Fuel, air, ignition. These three things are the crucial elements that allow your engine to put a smile on your face when you mash the pedal. The fuel is introduced to all Side X Sides by one of two methods depending on which model it is, either through a carburetor (or two) or through fuel injection. Air is sucked through both carburetors and fuel injection and won’t really be a subject of this story. Ignition comes from one of two things also: in the case of a carbureted engine from a CDI, and in fuel injected engines from an ECU.

In the case of fuel-injected engines, the ECU also controls the amount of fuel the engine receives. Before we get into the specifi cs of how all of this works, let’s tell you why you should care. First, upgrading either your CDI or ECU can be the simplest performance modifi cation you can do. And it could be the only performance modification you ever want to do. Even if you are not into highperformance, an upgraded CDI or ECU can offer features you might like, such as eliminating the reverse rev limiter or giving you a few more MPH of top speed. Or, and this is important, if you plan to do other performance modifications, you pretty much have to also upgrade the CDI or ECU.

Let’s take a look at them one at a time, beginning with the CDI. The initials stand for Capacitive Discharge Ignition, and every carbureted Side X Side has this system. The purpose of the CDI (the unit itself is often called a “CDI box”) is to provide the high-voltage spark that the spark plug(s) needs to ignite the air/ fuel mixture and to do so at precisely the right moments (it controls the timing). Factory stock CDI units also perform the function of limiting the RPM the engine can spin, most have a reverse limiter that severely limits the vehicle’s speed in reverse, and while they put out a very high voltage, aftermarket units can produce even more voltage. For reliability reasons and safety concerns, the manufacturers install CDI boxes that are relatively conservative when it comes to performance.

Read the article by By Doug Dixon in Side x Side Action Magazine Issue 22