Modifying exhaust to increase mileage?

[MetroMPG]

this is another one of those things that could be easily tested with the scangauge if we had a warm-weather winter tester. do a bi-directional run, record data, unbolt part of the stock exhaust, repeat run...

[SVOboy]

Originally Posted by MetroMPG

this is another one of those things that could be easily tested with the scangauge if we had a warm-weather winter tester. do a bi-directional run, record data, unbolt part of the stock exhaust, repeat run...

That's true, you could just make a can hole or something to reduce exhaust size.

Anyway, back to rh77's stuff. The way I understand bigger exhausts work for power is that they almost always increase high end horsepower at the cost of low end torque, so I think you might be on to something there.

[rh77]

I found this article -- some valve overlap and scavenging is interesting (it's written for big V-8's, but the science is the same)...

http://superchevy.com/technical/engi...exh/index.html

RH77

[kickflipjr]

With my old car I acutually put a smaller sized tip (1.5 vs 1.75) on it to try to get more backpressure. It didn't do much of anything but i did notice loss of power over 3k rpm

[GasSavers_JustMe]

Originally Posted by JustMe

Here is a link for a jet engine car exhaust:
http://www.aero-turbine.com/how/

Anybody know how to add an afterburner?

Seriously, check this out. They say their exhaust improves mileage. Here is another one:
http://www.spiralturbobaffles.com/semiinfo.html
.

[kickflipjr]

It seems we agree that backpressure is needed during normal operation.

Do you think there would be benifit for strait pipes / free flowing muffler for extended highway driving (at 2,500-3,000 rpm)?

I would say yes, but let me se what i can find on the net.