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Daniel.Hennessy@va.g -> bhp (5/8/2008 9:17:23 AM)

What is the difference between torque and horse power from the rider's perspective? And what is the "b" in bhp stand for? thanx

  
pacojoseph -> RE: bhp (5/8/2008 9:49:02 AM)

Torquier bikes will get you off the line quicker, but this phenomenon only lasts so long. As the revs build, high horsepower bikes will out accellerate high torque bikes. Big twins tend to make a lot of torque, and fours make a lot of horsepower. Thus, in a drag race, a Harley may keep up with you or even get ahead of you for the first 100 feet or so, but after that the race is over.
BHP means Brake Horsepower. 

Shadow1 -> RE: bhp (5/8/2008 10:20:15 AM)

+1 Paco
I have a buddy with a 916 Ducati - outruns me for the first 100 feet or so, unless I wind the revs up and dump the clutch, then it's no contest either way. Over any real distance, BHP will win over torque - the trick is to find a balance between the two.

Honda_Hurricane -> RE: bhp (5/8/2008 11:34:40 AM)

OK. Here we go.
Power is in modern time measured in watts (or kilowatts) but we all like to use the old formula of horsepower for caparing (HP=Kw*1,36).
What an engine produces is just torque (nothing else), in a modern country (sorry US/UK people) measured in Nm. To calculate the figure of power you take the torque and engine-rpm like this:

Torque: in Nm (Newtonmeter)
Engine speed in Rad/s (radians/second): one revolution is 2*PI radians=6,28
Convert rpm to rad/s like this: rpm*6,28/60=radians/s
100Nm at 6000rpm gives: 100*(6000*6,28/60)=62800watts, or 62,8Kw, which is the same as 85,4hp.

Just note that the max torque is lower in rpm than the max power, so 85,4hp is just the power at that particular rpm, not the max power. But at max power it probably produces less torque because the rpm has increased more than the power has.

A modern engine which reaches 100% fullness can produce 100Nm/litre (enginesize). Some good engines can actually reach a little bit above 100% (RAM air, good porting or other inventions) and therefore produce a few % more, but some normal engines produces a bit less than 100%. That means that a 600cc can have at most 60Nm (+ some %) torque. Good to know since if specs on bikes sometimes are exaggerated by manufaturers.

Since the torque is depending of rpm it can be raised by gearing. Double the gear ratio and you also double the torque. That is why a high power bike with less enginetorque ALLWAYS will outrun a high torque bike with less power. What really counts is the geared rear wheel torque.

Luis CBR1000F -> RE: bhp (5/8/2008 12:27:38 PM)

WOW!!! Now in spanish por favor.....just kidding (great explanation)[:)]

Griffin -> RE: bhp (5/8/2008 12:48:07 PM)

I'm a little frightened. I came close to understanding what H-H wrote.

jb -> RE: bhp (5/8/2008 1:07:48 PM)

the longer you can keep your valves open in an engine and the faster you can open them (i.e formula 1 uses air to open engine valves) the more air you get into yr engine then you can feed in more fuel to make more power, however there is a fine line for valve overlap which can lead to engine distruction, cbr1000's quiet a short stroke for a large engine hence producing good horse power and not as good torque, that why duke's are faster at slower speeds. ...... think ive just confused myself

in short, the more power you have u loose torque (turning effort) and the more torque you have  u loose hp, power. the longer the stroke of an engine the more torque it will produce, the shorter the stroke the more power or rpm. my 2c

MarkR -> RE: bhp (5/8/2008 2:18:49 PM)

A good example is if you drive a petrol and compare it to a torquer diesel in a car
the diesel will tow better and not be effect much by extra weight unlike the petrol, but the petrol will have more zoom.

A BlackBird will make more HP then a Nissan Patrol 3.0L diesel, but put the 1100 in the nissan, and I don't see it working out some how, no grunt.

Does this help, or am I somkeing something.

MarkR -> RE: bhp (5/8/2008 2:32:10 PM)

Also wouldn't a inline-4 be more ballanced than a v2 or v4?
not sure about the east/west type engines like BMW's have on some of thier bikes

HARDCORP 8654 -> RE: bhp (5/8/2008 8:40:41 PM)

quote:

ORIGINAL: pacojoseph

Torquier bikes will get you off the line quicker, but this phenomenon only lasts so long. As the revs build, high horsepower bikes will out accellerate high torque bikes. Big twins tend to make a lot of torque, and fours make a lot of horsepower. Thus, in a drag race, a Harley may keep up with you or even get ahead of you for the first 100 feet or so, but after that the race is over.
BHP means Brake Horsepower. 


Not going to get into the whole Keith Black and Mr. Langerfelt argument about horsepower versus Torque you can't have one without the other but foot pounds of torque is what push your ass down the pavement horsepower is merely bragging rights.  I'll take monster torque any day over horsepower, but you won't get one without the other

http://en.wikipedia.org/wiki/Torque

Shadow1 -> RE: bhp (5/8/2008 8:55:16 PM)

If you want both, you have to go for really BIG displacement, which we don't have in our machines, Gunny......[8|] or gear it to the point where it becomes like a dirtbike, lots of low end grunt, but no top end.
Are you running that 14/46 ratio set yet Gunny ? hooooooo, that'll haul ass ( but we'll have to wait for you at every fuel station)[:D]

Mark R, inline 4's are much smoother than v 2's or Boxer type motors (UGH- should have left them in Beetles)

HARDCORP 8654 -> RE: bhp (5/8/2008 9:04:09 PM)

Yes I understand the question shadow, but I'm just saying.  I will always prefer if given a choice between two motors pulling almost identical horsepower and one of them having a better torque curve.  It will be my choice.  And yes I did play with the 14 46 set up.  No need to clutch anything down, if you want the front end up with that setup and tank slap is a Mother Fvcker but from zero to 105 mph there is not much going to pass you

bluebeard -> RE: bhp (5/8/2008 9:09:52 PM)

Interestingly however jet boats like all other vehicles can have either power or torque. You can spin a smaller pump faster with a high horsepower/less torque engine to produce a large volume of output. However a high torque/lower horsepower motor will spin a higher volume pump producing greater output. Sounds like they would both do the same job but the high torque in the environment of jet sprints actually wins out. i.e faster acceleration over a short distance.

Honda_Hurricane -> RE: bhp (5/8/2008 9:17:52 PM)

As I mentioned earlier. With more horsepower you can allways by using gears get greater torque at the WHEELS than with less horsepower. No matter what torque the engine has. Why the Nissan Diesel feels stronger is that you dont want to drive the small displacement engine at max power rpm and constantly change gears to keep it in that range. But if you did (and it had enough gears with the right settings!) it would be faster.
With more torque (which really means a broader powerband since the max torque allways is limited by displacement) you can pull longer on each gear and dont have to get your left foot worn out by shifting all the time.



pacojoseph -> RE: bhp (5/8/2008 9:21:23 PM)

I stand by what I said. Torque only goes so far. Any of the current crop of racer rep 600's have torque numbers in the 40's (ft. lbs) but will still blow the doors off any big inch twin, producing twice the torque or more, in the quarter mile. What Harley rider hasn't learned that lesson the hard way. In the end, horsepower always wins. In any event, I don't really understand why anyone who thinks torque is king would ride any Japanese four. The one thing these bikes are NOT known as is torque monsters

  

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