I'm working on a CNC machined TGV delete to be used with v7 STI intake manifolds. I've modeled the part myself based on a factory aluminum TGV and had it 3D printed and test fit. The design will allow for standard Subaru injectors and rails for all injectors ports, this allowing flexibility when building up your fueling system (i.e. aftermarket injectors or rails for Subaru v7 Imprezza STI will fit in both lower and upper locations, along with factory v7 injectors/rails).
The benefit of dual injectors per cylinder is when you are chasing big horsepower, and a large single injector per cylinder (i.e. 1500cc and above) will achieve poor resolution at part load/cruise, resulting in a stumble or accelerator hunting at cruise. With twin injectors, you can retain the factory injectors for low horsepower duty, and allow the ECU to bring on the secondary injectors only as needed, thus providing factory levels of fueling control at low engine load and adequate fueling for high horsepower runs.
This design is intended to utilise your primary injectors in the lower injector ports for general duties, while the upper injectors provide additional fueling as required. This will require an aftermarket ECU to control the additional 4 injectors and it is best you consult with your tuner if your ECU is capable of managing the extra 4 injectors.
I'm currently working through the adapter for mounting the upper fuel injector rail and pricing with a CNC machinist with the final version to be cut from aluminum billet. As you will understand, the bigger the batch of these the lower the final cost, so if anyone is interested please get back to me via private message and I can put you on the list.
I'll post some pictures up here shortly of the 3D printed version, but please be aware that this isn't the final product, as details such as fillets will be added to improve machine-ability and reduce costs.
I'm happy to answer questions anyone has, just fire away.
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