As our race team continues the mammoth effort of swapping in a Mitsubishi four cylinder motor into a Chevrolet Chevette we decided to follow what NASCAR did recently and convert our carbureted fuel system to fuel injection.
This isn’t as daunting as it sounds. Our car runs a fuel cell, so adding the requirements for fuel injection is far easier than adapting a factory OEM fuel tank. There was one concern though, most fuel injection gas tanks have baffling around the fuel pump pickup to help prevent fuel starvation. Fuel starvation can lead to the engine running lean and causing catastrophic damage. This isn’t an issue for carb engines as the float bowl on the carb itself acts as a miniature reservoir for the fuel supply. We needed to add our own reservoir to prevent any fuel starvation under sustained cornering at the race track. Luckily, many racers have already solved this problem and have come up with a mass market solution called the surge tank. Adding one to our setup took a bit of planning and a couple of shipments from Summit Racing.
Our surge tank would provide the proper reservoir for the fuel injection pump but we need to ensure the tank is full by using a low pressure feeder pump that pulls from the fuel cell.
Once the surge tank has the required fuel, we need to give the fuel injectors the fuel they need at the required pressure they need. To do this we bought an inline EFI fuel pump and mounted a fuel filter between it and the surge tank.
Once we got the high pressure fuel into the fuel rail and fuel injectors, we needed a way to regulate the fuel pressure the motor would see. To accomplish this we mounted a fuel pressure regulator in the engine bay and plumbed it into to the fuel rail. The regulator will also ramp up the fuel pressure as boost rises when we plug in a vacuum reference line from the intake manifold. More boost is more air going into the engine, which needs more fuel to keep the needed air fuel ratio.
The regulator keeps the fuel pressure at the the proper level by returning whatever fuel isn’t needed to the surge tank. Running a line from the FPR back to the surge tank completes the fueling circuit and also completes the conversion to fuel injection for our fuel setup in the Chevette.