Guest Posted July 1, 2003 Share Posted July 1, 2003 I have a 70 GS with a 455 and a m-20 trans. 2.5 inch mandrel exhaust with an x-pipe and Stainless flowmasters. I am having an exhaust drone at idle. it is very annoying and I can't seem to get rid of it. I just put the x-pipe on in place of the h-pipe I had previously. The X made a huge difference, it got rid of most of the vibration at cruising speeds, but I still have the drone at idle. I am running a 750 edelbrock performer carb and the timing is at 11 degrees. any ideas? Link to comment Share on other sites More sharing options...
BUICK RACER Posted July 1, 2003 Share Posted July 1, 2003 I think you got your answer on V8Buick.com, get rid of the the Flowmonsters! Link to comment Share on other sites More sharing options...
Guest Posted July 2, 2003 Share Posted July 2, 2003 yes indeed, the consensus is that they are no good. My ears will like the dynomax super turbos.By the way, if anyone is having a vibration, take a close look at your exhaust. i put the x-pipe in and it cured all my off idle vibrations.thanks! Link to comment Share on other sites More sharing options...
NTX5467 Posted July 5, 2003 Share Posted July 5, 2003 It's surprising how much difference a muffler can make in exhaust sound dynamics. Several years ago, one friend had a '70 Dart Swinger 340 that he was getting ready for a muscle car shootout and another friend had a '70 Road Runner 440 6bbl that was being prepped for the same race. The Dart guy got 3 chamber FlowMasters and the Road Runner had Walker DynoMaxes on it. Both cars had loud exhaust notes, especially at idle. The Dart was so loud in the lower frequencies at idle it'd probably make a mobile boombox owner jealous! Similar with the Road Runner.As the pipes on both cars were the same size, they swapped mufflers and both cars got acceptably quiet. Such a difference! When FlowMasters came out, they were one of the few mufflers that were really lower in restriction and somewhat affordable, but they had a unique sound to them. Now, the landscape has changed and there are lots of other choices that make less noise and are just as powerful. In reality, that 5 or so extra horsepower they might make can carry a higher price tag in the liveability area.Another friend related that he got a length of flexible exhaust tubing (from NAPA) and used them at the end of the collectors on his stroker 440 street car Dodge Coronet. I recently saw a similar piece that's on a late model GM car. It's not cheap from GM, though, but he noted that it took ALL of the exhaust resonance out of his exhaust, making the car much more pleasant to drive.Exhaust resonances and "tinkle" are usually related to both pipe sizing and muffler choice, but can also have side issues of pipe/muffler material too and whether or not the intake manifold has a heat crossover passage in it (or it's blocked off). Of course, if the pipe is touching an underbody part or has insufficient hanger insulation from the floorpan, noise transmission can result. If you remember your high school physics, every piece of metal (and other substances) have a natural frequency at which they'll resonate at. There are also similar, but of lesser magnitude, resonances at multiples or fractions of the main frequency too (why you can drive through wheel imbalance speeds, usually). Think of an exhaust system as a slide trombone of sorts, but with one pipe length. If you change the total length of the piece of pipe just a little it will make it resonate at a different frequency (and a different note from the horn). Possibly, if you make one section of the pipe stiffer or put a slight bend in it, it could change the resonant frequency some also. Lots of little tricks that can be used from the front to the back of the system. On the front end of the air path through the engine, similar resonances are at play too. In earlier times, it could be the snorkle shape and inlet configuration and included runner shapes/lengths of the intake manifold (ram tuning). Now, it's progressed to all of the funny shapes pieces of plastic between the air filter box and the throttle body on modern cars (even the triangle shaped piece on the LT1 V-8s in Roadmasters/Caprices) not to mention the "beer barrell" shaped intake manifolds. There are good sounds, bad sounds, and too loud sounds in the automotive world. Everyone has their own preferences in that area, but it's a proven fact that a good sounding exhaust system is not the loudest sounding one either, for daily or continued use on the streets. In current times, there's really no reason not to have a reasonably quiet exhaust system that doesn't significantly hinder high rpm power output either.Just some thoughts . . .NTX5467 Link to comment Share on other sites More sharing options...
Guest Posted July 20, 2003 Share Posted July 20, 2003 I love my flowmasters! I changed the exhaust 4 times trying to come up with an exhaust sound that was unique and sounded good. I also had muffler clearance problems which limited my choices.I finally went with the flowmasters because nothing sounds as good. I have an h-pipe and it drones slightly from 1800-2200 rpm.I hear Spintech are supposed to have significantly less drone than competitors, but I haven't heard them on a car yet. Link to comment Share on other sites More sharing options...
Smartin Posted August 17, 2003 Share Posted August 17, 2003 2 words:X Pipe Link to comment Share on other sites More sharing options...
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