question for the horsepower Gods
10-19-05, 09:41 PM
#1
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question for the horsepower Gods
So i've been wondering, with the old way of calculating hp, it seemed that horsepower to the wheels was about 15-20% lower than crank hp if the car had an auto tranny Now my question is, that with the new SAE corrected numbers... for example the IS350 having 305ish SAE hp, would its real world wheel hp still be about 15% less, or is the SAE number going to be closer to the wheel hp number??
10-19-05, 10:56 PM
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It seems like the ratings are fairly close to the wheel hp ratings. The new Honda Civic Si for example has been shown to put down something like over 210+ hp at the wheels even though it's advertised as 197hp at the crank. It's probably mostly Honda underating the car but I think for the most part, new SAE hp ratings on manual cars will probably put down at the wheels around the same amount that is rated at the crank. Maybe a 5% drivetrain loss on manuals and 10% on auto's. We'll just have to wait and see until people start putting more new Honda and Toyota cars on the dyno. Apparently Nissan decided they are to cool to update their numbers so we can't use them. 
10-19-05, 11:27 PM
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Originally Posted by DrUnBiased
It seems like the ratings are fairly close to the wheel hp ratings. The new Honda Civic Si for example has been shown to put down something like over 210+ hp at the wheels even though it's advertised as 197hp at the crank. It's probably mostly Honda underating the car but I think for the most part, new SAE hp ratings on manual cars will probably put down at the wheels around the same amount that is rated at the crank. Maybe a 5% drivetrain loss on manuals and 10% on auto's. We'll just have to wait and see until people start putting more new Honda and Toyota cars on the dyno. Apparently Nissan decided they are to cool to update their numbers so we can't use them.
10-20-05, 12:18 AM
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Originally Posted by AgentWD-40
I know the new SAE ratings won't let you over rate, I also thought you couldn't under rate either. I thought it was pretty much reported it as is. Perhaps that is incorrect though.
10-20-05, 05:45 AM
#6
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Yea I think its playing a very dirty game if a good amount of the world has recalculated to SAE, but certain manufacturers haven't. Majority of the public has no clue between the difference of SAE or the old method crank hp or wheel horsepower.
10-20-05, 06:40 AM
#7
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Originally Posted by DrUnBiased
Yeah you know thats a good point. I wish ALL manufacturers would update their numbers so it wouldn't be so confusing.
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10-20-05, 04:33 PM
#8
All engines are rated at the crank, the "new" way of dyno'ing engines only benefitted GM, because, from what I hear they were the ones trying to get the SAE hp ratings to change and it did
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