Dreadful drone

[torresmd]

Need some advice about the drone I am experiencing. Several months ago I installed fabspeed headers and Brian's (Rarlyl8) dual out exhaust. I love the sound and noticed a huge improvement in performance but the drone is taking a toll on me. The drone seems to have increased gradually over the last several months. I did PM Brian a while back and he told me I should not be experiencing drone with his exhaust. So not sure what to do at this point. Any advice on the easiest way to trouble shoot this to find out if it is my headers vs. muffler? Maybe I am getting too old. Does anyone else experience drone with their exhaust setup? Anyone else experiencing drone with Brian's exhaust. BTW my drone is from about 2K to 2800rpm.

[930gt-40r]

I cant remember- are Brians mufflers servicable? If so, maybe try repacking them somehow and see if that solves it. It is likely that your 930 incinerated the packing and now your are experiencing drone because the sound is less muffled. Thats my theory- Ive heard a fairly new Rarlyl8 muffler and I didn't hear any resonance- but I guess after turning the muffler cherry red a few times, the packing takes a beating.
What kind of headers?

[911nut]

I wouldn't call it a drone but I have a resonance period at 1500 rpm with my Rarlyl8 muffler that's been present ever since I added my M&K headers. I just try not to run at 1500 rpm

[RarlyL8]

I've never experienced, or had report of, a drone at any rpm. The muffler is straight through with no baffles. If the packing is reduced the sound is louder but same physics apply and no drone. My track mufflers have no sound deadening material at all and do not drone.
There is a "ressonance" in the lower rpm band which is part of the flat 6 experience that I think sounds good as it adds a character that makes these engines easy to recognize by sound.
Is it possible that the drone is coming from the engine bay itself? I have experienced that when using tailpipes that do not stick out past the bumper. The sounds bounces back under the engine. Do your tailpipes face straight out or are they angled towards the ground?

[torresmd]

Thanks for the reply Brian. My tail pipes are angle slightly down but very minimal. The exhaust note is very loud in the cabin from 2-3K. 2.5K is the worst, and am barely able to have a conversation. At 3K is is quite and below 2K also no problem. Cruising on the freeway at 2.5K is painful. Not sure what has changed and why it has become so loud.

[RarlyL8]

Something is wrong. My mufflers are not loud unless on boost and are actually quiet at cruising speeds. Can you remove it and take a look inside?

[torresmd]

I will remove it and take a look. I am about to move and will wait till I get to the new house. If I have time sooner I will do it and get back with you.

[hoyabear]

Could your headers be leaking at the expansion joint?

[drmatera]

so the muffler and headers have been on the car with no drone and now all of a sudden it's droning? or did it happen as soon as you installed the system?

[JohnJL]

Solution: Keep it over 2800 rpm ;-)

[torresmd]

Originally Posted by drmatera

so the muffler and headers have been on the car with no drone and now all of a sudden it's droning? or did it happen as soon as you installed the system?

It has been a gradual increase in drone over several months.

[krasuskyp]

>>>datapoint<<<

I've got Brian's same fantabulous dual out system and aimed at same slightly down angle (tho sans headers) and NO drone

good luck

[torresmd]

I am definately not ruling out the possibility that the drone is coming from the headers. Since no one else seems to have an issue than it most likely is the headers or some other problem.

[drmatera]

seems odd that headers would cause a drone that gradually got worse over time. you think they would drone or not.. but weirder things have happened

[wjfk32]

Greetings! Ihad this same question nmonths ago. MY MECHANIC And I rebuilt our turbo engines/top end,port polished,cams etcetc,.All hoses,bearings rings.all done....We both installed bb muflers,dual 3inch. The only diff. I kept my eoru headers and sc cams. I get lots of thumbs up/sound. My mech has bb headers and sc sport cams. The DRONE Is Unbearable inthe 2000/2500rpm range. He believes its the muffler and is trying totake mine off. Chk with another muffler,thats your ans. hopefully.

[Tug68]

wjfk32 How can you say it is probably the muffler when you both have the same setup except for the headers????? It is probably the headers no???

[Chuck Jones]

I run a set of Europipe...and when I installed some GT3 headers, I started picking up a bit of drone...which has gradually gotten louder as time goes on. Granted, this is on my 996TT and not on the 930...which has Brian's exhaust system on it. I have no drone with Brian's system. I've never heard of a complaint of drone on any of Brian's exhaust systems.

I think the headers are the culprit....becasue it was after the install when the drone started on the 996.

[William930t]

Fabspeed headers so far have a decent reputation did you buy them new? Check for small cracks at the header collector union, though cracks have a more pronounced hissing sound. What are the chances that the drone is actually a vibration caused by loose exhaust hanger bolts or worn motor mounts?

[Chuck Jones]

William: Good point. I had the car on a rack last week and saw a hairline crack about 2 " long at the collector junction....no hissing or indication of coloration that would indicate it was leaking there, but I do need to get it welded.

[torresmd]

What if I replace the muffler with a zork and see if the drone is still present. That is pretty easy to do. If the drone is still present than it must be the headers or a leak or some sort of resonance vibrating into the cabin. Just a thought. I don't have a zork however. Would have to buy one. It seems like an easy place to start rather than bolting up new headers.