Exhaust Header "Theory" and "Practicum" Discussion

[Schrade]

Originally Posted by Kevin

that is the exact system I want.

The interior drone is really bad there, Mr. K.

Outside is not bad at all, until you hammer down.

But I'd still have taken it from Jeff, even if I'd heard the drone BEFORE I got it. AND, that was withOUT even knowin' how much cooler it runs (I STILL have not heard the fans come on, except when I rolled up the windows once last week, for A/C... )

In fact, I'd like to have an acoustical engineer examine and describe what's going on in this car.

[Kevin]

i've been told about the drove for years, but I hardly ever drive on the highway so i'm not worried

[Hog]

Here is a video on header theory comparing primary diameter, collector extension, and ceramic coated-black painted headers.

The results are surprising, smaller primary tubing doesnt always mean better low rpm torque. Black painted vs. ceramic coating difference is also marked.

Not an LT5 but the rpm range is close. I wish they had ran a stock manifold though.

https://www.youtube.com/watch?v=O1bXPNy1Yn4

[Bob Eyres]

Here are some things that I believe about exhaust:

The "which exhaust to use?" question is always a compromise between maximum flow, and reduction of sound, or drone. You can't have one without the other.

Maximum flow is afforded by the system with the least back pressure.

Reduction of sound, or drone, is enhanced by tuning the engine pulses to cancel noise. Almost always causing increased back pressure.

Ultimate maximum flow would be open, equal length headers, with the length tuned to the rpm range at which your engine needs the most help. Any exhaust attached to that header collector will compromise the flow to some extent, and reduce horsepower. With the possible exception of the X pipe.

Any restriction in the exhaust system will impede the flow of the whole system, ex: Crimped stock resonator inlet/outlet, (2 1/4"), reduces flow of entire system.

The larger the diameter of exhaust pipes, (behind the header collector), the less back pressure, and more flow. Bigger pipes = more hp.

The X pipe is the only device in the exhaust stream that can actually improve flow, by using alternating exhaust pulses to create low pressure, improving flow.