Loss of 22.5% HP

lando76

So basically most of you agree that not one dyno is accurate. One thread said " A normal dyno" which to me sounds a little broad. How about this I will go to three different dyno shops and pay three times what I want to pay and take the average. I do believe that most dyno shops have to have their machines calibrated by the state of some sort to charge customers money and be considered a business.

Ryan@IP

All dynos are accurate on their own scale, as long as they are well maintained (ours is). Even car manufacturers can't always agree on what to accurately rate engine power at. What you also have to consider is the formulas behind each dyno and how the numbers are determined. It is a fairly complicated process that takes in a scary amount of values to determine what numbers to output on the screen. As a previous poster pointed out, some dynos are load bearing; others are not. Some, like a Dynapack, measure from the hubs rather than the mounted wheels and tires.

There is no such thing as a "normal" dyno or a right vs. wrong dyno. We have our reasons for choosing a Dyno Dynamics over the other choices, but that does not mean that we feel DynoJet numbers are irrelevant. They are simply using a different scale than ours. The important thing is that you remain consistent on the brand of dyno that you go to. A DD's numbers will be comparable to just about any other DD's numbers, but directly comparing a DD result to a DynoJet gets a little more fuzzy. The only *true* way to measure horsepower output is through an engine dyno, not a chassis dyno. All we can realistically do is measure gains from our baseline on X dyno to the results on the same type of dyno.

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wstar

Well, in *theory*, the value of a a ft/lb of torque is based on international standards. Therefore any machine reading ft/lbs of torque from the spinning wheels of a car under the same loading conditions (meaning, some standardized approximate simulation of the weight of the car and aerodynamic load), with the same (hopefully minimal) wheel-slip error on the rollers, should read the same value.

I understand, to some degree, why the situation is as it is, but I think there is a "right answer" as to how much rwhp is actually being put out of the car, and I think the dyno mfgs could be doing a better job than they are of getting their results in line.

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