Intake Manifold Test with Fuel Injectors

I have some stock fuel injectors which proved handy for plugging the holes in the intake manifold where the fuel injectors would normally go.  I suspected that in terms of overall air flow, that is with all of the runners open, the inclusion of the fuel injectors to block the holes would have little to no affect on the airflow value for the intake manifold.  The reason being that the holes are less than an inch from the runner outlet and due to the orientation the air flow would have to reverse 180 degrees to exit via the fuel injector hole.

It will be necessary to have these fuel injector holes plugged during single runner tests so putting the fuel injectors in place now was beneficial beyond simply answering the question of whether or not they made a difference to the overall flow.


Intake manifold with fuel injectors installed
Intake manifold with fuel injectors installed

The results at 10″ of H2O were not a surprise:

Intake manifold without fuel injectors: 360 CFM

Intake manifold with fuel injectors: 362 CFM.

Because the air flow reading fluctuates as much as 3-4 CFM, even with the bench operating at steady-state, the results for air flow in the different configurations are essentially the same.