Volume III, Issue 8, Page 10

Consequences are not always made public...

So that you don’t think every product Edelbrock explored during its long tenure in the high-performance and racing industry was successful, there was one that had a particular affect on something the OEM elected to produce. Not long after, the following story unfolded.
Timeframe is the mid-70s.  The country had just experienced its first “gasoline shortage” (1973) and the specialty parts industry was still contemplating what to do about such issues in the future.  Edelbrock was no different.  In fact, it has begun researching the practicality of a sequential electronic fuel-injection system for small-block Chevrolet engines with the high-performance street market segment the principal target.

Realize that compared to current standards, on-board sensor technology was in its Stone Age.  If you’d brought up the term “mass air sensor” prior to 1980, blank stares would have been shared by all.   Throttle position sensors?  Same deal.  About all we had at our disposal for sensing engine load was intake manifold vacuum.

Now, let’s get a bit more technical.  At the very beginning of an engine’s inlet cycle, the first molecule of air to move is at the intake valve.  Air residing around the carburetor (or throttle body) isn’t aware anything is happening… yet.  As time passes and flow is initiated, air segments upstream of the intake valve begin to move toward the cylinder until the entire intake track is in motion toward the cylinder on its intake cycle.  Simply put, we’ve just described “elastic flow” that is characterized by a time delay from when air first moves past the intake valve until a full intake cycle is established along the intake track.

At the time of development, so-called “batch” electronic fuel injection had already been introduced by GM, along with multiple problems that such technology brought along in the process, including poor cylinder-to-cylinder charge mixture distribution and problematic exhaust emissions.  Of course, the OEM had just introduced something called a catalytic converter, so the emissions issue was less of a concern.  We chose to make the Edelbrock system sequential, following the engine’s firing order and thereby reducing some of the problems that accompanied the batch process.

However, lacking certain sensors, calibrating fuel delivery based on intake manifold vacuum (for load sensing) and with the problems caused by the elastic flow phenomenon became a real issue.  In fact, the problem manifested itself with a characteristic pop or backfire into the intake system virtually any time the throttle was opened suddenly.  The solution was to “Kentucky windage” the fuel delivery by providing the equivalent of a carburetor’s accelerator pump shot, during quick throttle operation.  The problem was determining how much fuel needed to be provided.  Long story short, the backfire issue was never really resolved when it came time to do Beta testing of the system in the field.  There were also instances where the system was affected by electronic garage door openers.  Like the time one of the field-test EFI systems was idling in the driveway of an Edelbrock employee when it was shut down as a neighbor keyed his door-opening controller.  Of course, there are some who say electronics is merely a theory.  And that, in a nutshell, sets the stage for the following.

At the time, Edelbrock had a property development division operating in the Phoenix/Flagstaff area building tilt-up structures for small strip malls and other types of businesses.  So it came to pass that one of the construction workers had a small-block El Camino ripe as a test bed for the up-and-coming EFI system.  Consequently, two key Edelbrock staffers were commissioned to Arizona to outfit the vehicle with a Beta version of the system.  Nothing could have been simpler… almost.

It took about a day to convert the carbureted small-block to EFI.  The practice was to leave the ECU (new on-board computer), plugged into its massive wiring harness that was the umbilical connecting the electronic brain to the engine and located inside the passenger compartment to facilitate adjustment to the various potentiometers that regulated fuel and spark.  A baseline calibration was the starting point and in-use tuning rounded out the process for optimum vehicle performance - routine stuff in the evolution of such a system.
Once the engine was fired and warmed and with an Edelbrock staffer driving and the vehicle’s owner riding shotgun, on-road testing began.  However, the ECU’s cover (when last screwed onto the controller body) accidentally produced a direct electrical short across some key internal components.  Whereupon, with the vehicle now under way, copious smoke began pouring from the ECU, causing the shotgun-riding vehicle owner to snatch up the controller and unplug the harness connector with one deft yank… while the engine was running.

When surveying the engine damage that followed, it appeared more than one cylinder had been overloaded with fuel, rendering hydraulic failure to a couple of connecting rods.  And, as you would expect, there was companion damage to other engine parts.  In short, the test didn’t come off as planned.  And even though, when finally introduced, Edelbrock’s revolutionary EFI system never fully engaged the market, one of the systems did get sold to GM, which was still sorting through its batch EFI issues.  A few years later, GM introduced its version of sequential EFI.  Now, this isn’t to suggest there was any material connection between Edelbrock’s failure and GM’s success.  But it makes you wonder that if that little electrical short hadn’t occurred when it did...  


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