Horsepower: Do you really use yours?

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Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.


That is not necessarily true. My 1er makes max HP well below redline.
 
Originally Posted By: mightymousetech
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.


That is not necessarily true. My 1er makes max HP well below redline.


You sure about that, confirmed by a dyno?
 
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.


This applies only if you are talking about peak power.
Anytime you are at WOT, you are using full available power for the given RPM.
 
Originally Posted By: SeaJay
Originally Posted By: mightymousetech
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.


That is not necessarily true. My 1er makes max HP well below redline.


You sure about that, confirmed by a dyno?


Yes. Redline is 7000 RPM.

D900-31T_2.png
 
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Originally Posted By: caprice_2nv
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.
That's not true. Most engines have a redline higher than what their peak HP is rated at.
Good point. Full power is listed, so there is really never any point in going over the peak-power RPM. Maybe engine braking down a very steep mountain might require redline, but thats all.

The relationship between torque, RPM, and horsepower is really very easy.
Horsepower = Torque x RPM
Really that's it, not any more complicated.

Horsepower is the energy flow rate.
You can take a given vehicle, at a given weight, assume zero wind, and you can say "It takes 198 hp to go 55 mph up a 8% mountain grade." That is the relationship. You could make a look-up table for your towing truck or any vehicle and figure out how much weight will affect going uphill.
 
Originally Posted By: oil_film_movies
Originally Posted By: caprice_2nv
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.
That's not true. Most engines have a redline higher than what their peak HP is rated at.
Good point. Full power is listed, so there is really never any point in going over the peak-power RPM. Maybe engine braking down a very steep mountain might require redline, but thats all.

The relationship between torque, RPM, and horsepower is really very easy.
Horsepower = Torque x RPM
Really that's it, not any more complicated.

Horsepower is the energy flow rate.
You can take a given vehicle, at a given weight, assume zero wind, and you can say "It takes 198 hp to go 55 mph up a 8% mountain grade." That is the relationship. You could make a look-up table for your towing truck or any vehicle and figure out how much weight will affect going uphill.



HP=(torque*RPM)/5250

So hp and torque are always equal at 5250 RPM.
 
Originally Posted By: mightymousetech
Originally Posted By: oil_film_movies
Originally Posted By: caprice_2nv
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.
That's not true. Most engines have a redline higher than what their peak HP is rated at.
Good point. Full power is listed, so there is really never any point in going over the peak-power RPM. Maybe engine braking down a very steep mountain might require redline, but thats all.

The relationship between torque, RPM, and horsepower is really very easy.
Horsepower = Torque x RPM
Really that's it, not any more complicated.

Horsepower is the energy flow rate.
You can take a given vehicle, at a given weight, assume zero wind, and you can say "It takes 198 hp to go 55 mph up a 8% mountain grade." That is the relationship. You could make a look-up table for your towing truck or any vehicle and figure out how much weight will affect going uphill.



HP=(torque*RPM)/5250

So hp and torque are always equal at 5250 RPM.


Just for the sake of accuracy, it's 5252.
 
I use all of the hp, even to redline at times for autocross. On the street I won't go full throttle to often. Might as well save it for the track.
 
Originally Posted By: Olas
Horsepower doesn't exist, it's a notional way to express torque over time.
That said, I regularly use as much torque in a give time as possible


Power is the rate at which work is done, whether it's expressed in kW or HP.
It is the product of effort and flow.
In electricity, it is Voltage x Current.
In hydraulics and pneumatics, it is Pressure x Mass Flow
In linear motion, it is Force x Speed.
In rotary motion, it is Torque x Rotation Rate.

The way that you get from torque and rotation rate to HP is:

950 ft* lbs x 2700 rev/min x 2pi radians/rev x 1 HP/550 ft*lbs/sec x 1 min/60 sec = 488 HP.

The amount of work that that engine does in one rotation is 950 ft*lbs x 2pi rad/rev = 5969 ft*lbs

James Watt is the one who defined the unit of "Horsepower", which he obtained by measuring how much work a horse could do in a given amount of time while operating a turnstile pumping water out of a coal mine. He measured the effort of the horse at 180 pounds, and the speed at 181 ft/min, multiplied them to get 32,580 ft*lb/min, rounded to 33,000, and called it a Horsepower. When the Metric system was defined, they honored James Watt by calling the unit of power a "Watt".
 
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Even in my 65hp jalopy using all the horsepower is breaking a few laws. Besides on-ramps on average don't even use half of any of my vehicles. The RV though used all the Chevy could muster in Colorado, of course it overheated also. If I lived in a rural area like I did growing up yeah I'd play a bit more!
 
Originally Posted By: mightymousetech
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.


That is not necessarily true. My 1er makes max HP well below redline.


In my sig car the peak HP of 425 is at the factory redline of 6400 rpm. This engine also has its torque peak of 420 foot pounds at 4400. Not a typical American V8
 
Originally Posted By: mightymousetech
Originally Posted By: oil_film_movies
Originally Posted By: caprice_2nv
Originally Posted By: SeaJay
Engines reach their full HP at max RPM. Unless the needle is buried at the red RPM line, you ain't using fill HP.
That's not true. Most engines have a redline higher than what their peak HP is rated at.
Good point. Full power is listed, so there is really never any point in going over the peak-power RPM. Maybe engine braking down a very steep mountain might require redline, but thats all.

The relationship between torque, RPM, and horsepower is really very easy.
Horsepower = Torque x RPM
Really that's it, not any more complicated.

Horsepower is the energy flow rate.
You can take a given vehicle, at a given weight, assume zero wind, and you can say "It takes 198 hp to go 55 mph up a 8% mountain grade." That is the relationship. You could make a look-up table for your towing truck or any vehicle and figure out how much weight will affect going uphill.



HP=(torque*RPM)/5250

So hp and torque are always equal at 5250 RPM.


This is not true. HP and torque are NOT always equal at 5250rpm.
This crossover point is only seen when using a certain constant or a certain equation to calculate the figures.

My dyno printout from the dastek dyno at Ric Wood Motorsport proves this
 
Originally Posted By: A_Harman
Originally Posted By: Olas
Horsepower doesn't exist, it's a notional way to express torque over time.
That said, I regularly use as much torque in a give time as possible


Power is the rate at which work is done, whether it's expressed in kW or HP.
It is the product of effort and flow.
In electricity, it is Voltage x Current.
In hydraulics and pneumatics, it is Pressure x Mass Flow
In linear motion, it is Force x Speed.
In rotary motion, it is Torque x Rotation Rate.

The way that you get from torque and rotation rate to HP is:

950 ft* lbs x 2700 rev/min x 2pi radians/rev x 1 HP/550 ft*lbs/sec x 1 min/60 sec = 488 HP.

The amount of work that that engine does in one rotation is 950 ft*lbs x 2pi rad/rev = 5969 ft*lbs

James Watt is the one who defined the unit of "Horsepower", which he obtained by measuring how much work a horse could do in a given amount of time while operating a turnstile pumping water out of a coal mine. He measured the effort of the horse at 180 pounds, and the speed at 181 ft/min, multiplied them to get 32,580 ft*lb/min, rounded to 33,000, and called it a Horsepower. When the Metric system was defined, they honored James Watt by calling the unit of power a "Watt".


Absolutely right
smile.gif

I couldn't go to the effort To type all that out but it's what I was getting at, hoping for a reply from the op
 
Originally Posted By: Olas
Quote:
HP=(torque*RPM)/5250

So hp and torque are always equal at 5250 RPM.

This is not true. HP and torque are NOT always equal at 5250rpm.
This crossover point is only seen when using a certain constant or a certain equation to calculate the figures.

My dyno printout from the dastek dyno at Ric Wood Motorsport proves this


The constant in the formula is 5252 (not 5250) as mentioned earlier, so the HP formula is:

HP=(Torque*RPM)/5252

If torque is in ft-lbs, then the T and HP are equal at 5252 RPM. Look at the formula and make the RPM = 5252. The formula becomes:

HP=(Torque*5252)/5252

The 5252 on top and bottom of the formula cancel out and leaves HP = Torque ... so it is true that the numerical value of HP and T will always be equal at 5252 RPM when torque is in ft-lbs units in that HP formula.
 
Oh, I hate this HP equals torque...they can't be equal, they aren't the same units. (Zee0Six, not a shot at you).

The NUMBERS are the same, simply because of the convoluted measurements involving royal longitudo pes, the average weight of a grain of wheat and barley and units of time have to be converted into a rate of doing work which is about 1/15 of the rate that an actual horse can do work (peak)
 
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