KW to HP?
#4
You won't believe how many times I've come across this question on the forums. I didn't know the answer to it myself until I came across this one poweretty.com website. Here you can find information about absolutely every car, including BMW. I found a table with the dynamics of BMW from generation to generation. Each series of this car is considered in detail. You can find a table that shows data in both HP and kW. Everything is done very simply and clearly. I was able to choose a suitable, powerful car with the help of this graph. It shows the car's power and simplifies your choice.
Last edited by WillyBolly; 03-15-2021 at 12:37 PM.
#5
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1kW = 1.3410 Hp.
or
1hp = 0.7457 kW = 745.7Watt
I rounded the conversion terms as my HP engineering calc goes a bit more places after the decimal.
Little Extra Geeky Engineering info (all 8 years of college paying off now! LOL)
HP = TORQ(ft-lbs) * RPM / 5252
Dynos measure TORQ & RPM and calculate HP.
or
1hp = 0.7457 kW = 745.7Watt
I rounded the conversion terms as my HP engineering calc goes a bit more places after the decimal.
Little Extra Geeky Engineering info (all 8 years of college paying off now! LOL)
HP = TORQ(ft-lbs) * RPM / 5252
Dynos measure TORQ & RPM and calculate HP.
#6
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HP is a marketing term invented by James Watt way back when. It was based on rotational torque and how much force a horse could generate in an hour by turning a mill wheel. Specifically, he determined that the horse could turn a 12 ft radius mill wheel 144 times in an hour while pulling with 180 pounds of force. The value was revised after Watt and others evaluated more data on a typical horse's performance. So as noted above, HP is actually a numerical calculation derived from torque. Because the HP is not rooted to physical constants, it was replaced in the 1970s in Europe by the kilowatt (kW) as the official power measuring unit. There are still a number of different horsepower definitions floating around, which is why we see 603 HP for the E63s in the US and 612 PS given for the European version. Both cars produce the same power in watts.
The SI (International System of Units) unit for power is the watt, named in honor of James Watt and is based on fundamental physical units. Specifically, 1 W = 1 kg x m^2 x s^-3.
I could go on, but this doesn't solve the question of how to display which unit on the dash . . .
The SI (International System of Units) unit for power is the watt, named in honor of James Watt and is based on fundamental physical units. Specifically, 1 W = 1 kg x m^2 x s^-3.
I could go on, but this doesn't solve the question of how to display which unit on the dash . . .
#7
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2018 E63S AMG
For grins I checked to see what horsepower units Mathcad had built in.
The horsepower type, the Mathcad unit, the power in watts (to five decimal places):
Horsepower, hp = 745.69987 W
Boiler horsepower, bhp = 9809.5 W
Electric horsepower, ehp = 746 W
Water horsepower, hhp = 746.043 W
UK horsepower, hpUK = 745.7 W
Metric horsepower, mhp = 735.49875 W
Setting the US E63s horsepower to exactly 603, the power is 449.65702 kW (to only five decimal places)
Converting the 449.65702 kW to the other horsepower units I get:
hp = 603
bhp = 45.83893
ehp = 602.7574
hhp = 602.72266
hpUK = 602.9999
mhp = 611.36341
Fun stuff
The horsepower type, the Mathcad unit, the power in watts (to five decimal places):
Horsepower, hp = 745.69987 W
Boiler horsepower, bhp = 9809.5 W
Electric horsepower, ehp = 746 W
Water horsepower, hhp = 746.043 W
UK horsepower, hpUK = 745.7 W
Metric horsepower, mhp = 735.49875 W
Setting the US E63s horsepower to exactly 603, the power is 449.65702 kW (to only five decimal places)
Converting the 449.65702 kW to the other horsepower units I get:
hp = 603
bhp = 45.83893
ehp = 602.7574
hhp = 602.72266
hpUK = 602.9999
mhp = 611.36341
Fun stuff
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#8
For grins I checked to see what horsepower units Mathcad had built in.
The horsepower type, the Mathcad unit, the power in watts (to five decimal places):
Horsepower, hp = 745.69987 W
Boiler horsepower, bhp = 9809.5 W
Electric horsepower, ehp = 746 W
Water horsepower, hhp = 746.043 W
UK horsepower, hpUK = 745.7 W
Metric horsepower, mhp = 735.49875 W
Setting the US E63s horsepower to exactly 603, the power is 449.65702 kW (to only five decimal places)
Converting the 449.65702 kW to the other horsepower units I get:
hp = 603
bhp = 45.83893
ehp = 602.7574
hhp = 602.72266
hpUK = 602.9999
mhp = 611.36341
Fun stuff
The horsepower type, the Mathcad unit, the power in watts (to five decimal places):
Horsepower, hp = 745.69987 W
Boiler horsepower, bhp = 9809.5 W
Electric horsepower, ehp = 746 W
Water horsepower, hhp = 746.043 W
UK horsepower, hpUK = 745.7 W
Metric horsepower, mhp = 735.49875 W
Setting the US E63s horsepower to exactly 603, the power is 449.65702 kW (to only five decimal places)
Converting the 449.65702 kW to the other horsepower units I get:
hp = 603
bhp = 45.83893
ehp = 602.7574
hhp = 602.72266
hpUK = 602.9999
mhp = 611.36341
Fun stuff
#9
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2018 E63S AMG
In my opinion, all these conversions are easiest to perform with the help of online converters, such as this one https://www.asutpp.com/kw-to-hp.html
There are many online calculators and several of my scientific calculators also have built in converters. But as was mentioned in an earlier post, sometimes it's nice to be able to put those years of engineering education to use and crank the numbers on your own.
That's why I like this channel: https://www.youtube.com/@EngineeringExplained
He takes the time to work through the math and show why things work out the way they do, including units along the way, in a pretty easy to follow process for the layperson.