This may seem like a simple question to many of us, but if you are not involved in the industry you may be wondering why were are going through all this trouble to create the Dynoperformance data base. After all, the car manufacturer gives us the power in the specs of the car. A dynamometer, or dyno, turns out to be the most useful tool for measuring a carís output power (see horse power vs. torque article) and this is actually how the manufacturer measures the power. Horse power and torque define the capability of a car to accelerate. Whether it is an engine dyno or a chassis dyno doesnít make much difference for the end result, it just turns out to be easier to test your car with a chassis dyno. A chassis dyno is typically a couple of big drums in the floor of the garage that you drive your car on to. Then, from the way in which your car turns the wheels, you get your horse power and torque curves. These curves give you a perfect profile of your carís power performance over the entire RPM range. An engine dyno is hooked up to your actual engine, so you need to have your engine removed. This isnít very practical for most of us, but is what the manufacturers use as they are designing the engine.
As we discussed in the Torque vs. Horse Power article, your final output power to the ground is not what the manufacturer says it is at the flywheel. This is because of the energy lost in the drive train. So, since we do not want to remove our engine every time we want to measure the output we use chassis dynos which give us rear wheel power output. This rear wheel output (or front wheel if you have front wheel drive) is what all after market manufacturers use to test their products (or tuning) and see if they get any gain. You frequently see ads saying buy this induction system because it will give you 15 rear wheel horse power. Now hopefully, the after market company has actually chassis dynoed the car in a fair before and after test. Unfortunately, what they report is often far from the truth. If this were the case, then you could go through a catalog and buy a handful of parts that would boost your power by 100 hp without using a turbo, supercharger, or N2O. Many times, the manufacturers are doing these test under ideal situations and under less than stock conditions.
For example, if I put an exhaust on my otherwise stock car, I might get a 5 hp gain. Now, if I put that same exhaust on the identical car but with a supercharger, I might get a 15 hp gain. This is because the combination of the supercharger changes the whole dynamic. Now, it is true that this exhaust gave me 15 hp with the supercharger, but the company will tell you that you will see this 15 hp gain without telling you the configuration. So, you will be misled to thinking that this exhaust is better than that one or that you will get 15 hp out of it on your car.
This is where Dynoperformance comes in. By creating this data base of all cars with various modifications, we can get an idea of what all these parts actually do for the car. One of our goals is to write a series of articles comparing before and after dyno data with different parts. We will also set out to either verify or disprove manufacturers claims about the gains associated with their products. A classic example is the air filter. I have heard outrageous claims that if you put in this filter you will get a 10 hp increase. We will test them, and along the way create a powerful data base where anyone can go to get info on performance parts. This will be very useful to people who do not have the time or resources to decide which parts are better. You will be able to go to the data base and do a search of a particular car with the modification you want. A list of dyno runs taken in that configuration will be displayed, and you can decide which parts worked best.
So, now we see why it is so important to have dynos. They are really the only tool available to us for measuring our carís performance. Of course, that info doesnít mean much on its own. That is why Dynoperformance is so important. It brings all of this information together in a way in which you can make an informed decision about performance options and not be fooled by false manufacturerís claims. After all, you wouldnít want to spend $600 on an exhaust that gives you 2 hp versus one that cost $300 but gave you 10 hp because you didnít have real world results.