Average Horse Power

[Mike Rolica]

Mike Rolica
Meridian Magnesium Products
Strathroy, Ont 
Ext. 260


	-----Original Message-----
	From:	digi [SMTP:digi at saturn.terahertz.net]
	Sent:	Wednesday, December 15, 1999 1:57 AM
	To:	gmecm at efi332.eng.ohio-state.edu
	Cc:	toyota-mods at cyberauto.com
	Subject:	Re: Average Horse Power

	Well,

	Torque is what is moving the car. That  rotational force is driving
the transmission. Horsepower is torque over time. More horsepower doesnt
mean a proportional increase in torque.
	If you need 300ft-lbs of torque to move your vehicle, and your
engine outputs 600ft-lbs of torque, then its going to hit 300 a lot faster.
So, more torque doesnt mean it'll all be used, it'll just get to as much as
it needs quicker.

	You will probably break loose, roast the tires and only use
300ft-lbs.  But no.. 300ftlbs to accelerate you vehicle at a certain rate.
600ft-lb would move you at twice that rate.... In the ideal world.  The
graph representing your rate of acceleration with torque would be more of a
logarithmic type graph.
	As you try to  reach higher acceleration there is more force to try
and over come.. newtons law


	The rate at which it acheives torque is horsepower, torque over
time.
	Thoughts? 


	Yes and no  the time is engine rpm, not time as in sec.

	Think of it like this  hp is a representation of how much torque you
engine produces at a certain rpm  Torque changes with gear reduction. Hp
does not.
	Ie if you engine makes 400ft-lbs at 5225 it will make 400hp.  If you
reduce it in a transmisssion with a ratio of 2: 1, your output torque of the
tranny would be 800 ft-lb but rpm would be 2613rpm 

	Hp =  torque * rpm/5225
	800 ft-lbs*2613rpm/5225 = 400 hp

	So hp is a good measurement for torque regardless of rpm   It goes
back to the good windmill explanation a while ago.  

	Btw gear reduction is about 75 to 90% efficient.  So you would loose
40-100 ft-lbs due to parasitic loss, depending on type and amount reduced.
	My truck is running at about a 8% loss 92% efficient in the tranny
and rear end.  Using a better lube like 75w 80 or atf synthetic believe it
or not ca reduce the loss. I.e. Before I had about a 10% loss, Did some
testing a couple of years ago with 305.  Was bored and found Machine design
interesting is school... was my thesis for that class.

	I really dont know what I'm talking about so splease correct and
don't fflame.  OK don't stutter ;0)