DYNO question...

[mindgam3]

Weight won't really be an issue at all.

Don't forget to add in the losses from the actual rolling road too. Losses will vary from car to car and its configuration, but as RC45 said, it will be somewhere in the 15-25% range....

Rolling roads are far less acurate than rolling roads, although the latest digital hub dynos, that cost about £40,000 per wheel are getting fairly accurate.

[T-Bird]

wow finally a thread where I have more experience using the given equipment than the others...

According to the guys at Mustang no 2 "identical" cars will ever have the exact same hp, because there are soo many factors involved from how the car was broken in etc the most minute details can determine the differences. now maybe if you had some way of getting the cars exactly the same in every single little detail it could be possible. And traction shouldn't be an issue on a dyno when trying to measure 400hp now we did have an 850ft/lb pickup spin the tires but it had absolutley no weight on the rear. but weight shouldn't affect the hp output of a vehicle at the wheels. The biggest and most important factor is getting all the settings correct in the computer they need everything from temp to barometric pressure elevation all that needs to be imput into the computer for a truely correct reading that is how some companies can get a guaranteed hp everytime they just fudge a few factors and bam.

[graywolf624]

According to the guys at Mustang no 2 "identical" cars will ever have the exact same hp

Hell even the same car will barely ever run the exact same hp...

Wheel diameter/ gearing will obviously effect the torque curve.

[T-Bird]

very true if you run the car one day then come back the next it could be off by 5hp more or less.

[RC45]

In the realm of performance tuning, "the dyno pull" is nto to determine actul output, but rather provide a way to evaluate the results of changes made.

By observing the delta youknow wether you are on the right track or not.

As with any "measuremnet" taken against a complex system - there are obviously many variables able to impact absolute numbers, but you can bank on the changes in output being a good measure of success.

This is true whether dynoing a car or bike, or benchmarking a PC, or measuring top speed or 1/4 mile drag race times.

And yes - even Nurburgring lap times -- Consistant dupliaction of results or measurable changes are what import

[T-Bird]

yeah we did a 1/4 mile pull on a Bonneville everything properly input in the comp and it only ran a 17.8 on 5 of 6 cylinders