bhp? torque? eh?

[fuzzy]

can someone explain exactly what bhp means? i know what it stand for but what exactly does it mean and what is the difference between brake horse power and torque and what sort of mods effects which? in as simple english as possible so i can understand it would be appreciated

[JOSEMI]

I heard once that the bhp is the ability of an engine to maintain the speed, although I am not sure if this would be the correct definition for it

Jose

[maxfield]

Ive always thought of BHP as pushing and torque as pulling if you get my meaning might sound stupid

[fuzzy]

what do you mean by pushing and pulling?

[Dan318-is]

torque, nowdays measured in newton metres, is the force exerted on the crankshaft by the pistons

power is the rate at which this happens

[Morat]

torque is the amount of twisting power that the engine has, power is torque times revs. Generally acceleration is improved by lots of torque and power gives you top speed.

This is NOT the a-level physics definition but its what it means for everyday use.

Someone will be along to correct me shortly

[Turbo-Brown]

Power is a means of numerically expressing a function of torque and engine speed.

Rolling roads don't measure power, they measure torque and engine speed, and these are multiplied together to give a power figure (assuming that radians/sec and Nm are the units used (BTW this gives a power reading in KiloWatts)

Typically rolling roads and the like give a torque reading in Lbft, and an engine speed in rpm. Power is calculated from these as follows: Power=((torque x rpm)/5252)

This is why on all power plots where the torque is in lbft and the engine speed is in rpm, the power and torque lines must cross at 5252rpm

The 'Brake' term comes from the fact that the torque being produced by the engine is measured against a brake.

And as if I've not worded that badly enough, here's something I tapped out yesterday on the subject!:

Apparently one horse power is 33000lbft/minute which means a mythical horse can shift a 33000lb weight, one foot in one minute.

The same horse can move a 3300lb weight ten feet in one minute.

In each case, the work done is the same as work done is force multiplied by distance (from GCSE science )

As we measure the torque of and engine against a brake, we get the expression Brake Horse Power, or BHP

Now we know that power is just a function of torque and engine speed, we can see that anything that effects either torque or engine speed will increase power.

E.g. if you increase the rev limit, for a given torque output you will see more power.

If you increase the amount of torque, for instance by upping the boost, you'll see more power for a given engine speed.

Very basically, that's all there is to it, the two variables of torque and engine speed.

How you go about making more torque for a given engine speed could be debated forever and a day though!

[Pad]

Torque is a rotational force, so very simply if your engine gives 200nm of torque then it could be considered to have the same turning force as a lever turning a shaft, if the force on the lever was 100Newtons was acting 2 metres down the lever from the shaft, or any other multiple of those two variables, such as 50Newtons 4 metres down the lever etc..

Power is a derived measure and strictly speaking is not a proper engineering measure, although useful for cars as rotational speed is very important. Power = torque*speed. If you want to get Hp from torque then multiply the lbft figure by the engine speed and divide that figure by 5252. About.

Nodding off now...

[rat]

[quote="Turbo-Brown"]Rolling roads don't measure power, they measure torque and engine speed, and these are multiplied together to give a power figure (assuming that radians/sec and Nm are the units used (BTW this gives a power reading in KiloWatts)

Typically rolling roads and the like give a torque reading in Lbft, and an engine speed in rpm. Power is calculated from these as follows: Power=((torque x rpm)/5252)

Oranges and onions - explain rad/s and Nm converted to Lb/ft

[rat]

I beleive horsepower comes from the amount of horse required to drag/lift one ton (2240 lbs)

Of course I could be talking utter bollox

[Pad]

I beleive horsepower comes from the amount of horse required to drag/lift one ton (2240 lbs)

Of course I could be talking utter bollox

yup!

you had it right with the lbft*rpm/5252...

[Turbo-Brown]

Oranges and onions - explain rad/s and Nm converted to Lb/ft

Sorry

There are 2pi radians in 360degrees, so one crank revolution/second = 2pi radians/second (probably not any clearer but that's the proper SI unit for it!)

And according to my engineering data book, 1 lbft=1.356Nm

[Turbo-Brown]

I beleive horsepower comes from the amount of horse required to drag/lift one ton (2240 lbs)

Of course I could be talking utter bollox

That's probably getting there, although there needs to be a time frame and a distance in there somewhere, so it's the power required to lift 1ton by X metres in Y seconds.

[Simon13]

lets put it in simple terms how i understand it too. Say u drive a car into a brickwall

BHP, will be how fast u hit the wall

Torque, will be how hard u hit the wall

get me!

[Pad]

rat,

dude, it occured to me that saying confirming you are talking bollox on my 6th post on here is not likely to win friends... sorry mate, no offence intended.

I still dont buy it though..

[rat]

rat,

dude, it occured to me that saying confirming you are talking bollox on my 6th post on here is not likely to win friends... sorry mate, no offence intended.

I still dont buy it though..

None taken Pad

I speak what I know, if I'm wrong I welcome any corrections

[bootyman]

I havent read most of the scientific pap above, cause i cant be bothered. The easiest way to explain it for me is, imagin there is a competition to pull a cart 100 meters. There are 2 teams in the competition and eack team say has 100 horses (which we'll use as BHP). So both teams have 100bhp. Understand so far??? Now obviously, 1 team will win, and the other team will come 2nd. Why is that when they both have 100 horses (100bhp) It's because some of the horses will have more explosivenes than others so even though each team has 100 horses, it's the team with the more explosive horses that will win, so look at bhp as the horses available to a car and look at tourque as the explosiveness of the horses to pull the car, so all you boys who go on about big bhp, it aint about that, it's all about the tourque cause there is no point in big power if you dont have the tourqe to get you there quick enough.

I THINK I'LL GO LAY DOWN NOW

[Turbo-Brown]

lets put it in simple terms how i understand it too. Say u drive a car into a brickwall

BHP, will be how fast u hit the wall

Torque, will be how hard u hit the wall

get me!

Think how hard you hit it will be a function of your speed and the mass of the vehicle, not what the engine's able to do.

To expand on Booty's point, if two engines make 100bhp with engine A making 100bhp at 3000rpm and engine B making 100bhp at 6000rpm, engine A will be making twice the amount of torque as engine B for the same power output.

[Rosc0PColtrane]

I havent read most of the scientific pap above, cause i cant be bothered. The easiest way to explain it for me is, imagin there is a competition to pull a cart 100 meters. There are 2 teams in the competition and eack team say has 100 horses (which we'll use as BHP). So both teams have 100bhp. Understand so far??? Now obviously, 1 team will win, and the other team will come 2nd. Why is that when they both have 100 horses (100bhp) It's because some of the horses will have more explosivenes than others so even though each team has 100 horses, it's the team with the more explosive horses that will win, so look at bhp as the horses available to a car and look at tourque as the explosiveness of the horses to pull the car, so all you boys who go on about big bhp, it aint about that, it's all about the tourque cause there is no point in big power if you dont have the tourqe to get you there quick enough.

I THINK I'LL GO LAY DOWN NOW

That's sort of what I thought (the bhp side, I know naff all about torque apart from it's good). The number of horses required to prevent vehicle from moving. Hence Brake Horse Power.

[320Touring]

james, this site explains it fairly simply

http://www.pumaracing.co.uk

and he's a fellow ford man so bangs on about turbo's too

[Simon13]

lets put it in simple terms how i understand it too. Say u drive a car into a brickwall

BHP, will be how fast u hit the wall

Torque, will be how hard u hit the wall

get me!

Think how hard you hit it will be a function of your speed and the mass of the vehicle, not what the engine's able to do.

To expand on Booty's point, if two engines make 100bhp with engine A making 100bhp at 3000rpm and engine B making 100bhp at 6000rpm, engine A will be making twice the amount of torque as engine B for the same power output.

I'm not sure this is true, i can't explain it in words because i'm crap at that. The car at 6000rpm will be going alot faster and will have more momentom too, engines make peak torque long before peak bhp too.

i think my point does explain it in an easy to understand way. What u are saying is true but it gets the point across in an easy way.

say both cars like top gear are driving into a wall both at 30mph, but one car is making more torque at this speed, this car will do more damage to the wall it hits. Forget what gear the cars are in. Say they are the same weight too.

[Martinaston]

All i want to know is how big's this fucking horse ?

[fuzzy]

ah, its all so much clearer now .if this mythical horse can shift a 3300lb weight 10 ft in 1 minute that means my 290 horses would drag a 957000 lb(435000kg) weight 10ft in 1 minute? ill need to tie a rope to my house tomorrow and try it .do you think that would be a fully loaded house or emptied out? i'll read your link tomorrow neil when im not under the influence and try to understand it

[CraigG]

ah, its all so much clearer now .if this mythical horse can shift a 3300lb weight 10 ft in 1 minute that means my 290 horses would drag a 957000 lb(435000kg) weight 10ft in 1 minute? ill need to tie a rope to my house tomorrow and try it .do you think that would be a fully loaded house or emptied out? i'll read your link tomorrow neil when im not under the influence and try to understand it

this is assuming you can aquire infinite traction

[Simon13]

look at it in a way we want to know E30's

over 200lbs of torque in an E30 is fun, 220 is great, anymore and there are problems getting the power down so it counts