Muffler Question

[jmacmaster]

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Originally posted by Quest: While I personally cannot tolerate automotive exhaust noise (excessive), I beg to differ RE: less restrictive exhaust flow = HP. Reasoning as follows: Have you ever look at Honda S2000's design, even with factory stock cat and muffler, this car is known to produce 100hp/1litre in N/A configuration (stock exhaust and intake). Have you tried installing aftermarket exhaust to see how see what sort of gain you got? I have (not on my car but someone in my pool of "autophools" did it and then dyno'ed it) and the hp dropped considerably (HKS manifold, cat bypass, low restriction HKS muffler, etc.). And you wonder why there are so many "loud" systems out there that would accelerate slower than your ordinary "cat-in", "restrictive" exhaust system? Note: think "exhaust scavenging" within a particular N/A gasoline engine.

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[jmacmaster]

quote:

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Originally posted by Quest: While I personally cannot tolerate automotive exhaust noise (excessive), I beg to differ RE: less restrictive exhaust flow = HP. Reasoning as follows: Have you ever look at Honda S2000's design, even with factory stock cat and muffler, this car is known to produce 100hp/1litre in N/A configuration (stock exhaust and intake). Have you tried installing aftermarket exhaust to see how see what sort of gain you got? I have (not on my car but someone in my pool of "autophools" did it and then dyno'ed it) and the hp dropped considerably (HKS manifold, cat bypass, low restriction HKS muffler, etc.). And you wonder why there are so many "loud" systems out there that would accelerate slower than your ordinary "cat-in", "restrictive" exhaust system? Note: think "exhaust scavenging" within a particular N/A gasoline engine.

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Well, you need to check into what people, especially in Japan and on the US west coast, are doing to the Japanese 4 and 6 cyl. engines, from the air intake to the engine and its internals, to add-ons, to the exhaust system. A ratio of 100 hp per liter is nothing anymore for these engines as rebuilt by modifiers. Small block 4 and 6 cyl. Japanese engines are commonly modified to 400 hp and more, and I can guarantee you that the stock exhaust system comes off to do that. In fact, you can't do it without taking off the restrictive stock exhaust system, in order to let the added hp breath out of the exhaust system.

 

[XS650]

quote:

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Originally posted by Quest: While I personally cannot tolerate automotive exhaust noise (excessive), I beg to differ RE: less restrictive exhaust flow = HP. Reasoning as follows: Have you ever look at Honda S2000's design, even with factory stock cat and muffler, this car is known to produce 100hp/1litre in N/A configuration (stock exhaust and intake). Have you tried installing aftermarket exhaust to see how see what sort of gain you got? I have (not on my car but someone in my pool of "autophools" did it and then dyno'ed it) and the hp dropped considerably (HKS manifold, cat bypass, low restriction HKS muffler, etc.). And you wonder why there are so many "loud" systems out there that would accelerate slower than your ordinary "cat-in", "restrictive" exhaust system? Note: think "exhaust scavenging" within a particular N/A gasoline engine.

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Scavenging happens well before the muffler. There is a way to add power by restricting an exhaust system though. It's called a turbocharger.

 

[rpn453]

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Originally posted by Quest: I beg to differ RE: less restrictive exhaust flow = HP.

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You're confusing exhaust tuning with restriction. The same diameter and length of piping with reduced minor losses (smoother flow) will produce more torque and power.

 

[2000_SL_1.9]

2001 Montero Sport 3.0L OEM muffler measurments, using a measuring tape: Length 19" Width 9.5" Circumference 28" Height 6" Pipe Diameter 2" With these measurments, I ended up ordering a Magnaflow, part # 12244. This has a 2" piping. You can go with part # 12245 if you want 2.25". The Magnaflow I ordered is 5x8 oval 2" diameter pipe, 18" body, total 24" including pipe extrustions from front and back of muffler and satin steel. I figured I'd save some money by not going polished. I'll just find a nice chrome tip and make a side exit exhaust. I've talked to several muffler shops and it seems Magnaflow is the recommended choice with Flowmaster coming in second.