The PERRIN Performance fuel rails represent a true advancement in boxer engine fuel delivery. The PERRIN Performance fuel rail kit is not just a replacement part. We have completely redesigned and redirected the fuel from the supply lines to the injectors, thus solving all fuel distribution problems insuring even fuel distribution to both banks of cylinders in the boxer engine. As clients continue to expand the HP in their vehicles this need for even fuel delivery is more critical. Failure to address this concern and your expensive motor will quickly require some major attention.
Our newest variant of this rail system is both easier to install and safer than ever before. To further prove our distinction as the industry leader in Fuel rail technology for Subaru applications, we now include genuine Goodyear DOT approved fuel lines and PERRIN Pyroshield! This fire retardant sleeve is placed over the fuel hose to protect the fuel lines from being subjected to extreme underhood heat created by high horsepower turbocharged monsters. This lowers the fuel temps, thus improving horsepower and increasing longevity. Available in both black and silver with aluminum PERRIN logo plates to suit any engine bay.
Features:
How a Fuel System Works
The fuel system consists of 6 main parts. Fuel tank, pump, Fuel lines, Fuel Rails/distribution blocks, injectors, and pressure regulator. All these parts work together to keep the fuel injectors supplied with fuel and at a steady pressure. All of which are important to making a fuel system function properly. The fuel tank holds the fuel, the fuel pump picks up and delivers fuel to the fuel lines. The lines transfer fuel from the pump to the fuel rails, and pump keeps continuous pressure behind the fuel injectors. The regulator controls pressure by bleeding off pressure/fuel to another fuel line dumping back into the tank, where the cycle starts all over again.
The most important part of this system are the fuel injectors. Ultimately these are what are delivering the fuel. But all the systems in front of them have to function properly in order for fuel to be delivered accurately. In order for the fuel injectors to work, they need fuel behind them and this fuel needs to be under a given pressure. As the injector opens up the pressure and fuel behind the injector allows for the fuel to be sprayed out in a fine mist. When the injector fires, fuel pressure drops slightly as the fuel pump tries to keep up. This pressure drop carries across the entire fuel system and affects all the other injectors.
Because the OEM rails are not designed to deliver fuel equally to each injector, this pressure drop doesnÂ’t affect all injectors the same. Some will have less pressure than others, and in turn not deliver equal amounts of fuel to the cylinders. The effect is not all cylinders run at the same Air Fuel Ratio (AFR), which effects the ultimate power to be had. Imagine this happening at high RPM, and high load where injectors are firing lots of fuel and firing very quickly. Bad things can happen.
The 2 factors that play into this unequal fuel delivery are the fuel lines being very small, and that the rails are not routed to deliver fuel equally to each injector. The cure is installing PERRIN High Flow fuel rails.
This diagram shows the routing of the OEM fuel system on a typical WRX.
So why does the OEM build them this way? Because it is cheaper, and for the stock power level, they work fine, but if your reading this, your not building a stock car.
PERRIN High Flow Fuel Rails
The PERRIN High Flow fuel rails fix all the OEM fuel rail problems, and go beyond. The PERRIN Fuel rails are designed to deliver large amounts of fuel equally to each cylinder. Starting from the Junction block, the fuel travels through large 3/8”ID hose, and tees off to both sides of the engine. This allows for equal fuel distribution, and more consistent Air Fuel Ratio between all cylinders. On modified cars with bigger turbos, and injectors installed, this means more power, and more-safer power.
Equal Length
One of the faults of the stock rail is they deliver fuel in a long row. Through one rail, across the engine to the other rail and out to the regulator. The PERRIN High Flow Fuel rails split the fuel to each side of the engine to equalize the flow, and the pressure drops. The pressure drops still occur even with our rails, but they are equalized out so all injectors see the same pressure, which means they deliver the fuel equally. There are other factors that play into this equal fuel delivery, like the larger size hose feeding the rails. This diagram shows the routing of the PERRIN fuel rails on a typical WRX.
Larger Diameter Hose
Our New Large 3/8”ID diameter fuel hose has 2 jobs, transferring fuel at a high rate of speed and acting as a pressure dampener. The hose is a DOT approved rubber fuel injection hose with proper liners for zero evaporative emissions. The hose is a 3/8”ID hose that is large enough to support 800WHP. Because the hose is rubber, and has some give to it, it acts as a fuel dampener. This helps dampen the pressure waves that occur, and in turn creates a smoother more constant fuel pressure.
PRYOSHIELD
As shown above the Pyroshield is a special hose cover. This cover is the same stuff used on race cars all across the world. The outer silicone cover protects the inner hose from fire, and from extreme heat. The fiberglass inner liner provides another layer of protective cover. The fiberglass provides 500 degrees of continuous protection. The PYROSHIELD in turns keeps the fuel cooler, prevents the possibility of fuel vaporizing in the fuel lines, and keeps the fuel line protected against extreme heat from the engine.
Phenolic Risers
All PERRIN high flow fuel rails come with built in Phenolic risers. This is another small but great feature we have added. These are spacer fit between the fuel rail and the engine. They are an insulating material that keeps the heat from the heads, heating up the fuel. This keeps fuel at a normal operating temp of around ambient temp. In contrast, without these spacers you can see fuel temps rise to more than 30 degrees above ambient, which isn’t good for making power. In a sense this feature adds power to you car.
Oetiker Clamps
PERRIN high flow fuel rails use superior Oetiker crimping clamps. Oetiker clamps have a more secure fit since there are no gaps in the seal and will not loosen up over time like traditional worm drive clamps. They are much easier to install with one squeeze of the Oetiker crimping tool.
What You Will See After Installation?
After the PERRIN fuel rails are installed, you will notice a few things change. With larger injectors, the car will idle smoother, and a slight increase in fuel economy will result. Tuners will notice a larger difference, as they are ones tweaking the AFRÂ’s and changing the timing. Because the injectors are delivering equal fuel to each cylinder, each cylinder will run the same AFR, and tuners can run the engine leaner and get more HP. Also tuners will notice a lower injector duty cycle at high load and RPM. Over all the increase in fuel delivery could be as much as 5%. The one thing you canÂ’t see, but will feel good about it that your car will run much safer. And when you have 400WHP, this is an important feature!
Included Items: 2 PERRIN Fuel Rails Oetiker Hose Clamps Fuel Hose Pyroshield Misc connectors Phonolic spacers Mounting bolts
Fits the following:
WRX models 2002-2007 STi Models 2007+ Legacy GT 2006+ require a 02-05 WRX fuel pressure regulator.
Available in Black and Silver. Chose from the pull down menu.
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