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LI Blackdak
Dodge Dakota
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6/24/2002
23:04:06
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 Subject: bhp vs hp
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what is the difference??? is ther even one???
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Doh
Dodge Dakota
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6/25/2002
02:43:42
|  RE: bhp vs hp
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BHP stands for Brake HorsePower, and is the amount of power the engine generates directly at the crank.
RWHP is Rear Wheel HorsePower, and is the amount of power seen at the rear wheels (it will be less than BHP due to transmission losses)
When commercials, dealerships, and the general public talk about HP they would most likely be talking about BHP since that is what manufacurers typically list. When speed freaks talk about their latest mods, they usually are talking about RWHP, and usually specifically say so.
I think I've got that correct, but if not I'm sure people will be along shortly with corrections.
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LI Blackdak
Dodge Dakota
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6/25/2002
09:27:56
| RE: bhp vs hp
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makes sense
i figured it was just that its eiter bhp or rwhp, but people always call bhp hp cause they dont care about rwhp
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nissan
Dodge Dakota
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6/29/2002
15:57:07
| RE: bhp vs hp
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go to the nissan board to ask this after all you always flame us, so just go away to nissan in the sky land.
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Bruce P
Dodge Dakota
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6/29/2002
21:30:42
| RE: bhp vs hp
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The automobile manufacturers USED to list engine horsepower back in the 1960s. Federal laws now state that the advertised HP must be RearWheelHorsePower with all accessories turned on. (such as AC)
BrakeHosePower means power as measured with an dynometer. (which is in reality a giant BRAKE which measures how much power it is removing while applying the braking)
RWHP can be measured with a brake (dynometer) thus may be refering to the very same thing as BHP.
Technically, Horsepower = Torque X RPM
Trivia from memory, I recall that 1 Horsepower= 746 watts so now you can calculate how many lightbulbs your engine can light up ;-)
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Hersbird
Dodge Dakota
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6/30/2002
00:52:09
| RE: bhp vs hp
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Bruce you are worng about the current manufatures claims being rear wheel HP, they measure off the flywheel and don't take into account drivetrain losses in the axles, drive shaft, or transmission. They do have the accessories installed now where prior to 1972 they used to dyno a "net" number which was without air intake, exhaust, and accessories as in the current "gross" ratings. If you dyno your Dakota about the onlt possible way is to use a rear wheel dyno, which will give you a number about 15-20% less then the factory flywheel claim due to the drive train losses. If you pulled the motor and dynoed just that with all accessories hooked up you would get close to the factory claims. If you removed all accessories, intake and exhaust restrictions you would get a number to compare to say a 1970 HP claim. Basically the current R/T motor may be the highest power mopar small block ever with maybe the exception on the 340 six pac motor of 1970 only. To answer the original question I'd say that BHP (brake HP) and just HP are really the same thing. The differences are in Net HP, Gross HP, and rear wheel HP.
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LI Blackdak
Dodge Dakota
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6/30/2002
01:02:26
| RE: bhp vs hp
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just curious...how do u dyno awd??? it probably costs more right??
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Diligent Dave
Dodge Dakota
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6/30/2002
03:58:19
| RE: bhp vs hp
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Yes. AWD vehicles require special dynometers that are quite a bit more expensive than those used for RWD and AWD vehicles.
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LI Blackdak
Dodge Dakota
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6/30/2002
11:26:50
| RE: bhp vs hp
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can i get a special dyno meter that just tells me that my intake+exhaust actually did add 25 hp(even if it really didn't) just to make me happpy??
200 hp li blackdak...lol
anyone know the rwhp of a stock auto V6, 4.7 and 5.9 dak
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IntenseDak39
*GenIII*
6/30/2002
11:32:43
| RE: bhp vs hp
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dave... another way to do AWD is to remove a set of axles to dyno one set of wheels
supercharged-intensedak3.9
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Hersbird
Dodge Dakota
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6/30/2002
11:32:44
| RE: bhp vs hp
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The dynos very a lot depending on weather (just like at the track!) Then there are also more drive train losses in an automatic then in a manual so you have to take that into account as well. I'm not sure about the others but I beleive the R/T's are about 200-210 RWHP stock.
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JonnyO
Dodge Dakota
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6/30/2002
14:51:42
| RE: bhp vs hp
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HP = Torque x RPM / 5252.
And it's not measured at the rear wheels but at the flywheel.
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BruceP
Dodge Dakota
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6/30/2002
23:07:24
| RE: bhp vs hp
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Mr JonnyO
One only divides by 5252 to "equalize" the resultant number based on what units the torque is measured in. (torque can be measured in PoundInchss, PoundFeet even NewtonMeters or hundreds of other WeightLengh combonations you can dream up.) Remember, one PoundFoot is the twisting force applied by one pound of weight at the end of a one foot lever.
RPM is easy to calculate because there is no "units" to Revolutions or Minutes.
BTW... Power can be measused at the flywheel OR at the wheels OR at the output of the transmission OR anywhere else you can dream up. It is just highschool physics.
My friends 2.2L 4-cylinder turbo Dodge Shadow has dynoed at 320HP at the rear wheels. (NO NITROUS ON THIS BEAST EITHER) Adding the 15% loss of the powertrain equates to about 360HP at the flywheel.
I wish my V8 Dakota could do that!
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Hersbird
Dodge Dakota
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6/30/2002
23:31:15
| RE: bhp vs hp
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Bruce are yopu sure that shadow is REAR wheel horsepower? I bet it dynos ZERO hp at the rear wheels unless he has done some serious drivetrain mods as well. Just giving you a hard time man, LOL!
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JonnyO
Dodge Dakota
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7/01/2002
00:04:39
| RE: bhp vs hp
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Bruce,
Naturally you CAN measure hp at the rear wheels... I wasn't saying you couldn't. What I was saying is that the ratings we see from auto manufactures are measured at the flywheel... not the rear wheels.
And... dividing by the constant of 5252 to "equalize" as you say... is necessary... otherwise we don't have an apples to apples comparison.
A vehicle that makes 300 lbs/ft of torque at 3000 RMP does not make 900,000 hp (300 x 3000)... it makes 171 hp (300 x 3000 / 5252).
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kota on 20s
GenIII
7/01/2002
00:56:41
| RE: bhp vs hp
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man, i wonder what 900,000 HP would feel like. you would probably (would) passout from all of the positive G's!
Eric, 98 5.2 5speed, K&N gen II, 50mm TB, 2bbl M-1, 1.7RR's, JBA ciramic headers, carsound cat, dumped gibson, and a lot more
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