Skunk2 Ultra Secondary Fuel Rail for 16-21 Honda Civic 1.5T

Skunk2 Ultra Secondary Fuel Rail for 16-21 Honda Civic 1.5T for Skunk2 Ultra Intake Manifold

The 1.5T is direct injected. The injectors spray straight into the cylinders, fed by a high-pressure pump driven off the camshaft. That works great at stock power. The trouble comes when you start pushing the engine. That high-pressure pump only moves so much fuel, and the DI injectors can only flow so much, no matter how good your tank pump is. Turn up the boost or add ethanol, which takes far more fuel for the same power, and the DI system tops out. Once that happens, it doesn't matter what else you've built. You can't make more power because you can't add more fuel.

The usual fix is adding a second set of injectors in the intake ports. This rail feeds them. It's built for the Skunk2 L15B7 Ultra intake manifold, which has injector bosses for exactly this. The DI system keeps doing its job, and the port injectors add fuel on top when demand climbs. That's what lets a 1.5T run serious boost or a lot of ethanol. It's a big-power part, though. If you're running a bolt-on tune on pump gas, the factory DI system has plenty of room and you don't need this yet.

This Is One Part of a Larger System

The rail alone won't add any fuel. A working port injection setup on the 1.5T also needs the Skunk2 Ultra intake manifold, a set of port injectors, a fuel supply to feed this rail, and a pressure regulator. It also needs a tuning setup that can run the extra injectors and blend them with the DI system. Plan the whole system before you buy any of it. Most people install it together with the manifold, since the manifold has to come off anyway.

Billet Aluminum, 17mm Bore

The rail is CNC machined from billet aluminum with a 17mm (0.669in) internal bore. A big bore holds a lot of fuel, so pressure stays steady down the whole rail even when four large injectors fire one after another. The injector at the far end sees the same pressure as the one closest to the inlet, so every cylinder gets the same fuel. The rail is hard anodized, a tough, corrosion-resistant layer formed into the aluminum itself. That's why it can run gasoline, race fuel, and ethanol blends without breaking down.

-8 ORB Ports

Both ends have -8 ORB ports. ORB (O-ring boss) is a straight thread that seals with an O-ring on the fitting. You don't need thread tape, and there are no tapered threads to over-tighten and crack the rail. Skunk2 says the ports support fuel systems for over 1,200 hp. That's far more than any 1.5T will make, so the rail won't be what holds your fuel system back. The two ports also let you run fuel straight through the rail, with a feed at one end and a return at the other. That keeps fuel moving and helps keep it cool.

Install Notes

Lube the injector O-rings with clean engine oil, seat each injector straight into the rail and manifold, and make sure all four are fully seated before you tighten the rail down. Use fittings that match the ORB ports, and leak-check at full pressure with the key on before you start the engine. Have the car tuned for the port injectors before it sees boost. Port injectors with no tune telling them what to do will either do nothing or flood the engine.

Fitment

• 2016-2021 Honda Civic 1.5T (L15B7), including the Civic Si
• Requires the Skunk2 L15B7 Ultra intake manifold. Does not fit the factory manifold
• Does not fit the Civic Type R
• Rail only. Injectors, fittings, regulator, and fuel lines not included