Why are your fuel rails located outside on some applications?
Most of the manifolds in the Hilborn line are a curved throat design. This design, based off of racing experience, allows the air to transition smoothly into the intake runner to help generate maximum power, but affords very little room on the inside for fuel rail installation. Outside placement of the fuel rails also allows our injector nozzle bosses to be raised in the throat and situated to spray the fuel into the wall. This process conditions the fuel by smashing it into a smaller droplet allowing it to enter the air stream in a more burnable state. This also helps the fuel to pick up heat off the wall to start the expansion process, providing extremely quick response in the combustion chamber for a tremendous increase in acceleration rate. We have found this process to be far superior than spraying the fuel directly onto the intake valve which promotes a larger fuel droplet and a reduction in combustion chamber response.