Horse Power and its Effectiveness

[Mike Rolica]

  I've said this before people buy horsepower, but drive torque.  You are
correct when you say horsepower is just torque over time, how quickly the
ability to do work.  It is directly related to torque.    

Hp= torque (in-lbs)*rpm/62025  You will also notice that every single engine
the torque is equal to the hp at around 5150 (5168 to be exact., that is how
I know if someone is bullshi**ing me on how much power their engine makes.
On a car , when you load an engine at a certain rpm at full throttle, the
torque is how much force is applied, how quickly that engine can gain rpm
while maintain that amount of twist is horsepower (work done)   You control
how much horsepower an engine makes by where and how much torque it produces
at that rpm.   The higher rpm  the more horsepower (if torque can be
maintained).  That is why diesel engines make wads of torque but no hp
because the torque is made at low rpm. Two engines with identical torque
curves will have the same hp curve, Roughly. As another thing that
influences hp is inertia weight, (weight of crank pistons rods etc. And the
engine relative to squareness.

I.e. longer stroke than bore motors produce more torque than hp because face
velocity of piston on power stroke( vel between piston and wall) is faster
has to go longer dist in same time (rpm)  force= mass*velocity so it will
have more rotational force torque. But hp is lower because they cannot
maintain torque at high rpm, the weight of the piston going down and it's
force has to suddenly change and go the other way. Become inefficient at
high rpm.  Also at high rpm, they have more friction and skirt/cyl wear due
to the large rod angle, more force applied to cyl wall.

That is why an under square like the 327 make huge amounts of hp.  It also
revs high too, but does not have the low end torque like a square motor like
a 383 Chevy.  It is a very complex subject.. tried to make it as simple as
possible.


"Build a motor for torque all the way through rpm range and hp will
follow..... build for torque talk about hp...,.sell hp....build torque..

Btw:, do you know why a 327 SJ (small journal)is better that a lg ?  Hint
think about speed..... and the problems with 440/383 dodge cranks and std
size mains :-)
Mike Rolica
Meridian Magnesium Products
Strathroy, Ont 
Ext. 260


	-----Original Message-----
	From:	digi [SMTP:digi at saturn.terahertz.net]
	Sent:	Monday, December 13, 1999 7:51 AM
	To:	gmecm at efi332.eng.ohio-state.edu
	Subject:	Re: Horse Power and its Effectiveness

	interesting thoughts,

	but you forgot torque. my understanding, hosepower is the ability to
do
	torque over time. it takes time to reach the torque peak, more horse
power
	the quicker it can reach that.

	g-force is a result of torque. your mass, has the resistance of
gravity,
	it is holding you back, thats what pushes you into your seat. torque
	accelerates the vehicle, and everything thats bolted down, you feel
the
	pressure of being accelerated.

	now were getting into inertia stuff. in space, where there is no
gravity,
	t every action has a equal and opposite reaction. if you accelerate
to
	100mph, and maintain it exactly (in theory), if you dont move you
shouldnt
	feel it.

	however, if you move, then you feel the velocity. as very slightly,
every
	action has a equal and opposite reaction. it'll produce resistance
to the
	acceleration, causing you body to feel deacceleration, then,
acceleration
	by the vehicle.

	im probably grossly wrong here. but my understanding is that gravity
is
	providing the only resistance, which is in the force pulling down,
which
	in turn produces friction etc etc and makes it what requires so much
power
	to accelerate.

	horsepower is directly related to g-force, however, its not just
your own
	mass that it is accelerating, it is the mass of the entire transport
	mechanism your in.

	which to measure acceleration by power, you must divide the mass by
power.

	these are just guesses, i have no real refrences. so please, please,
feel
	free to correct me if im wrong.

	just some thoughts, in the never ending quest for knowledge.

	more people will correct your bluff than answer your question.
	<snip>