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#21
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For me to get my car to pass inspection I cut up the flowmaster system and removed the H pipe piece and welded in a pair of bullet mufflers. That brought the noise level down but for this topic it also removed almost all the drone. I have a pair of aerochamber mufflers on the car and they drone a lot (on my car).
What I am planning to do, as the car is too quiet for my liking with the bullets, is installing flex couplers (like these https://www.ebay.com/itm/143213752138) after the headers and using the original style hangers like FormulaJones suggests. Hopefully the flex pieces and the hangers will keep the drone down (and give me my sound back)
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1968 - Pontiac GTO |
#22
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The drone is there with the top up or down. Although with the top down there is a lot of other noise to keep me occupied.
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1971 GTO Convertible 455 #64 Heads, HO intake and carb with MSD HEI, RAIII exhaust manifolds and 3:55 posi |
#23
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Quote:
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#24
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Can confirm. have same setup on my 66 convertible, no drone whatsoever.
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1966 Lemans convertible 455/5spd 1968 Firebird convertible 400/4spd Need more Pontiacs! |
#25
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drone
Is there any relationship between cam duration and/or LSA and drone? Billk
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#26
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Quote:
That's an excellent point. In addition to the exhaust itself, the timing of the pulses and volume of exhaust flow relative to engine speed play a role. Therefore exhaust closing point and overlap need to be considered. It'd be interesting to hear people's experience with trying different camshaft layouts and whether they noticed a difference in drone without any change to the exhaust system.
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"The Mustang's front end is problematic... get yourself a Firebird." - Red Forman |
#27
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Epilogue on this thread.
I replaced the Dynomax muffler with Pypes Turbo mufflers and 90% of the annoying resonance is gone. I still get a little at a very specific RPM but all in all I am happy with the result. Thanks to all those smart and experienced people who commented.
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1971 GTO Convertible 455 #64 Heads, HO intake and carb with MSD HEI, RAIII exhaust manifolds and 3:55 posi |
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