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Old 12-26-2009, 11:02 PM
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HEMI5150 HEMI5150 is offline
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Join Date: Dec 2009
Location: Fingerlakes - Upstate NY
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Vehicle: 2010 Dodge Ram Quad 4X4
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Originally Posted by Get Bit View Post
How is that misleading? All auto manufactures rate their vehicles HP at the crank, which is BHP. This also does not include the accessories that the engine turns, e.g. alternators, A/C compressors, etc.

Now, we as the consumer test the said HP via a chassis dyno, which reads at the tires and use somewhat of a broad range or % to determine the amount of loss there is between the flywheel and what it is actually putting to the ground. Manual transmissions eat up less power than automatics, so, depending on the setup, you can lose anywhere from 12-20% through the drivetrain.

All we care is about what it makes to the ground along with the correction factors and conditions in which the vehicle was dynoed in. Most stock 09 HEMI rams rated at 390hp will put down around 300-310 stock at the wheels. Now, these numbers can also vary with what dyno you're using. Mustang or inertia dynos tend to be a little lower than the more common dynos, like a dyno jet.

Dyno's are best for tuning and ensuring everything like timing, air to fuel ratios, etc are safe. The real test to see what power you are making is at the track. Trap speed based of weight of vehicle is a good indication of HP, the E.T. is the indication of how well and efficiently it puts it to the ground.
yeah thanks, i know how dyno`s work...
i own one for tuning race engines in my shop for the harley guys.
Guess i`ll just stick to tuning harley race engines, and just use this new 300hp dodge hemi to haul`m to the racetrack

You might be able to bullshit your way to the top, BUT, it wont keep you there

Never believe what you hear, and only half of what you see
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