Too loud, too old?

84Euro · 84Euro's Garage

Just installed a complete B&B stainless exhaust system with HE's I purchased from a fellow pelicanite. Car has a mildly warmed over early 3.6 motor(chip, cams, head work, air filter, Lt flywheel) and runs well. It sounds great except between approx 1800 to 2300 RPMs. It has a drone that radiates throughout the car and is very loud and in time will annoying. The idle is deep and almost mellow. Once above 2300 and at cruising speeds on freeway it is almost quite. The system is the long tube header design with the 2 in 2 out muffler. This is a DD and would like some advise on other alternative mufflers , mods, or would resonators tips effect the sound level? Anyone else have this or a similar system and have had the same problem?

dan79brooklyn · 01-23-2007, 06:22 PM

I have a B&B with dual exhaust outlet. It has a drone as well. Doesn't bother me much anymore...Sorry I can't offer any more help. I think I have also developed an instinct for not driving in that RPM range.

dd74 · 01-23-2007, 06:26 PM

I believe all 2/2 mufflers have some sort of drone. I had a Triad, and it droned. I simply got used to it. The only real way to get around the drone, I believe, is to go to a two-in-one-out muffler.

efhughes3 · efhughes3's Garage

Fabricate a cap for one side. It WILL take the resonance away. I made one for my Fabspeed 2 out on B&B headers, and I've got a drone from 2600-2800 RPM, and it cures it. Two small bolts, and it's off. I did a dyno run with the cap on before running with it off, and it did make the engine suffer by 7 HP.

Conekiller · 01-23-2007, 06:55 PM

my m&k 2 in 2 out drones at the same rpm's as well

84Euro · 84Euro's Garage

Thanks guys, I guess I'm not alone with this problem. I will try the block off method and see what happens. Included in the sale but not installed are two tips that are capped on the ends and have a large slot on the bottom for the exhaust to exit. Anyone have or using these? What are the results?
Thanks

masraum · 01-24-2007, 04:09 AM

Don't spend any time between 1800 and 2300 rpm?!

efhughes3 · efhughes3's Garage

Quote:

Originally posted by 84Euro
Thanks guys, I guess I'm not alone with this problem. I will try the block off method and see what happens. Included in the sale but not installed are two tips that are capped on the ends and have a large slot on the bottom for the exhaust to exit. Anyone have or using these? What are the results?
Thanks

Don't know what those are. I welded two tabs iwith drilled/tapped holes nside the RH pipe, and made a cover to shape that slips in the pipe and sits on the tabs. Two bolts later, I'm capped-no resonance, and a bit quieter. Great for when I take the wife somewhere or on a long drive.

randywebb · 01-24-2007, 10:45 AM

somebody should make these things in a few different diameters...

efhughes3 · efhughes3's Garage

Randy, were you going to include something in your post?

randywebb · 01-24-2007, 11:24 AM

?

not sure what you mean - I can't make them

efhughes3 · efhughes3's Garage

Oh, I thought you were going to suggest another fix, didn't realize you were talking about caps previously discussed. I'm a little slow sometimes.

Jgordon · 01-24-2007, 12:06 PM

Mike,

Glad you got the system on and running. The two blanked off pipes are the "limerock tips" - basically the exhaust flow is blanked off and forced to the ground to meet limerock's strict db limits. I got the system on and had the same issue, the advice I got was to put on the smaller more restrictive tips (which I did) or to blank one side off. Pretty much all 2-outs have the issue. I know some guys have gone even further with the tips - I think I have 2.75 inch outlets on, while some have gone down to 2.5 or 2.25 inches. Jack Olsen had a photo of his setup with two pipes that he had locally made, which brought it from the 3.5 inch (I think) down to 2.25 (I also think).

Post some pics, both so people can see the ride (It's a NAAAIIIICE) and to illustrate the limerock muffler tips. I had actually drawn them out (before I got a digital camera) but the search is broken.

dd74 · 01-24-2007, 12:37 PM

Is it generally true that the larger the outlets are on an exhaust system, the more noise it yields, yet at the same time, if the outlets are larger, it allows better breathing and more top end?

efhughes3 · efhughes3's Garage

That would seem logical to me.

randywebb · 01-24-2007, 02:09 PM

too wide, too long, too short -- all can interfere the wave resonance effects that make modern exhaust systems work well

it's like anti-freeze -- more is not always better (aka: optimization takes place at an interior maximum on the response surface)

aka: "Goldilocks Principle"

84Euro · 84Euro's Garage

Thanks again Jared, got the system installed the day before I left to the airport to go to Daytona( Two days ago). Took it around the block and then to the airport parking lot. I will try the "Lime rock Tips" and post pics and results when I get back.

NY65912 · 01-24-2007, 04:50 PM

After reading this thread I was surprised that the general consensus is that all systems that are 2 in 2 out drone. Not to be a contrarian but I really don't feel that I have any drone with my Monty 2 out being fed with SSIs.

I guess I'll just have to take it out for a "test" drive and listen closely.

Truth be told I'm usually not in that rpm range and I'm enjoying the music of the carbs and exhaust.

randywebb · 01-24-2007, 08:21 PM

mine does & it's SSI's into a Monty 2 in/2 out (3.2L carbed motor)

but it is very small and limited in the rpm range too

Early_S_Man · 01-24-2007, 08:48 PM

Anybody ever try adding a slip-on & clamped extenesion to one side ... say, 2 - 3 inches, to see if that makes the drone go away or changes the characteristics??? If it did alter the drone ... you could try trimming it down, say 0.5" at a time to see where the drone was essentially gone or less bothersome?