Muffler replacement huge horsepower gains!

[Mdman352]

I have a Contemporary at Nicks now and I stuck a bore scope (used for examining rifle bores) inside of my collectors and I do not have ANYTHING in mine. WHAT DID YOU SAY??? I have taken to wearing small ear plugs during driving (26 dba reduction. available at Walmart) that I use to compliment my hearing protection while shooting. Stopped the ringing and you can still hear.
David

[CobraEd]

No backpresure is good

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[Silverback51]

Originally Posted by CobraEd

No backpresure is good

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That is why so much time and effort is put into equal length headers, and collector design. You want the exhaust pulse of one cylinder to cause a negative pressure zone in the other primary tubes so you have a scavenging affect.

This rumor of backpressure being good has been around since I was a kid.

[Rare Iron]

Originally Posted by CobraEd

No backpresure is good

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Here's an exhaust teaser - & I will maintain that correct flowpath & exhaust pipe diameter IS critical, as well as using mufflers of some sort in an exhaust system. A good friend of mine is one of the supervisors for floor operations at the Chrysler Viper development plant on Featherstone in Auburn Hills, MI.

Several years ago, while experimenting with different exhausts for the Vipers, they decided to plumb & run a 3" straight-pipe system on a test mule Viper, and dyno it. Like, no mufflers = no backpressure = a good thing! Plus, maybe it would sound good on the V-10 to boot. They did their thing & then brought it up to operating temp., where they discovered the motor was running about 30 degrees hotter, plus it lost about 30 HP. They shut it down, let everything cool off, & then they installed Super Turbo mufflers & re-ran the test. Everything went back to normal. They concluded there was an "expansion chamber" needed in the exhaust system for optimum running conditions. Also, on any application, if you reduce backpressure too much or use too large of a system diameter, you will lose bottom-end & midrange performance - you'll FEEL it. You must pay attention to what power your motor is putting out, & relate that to an optimum exhaust system diameter. My advice is that you transition to a 3" muffler flowpath when you are up around 480 HP, IF you are looking for optimum performance. There is a quantum leap in exhaust flow cfm when going from 2.5" to 3" diameters.

-Eric

[CobraEd]

This is because when you open up the exhast, you need to richen the mixture to compensate or it will run lean and hot !!!!!!!


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[CobraEd]

during the 60s when I was in high school, a lot of kids would go to the drag strip with basically stock cars. the cars would run fine. But when they would disconnect the exhast system at the manifold for a run down the track, the cars would break up badly. This is because they did not richen the jetting as necessary to work with the freer flowing exhast


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