Most motorcycle riders have seen a dynamometer (Dyno) in action by now. They've seen them at motorcycle shows, racing events, power 'shoot-outs' or even at the local bike shop. They're certainly an attraction, a lot of fun, and, of course, downright deafening. Before the Dyno came along, many of us had to spend endless hours trying to get the jetting just right or struggling to get that little edge over that big mouth down the street. The Dyno has greatly simplified the task of getting everything dialed in the way you want it. The Dyno at my shop is used almost daily during the summer months to optimize the racer's needs or the everyday rider's desire to get his 'baby' purring like a kitten.
Considering the tremendous assistance the Dyno provides and the far greater service capabilities associated with it, every owner / operator must be thrilled beyond words with the expanded capabilities; well, not exactly. There's just one problem, and it's a hum dinger. The problem here is that nearly everyone involved tends to exaggerate the results for one reason or another. By the time the customer gets drawn in, the numbers are downright ludicrous. Even the bike owner feels the pressure to enhance the results in an effort to stay competitive, impress their friends or just plain feel good about all the money they've spent on performance hardware and shop labor costs.
Case in Point
The following is just one example of how this widespread bending of the truth takes place. We'll use the installation of a header as an example, although any number of other items such as a jet kit, hotter cams, supercrank, or a dozen other things would be just as applicable. Almost everyone from the Dyno operator, to the store where you purchased the header, to the header manufacturer, and last but not least, the bike owner, all benefit from bumping up the numbers a bit. This all gets in the way, however, of an intelligent and meaningful understanding of the Dyno test and of the true benefit of the product being evaluated. Lets take each of the afore mentioned situations:
The Dyno operator
If the shop performing the Dyno tests sold you the header, they have a vested interest in recording an improvement in power. If you've requested a before and after test, the Dyno operator will instinctively want the 'before' test to be less than impressive. He may deliberately 'hold back' or otherwise resist getting everything he can from the bike. He may select the least impressive or lowest horsepower curve as the 'before' example for comparison. He'll probably make only three (3) runs and move quickly to install the new pipe. After the header has been installed he'll make a whole battery of tests to get the highest possible result. Not only that, he may suggest installing a jet kit, a new set of spark plugs, a K&N air filter, or maybe even a valve adjustment. He will automatically resort to doing everything he can to get the best results. When it's all said and done, the header will get all the credit for the overall improvement. "Wow", a ten horsepower gain. You probably got no more than two or three HP from the header while the tune-up and other items are responsible for the rest. We've just chronicled a typical situation where the Dyno operator has done a little 'creative testing' to get the results that the customer and his boss were expecting. In all likelihood if the test had started with the new header and ended with the stock one, the tests would still manage to show some improvement. In industry R&D testing we call this "getting the anticipated results". It's a powerful force and it can influence even the most ardent testing procedure. What I'm saying here isn't that all Dyno operators are a bunch of crooks, but rather that they are human and may simply be responding to what they believe everyone is expecting from them and the header.
The store
The store where you purchased the header also benefits from the exaggerated claims. They fear selling and installing expensive hardware only to document a small gain or even a loss in horsepower. Customers might demand that the header, or whatever, be removed, This can be more than an inconvenience to the shop as the merchandise may have been special ordered and shipping charges and re-stocking fees may result. They understandably dread the hassle, the lost sale, and a very unhappy customer and most of all, the negative gossip about their inability to get impressive horsepower gains.
The Manufacturer
The manufacturer in particular, has little to restrain such optimistic assertions. Even if they're not guilty of outright deception and exaggeration, they tend to record only the most optimistic numbers. I have often tested headers that actually resulted in a power loss, but I have never heard of any manufacturer or vendor claims of reducing your bike's power by five (5) or ten (10) hp and all for only $650.00. In other words everyone seems to be using the highest numbers as a matter of record. I recently called my favorite header manufacturer and inquired as to what I could expect to gain on a customer's ZX-12. They said "seventeen (17) hp, no problem". Of course I knew this was ridiculous as the number was way too high and any sort of meaningful testing would have resulted in a 'range' or span of expected horsepower gains, and not a precise number like '17'. Every application is different, and the actual results can vary widely. After installing the pipe, I called them back to let them know the actual results. "We picked up almost three (3) horsepower", I said. "Wow, that's pretty good", he replied. This would all be pretty funny it weren't so unfair to the customer.
With almost no exception, everyone that gets their bike tested at a local Dyno facility comes away disappointed. We read all the magazine test reports and the editorials on some sort of engine build project usually culminating in a Dyno test displaying incredible gains in power. This reminds me of a little tongue-in-cheek story I read many years ago about a man attempting to make a measurable improvement in his car's mpg (miles/gal). He installed a number of devices, all with some sort of 'promised' increase in mileage. A better carburetor was going to save 10%, hotter plugs another 4%, keeping all the windows up another 6%, increasing the tire pressure by 5psi, thinner oil another 2%, etc. All this has worked so well that he now has to siphon off about three (3) gallons of gas every week.
Personally as a Dyno owner and operator, I'm getting a little weary from all the exaggeration. Last summer I deliberately tested some of these observations on a customer. He brought in his Orange County Chopper for Dyno testing. The series of 4th gear runs netted 107 hp after the conventional SAE correction factors were applied. I felt this was pretty darn good for the bike, but here again he had expected far more. I announced that I could probably get a much higher result by 'fooling' the Dyno's computer. The very next test resulted in 146 hp. "Now that's more like it", he said. I tried to explain that the 107 number was correct and even showed how the 146 hp test actually displayed the same 107 hp curve when discounting the electronic 'spike' that I had deliberately generated. I was attempting to illustrate how easy it was to get artificially high readings and how some of the incredibly high numbers he'd been hearing about may have been less than accurate, but none of this mattered one bit. He tore up the real test results and carefully folded up the bogus one and left the shop with a great big smile on his face. A few weeks later some of buddies told me about his monster 146 hp chopper. He got what he wanted, great big horsepower / torque numbers he could brag about to all his friends. Knowing his bike's true horsepower was of no interest to him whatsoever.
I'm not suggesting the the Dyno is of no value. On the contrary, it's an extremely valuable tool. Everyone just needs to have a greater interest in getting the 'real' numbers from the Dyno. I suggest starting out by telling the Dyno operator to give you the accurate numbers. "Don't worry about giving me the bad news. I want to know if my bike has a problem. Don't compound my problems by giving me what you think I want to hear". Boy, would that be nice.
So don't let the lack of 'truth in advertising' spoil the pleasures of enhancing your bike's performance. Most of these products do deliver some measurable gain in power. The advertised claims, however, may be pure fantasy and, as mentioned above, may gain very little or even lose a little ground. So try to sift through all the hoopla and hopefully you can find some realistic testing data before shelling out your hard earned dollars. Today's sportbikes, in particular, are already pretty well engineered for performance. It's far more difficult today to ramp up a bikes performance than it was just a few years ago. When the whole world of performance building products are promising the moon it's especially difficult for any performance shop to be honest and give you the cold hard truth.
Dave Leonard
Precision Cycle Works
