Hey All,

I just finished installing a K&N CAI and also have Flowmaster Duel exhaust on my truck. Justing just got me my custom tunes and i installed them also. Since all this I have noticed a large increase in this drone noise. I am not sure whether it is from the exhaust or CAI. I will say WHAT a difference in throttle response with the tunes from VMP!

How do i quiet the drone?

 

Remove one, or both, mods.

The 2010 exhaust and OEM CAI are already superior, and - as you have discovered - DO NOT DRONE.

The OEM exhaust is actually freer flowing than that Fartmaster. And you've impacted yer low-end torque negatively as well. That was a downgrade, bud, and ill-advised.

Sorry. Don't shoot the messenger. I know you will anyway, though

 

I beleive it is the CAI causing it. I dont know if i agree with you on the exhaust being freer than the flowmaster. I am thinking about removing the CAI and putting the stock back on and trying the GOTTS mod to it. See i feel like to low end torque is mush much stonger than before though. So not sure how it could be down graded. I wonder if its something Justin at VMP can compensate for?

 

Compensate for? No.

You need not agree - but the fact is the OEM muffler is not chambered, nor contains any silly little baffles; the Fartmaster is/does.

Yer low-end grunt loss is being partially offset by the custom tuning - so you are net-positive. But you'd have even more with the stock system back in place. Guaranteed. It was DESIGNED to maintain the grunt on the Stock factory PCM calibration.

Again - sorry. Just presenting the facts. Thanks for keeping it holstered, bud

Gotts = a Good idea. Here's why: https://www.f150online.com/forums/20...highlight=2009

Is that a great read, or what?


MGD

 

Exhaust drone & exhaust noise while both are different by definition, both are created as a result of impactors/promoters. Exhaust drone is that which is caused by harmonics- a sound wave generated which in essence takes the exhaust sound and sends it back up the exhaust system (towards the engine) and is released or transferred into the passenger compartment. This transfer typically happens where large contact areas exist that have little to no sound dampening qualities and/or materials- as a result of the muffler construction or vehicle manufacturer. Flowmaster (convention chamber units) have no insulation except for the outer skin of which they are built of- expect drone.


Exhaust Noise (in passenger compartment) is what most people actually complain about. While harmonics do play a contributive role, it is not the primary cause.

Impactors/Promoters

I would love to tell everyone that “x” is the cause 99% of the time for exhaust noise complaints, but it is typically a series or combination of numerous factors which leads or develops the level of noise which is uncomfortable to the ear. The first “rule” of an exhaust system is that the noise should be generated at the point of discharge (i.e. tailpipe tip). Obviously, if the tip terminates at your door or immediately under the passenger compartment, the sound level will be much greater at the exhaust discharge point than if the tip exits the rear of the vehicle, but this is common sense.

Assuming that there are no exhaust system leaks and isolators are correctly installed at all mounting points, what is not acceptable by industry standards, is when an exhaust system has been installed correctly, exiting well past the passenger compartment to have substantial exhaust sound transfer into the passenger compartment at a level which does not allow a person to talk without raising their voice to well above ambient noise levels. Whether you love to hear your engine roar (which I do), stereo blast or have a conversation, this interferes with your ability to enjoy what you like.

Now for the Causes

The first problem is most muffler shop staff today have little to no knowledge of exhaust systems, the “tricks” to installing a system that will “please” the customer, and simply verbally repeat the marketing materials provided to them by the system manufacturer. As previously noted by several others, there are 3 basic muffler designs, Absorption, Diffusion, and Chamber (Resonator), no matter which one suits your ear best, the criteria for promoting unnecessary in-cabin noise is the same.
Impactors:

Exhaust system material thickness should be no less than 16 gauge- double-walled pipe was commonly available through the 1970’s until manufacturers began seeking ways to reduce costs. Many of the “Muffler Chains” who marketed lifetime warranties always used double-walled pipe before “stainless steel” became the “in-crowd”. If a shop had it available, I would choose double-walled aluminized coated steel or 14 gauge stainless steel (depending on environmental conditions or personal tastes) - it is very quiet, solid and in terms of costs, pipe is pretty cheap, depending on length, 16 gauge aluminum coated runs about $11 to $20 wholesale (depending on diameter), stainless about double for the same gauge.

The muffler should be located as close to the axle (far away from the passenger compartment) as possible, allowing at least 3” of straight run pipe before a bend occurring (if installed to the forward position of the axle), with the overall length as long as possible. In the oem location, 24" will fit fine, located at the head pipe, 30" will fit fine as well and eliminate almost any possibility of drone in this particular location due to the size, length and insulation qualities (and yes, Allied does make units this long).

With regards to the 5.4/4.6 engines, The head-pipe (the pipe installed in between the exhaust manifold and the muffler) should be no greater in inside diameter the 2 7/8”, at 3” it now becomes a contributor.

Duel Tailpipes should be limited to no greater than 2.25” inside diameter, single tailpipes 3” maximum inside diameter- tips which are larger can certainly be installed but should be limited to 12” in length and have a discharge point past any material that may “catch” a sound wave or exhaust. When you exceed these diameters, it now becomes a contributor.

Tailpipe length in general should be as short as possible, minimal bends, etc, terminating past the axle, 1.5" past the body or bumper. Lengths greater than 4 feet promote “drone” (i.e. harmonics), typically about 3 ½ feet past the muffler.

Pipe diameter reduction should occur before the muffler. While many muffler installers like to use mufflers which reduce pipe diameter or split the exhaust at the point of discharge at the muffler, or install reducers to connect the tailpipes after the muffler induces “noise”.

Ultimately, it is the quality of the material and the installer which 90% of the time leads to a successful installation. I would like to also emphasize that it is not necessary to spend a fortune on a muffler ($100+) or system to have an excellent sounding, performing and long lasting result.

 

MGDfan i appreciate your opinions and thoughts. I was just asking for some thoughts on what may be causing the noise "drone". I am still going to talk to Just to get his thoughts also. I am going to see how much canges with reoving the CAI and doing the GOTTS mod also. I am not sure if Just will need to re-adjust the tunes for that or not.

Thanks for the info

 

Hey.

For certain, IF you choose to remove the K&N, you must get your tunes revised, because the embedded MAF transfer function will need to change from the one specfic to the K&N, back to the OEM MAF TF (Gotts/snorkel removal does not affect same).

The GOOD news is, within the 6-month support period, those revisions to each of your tunes is Free. (After that period expires, it's $59 for changes to 3 tunes). Gotta love that price, eh?

Good luck, bud.


MGD

 

+1..............

 

+2....

 

+3! MGDfan speaketh truth!

 

x4 mgd!

 

+5 yup stock is the way..............