280 whp = what at flywheel?
#21
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Originally posted by 287HP
A 6% loss would mean that a 287hp Z would lose only about 17 hp by the time it got to the rollers. And a stock z does not dyno at 270. A manual rear wheel drive car usually loses around 15-18% to the wheels.
A 6% loss would mean that a 287hp Z would lose only about 17 hp by the time it got to the rollers. And a stock z does not dyno at 270. A manual rear wheel drive car usually loses around 15-18% to the wheels.
#23
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figure 15% loss on 287 = (287fwhp x .85 = 244rwhp) STOCK
take 280 whp/85 x 100 = 329hp
about 330
Taking a 230rwhp avg on stock Z's, about 20% loss, the actual fwhp of 280 rwhp that would be about 350fwhp
These are all estimates and all cars are different, there is only one way to get actual #'s, do a dyno at the wheels, and pull the motor and dyno it seperatly
take 280 whp/85 x 100 = 329hp
about 330
Taking a 230rwhp avg on stock Z's, about 20% loss, the actual fwhp of 280 rwhp that would be about 350fwhp
These are all estimates and all cars are different, there is only one way to get actual #'s, do a dyno at the wheels, and pull the motor and dyno it seperatly
Last edited by TwiZted; 02-22-2005 at 03:38 PM.
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Wow, what a lesson in math!
I have one question about the % of drivetrain loss. Can someone explain why as you increase power, your drivetrain loss is proportional? I mean isn't drivetrain loss due to energy loss through inertia and friction (heat loss). I guess I don't understand how making more power increases the drivetrains inertia or friction.
So based on the above assumptions (drivetrain loss is close to constant), my theory is that the correct formula for bhp is: BHP = WHP + (287 x %DTL) where %DTL ( percent drivetrain loss) is a guesstimate based on the fact that 287 bhp is Nissan's rating and dynos show 230-240 whp.
I have one question about the % of drivetrain loss. Can someone explain why as you increase power, your drivetrain loss is proportional? I mean isn't drivetrain loss due to energy loss through inertia and friction (heat loss). I guess I don't understand how making more power increases the drivetrains inertia or friction.
So based on the above assumptions (drivetrain loss is close to constant), my theory is that the correct formula for bhp is: BHP = WHP + (287 x %DTL) where %DTL ( percent drivetrain loss) is a guesstimate based on the fact that 287 bhp is Nissan's rating and dynos show 230-240 whp.
Last edited by arizzee; 02-23-2005 at 05:21 AM.
#25
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Originally posted by arizzee
Wow, what a lesson in math!
I have one question about the % of drivetrain loss. Can someone explain why as you increase power, your drivetrain loss is proportional? I mean isn't drivetrain loss due to energy loss through inertia and friction (heat loss). I guess I don't understand how making more power increases the drivetrains inertia or friction.
So based on the above assumptions (drivetrain loss is close to constant), my theory is that the correct formula for bhp is: BHP = WHP + (287 x %DTL) where %DTL ( percent drivetrain loss) is a guesstimate based on the fact that 287 bhp is Nissan's rating and dynos show 230-240 whp.
Wow, what a lesson in math!
I have one question about the % of drivetrain loss. Can someone explain why as you increase power, your drivetrain loss is proportional? I mean isn't drivetrain loss due to energy loss through inertia and friction (heat loss). I guess I don't understand how making more power increases the drivetrains inertia or friction.
So based on the above assumptions (drivetrain loss is close to constant), my theory is that the correct formula for bhp is: BHP = WHP + (287 x %DTL) where %DTL ( percent drivetrain loss) is a guesstimate based on the fact that 287 bhp is Nissan's rating and dynos show 230-240 whp.
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Originally posted by arizzee
But what I mean is that if you haven't added weight to the drivetrain, how does making more power also increase the drivetrain loss?
But what I mean is that if you haven't added weight to the drivetrain, how does making more power also increase the drivetrain loss?
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So for example, I dyno my stock Z and get 235 whp. This equals a 52 hp or 18% drivetrain loss.
So I then add an APS TT and dyno 400 whp. Using the % drivetrain loss method, my bhp is 400whp + (400 x .18) = 472bhp.
So using that calculation method somehow means adding a TT adds 20 hp to the drivetrain loss. My common sense says that is not what has happened, but indeed my drive train loss is about the same (hard to factor heat loss).
I think it's more accurate to assume the same drivetrain loss (a supercharger is another story), so I'd figure bhp as 400whp + 52 hp = 452 bhp
But I know very little about internal combustion engines so I'm probably missing it.
So I then add an APS TT and dyno 400 whp. Using the % drivetrain loss method, my bhp is 400whp + (400 x .18) = 472bhp.
So using that calculation method somehow means adding a TT adds 20 hp to the drivetrain loss. My common sense says that is not what has happened, but indeed my drive train loss is about the same (hard to factor heat loss).
I think it's more accurate to assume the same drivetrain loss (a supercharger is another story), so I'd figure bhp as 400whp + 52 hp = 452 bhp
But I know very little about internal combustion engines so I'm probably missing it.
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guys correct me if am wrong !!i read this in a car mag once !
if you devide the cars Hp by 1.15 you will get the wheels HP ...
and if you maltiply any car clame whp by 1.15 you will get the fly wheel hp !
if you devide the cars Hp by 1.15 you will get the wheels HP ...
and if you maltiply any car clame whp by 1.15 you will get the fly wheel hp !
Last edited by omarv6; 02-23-2005 at 07:00 AM.
#30
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Originally posted by omarv6
guys correct me if am wrong !!i read this in a car mag once !
if you devide the cars Hp by 1.15 you will get the wheels HP ...
and if you maltiply any car clame whp by 1.15 you will get the fly wheel hp !
guys correct me if am wrong !!i read this in a car mag once !
if you devide the cars Hp by 1.15 you will get the wheels HP ...
and if you maltiply any car clame whp by 1.15 you will get the fly wheel hp !
#33
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If your car is losing 18% then 82% of the power your making is at the wheels.
Take whatever rwhp you have divided by 82 x 100 and you'll get your approximate fwhp.
This is just an example if it was 15% loss you would divide by 85
of course this is assuming that the 287fwhp Nissan gives is infact correct
Thats why horsepower is just a figure it doesnt determine speed, torque is a much better guage of how fast/powerful a car is as it is an actual measure
Take whatever rwhp you have divided by 82 x 100 and you'll get your approximate fwhp.
This is just an example if it was 15% loss you would divide by 85
of course this is assuming that the 287fwhp Nissan gives is infact correct
Thats why horsepower is just a figure it doesnt determine speed, torque is a much better guage of how fast/powerful a car is as it is an actual measure
Last edited by TwiZted; 02-23-2005 at 10:24 AM.
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