How to Choose a Street Ignition

By: Jeremy Stoermer | 01/04/2019 < Back to Motor Life Home

We all know the basics of how an engine works. The air fuel mixture is compressed into the cylinders, which is then ignited by the ignition system. Just one small spark is all that’s necessary to combust this air/fuel mixture and complete the power stroke. So spark is spark right? Well not quite! Most stock ignitions only produce a single weak spark to fire the spark plug. And that may be good enough for a stock engine, but it’s not ideal if you really want to get the most out of your engine's potential.

One of the easiest ways to take advantage of increased spark energy is to install one of our Ready to Run or HEI style distributors. They act as a stand-alone ignition system and produce about 2 1/2 times the spark energy that a stock electronic ignition does. Since the ignition is built right into the distributor, you’ll only need to connect a few wires to be up and running. Some models even allow you to fine tune the ignition timing curve to match your engine’s performance needs.

If you’ve been around the automotive scene at all then you’ve heard of MSD. 3 simple letters, but do you know what those letters stand for? Multiple Spark Discharge, it’s a design that was patented by MSD in the 1970’s. And you may have also heard that installing a multi-spark ignition can give your engine more horsepower and better throttle response. Well it’s true, but why and how? Let’s take a closer look at how a Multi-Spark Ignition works.


At lower rpms an MSD Ignition fires your spark plugs multiple times during each cycle, rather than just once like most OEM ignitions do. But that’s not the only thing going on. Unlike stock-inductive type ignition systems, MSD ignitions incorporate capacitive discharge technology. Here the supply voltage is stepped up to as much as 535 volts, all compliments of a custom MSD transformer, then it’s stored in highly efficient capacitors. This multiple plug firing combined with our capacitive discharge technology, produces a high powered spark, which is then unleashed to the coil at full output voltage no matter what the rpm. A hotter spark ensures that you’ll experience a smoother idle, better throttle response and more complete combustion from idle all the way to the red line.

A powerful spark is even more important when you make performance upgrades to your engine, this can include adding an aftermarket intake, better flowing cylinder heads, and less restrictive headers or exhaust. These engines will require more air and fuel to maintain the correct air/fuel ratio. This is where the MSD ignitions really shine. With the combination of multiple spark and capacitive discharge our ignitions provide a stronger, hotter spark to completely ignite the air/fuel mixture under these demanding conditions . 

So how do I get the benefits of multiple spark and capacitive discharge technology? There are actually several ways you can take advantage.

Our entry level MSD 6A works on virtually any vehicle utilizing a 12-18 volt electrical system. It can be triggered using breaker points, a magnetic pick-up or the output of an electronic amplifier. The 6A is our budget minded analog ignition and is designed for use on stock to slightly modified street machines, trucks and street rods. The powerful multiple spark capability of the MSD 6A, ensures complete combustion throughout the entire rpm range. Along with benefits like easier starting, improved throttle response, reduced plug fouling, more power and even increased fuel economy.

MSD’s 6AL shares the same circuitry as the 6A but with the addition of a built-in adjustable rev limiter. Rpm control limits are adjusted in 100 rpm increments and when the engine reaches the selected RPM limit, our Soft Touch circuitry begins dropping spark to various cylinders. Then on the next cycle, these plugs are fired again to prevent fuel from loading up in the cylinder. This results in a smooth and accurate RPM limiting action without backfires or blowbacks that could damage the motor should you happen to miss a shift or have a catastrophic parts failure. The combination of powerful spark, the ability to add a 2-step rev limiter and the safety of our Soft Touch Rev Control makes the 6AL a perfect choice for entry level street/strip racers, and is one of our most popular cdi ignitions produced.

For those who enjoy the simplicity of the 6AL but also need to control timing on supercharged or turbocharged cars, our MSD 6BTM has you covered. This analog ignition offers multiple spark, capacitive discharge technology and a high RPM rev limiter along with a built in map sensor to detect boost pressures and the capability to retard timing anywhere from 0 to 3 degrees per pound of boost.

The Digital 6 Plus is a step above of our popular 6al ignition offering additional features that put you in control of your engine’s ignition. It uses MSD’s high speed RISC micro-controller to control ignition output while continually analyzing inputs such as supply voltage, trigger signals and rpms. Our high speed controller makes quick compensations to the output voltage, multiple spark series, timing and rpm limits in order to maintain accurate timing signals to within a tenth of a degree and precise rpm limit accuracy.

Our Digital 6 plus uses Soft Touch Rev Control just like the 6al but with two different rpm limits. Soft Touch circuitry provides a smooth and accurate rev limit by dropping the spark to individual cylinders and produces a load-free rev limit. You can select two rev limiters –the first limit can be used for staging, and the 2nd limit for top end over-rev protection. Both rpm limits are adjusted externally in 100 rpm increments with our easy to use rotary switches. There’s also a single stage retard step that’s activated when 12 volts are applied, and remains active until the 12 volts are removed. The retard is adjustable from 0 to 9.9 degrees and can be adjusted in tenth of a degree increments. It’s perfect for nitrous applications and can be connected to a nitrous solenoid activation wire or micro switch on your shifter.


Depending on what you will be triggering your MSD box with, some of you may need the flexibility of a hall-effect input. The answer to this need is the Digital 6AL-2 and Programmable Digital 6AL-2. The 6AL-2 offers all the features of the Digital 6 Plus box in a more traditional MSD case while the Programmable Digital 6AL-2 is loaded with features such as a 3 step rev limiter, a single stage of timing retard for use with nitrous, programmable timing curves and a boost timing curve for supercharged or turbo applications. The Programmable Digital 6AL-2 is easy to set up using MSD’s Graph View software from your PC.

Why wouldn’t you want increased spark energy that results in a smoother idle, better throttle response and more power? In the end It just makes sense to add an MSD ignition to your engine.

To learn more about MSD distributors and ignition systems or to watch more how to videos visit our website at MSD

Tags:MSD, Video
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