Extra staged injectors or auxiliary injectors

Hi Andre

I'm changing from 4 x 1650cc injectors to 6 x 1650cc injectors on my 13b turbo engine with the extra 2 injectors mounted in the elbow just before the throttle body.

My ecu is a Vipec V88. Would it be better to setup the extra 2 injectors as additional secondary injectors (total of 4) or set them up as auxiliary injectors.

I would suggest using auxiliary injection with your configuration for the additional injectors. Since they are mounted pre throttle body, you're going to want to ensure that they are only active at WOT or very close to it. This may not be the case with your staged secondary injectors (depending how you're staging them in).

Auxiliary injection will give you more control over how and when these injectors function independently of the secondary staged injectors. Using this technique however will affect the shape of the main fuel table as you will need to reduce the fuel table numbers to account for the fuel being added by the aux injectors.

My preference would be to fit the extra injectors on the intake runners and run them simultaneously with the secondary injectors in a staged configuration. This ensure because of their location, that all the fuel is delivered to the correct rotor.

Thanks Andre.

Yeah I had originally planned to mount them in the top of the inlet manifold however as the car will still see occasional street duties which won't require the extra 2 injectors it would be easy to change the elbow and have it more likely to past roadside inspection should I be pulled over.

Might just get another uim to swap over for street use.