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  #11  
Old 06-30-2010, 10:48 PM
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Originally Posted by 335xray View Post
Yes, it is unsprung weight. Wheels, tires, rotors, calipers, suspension bits.

Then transmission friction, internal engine friction, differential etc.
Why does unsprung weight matter for driveline losses? Why does engine friction matter for driveline losses?
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  #12  
Old 07-01-2010, 05:55 AM
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there are more and more high HP claims on these cars, but how come different tuners quote different results with the same kinda combo - chip & exhaust.
it would be interesting to read a customer's view of a chipped vehicle.
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  #13  
Old 07-01-2010, 02:49 PM
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All that is factored into the loss factor are rotational inertia and friction in the transmission and drivetrain.
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  #14  
Old 07-01-2010, 03:05 PM
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Originally Posted by Iluxa View Post
there are more and more high HP claims on these cars, but how come different tuners quote different results with the same kinda combo - chip & exhaust.
it would be interesting to read a customer's view of a chipped vehicle.
Because it is the internet, and there are no penalties for lying.

Customer opinions may matter, but what would be more valuable would be independent verification by a certified authority. Customers don't tend to have dynos available to them, and they also tend to have a vested interest in their tuning investment having been a wise one. Few customers are going to compare multiple tunes.
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  #15  
Old 07-01-2010, 04:57 PM
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Originally Posted by 335xray View Post
I guess the range is between 20-30%, but 30 is pretty high.
AWD and automatic.
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  #16  
Old 07-01-2010, 05:18 PM
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AWD and automatic.
What is really funny is that the numbers he shows aren't 30% in any case. He calculated 30% of the wheel hp, instead of 30% of the presumed flywheel hp. His number of 167 hp losses in the drivetrain is actually 23% of the measured wheel hp. Even that number is questionable, as it means that 167 hp = 125 kw are being radiated out of the transmission and differentials as heat.

If the standard vehicle makes 550 flywheel hp, and actually had 23% driveline losses, that means that 126 hp is being dissipated as heat. Why would modifying the engine result in 41 more hp being lost in the driveline? It is the same driveline as before the modifications. Any discussion of driveline losses as a percent is on a shaky foundation to start.

I don't know what is worse; this tuner not knowing any of that; or making an error in the calculation if we give him a pass on his illogical approach; or him knowing it is all bogus and trying to use it to sell his tune.

Wonder if it comes with a dash plaque saying 724 hp?
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  #17  
Old 07-06-2010, 08:19 AM
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Good post.
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  #18  
Old 07-06-2010, 04:13 PM
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Paging cmyX6go..... next car right here.
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  #19  
Old 07-06-2010, 04:23 PM
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Paging cmyX6go..... next car right here.
724 horses is INSANE! Every day I'm floored when I kick my 440 and I think about the difference going to 550 on the ///M. But 724?!?!?!?!??!

What do you think? 5 mpg?
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  #20  
Old 07-07-2010, 10:25 AM
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I want a 1000 hp.
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