Classic Fuel Injection

My years with Dynaformance were based around the design, development, and marketing of the Classic Fuel Injection system. The injection system was born in the late days of Dynatek Racing. We had exhausted ourselves in the now saturated Mustang marketplace and had a large undertaking with Superformance and Shelby replica and continuation cars.

The injection system was developed as a product of a styling exercise when designing an air cleaner system for the problematic, yet stunning Weber carburetor; in which we also sold. While studying airflow and fueling issues, we thought it would be an enthusiast hit to develop a look-a-like system that kept the retro aesthetics, but featured modern fuel injection. Other companies produced an individual throttle body system, but none that captured the classic essence that drove customers to the fickle carburetors.

History Revisited

The idea to capture the essence of the Weber carburetor while harnessing the spacial requirements and function of a modernized fuel injection unit was daunting at best. Not only did it have to look right, but we had to make enough change to the system to protect ourselves from any sort of copyright or trademark infringement. Once we had determine the initial aesthetics we turned to the packaging aspect.

The final product was truly genius in design.

What was constructed were hollow castings essential turning each two runner assembly into a giant linked throttle body; each housing a pair of fuel injectors, and fuel fittings. The top portion of each was cast solid, then machined and o-ringed to become a ‘wet’ hat that fuel ran through. Dummy adjustment screws were set into the original positions. Custom banjo bolts were designed and produced to allow for proper fuel volume. The system had to withstand changes in fuel pressure from an original design of 6-8 psi, to accommodate 40-50 psi or higher.

The lack of choke horns allowed us to increase the throttle body bore size internally and maximize airflow. The hidden injectors sprayed downward onto the butterfly plates while the injector harnesses were run out of the bottoms of the throttle bodies. Since the computer required a means of airflow measurement to compensate for fuel delivery; special intake manifolds were developed with a sealed hollow plenum underneath that was tapped into each cylinder runner. This plenum had to be large enough to provide as a balanced manifold to feed signal to a remote mounded MAP sensor. A provision for a throttle position sensor was cast and machined into the firewall facing body to coordinate throttle opening to the ECM. The final product was truly genius in design.

During the prototype and R&D stages, multiple systems were produced to test theory and functionality. These included concept model SLA or rapid prototype units to show the final form and CNC billet aluminum assemblies for testing on running engines/vehicles.

Creating a Legend

Shown here are the undersides of the plastic prototype units, a mock 3-D model of the working prototype units and a proposal of the initial banjo style fuel fitting design. We were able to construct a working 2 piece traditional banjo assembly for the final design. Challenges were faced with sealing the much higher levels of fuel pressure.

Development and refinement of the system continued for approximately a year and a half from initial design to initial customer sales.

Working prototypes led to final production units that met our high standards of aesthetic and mechanical function. With this step out of the way, we sought to tackle our next hurdle; making the systems function live and assemble a package that can be handed to the customer complete with a startup tune and a semblance of self learning technology. We wanted these systems to be as plug-and-play as possible.

We wanted these systems to be as plug-and-play as possible.

Fortunately, most of our development work had crossed into these conflicts and we had a strong head start on functionality. Using a Speed Density design to control fueling; changes were made by the computer by monitoring intake air temperature, coolant temperature (cold start mapping), manifold pressure (vacuum), throttle position, and exhaust gas temperature. We developed a terminated wiring harness and tested with an optional retrofit fuel pump kit which supplied a 255 lph pump, 3/8 (-6AN) line, high pressure regulator and a return kit. An electronic distributor was the only necessary addition to be provided by the end user.

Initial units proved extremely effective on most street driven sub 450 cubic inch displacement engines with non radical cam shafts.

Manuals and schematics were developed to walk the end user through the entire installation and retrofit process. Full breakdowns of all included items on the fuel system were also included.

Challenges here were trying to eliminate the amount of technical support required when a vague guide is sent out to the public. Having a wiring harness with every pigtail end being unique, sans injector clips was a huge help here. Even still, it took a full understanding of the system to blindly guide customers over the phone in all aspects of installation and tuning.

Heavily Tested

Products that don’t function as they are intended or designed can be considered paperweights in the automotive industry. This was not the case for the Classic Fuel Injection system. Multiple hours were spent using an engine dynamometer building and testing systems across a variety of engine makes. Not to be limited by our initial repli-car based market; systems shown here include the big block Chevrolet, The 392 Chrysler Hemi, and the GM LS series cross ram intake manifold.

Products that don’t function as they are intended or designed can be considered paperweights in the automotive industry.

Each system had it’s own unique characteristics for tuning and fuel/timing delivery. I worked in a team with our engineer to develop manuals for the customer to easily understand the parameters of the programmable ECM units if one were to choose to go away from the simplistic ‘self learning’ modules. Through testing, we found the Classic Fuel Injection was capable of supporting over 650 horsepower while remaining naturally aspirated. A total draw of all eight runners allowed for an incredible 2300cfm of total airflow.

A Marketing Sweetheart

The great success of the Classic Fuel Injection found us once again seeing multiple magazine coverage. Having deep roots in the vintage Cobra and GT40 marketplace; it was fitting to have two full features in Kit Car magazine. Articles were focused around the gains swapping from carbureted to the CFI system, and a full comparison installing the CFI in place of a traditional Weber unit on a vintage GT40 racecar.

These images show the final images of the Classic Fuel Injection development for the vintage market. The systems were a huge success amongst the crowd of current Weber carburetor users and grew an instant following among repli-car -continuation vehicle marques such as the Superformance, ERA, and Shelby.

huge success among the crowd of current Weber carburetor users.

To the untrained eye, it was near impossible to tell that these were actually fuel injected and offered modern driveability, increased fuel mileage and horsepower. The intake manifolds that had been redesigned to maximize the full potential of the throttle bodies’ increased airflow were also quick to sell, as they boasted a tremendous improvement from the vintage manifolds suited for a 48IDA Weber base.

These systems would eventually continue on today with great success as Eight Stack; now by Borla.