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Ok ...how do you find the difference b/t crank hp and whp

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Old 01-06-2008, 12:28 PM
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R3V9K
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Ok ...how do you find the difference b/t crank hp and whp

is there like a math problem or something that will tell you how much crank hp you have. Can you take your whp numbers and convert them? i was just wondering this during work lol.
Old 01-06-2008, 12:34 PM
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depends on the car. For the rx-8, it's 11 - 15% less for whp vs crank.
Old 01-06-2008, 12:34 PM
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either get dyno results from the same engine on an engine dyno and chassis dyno and compare.... or do a whole lot of research, get a Mechanical Engineering degree, and do a whole lot of calculating

...or just make use of a general percentage assumption
Old 01-06-2008, 12:46 PM
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Originally Posted by mysql101
depends on the car. For the rx-8, it's 11 - 15% less for whp vs crank.
I'm guessing the losses (as a percentage) reduce significantly as you increase the hp by boosting ?
Old 01-06-2008, 12:47 PM
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You can test it yourself - enter quarter mile times and speeds, weight etc. and it will give you a rough estimate.

http://www.dragtimes.com/horsepower-...calculator.php

S
Old 01-06-2008, 12:53 PM
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Originally Posted by Brettus
I'm guessing the losses (as a percentage) reduce significantly as you increase the hp by boosting ?
The problem is few of us are taking our engines out and doing an engine dyno then doing a regular dyno to compare.

We estimate based on the numbers we do have. I guess it matters if you think Mazda is accurate with the 232 hp claim.
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