Everyone who's ever heard a flowmaster muffler is probably aware of the annoying resonance at low RPM. Does anyone know of any solutions or ways to reduce this? I personally don't think the muffler is too loud at 2500+ RPM, but at idle it's annoying.
Get a different muffler. The drone is almost a trademark of the Flowmasters. It gets worse if you are running 2.5 or bigger exhaust. You can try adding some type of resonator before the muffler. Keep the ip size the same as exhaust size. running 3 inch tip on 2.5 exhaust increases the drone. Any good muffler is going to drone a little, the flowmaster is one of the worst, however. If any body disagrees, please post a good performance muffler that is quiet. I plan on using a 3 inch Walker Ultraflow on my turbo car. Thankfully the turbo will help quiet it a little bit.
I was thinking about maybe putting a supertrapp tip with the removable shims after the flowmaster,but I dont know if it is so long that it would look bad hanging off the muffler.You are right on the drone below 2500 it is ANNOYING,but the sound at high rpm is awesome IMHO. later,norm
I know this is going to sound crazy but I just went to school for this type of thing through Ford Motor Co. and the instructor told us an old trick he used to use. Take an old car antenna (the whip type not the collapsable ones) about 3 feet long and start at the front of the vehicle exhaust system,lay the end of the antenna on the exhaust and start moving toward the end of the car the spot where the antenna vibrates and jumps around the worst is the point of resonance, he says that something as simple as clamping an old exhaust pipe clamp on this spot will geatly reduce the resonance but any kind of weight that you can attach to the pipe will work. I haven't had the chance to try it yet but I recently added a Mustang Cobra to my insurance policy (whole other story) and it has flowmasters, my old Mopar also has them and both have the resonance, I am going to try it as soon as I get a chance, but if you try it any time soon let me know if it really works. This is no B.S. I am a certified Ford technician (gotta make a living somehow) and go to school regularly, the instructor claims that FOMOCO has spent mucho bucks trying to solve NVH (noise,vibration,harshness) problems, so if he believes that it was worth mentioning then I'm at least going to try it. If it works for you e-mail me and let me know, I'd be interested to know.
I'm going to be installing a Dynomax Race Magnum 3" muffler on my car tomorrow. Had a 3" Flowmaster, and had the same droning symptoms, plus it was creating a bit more backpressure than I wanted - 9.5psi at the turbine outlet when the boost pressure was 18psi.
As a test, I replaced the Flowmaster with a straight 3" pipe, and got 3.5psi at the turbine outlet, so it appears that the Flowmaster was responsible for about 6psi of backpressure at 18psi of boost. BTW, the straight pipe sounded _really_ good, especially on boost - it sounded like a freaking Winston Cup car. Unfortunately, though, it's a bit too loud to remain inconspicuous, if you know what I mean...
I'll let you know how the Race Magnum works out. The sales guy (they sell both Dynomax and Flowmaster, BTW) said that the Race Magnum was actually a bit quieter than the Flowmaster, even though it's a straight through design.
I did a lot of research on exhaust while I was building my VR and found that the best thing to do when running a 2.5" exhaust is to put a small resonator about 9" back from the collector. ine is a glasspack. It really cuts the resonance way down. My VR, by most comments, sounds really good and is just a glasspack in the tunnel and a 3" Monza tip at the back.
I only have a glass pack, approx 2.5 ft long, the rest is a straight pipe. sounds pretty **** cool IMHO. A friend just bought a muffler made by Hooker ( header company ) it's adjustable. It kinda works like a Supertrap but looks much better and sounds F*#@king Cool!!! Especially on decelleration.
GOD! That John guy sounds like a Ford Factory Guy! Ever notice how Ford ALWAYS corks the **** outta their exhausts, so grandma and grandpa might EVEN consider buying a Rustang? Straight pipe, ****! Run a shortie right off the header out the side benind the front wheel. That way nice flames come out on decell...
I think I spent too much time in the sun this weekeend...