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Old 05-12-2003, 08:36 PM
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Post Another Exhaust Question

I run dual 12 inch blue bottles behind my 300 horse 350, i have 2.25 inch pipe and i was wandering if it would be louder (and or add more HP) by mounting the mufflers right before the tailpipes. by the way this is a halfton truck.
Brandon

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Old 05-13-2003, 03:00 AM
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By mounting the mufflers as far back as you can will help with the flow. By the way this is done on the Vette, it keeps the exhaust gass's hotter and un restricted which in turn keep's the flow faster. There was a dyno test on color, black and silver/white. The silver/white made 7 to 15 HP more because the black took more heat out of the pipe and slowed the flow.
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Old 05-13-2003, 05:05 AM
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1Bad, I thought the theory behind wrapping your headers was that it helped cool the exhaust gases thus promoting easier exhaust flow and creating more hp? Doesn't that contradict the vette theory?
There was also a thread elsewhere on this site that explained, like what you said, that placing the mufflers back after the pipe (like back by the rearend) actually does several positive things, one of which is that it helps get the roar back behind the passengers in the vehicle, as well as helping with exhaust flow, just can't remember (gettin old!) exactly why, but it has something to do with the gases having cooled enough I think.....
Now you have me wondering.......ugh <img src="graemlins/drunk.gif" border="0" alt="[drunk]" />
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Old 05-13-2003, 05:39 AM
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wrapping your headers prevents the gasses from cooling (think about it, do you wear a coat on a cold day to keep you cool?), heat in the headers promotes faster flow through the rest of the system

As 1Bad80 said, mufflers also cool the exhaust gasses and this slows the flow, by putting them right at the back they don't cool the gasses as soon so you get a faster overall flow
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Old 05-14-2003, 02:52 PM
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ooooooooooohhhhhhhhhh....just call me cixelsyd!
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Old 05-14-2003, 03:43 PM
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I thouht wraping or powercoating was mainly to kee engine bay temps down........Steve
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Old 05-14-2003, 04:20 PM
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Coated headers are now almost required on the street scene. The ceramic coatings are worth years of shiny header appearance, and stop's rust, and their also silver to reflect the heat back into the pipe. Wraping the pipe's make's them embrittled, and they crack easier. The wrap was developed at the track to stop the heat inside the car when racing and also help's with the flow keeping the exhaust gas hot.
Taken from site that Steve posted.
<a href="http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm" target="_blank">http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm</a>
As discussed earlier, exhaust gas is hot. And we'd like to keep it hot throughout the exhaust system. Why? The answer is simple. Cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large exhaust pipe will cause a slow exhaust flow, which will in turn give the gas plenty of time to cool off en route. Coating the entire exhaust system with an insulative material, such as header wrap or a ceramic thermal barrier coating reduces this effect somewhat.

[ May 14, 2003: Message edited by: 1BAD80 ]</p>
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Old 05-16-2003, 11:17 PM
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Cooler gas has less volume.
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Old 05-20-2003, 11:00 AM
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I believe I would be running a 2.50" exhaust then maybe contact the guys at Flowmaster for optimum muffler placement. Chances are they have documented research on this and can help solve your problem.
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