inferno
Horse power per liter is just what it sounds like. the amount of horsepower an engine makes with one liter of displacement. if you take the hp/liter figure and multiply it by the size of the engine in liters you can see how much horse power it makes. consequently, and more comonly, you can also take the amount of horsepower the engine makes and devide it by the engines displacement in liters and you get its hp/liter. For example you could have a 3.2 liter V6 producing 125 hp per liter that would make 400 hp. or you could have a 5.0 liter V8 producing 80 hp per liter that would also make 400 hp. the reason hp/liter is important stems back to the power to weight ratio. Of those two engines which is going to be lighter? The V6. a lighter engine makes a lighter car. sure the V6 dosent have the flexability of the V8 (ie less torque in the low rev region) but a good transmission and driver can make up for it and be faster in the end thaks to the lighter weight. Hope that clears it up.
Not to jump off the subject, or try and argue with anyone. But hp/liter not an acurate way to measure the performance of an engine for many different reasons. First, Cylider displacement does not corolate equally with engine size or weight. a good example of this is the VQ series engine in the 350Z and the infinity G35. It has a displacement of 3.5 liters and makes in its most powerfull trim 295hp. It makes about 84hp/liter. If you compare it to the GM LS2 in the new GTO and Corvette, you find that the VQ35 and LS2 are within an inch in every extirior dimension and have about the same weight. Keep in mind that the LS2 is a 6 liter engine. Also, they are releasing an LS7 version, that is the same external size as the LS2, weighs a little less, but has a cylinder displacement of 7 liters.
Another example Honda with there amazing 2.0 from the S2000. 120hp/liter. But what most peaple do not realize, is that the amazing 2.0 weighs in at about 350lbs, just as much as the Honda 3.2 liter V6 that makes 270hp in the new acura TL.
Another thing that hp/liter fails to represent is that an engine in motion can not be compared with a static number. By that i mean that an engine may dicplace only 2 liters, but the speed at which it is spinning is not taken into account. A 2 liter motor that can spin to 9000rpm will make a third mor power then on that can only spin to 6000rpm, all things else being equal. Of course, it would make sense, because it is moving a third more air. the more air in, the more power you make. 2 liters 9000 times or 3 liters 6000 times, same thing.
This is the reason that most racing engine have very high redlines, when you limit the internal size of an engine, the only way to move more air is to spin faster. now in F1 we see 3.0 reving out to 19,000 rpm. and they make 900+ hp.
Meow! (='.'=)
I AM SCARED!!!!! 
) or a 350 (for the camaros 
