How to measure intake runners for equal flow?
 

I am working on an intake manifold and would like to test different plenum designs on how equal each runner is flowing. I am also curious in seeing how the stock manifold flows. What would be the easiest/cheapest way to do this? I don't need actual CFM numbers or anything, just how the runners flow relative to each other.

Searching Google, I've come up that all you really need is a shopvac and a manometer. But, I haven't been able to exactly figure out how to hook everything up. Do I blow through the throttle opening while measuring the pressures at the port exits? Do I plug up the other runners except for the one I am measuring? I've also seen some guys suck through the port and measure the pressure at an injector boss, but the 1.8 doesn't have injectors on the manifold.

I've also thought about putting clear tubes on the port exits with a ping pong ball inside each one and then blowing through the throttle body opening seeing how far/equal each ball 'floats' up.

Any comments/suggestions?

Thanks,
--Ferdi

I would say blow through the throttle body and measure each runner at the same time with 4 measuring devices. Just my uneducated opinion

Theory sounds about right....rig each runner up to one of those huffer deals they make people blow into at the hospital to measure lung capacity, lol...

But wouldn't you want to do each separately with the others blocked off and run 1-4 and 2-3 together as that is how the manifold will see flow in the car? 3 will never see flow with 1 or 4 and vice versa so it doesn't make sense to test all at once. This is based on my on conjecture and not based on any logic or training.

I'd say there's some merit in this....at least it makes sense to me....