Mustang Ignition Coil Replacement Upgrade

Tech Ignition Coil Replacement
It's easy to forget about maintenance intervals, even for car people like us. Believe it or not, non-moving parts do wear. Maybe not as fast as moving parts (serpentine belts, brake rotors, and so on), but they do wear down nonetheless due to heat, age, vibration, and more. Of course, with stock spec'd parts, they're usually built to handle stock applications. So when your Mustang gets some age and mileage on it, or you start beefing up the performance levels, what happens to those stock parts? They just can't cut it anymore.

When was the last time you thought about an ignition coil or coil pack? Maybe when your buddy's Mustang died on the side of the road or started missing badly at the track and a new coil or coil pack fixed the issue, right? Don't feel bad, we're pretty much the same way when it comes to things like that. So will replacing a stock ignition coil pack on your modular Ford really help? We've been told that the hotter spark of aftermarket coils not only makes more power (depending upon the engine's performance level), but also allows for easier and faster starts, better idle quality, better fuel economy, and even better emissions. A tall order? That may be so, but we're sure that hotter spark and cleaner, more complete burning of the air/fuel mixture has to help these areas in some respect.

We headed out to Granatelli Motor Sports (GMS) to check out its complete line of coil replacements for modular Fords and dyno test its most potent setup to see if these little dynamos really do make a difference. Read on to see what we discovered.

To cover a wide range of both passenger car and high performance applications, the company also offers its OEM Series replacement, the MPG Plus, the Hot Street, and the Pro Series coils, in addition to the Pro Series Xtreme kit that we would be testing. The GMS MPG set offers up to a 15 percent improvement in highway mileage as well as improved starting. The Hot Street coils are rated at 40,000 volts, while the Pro Series coils are good for 60,000 volts. Our Pro Series Xtreme kit was part number 28-181SC, and it has a MSRP of $599.

We weren't sure how much gain to expect with the ignition kit, and JR speculated that maybe 8 to 10 extra horsepower might be gained on a naturally aspirated engine like the GT/CS. After baselining the practically new car (1,180 miles), the factory coil-on-plug ignition will be replaced with the Granatelli kit. Remember that these figures were taken on a Mustang chassis dyno and not a DynoJet. The figures on the Mustang dyno come out lower and the new car we were using wasn't really broken in yet. Here are the results of the '08 GT/CS baseline pull.

Back on the Mustang dyno, the car recorded the following numbers. They were far better than any of us expected. The higher and flatter torque curve was especially impressive.

The dyno showed an incredible improvement of 27 hp and 33 lb-ft of torque. We were all surprised by the substantial gain. JR checked every variable to see if anything was impacting the outcome and everything checked out normal. Remember, JR predicted an improvement in the 8 to 10 horsepower range. There was certainly nothing wrong with the car on our baseline test, as the GT/CS wound up smoothly and made respectable numbers. We decided to retest the car, this time hot, to simulate actual operating conditions rather than cooling down to obtain the best test numbers. We ran the car again.

Here the car provides almost the exact same result. In fact, the horsepower figures are identical while the torque figures are down by 9 lb-ft, but still 24 lb-ft better than the OE coils. JR explained that torque figures are the first to suffer when the heat factor goes up. However, the value of the new coil pack ignition was reaffirmed as the same horsepower figures were maintained. We're not kidding here folks, and these tests were carefully conducted. While we're interested in every extra horsepower we can muster, a gain of 8 or 10 ponies is one thing, but an improvement of more than 25 horses is quite another, and we'd be willing to take the bet on the GMS kit without a doubt. We're not saying that a 27 hp gain is guaranteed on every car. What we are saying is that on that day, JR's kit was worth 27 hp and at least 24 lb-ft of torque on a new '08 Mustang GT/CS with 1,180 miles on it.