exhaust mod idea

[bandit86]

if freeflow exhaust gives more performance, how about a super restrictive exhaust, maybe with one of those tractor flaps with a small spring to hold it close tighter. less crankcase venting wil work like an egr.

Then you need some 1/2 or 3/4 inch emt tubing and from the back run it to the intake for the ultimate EGR mod.

this way, the extra pressure on the exhaust forces more exhaust gas into the intake, kinda like the exhaust fed back into the intake but the springloaded flap will allow some exhaust to escape and allow some fresh air to be sucked in

Seriously though, what would increasing the backpressure do?

[Bicycle Bob]

Increasing back pressure will increase "pumping losses."

[some_other_dave]

Backpressure itself does not do anything good for your fuel economy, your performance, or your engine.

Exhausts that produce backpressure under some circumstances can improve your fuel economy, or your performance. For FE, though, the gains are likely really tiny.

-soD

[autoteach]

Um, I do need to jump in here (in my mind, anyways). Backpressure and exhaust port velocity are different. Understanding this concept will debug your mythological gains by blocking off of the end of your exhaust pipe. You could gain some mpg, possibly (there are many other things that come into this equation) by making your own exhaust head pipe with small diameter tubes (and a tri-y, stepped construction). Just a thought...