Old Chuck

Getting close to pulling the trigger on a '90 with 302 conversion. It has flowmaster mufflers. Like many cars with flowmasters, this car has a bad drone with the top up at cruise. It sound great going through the gears but does drone more then I like at cruise. Looking ahead, is there anything about the exhaust on the Monster set up that makes muffler choices difficult?
Put GT 500 axle backs on my 2012 5.0 Mustang and it was a great compromise and just wondering...

tbone heller

The installation of an X-pipe should reduce the drone. I am running Magnaflows with high-flow cats & an X-pipe with no drone at all.

When installing a Flowmaster American Thunder system on my 1988 Mustang GT, I remember something in the instructions about installing ANOTHER crossover pipe in the factory convertors/H-pipe to eliminate drone. You could try this approach also. I did not put another crossover pipe in the Mustang, & only experience drone when somebody in riding in the passenger seat.

charchri4

LOL you have that problem too?? My car is super quiet and rides like a dream except when my wife is in the car. Just can't figure that out....

Agreed on the X pipe ^^. Any idea if it has a X already and what number flowmasters are in it? If they are 10s you might be in for a fight.

Screw type and insert type drone killers are hard to fine for 2.5" collectors but there is one good one out there that I know of. These things are stupid expensive for what they are but the work better than anything I have tried to kill drone.
http://www.summitracing.com/parts/cci-2di25r/overview/

Or the bigger 3 disc version
http://www.summitracing.com/parts/cci-3di25r/overview/

If those flowmasters are anything above a 40 I bet you shove a 2 disker in each collector the drone will be gone. If they are 10s a 3 disk should do the trick as lots of guys use just that for a muffler. I used one 3 disc after the Y pipe in one of my Camaros as the only muffler with full exhaust out the back and it did not drone. Sounded mean as hell at WOT though!

Old Chuck

Thanks for the ideas. When I get the car will look at the exhaust and see what model flowmasters they have. Will also check out the X and crossovers as well as the inserts IF all else fails..I did not think that I was the only person that had experienced the dreaded drone. Interestingly, the present owner said that he had not run the car with the top up before and had not heard it by himself with the top down...Sound and harmonic issues are tough to pinpoint and correct at times...

SC 97 M

I appreciate the help with resolving the drone. I really enjoy the passenger drone comment.

I'm curious if there are alternatives to the plugs to keep in mind when having a shop fab my exhaust system.

R,
Chris

charchri4

Oh yeah Chris there are all kinds of them. If you have room there are tons of bullet style resonators that will fix it right up. The problem is the cases for a 2 1/2 pipe are over 3" and that cuts in to the very little bit of ground clearance most of us have already. I know FM put resonators right before the axle now so it can be done but it is tight. You may just have to see when you get it in the air what will work.

There is nothing wrong with the insert style stuff except no performance V8 anywhere runs 2 1/2 collectors like we do so there are very few options.

Check out the insert style stuff here:
Muffler - Schoenfeld Headers

They work by creating turbulence which is not the best for flow but they do kill the drone just fine. I've never seen one sized for 2 1/2 though. Their bullet mufflers if they would fit before the axle would work fine as resonators.

Screws work OK too and can be less restrictive if modified. I usually drill a few holes in them and run as few turns as possible.
Speedway Auger Style Muffler - Speedway Motors, America's Oldest Speed Shop

But the same problem with no 2 1/2 options...

Then there is the ever popular but stupid expensive vortex cones.
http://www.summitracing.com/search/b...rder=Ascending

I have never tried them but notice the lack of 2 1/2...

Now if you run a system that has a bit of 3" pipe in it like the early FM systems the above stuff would work.

Or little resonators in the spot where it is 3" just before the axle. They did have drone complaints on the above set up but any of the above options in the 3" Y would have fixed it.

Notice his cats mid ship. Terrible place to put them but no question running cats helps too and if they would have put them on the end of the headers where they belong it would have helped the drone.

So for resonators near as I can tell there is either the car chemistry ones in the post above or losing some ground clearance. And ground clearence for me is a really big deal...


By the way full disclosure. I may not be the best person to ask about drone and exhaust. I am running the same FM set up as the blue one people complain about and think it's just fine. My cats are up at the headers though so that would cut the drone. Thing is I seldom send more than 30% of my exhaust to muffler and right now I am building a bigger more direct 3 1/2 cut out because this 2 1/2" cut out that diverts it is too quiet.

My opinion on volume and drone is heavily influenced by growing up next to a guy with a 67 big block corvette with 4” side pipes and just enough baffle not to rasp. It was very loud and very big and will forever be my bench mark of what a car should sound like. So yeah drone matters when the cut out is corked up but that dosn't happen very often so you might want to take what I say with a grain of salt.

Wanna hear it? This is a link to the sound of mine with the above FM exhaust and the 2 1/2 cutout. The cut out closes at 30 seconds then at 1 minute I drive out of the garage and stop at the end of the drive way. http://www.fileswap.com/dl/Fr3iihZvM...1_min.mp3.html Sorry about the squeeky belt it was a very wet night and I just washed it to put it away for the winter.

PS if anyone wants to buy that cam it is for sale. Yep I'm goin bigger there too...

.

tbone heller

It may more reasonable to just replace the Flowmasters with some Magnaflows & be done with it.

MRM331

I use a set of Borla ProXS mufflers and Magnaflow high-flow cats with an H pipe. My tubing is only 2.25.

On my first two builds I used 2.5 tubing and flowmasters (with the same cats). The drone was awefull. On my third I switched to the Borlas and added two unequal length resonators into the system to slightly change the harmonics of each side...no drone.

I'm not sure the resonators were needed as my current car does not have them and does not drone. the Borlas are very quiet at idle and cruze and really only open up when at full throttle. At most Miata events the turbo Miatas usually out volume me by quite a bit. Last spring I had a 1" removalble plug welded into each pipe right before the muffler. If I need a bit of volume I just reach under there with a ratchet and take them out...takes about 45 seconds to take them out or put them back in.

I had them out for the track videos I posted from last year. Even with them out the car is only about as loud as the one I built with Flowmasters at idle and cruse. At full throttle it sounds like a NASCAR stock car.

-Jason

charchri4

And the good news is no matter what you do the Ford will sound better than an LS any day!

brendabrown

I like my Dynomax ultra flow. Good sound and great flow.