First up in our race-ready fuel system is the fuel itself. We’ll be using Pro Racing Fuels’ Mark 5, 114-octane race gas, designed for ultra-high-compression/forced-induction applications. Pro Racing Fuels is a pioneer in unleaded race gas technology, and as such has a complete range of unleaded race gas from 98 octane (GT98) up to the 114 (Mark 5). The Mark 5 is available in 20-liter containers, but for our use the 205-liter drums are better suited. Using unleaded fuel results in increased wideband sensor life and is unquestionably better for the environment and for the people handling the fuel.
Pro Racing Fuels also offers alcohol fuels, but we’ve decided to use a gasoline-based fuel to ensure adequate range on a tank to run 20-minute sprint races (and for the smell of excitement only race gas offers).
The Mark 5 is filled through a filtered funnel (this makes sure no debris ever enters the fuel system) into the OEM filler neck that ends up in the stock tank. The filler neck evap connections are crimped and welded shut, maintaining the factory-mounting tab for the filler neck. We have chosen to use the stock tank because it’s very well protected — located above the subframe and within six points of our rollcage. It offers the necessary capacity and doesn’t expire (unlike a fuel cell does after five years).
To make the stock tank as safe as possible for race use, we’re using an Auto Analyser Performance evap delete/vent system that features a billet vent mount complete with roll-over check valve and discriminator valve. The roll-over valve ensures that if the vehicle ends up on its roof, it won’t leak fuel from the vent. The discriminator valve seals up the vent when the tank is full of liquid, preventing fuel from spilling out the vent. We routed the vent behind the fuel filler door with an AN-3 bulkhead fitting.
Transferring fuel from the tank is carried out by a Full Blown dual-pump setup. Using a pair of Full Blown 340-liter/hr in-tank pumps ensures adequate fuel supply for our horsepower goals. The Full Blown billet hanger allows the stock fuel-level sending unit to be maintained, which is a nice touch. We opted to replace some of the included brass fittings with XRP’s 90-degree male pipe to AN fittings. These compact fittings fit under the stock fuel-pump access door and make for a clean install. Be sure to not overtighten the gear clamp securing the pumps, as it’s possible to damage the pumps and cause premature failure. The kit includes a pair of filter socks or strainers for the pumps, but we opted to fit the OEM strainer on one of the pumps because it’s slightly taller, allowing it to pick up right to the bottom of the tank. The completed assembly bolts up nicely to the original mounting points, giving a perfect seal and looking great.
While it’s possible to feed the in-tank pumps directly to the fuel rail, anything less than a half-tank of fuel will result in starvation during track use. To combat this, the Full Blown pumps are being used as high-volume/low-pressure transfer pumps feeding an Integrated Engineering surge tank. This compact surge tank holds a pair of 044 Bosch Motorsports fuel pumps along with 2.3 liters of fuel and ensures that even if the in-tank pumps momentarily run dry, fuel will continue to be supplied to the engine. The surge tank features rubber isolated mounts to minimize vibration/noise. The available outlet manifold is the cleanest way of pairing up the Bosch pumps that I’ve seen and allows to go straight from the two pumps to a single -8 outlet. By keeping the pumps in the surge tank, they’re cooled by the surrounding fuel, increasing pump life, and the outlet manifold greatly reduces the amount of hose/fittings required minimizing failure points. The system is plumbed as follows:
- Main tank pumps feed surge tank
- Surge tank 044 pumps feed fuel rail
- Engine return feeds surge tank
- Surge tank overflow returns to main tank
We opted to install M18x1.5 to -10 fittings to the bottom of our 044 pumps to help them reach closer to the bottom of the Integrated Engineering tank. This ensures they can scavenge as much fuel as possible from the tank before the engine starves. Finally, a custom bracket was fabricated/welded in place to relocate two of the surge tank mounting points to better suit the desired mounting location.
All four fuel pumps can be run simultaneously if required; however, initial testing will be done with one transfer pump and one high-pressure pump with the redundant pumps operated by a dash-mounted switch in case of pump failure. Running the extra pumps unnecessarily reduces power output by increasing current draw on the alternator. The high-pressure pumps feature in-line check valves to make sure the pump doesn’t back feed the fuel through the second pump.
The high-pressure 044 pumps now feed a -8 inline fuel filter before heading to the AEM fuel rail. AEM’s S2000 specific fuel rail is manufactured from billet aluminum, then anodized black. The rail features an extra port for a fuel-pressure sending unit (a valuable data analysis tool) and works with its adjustable fuel pressure regulator. The two pieces are a straightforward bolt-on installation and ensure adequate flow to the injectors for our horsepower goals. Injectors are RC engineering 1,000cc and, as with all RC injectors, come complete with flow charts showing exactly how much fuel each one is flowing. This information provides great peace of mind, knowing that we’re starting with tested units that are all flowing near identically. Finally, the unused fuel returns to the surge tank via a -6 line.
Our completed fuel system offers more than adequate flow for our horsepower goals while offering excellent reliability and consistent output, even in high g-force situations. Most importantly, the necessary safety items are in place should things go wrong out on track.