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Old 06-14-2008, 07:20 AM   #1
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Default crank hp vs. whp and bhp

98 prelude, with cai and 2.5" catback... guessing i'm at about 205-210 crank hp although the car has 157k on it.

Just wanna know the difference between 195 hp @ crank and WHP...

Maybe 170?

Also, what is BHP? Brake horsepower... is that at the crank?
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Old 06-14-2008, 09:10 AM   #2
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Default Re: crank hp vs. whp and bhp (Acidcrakker)

lol, BHP can stand for Brake Horsepower or Base Horsepower

edit: Brake Horsepower is measured at the crank. It doesnt measure the power of your brakes (lol), but gets its name from a old method they used to measure it (I think).
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Old 06-14-2008, 10:05 AM   #3
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Default Re: crank hp vs. whp and bhp (honda3431)

Thanks, but I was actually asking what my whp is if my bhp is 200... not asking for a specific number but more of an estimate.
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Old 06-14-2008, 11:13 AM   #4
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Default Re: crank hp vs. whp and bhp (sdr85)

Id guess your around 160ish range with cai and exhaust, no header? And as for the confusion over BHP and WHP...it does stand for brake horsepower because thats the way an engine dyno works, either a water brake or an electric brake (eddie current) and yes it would be at the crankshaft. And in case you were wondering how much power is lost through the drivetrain, its not a percent loss its a set ammount, based on the resistance/weight of the whole drivetrain. Ill just pick some numbers,lets say you make 200BHP with a 15% drivetrain loss, that would be 170whp (30HP loss), but if the same car gets a pet snail and makes say 400BHP with the same 15% drivetrain loss, that would come out to 340WHP yeilding a 60HP loss. theres no way the drivetrain takes more power to turn when you make more power...its a fixed number. hope that helps
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Old 06-14-2008, 01:00 PM   #5
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Default Re: crank hp vs. whp and bhp (jeremiah87)

Quote:
Originally Posted by jeremiah87
Id guess your around 160ish range with cai and exhaust, no header? And as for the confusion over BHP and WHP...it does stand for brake horsepower because thats the way an engine dyno works, either a water brake or an electric brake (eddie current) and yes it would be at the crankshaft. And in case you were wondering how much power is lost through the drivetrain, its not a percent loss its a set ammount, based on the resistance/weight of the whole drivetrain. Ill just pick some numbers,lets say you make 200BHP with a 15% drivetrain loss, that would be 170whp (30HP loss), but if the same car gets a pet snail and makes say 400BHP with the same 15% drivetrain loss, that would come out to 340WHP yeilding a 60HP loss. theres no way the drivetrain takes more power to turn when you make more power...its a fixed number. hope that helps
im pretty sure its still a percentage of power lost.
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Old 06-14-2008, 02:16 PM   #6
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Default Re: crank hp vs. whp and bhp (sdr85)

Quote:
Originally Posted by sdr85
98 prelude, with cai and 2.5" catback... guessing i'm at about 205-210 crank hp although the car has 157k on it.

Just wanna know the difference between 195 hp @ crank and WHP...

Maybe 170?

Also, what is BHP? Brake horsepower... is that at the crank?
Considering the age and mileage, factoring that to make loss of compression, I'd say you're at about 185 BHP. Factor in that you're OBD2 and those mods don't do **** on OBD2, you're looking at around 160-165 WHP or less. Swap to OBD1, get it tuned, you could easily make 170 whp.
Your butt dyno might have mislead you because the car breathes better, but OBD2 resets everything back to stock settings after a short time of driving it. You might end up with 1 or 2 hp extra, which is crap considering how much just those 2 mods cost.
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Old 06-14-2008, 02:22 PM   #7
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Default Re: crank hp vs. whp and bhp (Si Speed)

ill argue that the mods do make a difference greater than 1-2whp, not much more.. but i wouldn't say that its that miniscule. the better breathing contributes to power throughout the powerband not just to peak.. so the gains for a fun DD would probably be worth it. (since reliability isn't compromised)
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Old 06-14-2008, 07:48 PM   #8
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Default Re: crank hp vs. whp and bhp (Acidcrakker)

Quote:
Originally Posted by dartonh22

im pretty sure its still a percentage of power lost.
Think about it, its measured as a percent loss...thats just another way to say that we made "X" power at the crankshaft and "Y" at the wheels and the difference is "Z". The drivetrain doesnt know what power the engine is making, it only knows that it takes "Z" power to turn it all. If it takes "Z" to turn the drivetrain at 200BHP, then at 400BHP the drivetrain didnt grow a brain and get greedy for HP, it still only takes "Z" to turn the drivetrain.
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Old 06-14-2008, 09:23 PM   #9
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Default Re: crank hp vs. whp and bhp (sdr85)

Just go get your car dyno'd. WHP = Wheel Horse Power BHP = Brake Horsepower. Both of those mean power to the wheels basically. You can't really just guess how much HP your car has because it is unreasonable. You can always just go get some baseruns

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Old 06-16-2008, 08:17 PM   #10
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Default Re: crank hp vs. whp and bhp (Acidcrakker)

Quote:
Originally Posted by Acidcrakker
some people shouldnt breed

Im pretty sure that BHP means Block Horse Power. If Im wrong about that I probally shouldnt be breeding either.

Whp is your hp at the wheels

just because you make 200 hp at the crank doesnt mean all 200 is going to make it to the wheels.
wrong, it's BRAKE horse power. power to the flywheel. wheel horse power has more variables than bhp. the only way to know is to use a wheel dyno
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Old 02-22-2010, 07:04 PM   #11
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Default Re: crank hp vs. whp

i know nothing about this stuff so heres a question on the dyno it said i made 198 hp how much would that be in wheel horse power and crank hp any help thanks
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Old 02-23-2010, 12:44 PM   #12
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Default Re: crank hp vs. whp

As a rule of thumb, WHP is 0.85*BHP. This assumes a 15% driveline loss, which is just about standard for a manual transmission car.

So, 200 bhp = 170 whp. but stock preludes never made 200 bhp, even if the brochures said so. A perfect condition H22A_ making 190 bhp should make 160 whp. That being said, every dyno is different and ambient conditions effect the dyno plots.

FWIW, my '01 base w/ I/H/E, w/ Hondata S200 tuned by Church made 189 whp peak.
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Old 02-23-2010, 01:15 PM   #13
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Default Re: crank hp vs. whp

I don't know how you guys can make guesses considering the 20%+ variation in dynos.
I have to ask; What does it really matter?
Church=Highest reading dyno in the country, but people don't go there for BRAG #'s. They go there for top-notch tuning which has been weak has of late from what I have heard.
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Old 02-24-2010, 07:40 PM   #14
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Default Re: crank hp vs. whp

I had to read all the way down to post 15 before someone made an intelligent comment...wow.

Anyway, whp can be calculated by taking approximately 15% of the Crank Horsepower (sometimes called BHP, which stands for Brake Horsepower) So, 200 *.15 = Approx 170whp.
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Old 02-25-2010, 05:46 PM   #15
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Default Re: crank hp vs. whp

this thread is fully ridiculous
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Old 02-25-2010, 09:14 PM   #16
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Default Re: crank hp vs. whp

Quote:
Originally Posted by jonbar87 View Post
I had to read all the way down to post 15 before someone made an intelligent comment...wow.

Anyway, whp can be calculated by taking approximately 15% of the Crank Horsepower (sometimes called BHP, which stands for Brake Horsepower) So, 200 *.15 = Approx 170whp.
who gave you those figures ? lol 200x0.15 def does not equal to 170whp. show me a stock prelude putting 170whp down from the factory.. and furthermore, how is your comment any more intelligent than any of those before you? you stabbed at an answer you probably believe is right, but isn't close to a definitive answer to the argument.
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Old 02-26-2010, 08:03 AM   #17
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Default Re: crank hp vs. whp

Quote:
Originally Posted by dagle
who gave you those figures ? lol 200x0.15 def does not equal to 170whp. show me a stock prelude putting 170whp down from the factory.
USDM H22A1 (190bhp)
140,000 miles
fleaBay CAI
2.25" POS catback exhaust
untuned (stock computer)

That's pretty stock making very close to 170whp
H22A1 = Red line:
Click the image to open in full size.

15% drivetrain loss is typical for those that take a 4-cylinder NA engine tuned/broken in on an engine dyno and installed in a car and re-dynoed on an inertial dyno.
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Old 02-26-2010, 08:03 AM   #18
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Default Re: crank hp vs. whp

Quote:
Originally Posted by dagle View Post
who gave you those figures ? lol 200x0.15 def does not equal to 170whp. show me a stock prelude putting 170whp down from the factory.. and furthermore, how is your comment any more intelligent than any of those before you? you stabbed at an answer you probably believe is right, but isn't close to a definitive answer to the argument.
well, 200 * .85 = 170, but no stock preludes are making 170 whp because they never made 200 bhp. they all make 190 bhp and 190 * .85 = 161.5 whp. Which is just about right, maybe a little high.
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Old 03-01-2010, 01:53 PM   #19
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Default Re: crank hp vs. whp

BHP is useful, but WHP really tells you what you have. Looks bad to post WHP though.
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