Optical pickup distributors make more power
By Cam Benty
You would think that after 60 years of development, there would be no “easy” ride to improve performance of legendary American V-8 engines. Clearly that is far from the case.
The innovation that led us to the above conclusion comes in the form of a more efficient ignition system that delivers pinpoint firing accuracy. This new system is even better than the magnetic pickup firing system design that has become the stalwart of the racing and high-performance industry. After all, what could be more accurate than an ignition fired by magnetic pulse, right?
The answer to that question — an optical pickup! The newest XDi Sportsman distributors from Fuel Air Spark Technology (FAST) integrate an advanced Hall-effect style pickup that converts the current ignition timing into a signal that CD ignition controls can then read. The result is timing that is within a ½-degree of timing perfection.
While accuracy is clearly important, there is a bigger reason for such celebration. With magnetic pickup style distributors, in order to avoid detonation and other forms of engine damage, the timing is actually retarded at peak rpm limits because this pickup design does not allow enough time for the spark plug to fire in the “window of time” allotted.
Unfortunately, allowing your distributor to determine whether or not you can have the full range of power seems contradictory to the entire engine building process. Magnetic pickup distributors actually suck power out of your engine — all because of the inaccuracy of the timing system that retards engine timing at key moments in the rpm range.
Case in point: If you have a magnetic pickup-triggered distributor and want to have 34 degrees of timing, you actually have to lock it down for 36 degrees because at peak rpm, the distributor is designed to pull out approximately two degrees of timing. That translates to a loss of 2 to 5 hp and lb-ft of torque.
With the optical pickup distributor, you can set the timing exactly where you want it and avoid the engine retard mode. That means you get all the power, all of the time. For racers usually overjoyed to find a ½ horsepower to have an advantage over their competition, picking up 2 to 5 hp and torque is huge.
“This is especially important in rev-limited racing classes,” says FAST Technical Director Terry Johnson. “The biggest benefit of a Hall-effect pickup design is that there is no retard event, commonly called ‘magnetic pickup compensation,’ so you can ensure your timing remains stable from idle to race rpm. I can honestly say I have not had one engine builder who was not completely sold after witnessing the change in power on the dyno after bolting up one of our distributors.”
The mechanical side
Inside the CNC-machined billet housing is a polished stainless steel shaft that is supported with a sealed ball bearing on the top and a long bushing on the bottom. FAST also has gone to great strides to reduce end play in the distributor to take out any timing variation or damage to the drive gear. XDi Sportsman distributors are available for most styles of American V-8 engines, including the usual suspects from Chevrolet, Ford, and Chrysler.
Each distributor is supplied with a high-quality rotor and distributor cap. A FAST ignition control (E6 and E7 series) must be used. Note, there is no mechanical advance and the timing is locked out – so these are not ideal for street applications. The XDi is available with a large diameter Ford style cap or smaller diameter GM points size cap with HEI terminals. Also, most applications are available with either steel or bronze gears.
The difference between the timing systems is clear — and even your distributor can see it . . . optically speaking.
Source: FAST, fuelairspark.com