wils5150
Mass
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Joined: 07/31/2007
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I am going to need to replace my exhaust from mufflers back. any ideas on a cheaper dyi solution? curious about cost. I do not need a top of the line system. I am thinking flowmasters . its a 87 allegro on a p-30 chassis 454 motor. the wheel base is 137 inches.
Thanks in advance
wils
87 Allegro 24 ft. 454.
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f.wernlein
Northern Virginia
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Joined: 12/13/2007
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Several years ago I replaced my OEM muffler and some adjoining tail pipe. I was very pleased with the results I got from a Flowmaster muffler and from Auto-Jet for the tailpipe section. Both have good internet sites with loads of info. Odds and ends such as clamps I just got from NAPA.
The OEM muffler was much more restrictive than the flow thru Flowmaster...after install I had a slightly "throater" tone, but not much louder. I could tell that by this change alone, I could feel an improvement in performance in my coach accleration.
Frank W.
1985 BlueBird Wanderlodge
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Daveinet
il
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Joined: 10/29/2003
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Flowmasters are more restrictive and noisier than straight through packed type mufflers. Without making any other changes, I lost nearly 3 mpg, 2 seconds (~15%) of my zero to sixty times. After playing around with tunning and even adding more back pressure as instructed by the clueless help at Flowmaster (talked to 3 different techs), I gave up and put MagnaFlows. My mileage came back, performance increased, and they were quieter. Packed mufflers will be quieter because they absorb mid and higher frequencies, which get reflected right through the Flowmasters. Mid and higher frequencies are important because that is what competes with speech. Also the case is very thin on the Flowmaster and causes interior resonances that are very annoying. I still have the 70 series Flowmasters laying in my garage, they only have ~1K miles on them. Big waste of money.
A decision you will need to make is if to go with duals, or Y into a single. Single 3 inch will have more bottom end, duel 2.5 will have more top end.
Dave
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Kenneth
Washington, the state
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Joined: 03/20/2001
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Quote: even adding more back pressure as instructed by the clueless help at Flowmaster clueless, because backpressure is always bad. What is needed is the correct diameter pipe for the intended running rpms of the rig.
Quote:Single 3 inch will have more bottom end, duel (sic) 2.5 will have more top end. 3" diameter has 2.35 square inches of area. Dual 2.5" has 3.9 square inches of area. Ignoring surface loses for this, the dual 2.5" are too big for good low end power. Plus, true duals are inferior to duals with an x-pipe crossover or a properly sized single. True duals have gas congestion when two cylinders on the same side fire in sequence.
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wa8yxm
Wherever I happen to park
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Joined: 07/04/2006
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There is no cheeper solution, only more expensive ones,, Unless you plan on selling soon that is.
Nothin adds excitment like something that is none of your business
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Daveinet
il
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Kenneth wrote:3" diameter has 2.35 square inches of area. Dual 2.5" has 3.9 square inches of area. Ignoring surface loses for this, the dual 2.5" are too big for good low end power. Plus, true duals are inferior to duals with an x-pipe crossover or a properly sized single. True duals have gas congestion when two cylinders on the same side fire in sequence. Area = 3.14159 * D squared/4 or around 7 square inches. dual 2.5 is 9.8 square inches. But you have the right idea. And I knew that spelling didn't look right.
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