There are plenty of variables that affect the quality of the combustion in the cylinder ranging from fuel quality, the condition of the spark plugs and wires, driving habits, air flow, temperature, even the design of the head and intake manifold can work against complete combustion. Imagine how the dynamics change when nitrous, a turbo or a supercharger are added to the mix.
"With boost pressure," says Ryden, "all of a sudden, the air/fuel mixture is being forced into the cylinder and this dramatically increases the cylinder pressures under combustion. This makes it tougher for the spark to ionize, or jump the gap. This is where the need for high voltage arises. The need for an ignition that can supply the extra oomph to get a spark to flow across the gap."
"Not only will a CD multiple-sparking ignition produce benefits, but remember that spark plug wires and the coil both have important roles in the ignition system. Once again, OEM wires and coils are designed for the masses and they leave a lot of room for improvement.
"For instance, factory plug wires will have resistance values (the measurement of the resistance to the flow of electricity) upwards of 5,000-10,000 ohms per foot! The MSD Super Conductor plug wire has less than 50 ohms per foot-that means more energy can make it to the spark plugs when it is needed most. A lot of people look at ignition boxes as race-only pieces but that is just not the case. In fact, a lot of these ignitions are legal to install on pollution-controlled engines!"
Real World Performance UpgradesWhen do you need an ignition upgrade? Unfortunately that question has no singularly correct answer. The basis of the answer starts with the capacity of your stock ignition, the condition of the system on your particular engine, and the intensity of the mods going into your car. If you are adding forced induction to a naturally aspirated engine the added cylinder pressure could very well overwhelm the OE ignition system. If you have a factory turbo car and are upping the boost a few pounds you should be okay but if the plan is to run a 100-shot of nitrous an upgrade may be in order.
The first line of ignition upgrades should consist of amplifier boxes for inductive ignitions that not only add to the voltage going to the coil but speed the coil charging time, which helps keep the energy up at high revs. Additionally, an upgraded canister style coil with more windings will generate more power on the secondary side of the system.
The next step is CD ignitions; as discussed earlier, most likely the first step for a turbo conversion build-up or any mod that greatly increases cylinder pressures. From here coil upgrades and amplification boxes for multi-coil and individual coil systems kick in. Some of the top-end boxes in this range are highly programmable, controlling everything from simple rev-limit programming to individual cylinder spark tuning. The key is to consider the effect your proposed modifications will/may have on the ignition system and make upgrades where needed.