where do HP come from???

[corvette97]

i know that this sounds pretty stupid but, i've seen the difference between engines, some are bigger and less powerfull than smaller engines, i know that the modificatios bring more HP but i mean STOCK cars, the acceleration and weight are the main factors right??? thanx in advance to you answer!!!

[snacky]

that's too big a thermal dymanics lecture to be posted here, but here's a quickie.

Potential ( or is that chemical ?) energy is stored in gasoline fuel. When that fuel mixes with oxygen (air), is compressed and ignited... kinetic energy, heat energy, water, and other byproducts (exhaust) are given off. That kinetic energy is transferred to the drive wheels where it does work. Work is commonly measured in HP, or kilowatts.

I'm sure I'm way over simplifying things so please add more between the lines.

[oldsnail]

www.howstuffworks.com

[godspeed06]

yea, i remember howstuffworks will explain a lot of automobile quandaries. good link.

[hgt]

Really interesting site. Thnx 4 the link.

[Zonda11]

Someone has taken a little physics,,,,,, Howstuffworks has everything covered.

[dis3as3d]

horsepower is nothing without torque :fist:

[BADMIHAI]

and torque is nothing without HP....

[corvette97]

thanx, nice link, and the thing about hp and torque make me laugh...i dont know why lol

[sickx]

No boys, it's actually there is no HP without Torque. Contrary to popular belief, HP is not directly measurable--it is a function of Torque.

HP=Torque*RPM/5252

Every notice where the HP & Torque curves intersect on a dyno chart?

[corvette97]

and the displacement of the engine and the # of cyl. are not so importnt factors????

i knew that the HP are another way to measure energy, the kinetic enrgy, but i think that a bugger engine outputs more power so, basically i think that big biger engine more hp, (obiously)

[sickx]

Bigger engine does NOT necessarily equal more HP:
S2000: 2.0L 240HP
60s 250 Chevy V-8: 150HP.
Why? The S2000 revs to 9000rpm, while the SBC revved only to around 4.5k back in the day.

Torque is a different story altogether...larger=more (generally, and we're talking NA).

[snacky]

generally longer stroke = more torque
HP applies a time factor to the equation, so shorter stroke = higher revs = more HP

some engines are designed for specific applications, F1= HP, bus = torque

depends on fuel too. diesel engines produce more torque @ lower rpm, that's why the big rigs, large boats, and trains use em.

electric motors are interesting too, 100% torque @ ZERO RPM = instant wheel spin off the line !

# of cylinders effect smoothness, the smoother an engine is, the more stroke you can add and more revs too = more torque AND hp.

however, more cyls= more weight + more internal friction+moving parts+more complexity and things to break

Originally Posted by corvette97 i know that the modificatios bring more HP but i mean STOCK cars, the acceleration and weight are the main factors right??? thanx in advance to you answer!!!

power/torque, gearing and weight are the 3 biggest things effecting how a car launches. oh and tire grip too.