Fast"
And you know what both of these "Fast feelings" have in common? Lots of HP.
Sorry for the novel... Hope that helps
