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Dyno Tuning - Shop Talk

0701_chpp_01_z Dyno_tuning Engine_hoist 2/1

Lately we've been inundated with questions regarding the use of engine dynos. Many of you inquired as to why we only pull from a certain rpm range, while others questioned the validity of the numbers produced and what advantages a dyno can offer. Foremost, the dyno is a tool, a method of gathering information and a way to help us evaluate a multitude of engine parameters, and it's proven to be an invaluable resource, providing a wealth of information to help us understand an engine's performance.

One question that especially stood out was why we didn't show the horsepower and torque figures beginning at 0 rpm. In reality, an engine dyno relies on a water brake to load the engine and slow it down, which consequently requires the engine to first generate enough engine speed to function properly. When we do a pull, the handle is preset at wide-open throttle, and we're relying on the dyno to lug it down. In a carbureted application, the carb needs airflow to meter the fuel. When there's no airflow or air speed, fuel isn't being atomized, let alone getting pulled through the boosters, and can cause the carb to literally stop functioning. Fuel-injected combinations, on the other hand, will allow you to pull lower, but that's only because you can custom-map a calibration at very low engine speeds. Starting to get the idea?

Now is there really an advantage to using a dyno? Absolutely; would you rather drop a bullet in between the fenderwells not knowing how it'll perform, let alone having to wonder if it'll leak or have other gremlins arise, requiring you to pull the motor right back out? How about factoring in that you'll have no idea where to begin tuning? Throw in a power-adder combination and you're only asking for trouble. Remember, power-adder combos will continue to make power and let go just as quick if you don't have a safe way to monitor it. At least on the dyno you can tune not only for drivability, but also WOT, and have a safe baseline to work with.

While we try to cover every aspect of what's going on in the world of Chevys, one of our primary responsibilities is to showcase anything and everything available on the market today. If we have access to it, we want to test it, and that's what the dyno enables us to do. I completely acknowledge the fact that this is an overly simplified explanation-I'm only hitting the tip of the iceberg. Maybe it's time to dispel some of the myths, disclose the costs, and walk you through a typical dyno session. Are you up for it? E-mail the address listed below and let me know.

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