Radium Engineering has just released a collection of fuel rails for the popular 1990's Nissan 4-cylinders. The KA24DE, S13 SR20DET and S14/S15 SR20DET have been popular for many years. All of these engines come from the Nissan factory with side-feed injectors. High-flow side feed injectors are expensive and not many aftermarket side-feed fuel rails support the increase in fuel flow. A popular alternative is to convert to the more common, less expensive, top feed fuel injectors. We decided to start with a clean sheet of paper and solve the issues that can be found with top feed conversions and add some bonus features as well. See below for the details on our new fuel rail designs.
The KA24DE fuel rail has a large 0.69″ (17.5mm) bore and converts the system to a top-feed style fuel injection. This fuel rail was designed to work seamlessly with injectors from Injector Dynamics, although other brands with the same injector height will work. The CNC machined fuel rail securely fastens to the factory intake manifold mounting bosses with two anodized aluminum spacers and stainless steel bolts (included). There are four customizable ports on the fuel rail for flexibility in plumbing of the fuel system. The front port is a 3/4-16 (-8AN) O-ring thread. Radium offers a variety of different screw-in adapters for this port (-6AN, -8AN, -10AN). The rear port is 3/8NPT that can accommodate an adapter fitting for -6AN hose or a fuel pulse damper. Also available for the rear port is a special adapter (sold separately) that allows installation of the OEM Nissan fuel pressure regulator.
The center bottom port is threaded for 3/8NPT and is ideal for a fuel pulse damper, an adapter to connect a -6AN hose or a simple plug. The center top port on the fuel rail is 1/8NPT and works for a fuel pressure gauge or pressure transducer. An anodized black aluminum plug is also available. All Radium designed Nissan fuel rails feature laser etching and CNC machined engraving.
When converting from side to top feed fuel injectors, a new lower injector seat is necessary. Radium designed each anodized aluminum injector seat to use a Viton O-ring which provides a positive seal with the intake manifold. The seats are compatible for injectors with 14mm lower O-rings.
The KA24DE fuel rail kit comes with everything needed for a trouble-free bolt on installation. Optional fittings for the ports can be configured on the product page.
The ever-popular SR20DET is another highly modified engine in need of a high quality, well-engineered top feed conversion kit. The Radium SR20DET S13 fuel rail has a 0.69″ (17.5mm) bore that is CNC machined from billet aluminum. The arrangement of the ports is similar to the KA24DE fuel rail. Several fitting options are availabe for each port. It is also designed for the same height fuel injectors as the KA24DE fuel rail.
The S13 SR20DET fuel rail mounts to the factory bosses using 3 unique stainless steel brackets for a quick bolt-on installation. This fuel rail also fits the popular GReddy intake manifold without modification. The 3/8NPT center port on the S13 SR20DET fuel rail can accomodate a fuel pulse damper, a -6AN adapter fitting, or a simple plug.
The S13 SR20DET fuel rail kit comes with everything needed. Optional fittings for the ports can be configured on the product page.
We could not ignore the most modern SR engines. The S14 and S15 generations are known for their variable valve timing, ball bearing turbos, and top mounted throttle body. A throttle body in this position places the inverted intake plenum on top, above the fuel injectors, making the top-feed conversion more difficult.
Initial assessments revealed that the OEM steel idle air bypass line tubing was causing fuel rail clearance issues. To solve this, a billet IACV spacer with a threaded port was designed. This alows the use of a rubber hose to bypass air for the idle motor while eliminating interference with the fuel rail. It was also discovered that Nissan has discontinued the S14/S14 IACV gaskets which lead to a Radium produced version which can be found HERE (one is included in the fuel rail kit).
Even with the limited overhead space created by the S14/S15 intake plenum, a high quality, 0.69″ (17.5mm) high flow top-feed fuel rail fits. This fuel rail has a similar port arrangement as the other two Nissan rails. However, there is no 1/8NPT port on the fuel rail. If a 1/8NPT port is required for a pressure gauge or transducer, CHECK THIS OUT.
The fuel rail has a single 3/8NPT center port that can be used for a fuel pulse damper, -6AN male fitting, or plug. Notice the small amount of clearance available above the fuel rail.
Shorter fuel injectors (such as those produced by Injector Dynamics, RC Engineering, etc.) must be used. Details are shown here.
Special injector seats (25mm diameter) are used on the S14/S15 intake manifolds and seal with Viton O-ings. The Radium fuel rail mounts to OEM bosses using anodized aluminum spacers for a quick bolt-on installation.
The S14/S15 fuel rail kit comes with everything needed. Optional fittings for the ports can be configured on the product page.
All of Radium Engineering products are made right here in USA and come with a 1 year warranty. We are offering several pieces of these fuel rail kits individually for people looking for these special parts for a custom installation. To see all the Nissan-specific Radium products CLICK HERE.