Our baseline run sported nothing more than an upgraded HEI distributor module from Pertronix. The module increases the intensity on the factory ID spark and helps the engine start and run smooth but is not required to run with the Second Strike box. For our "Budget Bliss" story (Apr. '06) we installed one of these modules to see an improvement in starting and drivability, but no considerable power changes were gained on the chassis dyno. The results were identical to our previous test, posting 294 hp at 5,900 rpm and 357 lb-ft of torque at 3,700 rpm.
To make the best use of our dyno time, we set the box on our Camaro's fender and simply plugged the wires in. The plan was to run the Second Strike box with the gap at 0.035 inch while tuning in the CAO, then run the engine again with the spark plugs gapped at 0.045 inch while playing with the CAO. The 0.045-inch gap would increase the spark's traveling distance, therefore decreasing its intensity and simulating a condition where high cylinder pressures were present, similar to a supercharger or turbo application.
Dyno-MiteWe began with the plugs gapped at 0.035 inch, the total timing set at 36 degrees, and the Second Strike spark disabled with the CAO set at zero. The power numbers came across the dyno screen the same as before, showing us that we had a steady baseline of 294 hp and 357 lb-ft of torque. With that in mind, we went back under the hood and moved the CAO dial to the No. 3 position to begin firing our CD spark 6 degrees after total timing occurred. With a fairly light advance spring kit in the distributor our CD spark was introduced at 30 degrees of timing, which occurred at approximately 3,300 rpm. The increased spark energy added power to the mid- and high-rpm range dyno curve and lowed the peak horsepower point by 900 rpm. At 5,000 rpm the engine made 306 hp and at 3,600 rpm it made 371 lb-ft of torque. That's a gain of 12 rwhp and 14 lb-ft of rear-wheel torque! The fact that peak power was brought down by 900 rpm shows us that a properly firing cylinder will make more power sooner, therefore leaving additional room for high-rpm induction system improvement.
Up next on the testing block was to gap the plugs to 0.045 inch and run our HEI module-upgraded ID ignition system without the help of a Second Strike CD spark. We set the CAO dial to zero and watched, knowing the additional gap would hurt the power. The fact that a factory sparking-ignition system could not keep up with the situation caused this configuration to deliver 290 hp at 5,400 rpm and 343 lb-ft at 3,300 rpm. In fact, we lost power throughout the entire powerband. Our theory proved true, and we were interested in seeing how much of a gain the additional CD spark would reveal.
We then cranked up the Second Strike feature on the CAO dial to fire the cylinders 6 degrees after total timing. Having changed nothing other than the CD spark timing, our engine responded right back to life, posting nearly identical power figures as in the first test. The peak power gains were very similar, but when the first and third dyno charts were graphed over one another, it became apparent that the midrange power numbers were down during our third dyno pull.
Upon reviewing the data, we realized that the additional 0.045-inch plug gap was drastically affecting the spark plugs' ability to fire the combustion chamber completely under pressure before the CD spark was being introduced. To remedy this problem, we turned our CAO dial to fire the CD spark 10 degrees after total timing. The second CD spark was then introduced at 26 degrees of timing (approx 2,900 rpm) to fill in the midrange power loss. This immediately solved our problem and presented us with an almost exact power curve as the first test.
The Final WordOur application made the best use of its HEI upgrade module and 0.035-inch plug gap to handle the sparking power in its current form. The Second Strike CD spark filled in the high-rpm gaps to produce more top-end average power, but any gains at the track would be minimal. In the event that we step up our engine combination to include more cylinder pressure, using power adders or high-compression pistons without the Second Strike box, the increased 0.045-inch gap would be the way to go. As engine power increases, larger power losses will be seen if the ignition system is inadequate. With a Second Strike ignition box under the hood, you will strike out the competition every time.