Quote:
Originally Posted by Steve W
The numbers will depend on which brand of dyno you use. After dyno tuning hundreds of 911s on machines such as Mustangs, Dyna-packs, Dyno Dynamics, Superflow, Land&Sea, Dynojets, the most consistent numbers come from Dynojets, close enough that the same car dyno'd on one in Los Angeles will be within 3-4 hp SAE corrected of one in South Carolina. There's no operator alterable factors that can fudge, either accidentally or intentionally the HP and torque numbers, why many racing organizations use Dynojet numbers to classify cars. Given the same state of tune and chip program, I typically get hp and torque curves within 1-2 hp of each other between runs, even on different days. A 40 hp spread from a dyno is horrible resolution!!
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My point was indeed that dyno numbers will vary. I like when people that I cannot access directly do runs on dynojets so they can send me the runfile, then with the WinPep software I can scale the hp/tq/afr curves in a resolution that shows me the detail in any format, or even in speed, and/or time. All useful TUNING information. When I stated 30something hours on the dynapack, I was only referring to my own 911. I've been tuning cars on streets and dynos for many years now.
I chose the dyna-pack because it takes the wheels out of the equation, and they actually tend to give the most realistic and consistent numbers of any of the other makes I've ever dealt with. I can cause any roller based machine to change output by changing the tire pressure. An operator or anyone else can also use the winpep software to display the run in many ways, and manipulate many variables. Dynojets tend to read higher than other dynos, just as Mustand dynos do. In fact, the Mustang dyno has a 'dynojet' setting to emulate a dynojet, and it will indeed yield a higher output number.
While a good dyno will indeed do proper SAE correction if told to, that doesn't negate the fact that the car does not produce the same power and have the same volumetric efficiency on a 45 degree low humidity day as it does in 90 degrees with 80% humidity. I don't think anyone will argue that.
Regards,
Russell