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General fuel injection question
Hello all! My question is, why is there a secondary fuel rail? I have tried googling it and have turned up nothing.
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The secondary fuel rail feeds the secondary injectors.
The RX-7 (above '85) uses a staged injection system. A set of primary injectors operate most of the time close to the intake ports. These are used at light load such as idle, cruise. A set of secondary injectors are mounted higher on the manifold in the secondary port runners. When load is high enough, those injectors activate and supply the additional fuel required. Depending on year, this typically happens around 3800 RPM and 2" of vacuum. This allows Mazda to supply the fuel required to the engine but keep injector size reasonable so that they have good resolution at low fuel requirements. It's also nice for us, as a common upgrade to increase fuel delivery (for higher boost) is to upgrade the secondary injectors. Maintaining drivability at low loads. |
^Nice explanation.:icon_tup:
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Originally Posted by Aaron Cake
(Post 11864226)
The secondary fuel rail feeds the secondary injectors.
The RX-7 (above '85) uses a staged injection system. A set of primary injectors operate most of the time close to the intake ports. These are used at light load such as idle, cruise. A set of secondary injectors are mounted higher on the manifold in the secondary port runners. When load is high enough, those injectors activate and supply the additional fuel required. Depending on year, this typically happens around 3800 RPM and 2" of vacuum. This allows Mazda to supply the fuel required to the engine but keep injector size reasonable so that they have good resolution at low fuel requirements. It's also nice for us, as a common upgrade to increase fuel delivery (for higher boost) is to upgrade the secondary injectors. Maintaining drivability at low loads. |
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