On The Dyno
We strapped our '66 Mustang down to our new Dynojet dyno that resides in our Tampa tech center and let it rip. Our baseline run gave us a peak power figure of 162.41 hp at 4,900 rpm and peak torque came in at 190.13 at 4,200 rpm. Once we installed the gaggle of Pertronix gear and warmed the engine to the same test temperatures as the baseline, we came away with 155.82 hp at 5,000 rpm and 177.52 lb-ft of torque at 4,300 rpm. That's a loss of 6.59 hp and 12.61 lb-ft of torque. We were a little confused why we would lose power and torque over the Ignitor II, which is a similar product, until we spoke to one of Pertronix's engineers.
While we were trying to perform an apple-to-apple test by not touching the timing of the engine, we were in fact reducing the ignition timing due to the way the Ignitor III works. The Ignitor II uses a magnetic wheel adapter over the distributor shaft, whereas the Ignitor III reads firing position directly off of the distributor shaft's lobes. It's the difference in the way it reads the distributor's position that lowered our timing. If we had actually put a timing light on the engine and verified timing and adjusted it to match our baseline test, we were assured that our numbers would have at the least matched the old Ignitor II if not surpassed it.
Another area of concern for the Pertronix folks was the fact that we were powering our Ignitor III through the stock resistance wire. While we did this for the original Ignitor II as well (not wanting to cut into our perfectly good dash wiring to bypass the resistor wire), we were told by Pertronix that because of the power demands, the Ignitor III really needs to see full battery voltage. As such, Pertronix has developed a power relay kit that easily wires up under the hood between the Ignitor power input and your battery to give it full voltage. We've got one coming and hope to report back on what the relay and more timing will do for our upgrade.