Dyno Numbers..
02-18-2008 | 12:51 AM
#11
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Originally Posted by Spec_Ops2087,Feb 18 2008, 01:16 AM
Tire slip is hardly EVER an issue on a dyno, if its an issue it shows on the dyno graph very clearly.
The difference between dyno-pack and roller type dynos is rotational mass difference between the wheels being mounted and not being mounted.
The reason why dynoing now and dynoing 4k miles later is different is because the conditions in which the car was dynoed are different. This is why dynos use STD or SAE smoothing to try and account for differences in temperature/altitude/humidity/etc but of course it is not 100% accurate.
The only accurate dyno is the delta horsepower and torque of back to back dynos. Who is to say one type of dyno is very accurate at showing horsepower numbers but yet another one isn't? The only thing they are accurate at is showing the difference between two numbers as that will never be different between dynos (again to a certain degree of dyno error).
The difference between dyno-pack and roller type dynos is rotational mass difference between the wheels being mounted and not being mounted.
The reason why dynoing now and dynoing 4k miles later is different is because the conditions in which the car was dynoed are different. This is why dynos use STD or SAE smoothing to try and account for differences in temperature/altitude/humidity/etc but of course it is not 100% accurate.
The only accurate dyno is the delta horsepower and torque of back to back dynos. Who is to say one type of dyno is very accurate at showing horsepower numbers but yet another one isn't? The only thing they are accurate at is showing the difference between two numbers as that will never be different between dynos (again to a certain degree of dyno error).
Thanks
02-18-2008 | 08:21 AM
#13
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From: Seattle, WA
Originally Posted by ace123,Feb 18 2008, 11:38 AM
tire slip? i'd think rolling resistance, rotational inertia, and those types of power drainers are the HP culprit.
That's why slapping on 18"+ rims on this car is just dumb - you're making the car lose the power that it's actually putting down to the ground but some people just don't understand that.
02-18-2008 | 09:04 AM
#14
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From: Orange County CA
Last time I was at a dyno and had issues with tire slippage was when we were dyno'ing a 850HP Supra.... Unless you have a High HP S or bald skinny rear tires, I dont think slippage will be an issue 
02-18-2008 | 09:39 AM
#15
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From: New Jersey
Originally Posted by afwfjustin,Feb 18 2008, 12:21 PM
Exactly... with the Dynapack you're taking a HUGE component of the driveline out of the equation (the wheels). Just think if you could take out the rear axles, and diff, and driveshaft - you'd dyno even higher (flywheel hp)!
That's why slapping on 18"+ rims on this car is just dumb - you're making the car lose the power that it's actually putting down to the ground but some people just don't understand that.
That's why slapping on 18"+ rims on this car is just dumb - you're making the car lose the power that it's actually putting down to the ground but some people just don't understand that.
02-18-2008 | 09:45 AM
#16
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From: Bay Area, CA
Originally Posted by afwfjustin,Feb 18 2008, 09:21 AM
That's why slapping on 18"+ rims on this car is just dumb - you're making the car lose the power that it's actually putting down to the ground but some people just don't understand that.
02-24-2008 | 08:25 AM
#19
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Originally Posted by NA20,Feb 24 2008, 01:47 AM
WHP numbers can be affected by the tightness of the straps holding the car, and tire pressure too...
The Dynapack is more consistent since it eliminates these variables...
The Dynapack is more consistent since it eliminates these variables...
02-24-2008 | 02:04 PM
#20
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From: Little Rock, Arkansas
i dont know much about what dyno does what best, or which is better, but from the way i see it, a 10hp gain on one will not be a 10hp gain on another. here's my example
lets just agree that all s2000's make 240 crank hp exactly from the factory.
say for instance, you get a baseline number on one dyno of 200hp to the wheels.
you put on your "10hp" part, dyno again, and you get 210hp
next, lets say you dyno the same car before the "10hp" part on another dyno for that baseline. and just to make it easy, you come up with 150hp. 3/4's of what the other dyno said.
so from this, we can assume that the 10hp you gained from the part on the other dyno, is only gonna gain 3/4's of that on the second dyno.
so on the second dyno, that mod would only "gain" 7.5 hp.
hope this is clear enough to understand, and remember, i have no experience with dyno's or trying to prove gains from modified cars. this is just my speculation on this particular subject.
lets just agree that all s2000's make 240 crank hp exactly from the factory.
say for instance, you get a baseline number on one dyno of 200hp to the wheels.
you put on your "10hp" part, dyno again, and you get 210hp
next, lets say you dyno the same car before the "10hp" part on another dyno for that baseline. and just to make it easy, you come up with 150hp. 3/4's of what the other dyno said.
so from this, we can assume that the 10hp you gained from the part on the other dyno, is only gonna gain 3/4's of that on the second dyno.
so on the second dyno, that mod would only "gain" 7.5 hp.
hope this is clear enough to understand, and remember, i have no experience with dyno's or trying to prove gains from modified cars. this is just my speculation on this particular subject.
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