Last month, we set out on an adventure to further enhance our in-house Lightning project, the Fridge. We had been successfully running a Whipple 2.3L blower on top of our built 5.4L engine. However, we became bored with the 669 rwhp and 732 rwtq on tap. It was time to step things up a bit, so JDM Engineering dropped on the massive 3.4L supercharger from Whipple. That helped our fortified Two-Valve truck engine generate 710 rwhp, which unfortunately taxed the fuel system to the limit. We had plenty of fuel injector (60-pound) and fuel-pump capacity (twin Walbro 255 lph), but our truck lacked larger fuel rails and fuel lines. Our hungry engine needed to gulp more dead dinosaurs in a big way.
To give you a quick recap, the truck is a '99 SVT Lightning that has been a staple in the MM&FF project-vehicle lineup. It began life as a Ford press vehicle, and was then handed over to the magazine to serve as a rolling testbed for the latest Lightning parts on the market. It has evolved from a low 13-second ride to a scorching 10-second street beast.
A JDM Engineering 5.4L engine was installed five years ago and has served as a reliable platform. Over the years, a new Level 10 transmission, a built rearend, and many other parts and pieces have found its way onto the Fridge. The Whipple 3.4L blower is the fourth supercharger (if you count the stock one) to be bolted to the engine. We also dabbled with a nitrous hit on top of the Whipple 2.3L unit.
It was time to take the truck to the next level, and the only way we could do that was with a larger fuel system. Unlike other '99-up modular-powered Ford vehicles, the Lightning utilizes a return-style fuel system. That means the rails are fed fuel, and the injectors use only what they need with the unused gasoline returning to the fuel tank. The fuel rails have constant pressure due to a fuel-pressure regulator, which restricts the fuel flow from returning back to the tank. The fuel rails are pressurized to 39 psi in stock trim, and-more importantly-most fuel injectors are rated at that pressure. One trick to get more gasoline to the injectors is to raise the fuel pressure. A 60-pound injector's pressure increases when the fuel-rail pressure is greater than 39. Usually under boost, the fuel pressure jumps 1 psi per 1 psi of manifold boost.
As with everything in this hobby, there's a point of diminishing returns, and you can crank the fuel pressure only so high before the injectors max out in effi ciency. The problem with the Fridge was that we couldn't feed the injectors more pressure because of an inadequate supply line, fuel rails, and return line. The prescription for relief was in the form of a JDM Engineering fuel system. It consists of a JDM billet fuel hat, twin Walbro 255-lph pumps, larger supply lines, a high-flow Mallory fuel filter, Aeromotive 1/2-inch fuel rails and billet fuel regulator, and larger return lines. We retained the JDM 60-pound injectors, which have been on the truck for quite some time.
The game plan was to have each pump feed a -6 size line, which goes into the fuel filter. The filter acts like a Y-block in that it has two -6 feed lines in and a single -8 line out. The -8 line goes to the engine bay where it supplies the Aeromotive fuel rails. Jim D'Amore of JDM Engineering added stainless steel fittings to every fuel connection inside the engine compartment. His rationale was that since the engine moves under acceleration, the stainless steel fittings are more durable and not prone to cracking like aluminum fittings. We have never seen that kind of damage to aluminum fittings, but since D'Amore has never steered us wrong in the past, we went with the stainless steel stuff.