I've been doing some research on resonance (inertia supercharging) because I'm planning on building an intake manifold soon. Everywhere I search doesn't tell me whether or not bends in the intake runners or the taper of the runners will affect resonance. Anyone have any idea?

Also, I've figured out the volume of the plenum (3.3-4.4 Liters). Is a plenum this big going to hurt the low-end or mid-range? I know it will help a lot up top, but I'm wondering if I should make some sort of a varaible-volume plenum (see:NSX).

Thanks in advance for any info.

wow, you got one hell of a project on your hands.

I guess you are an n/a car. well, it is a pretty complicated science.and its not just runner length, its also runner volume. also, remember, air flows like water. try to steer away from uneven pressure areas in the plenum. tapered will always be better becouse it allow the air to funnell a little bit and helps smooth changes in direction with the air. also keep in mind, whenever air has to change direction or change shape it will loose momentum. you will always want the straitest possible shot form the throttle blade to the valve



that is all I can help, the rest is up to you

Yep, it's definitely frustrating at times. I've been doing research for about 2 months, and I have a couple designs I'd like to try out. And yes, it's an n/a car. I'm not looking for serious power, I just can't leave well enough alone Thanks for the info, that's pretty much what I was looking for.

Oh the joys of intake manifold construction and design.....tough stuff.
First of, how high are you spinning your motor? What are you cam specs? Where do you want your power to be? How accomplished are you as a welder if your welding the intake yourself, hopefully out of 6061 Al.

Now, this is all in general, until I know what your engine specs are I can't help you with specifics.

Generally, you will want about 50-60% of your engine volume as the plenum volume. The higher the rpm range you want to make power in, you will want more plenum volume for the engine to gulp air from.

Generally longer runners will increase torque at a lower rpm range.

Get back to me with those specs and we can talk numbers. Good luck.


1988 Pontiac Fiero, engine transplant underway.
2004 ECOtec, built and boosted

I know this doesn't show alot of details, but here's a 2.2L with a fabbed intake: Byron's Sunfire.
Obviously a dual TB, with what looks like a small plenum. I cant tell about the runners. Also, you can a custom fuel rail('98+ w/ AN fittings?)

Nice headers, look like some long primaries.

I do know he used a mechanical roller cam, using the old 2.8L V6 roller rockers from Crane.

Not bad ET & trap speed for an N/A 2.2L OHV, he did better than what's posted there.