Improving your dB Drag Racing Score

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Originally appeared in the August / September 1997 issue of Car Sound magazine.

Improving Your Score

Improving your score in dB Drag Racing is usually an incremental process. Sometimes, all it takes is a little bit of trial and error to achieve a slight improvement in SPL. If you want to make really big gains, however, changes to the system itself are often required. One of the most difficult, yet beneficial, changes you can make, involves your vehicle's electrical system.

Electrical System

It takes power to make power. This is an irrefutable fact of nature. It doesn't matter how many amplifiers you have, they will NOT be able to produce their rated output power unless they have an adequate source of energy. To make matters worse, amplifiers are not overly efficient at converting the raw DC power from the vehicle's electrical system into a usable musical signal. In dB Drag Racing, a strong electrical system is essential. Here are a few guidelines to use when designing the electrical system for your next dB Dragster.

First, calculate the projected total output power for the amplifiers in your system. This number should represent the total amount of power being delivered to the speakers. For example, if you are using two 500 Watt amplifiers, the total output power would be 2 x 500 = 1000 Watts. (Be sure to take load impedance into account when making these calculations.)

Next, multiply this number by 1.4. (Assuming the amp is approximately 60% efficient.) This will result in the required input power in Watts. In our example, we would need 1000 x 1.4 = 1400 Watts.

At this point, we know that your amplifiers require 1400 Watts of input power in order to deliver 1000 Watts of usable power to the speakers. To determine the required input current, we use the following equation: Current = Power / Voltage. Lets assume the alternators are producing 14 Volts DC at full output. In our example, the current requirements for your amplifiers would be Current = 1400 / 14 or 100 Amps. In other words, if your alternators are producing 14 volts, your amplifiers will require 100 Amps of current when playing at full output.

This is the amount of current that your electrical system must provide to your amplifiers during competition. Typically, this energy is provided by the alternator and the battery. If the output capability of these devices is less than the total power requirements of your amplifiers, your amplifiers will not be able to deliver their rated power to the speakers.

To alleviate this, you can do one of three things;

You can upgrade your existing alternator and/or add an additional alternator.
You can add additional batteries.
You can do both.

Due to the limited space available in the engine compartment of most vehicles, you will probably be limited on the number of alternators you can install. If this is the case, you may need to add additional batteries in order to make up for the shortcoming of the alternators. When using multiple batteries, remember to make sure that they are all as identical as possible.

You will also want to reduce losses in the power distribution system. Use the largest gauge power cable you can afford. In addition, you should invest in high-quality power distribution blocks and interconnects. This will insure that the power being produced by the electrical system actually reaches your amplifiers with a minimal amount of loss.

If you elect to use stiffening capacitors, they should be installed as close to the amplifier as possible. Used properly, these capacitors will reduce the effects of any losses that may exist in the power distribution system.

A strong electrical system is essential in a dB Dragster. By providing an adequate amount of power to the amplifiers, you will be rewarded with a system that plays to its full potential.

Wayne's World