Alright, everyone knows what I have been going through with my dual super44s and the horrible drone. I put the H-pipe in and it dropped the drone from 60 mph to 40, which is right at in-town cruising speeds. I would rather have it at highway speeds. Anyway I made a cap and plugged the driver side tailpipe, figuring it would force the "useless" tube and muffler to act as a resonator, possibly eliminating the drone. This is a 2-1/2" pipe, H-ed off, and then running 2-1/2" each into 2 Flowmaster Super44 mufflers, and dumped at the axle. Well, with one tailpipe plugged, it was MUCH quieter. And it felt like it had more bottom-end torque. Seems like it ran from idle up to 6000 rpms much quicker, and the drone was still there, but barely audible. My rear-view mirror was not rendered useless, as it has been for the past few years due to all the vibrations. It didn't idle or run any different, as far as I can tell, at least not negatively. It idled in the garage without causing deafness, and I didn't trigger any car alarms in the neighborhood. Yet, it still had the nice flowmaster SCREAM when I nailed it, that cougar-scream that I really like. I will take the entire pipe off and cap it at the H-pipe next, and see if it makes any difference. Didn't have time to let the pipes cool down and do this today before it got dark on me.
Cool, sounds like you're on to something. What if you capped or blocked the h pipe in the middle keeping both pipes even. I think it would act the same as a resonator and keep the flow even. Sounds good in my head.
Good experimenting I never had any drone with my old setup: http://youtu.be/tep__cXgTRA But that was with a mild mild cam,40s with turndowns at the axle,2" pipe and manifolds.
The H-pipe is new. I just put it in weekend before last. Before that, the two sides were completely separate. And drone was at 60-65 mph. After H was put in, it pulled it down to 40-50 mph. If this continues to work out, I will likely go to 2-1/2" pipes coming together prior to a 3" glasspack, then out either the bottom or possibly out the side if i can manage it. I never had a drone until I added headers and went dual. When i was dualled but from stock manifolds to sidepipes, it was quiet. When i put in headers and went to dual glasspacks, even exiting out the sides in front of the wheels, I had a slight drone. It got WAY worse with the dual Flowmaster dumping under the car. I guess the stock manifolds cancelled out all the drone-making pulses, where the headers let them amplify on the way back???
Have you tried running the pipes out the back or out the side? I think the turn downs are casuing the problems. I have headers, 2.5" pipes, and the tailpipes are cut off right now at the mufflers. I don't have any drone. ya its noisy but tolerable. When the tailpipes are on it is a whole different sound.
It would probably help, the drone could be the sound waves bouncing back towards the car. get the soundwaves out from under the car with tailpipes, or no turndowns will keep it from bouncing up at you. remember when having side exit exhaust and driving by a concrete wall on the freeway or something? How it would echo and dron back at you? Same kind of thing. I actually think the H-pipe helps creat the drone. Ive had the same mufflers on a Mustang as I do in my maverick. Mustangs always have drone issues with flowmasters. I've never really noticed on my maverick. Plus I have no H-pipe. coincedence? maybe. but first step for you i would say is cut off the turn downs. see how it works. If it still drones or is too loud the extend the pipes out from under the car and see what happens.
3 chamber flows help w/ resonance somewhat. Ive thought about using this for some time now in conjuction with my 40 series 3" exhaust http://www.flowmastermufflers.com/s...1=Exhaust Accessories&sc2=Resonator&sc3=&sc4=
Just another muffler in line? Not much room for the ones I have. Not sure if I can fit another set under there. I will try to turn the mufflers so that they face outwards. See if that makes a difference.
imo and from what ive noticed from other cars, it can just be the series of muffler yer running. but thats just what i think...
Pipes that open under the car or turn down directing sound under the car will cause a drone. If the pipe is tuned (mis-tuned) to the exact length you can get a drone that also adversely affects the power of your engine. A pressure wave hitting the port at the same time the valve is open will cause a big dip in power.
I don't think it's this, i've heard guys with every series complain about the drone, and a bunch of others never have a drone. I think it comes down to pipe length and sound resonance in the pipe. Most if not all new cars have a resonator built in, a lot of guys in the performance world are incorporating them into their systems as well. Just to clean up the tone and get rid of the rasp(on inline engines). They also say they get rid of the drone, but who knows.
