what does BHP mean?
02-23-02, 07:06 PM
#3
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one guy was telling me about the fwhp his rx7 had.. and im like fw?? as opposed to rwhp.. but then i realized he meant flywheel horsepower. but fwhp usually means front wheel horsepower.. so thats why we say bhp when we are talking about hp.. so we dont get confused
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02-23-02, 08:21 PM
#8
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Originally posted by J-Rat
I was under the impression that BHP was "braking horsepower", and that it was a measurement used when Dynos werent available.
I was under the impression that BHP was "braking horsepower", and that it was a measurement used when Dynos werent available.
Brake horsepower is horsepower measured at the crank, as the engine is installed in the car. (accessories, etc.)
Dynos have been around probably as long as engines have been around, maybe longer
Chassis dynos, I don't know, the earliest mention I've heard of a chassis dyno was around 1970 or so and I'm pretty sure they were nothing new back then... anyway I think BHP is a newer term than that. Back in the ol' days (and still done today) you pulled the engine and mounted it up on an engine dyno if you wanted to dyno-tune it. Chassis dynos are SO non-repeatable, with so many variables, that it's not funny. Change to a different gear, get a different reading. Change your tires, get a different reading. Change tire PRESSURE, get a different reading...Let's check Google...
http://www.harcourt.com/dictionary/d...7/1477100.html
brake horsepower Mechanical Engineering. the actual horsepower of an engine measured at the flywheel by the use of a dynamometer.
You could make a simple dyno at home, by gutting a transmission so it's direct drive, putting a large disc brake at the end, letting the brake pivot around the output shaft and attaching the caliper to a 1' long fulcrum, stopped up against a scale. If the scale reads 200 pounds when you use the brake to hold RPM constant, that means the engine is putting out 200lb-ft of torque. (1' long fulcrum, 200 pounds of force) Then you plug that in to a simple formula and you get your HP for that RPM. The brake wouldn't last too long though
02-24-02, 12:04 AM
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Originally posted by peejay
You could make a simple dyno at home, by gutting a transmission so it's direct drive, putting a large disc brake at the end, letting the brake pivot around the output shaft and attaching the caliper to a 1' long fulcrum, stopped up against a scale. If the scale reads 200 pounds when you use the brake to hold RPM constant, that means the engine is putting out 200lb-ft of torque. (1' long fulcrum, 200 pounds of force) Then you plug that in to a simple formula and you get your HP for that RPM. The brake wouldn't last too long though
You could make a simple dyno at home, by gutting a transmission so it's direct drive, putting a large disc brake at the end, letting the brake pivot around the output shaft and attaching the caliper to a 1' long fulcrum, stopped up against a scale. If the scale reads 200 pounds when you use the brake to hold RPM constant, that means the engine is putting out 200lb-ft of torque. (1' long fulcrum, 200 pounds of force) Then you plug that in to a simple formula and you get your HP for that RPM. The brake wouldn't last too long though
http://www.race-technology.com/WebPa...omparison.html
08-13-03, 10:27 PM
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Formulations
http://www.angelfire.com/darkside/de.../Formulas.html
Just go down to the strip and do a couple runs, or you can take your dyno sheet and figure out your 1/4 mile times
Just go down to the strip and do a couple runs, or you can take your dyno sheet and figure out your 1/4 mile times
08-14-03, 12:22 AM
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Dunno where people get "base" horsepower from, but it's incorrect. As mentioned above (some 18 months ago...) it's brake horsepower, as measured on an engine brake (the old name for a dynomometer).
08-14-03, 01:01 AM
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Originally posted by 650bhp
Always was base horse power to me I.E at the flywheel
Always was base horse power to me I.E at the flywheel
IHP = Indicated Horsepower = Total horsepower converted from heat energy to mechanical energy. IHP = BHP + FHP
BHP = Brake Horsepower = Actual horsepower developed and available for work. BHP = IHP - FHP
FHP = Friction Horsepower = Amount of total horsepower required to overcome friction of the engine and accessories. FHP = IHP - BHP
Types of BHP:
Gross BHP = Horsepower produced with the engine on an engine stand with only the requied drive components (oil pump, water pump, etc.) and special dyno-only exhaust and intake.
Net BHP = Horsepower produced by the engine as installed in the vehicle.
08-14-03, 07:30 AM
#17
trying to build a racecar
It stands for brake horsepower. peejay has it very close.
Quoted from an engineering text
*************
Early Dynomometers were called "Prony brakes", or simply brakes, because they used brake shoes to press against the flywheel to apply the desired load (Obert, 1973). The terms "Dyno" and "brake" were essentially synonymous at one time. Therefore, the current usage of the terms "brake power" and "brake torque" refer to the power and torque readings obtained with the engine mounted on a dyno.
***********
Hope that clears things up.
Quoted from an engineering text
*************
Early Dynomometers were called "Prony brakes", or simply brakes, because they used brake shoes to press against the flywheel to apply the desired load (Obert, 1973). The terms "Dyno" and "brake" were essentially synonymous at one time. Therefore, the current usage of the terms "brake power" and "brake torque" refer to the power and torque readings obtained with the engine mounted on a dyno.
***********
Hope that clears things up.
08-14-03, 07:35 AM
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Originally posted by Evil Aviator
I am not aware of any "base" horsepower. Here are some SAE standards:
IHP = Indicated Horsepower = Total horsepower converted from heat energy to mechanical energy. IHP = BHP + FHP
BHP = Brake Horsepower = Actual horsepower developed and available for work. BHP = IHP - FHP
FHP = Friction Horsepower = Amount of total horsepower required to overcome friction of the engine and accessories. FHP = IHP - BHP
Types of BHP:
Gross BHP = Horsepower produced with the engine on an engine stand with only the requied drive components (oil pump, water pump, etc.) and special dyno-only exhaust and intake.
Net BHP = Horsepower produced by the engine as installed in the vehicle.
I am not aware of any "base" horsepower. Here are some SAE standards:
IHP = Indicated Horsepower = Total horsepower converted from heat energy to mechanical energy. IHP = BHP + FHP
BHP = Brake Horsepower = Actual horsepower developed and available for work. BHP = IHP - FHP
FHP = Friction Horsepower = Amount of total horsepower required to overcome friction of the engine and accessories. FHP = IHP - BHP
Types of BHP:
Gross BHP = Horsepower produced with the engine on an engine stand with only the requied drive components (oil pump, water pump, etc.) and special dyno-only exhaust and intake.
Net BHP = Horsepower produced by the engine as installed in the vehicle.
Evil Aviator.........you posting that reminds me of all the formulas I had to remember to calculate horsepower at riddle
08-14-03, 07:36 AM
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Originally posted by Travis R
It stands for brake horsepower. peejay has it very close.
Quoted from an engineering text
*************
Early Dynomometers were called "Prony brakes", or simply brakes, because they used brake shoes to press against the flywheel to apply the desired load (Obert, 1973). The terms "Dyno" and "brake" were essentially synonymous at one time. Therefore, the current usage of the terms "brake power" and "brake torque" refer to the power and torque readings obtained with the engine mounted on a dyno.
***********
Hope that clears things up.
It stands for brake horsepower. peejay has it very close.
Quoted from an engineering text
*************
Early Dynomometers were called "Prony brakes", or simply brakes, because they used brake shoes to press against the flywheel to apply the desired load (Obert, 1973). The terms "Dyno" and "brake" were essentially synonymous at one time. Therefore, the current usage of the terms "brake power" and "brake torque" refer to the power and torque readings obtained with the engine mounted on a dyno.
***********
Hope that clears things up.
08-14-03, 07:38 AM
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Re: Formulations
Originally posted by Kyrasis6
http://www.angelfire.com/darkside/de.../Formulas.html
Just go down to the strip and do a couple runs, or you can take your dyno sheet and figure out your 1/4 mile times
http://www.angelfire.com/darkside/de.../Formulas.html
Just go down to the strip and do a couple runs, or you can take your dyno sheet and figure out your 1/4 mile times
**** bud.....this thread is a year old.....where you grave digging
08-14-03, 08:16 AM
#21
trying to build a racecar
Right, but the Prony brake dyno was basically a giant drum brake.
I didn't read all of this page, just skimmed it, but it looks pretty good.
http://www.buckleyoldengineshow.org/horsepower.htm
Besides water brake there is also an an eddy current dyno, a couple versions that use AC and DC motors to act as generators/starters, and an adjustable frequency dyno which is basically a fancy, multi-pole, AC motor.
I didn't read all of this page, just skimmed it, but it looks pretty good.
http://www.buckleyoldengineshow.org/horsepower.htm
Besides water brake there is also an an eddy current dyno, a couple versions that use AC and DC motors to act as generators/starters, and an adjustable frequency dyno which is basically a fancy, multi-pole, AC motor.
08-14-03, 11:40 AM
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The number that matters is what's put to the wheels. All car manuf's list their numbers in bhp (gross) in order to claim the best looking figures.
Look at Nissan, there's claims that the Sentra SE-R spec V isn't anywhere near the published figures. This type of business practice should be more closely governed by the state.
Wouldn't everybody prefer seeing numbers produced from a chassis dyno? That way there's no fudging the truth. If the Government took the average of 5 cars pulled from the line and forced the manufactures to post their figures, the public would be better for it.
It's like buying a house and the builder overstates the square footage by a couple hundred. Nobody would stand for that, so why should we stand for this?
Look at Nissan, there's claims that the Sentra SE-R spec V isn't anywhere near the published figures. This type of business practice should be more closely governed by the state.
Wouldn't everybody prefer seeing numbers produced from a chassis dyno? That way there's no fudging the truth. If the Government took the average of 5 cars pulled from the line and forced the manufactures to post their figures, the public would be better for it.
It's like buying a house and the builder overstates the square footage by a couple hundred. Nobody would stand for that, so why should we stand for this?
08-14-03, 04:40 PM
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Originally posted by ERAUMAZDA
Evil Aviator.........you posting that reminds me of all the formulas I had to remember to calculate horsepower at riddle
Evil Aviator.........you posting that reminds me of all the formulas I had to remember to calculate horsepower at riddle
08-15-03, 07:02 AM
#24
trying to build a racecar
I'm pretty sure all major car companies follow SAE standards when they figure engine output. Engine dynos have more repeatable results because there are fewer variables in the equation (no tranny, no diff,no brakes, no tires, no rollers...) I think SAE standards dictate the conditions at which the engine is tested. If you want I can look them up.
If there are gross differences between then engines on the stand and cars coming off the assembly line, then that is a quality control issue, not them fudging the numbers.
If there are gross differences between then engines on the stand and cars coming off the assembly line, then that is a quality control issue, not them fudging the numbers.
