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Hey all, I am about at the end of my rope with my 94 F150. After she sat for a few years I had to replace the entire exhaust among other things (see list below). My issue is that I have now been through 6 different exhaust combos and I still have a drone between 1300 and 1500 RPM under load. It is killing me. I just got muffler #6 put on today and she sounds nearly stock quiet except for the drone at 1300-1500. Has anyone else fought this battle and won? I have owned this truck since 2000 and until I did the heads, cam and long tubes, I did not have this issue. I am starting to wonder if its a combination of the long tubes and pipe diameter and harmonics of the 5.0. Any and all help would be appreciated!
1994 F150
302
3 bar gt40 heads ported
trickflow springs
35-349-8 cam
Flowtech long tube headers
Custom y pipe 2.5" to 3"
3" Magnaflow cat
3" to dual 2.5" stainless muffler (not sure of brand. put on by Lou's custom exhaust)
2.5" tail pipes exiting at 90* behind rear tires.
I have tried summits house brand mufflers ( sound like 40 series Flowmaster)
4 Different Magnaflow mufflers ( 13288, 12288, 12388, 14288)
wow! Hard to believe you have drone with cat on and muffler, the 12388 would have been the quietest(longer equals quite), I know you have long tubes, but if there's any way you can get a H-pipe put in front of the Y, it would kill a more of the drone, or add a glasspac in front of muffler, and lastly, I've seen resonators on tail pipes help, some also.
It is beyond frustrating and disheartening. I do not have room for an H pipe due to the position of the headers and the design of the Y pipe. It is almost like a really bad joke someone is playing on me. No matter what I do the entire truck resonates around 1400 RPM which happens to be cruising RPM around 30 and 45 mph which is 95% of the roads I drive on.
Originally Posted by torq'ta 5 8
wow! Hard to believe you have drone with cat on and muffler, the 12388 would have been the quietest(longer equals quite), I know you have long tubes, but if there's any way you can get a H-pipe put in front of the Y, it would kill a more of the drone, or add a glasspac in front of muffler, and lastly, I've seen resonators on tail pipes help, some also.
Drone is generated with sympathetic pipe diameters and lengths. If you had asked me I would have suggested not using any 3" diameter pipe with a 5.0 exhaust but since you got it now the next best thing to do is change the location of the mufflers. This won't necessarily remove the drone but will move it to a different rpm range where the engine doesn't spend as much of it's time. So I'd suggest moving them forward in the system as much as you can instead of the stock location by the rear axle.
Drone is generated with sympathetic pipe diameters and lengths. If you had asked me I would have suggested not using any 3" diameter pipe with a 5.0 exhaust but since you got it now the next best thing to do is change the location of the mufflers. This won't necessarily remove the drone but will move it to a different rpm range where the engine doesn't spend as much of it's time. So I'd suggest moving them forward in the system as much as you can instead of the stock location by the rear axle.
Conanski, what would you recommend for a good header back 5.0 exhaust?
I saw a guy on Youtube kill his exhaust drone with a Helmholtz resonator. Basically just a bit of exhaust pipe branching off at 90°, capped on the end.
GroundRat,
What I'll share I can't vouch for, I'm only trying to offer another possible and economical option to consider. Also, Conanski and or SUBFORD may comment on what I'll share, and you might ask a reputable local exhaust expert in your area.
Maybe enlarged exhaust tips might reduce the drone noise at your usual driving MPH range. I have enlarged (stainless) exhaust tips exiting behind the rear tires on my 95 F-150 Regular Cab, SWB, 5.0L with 2 1/2" exhaust pipe and Magnaflow 40s Mufflers. The exhaust tips have to be around ~ 2 3/4" / 2 7/7", if not 3", bell shape and are welded to each side exhaust tail pipe.
In my case, I get a muffled drone at precisely 67 MPH, but I love the sound, reminds me of my earlier years running heavy equipment. Sorry, I'm at work and don't have a better picture of the exhaust tips.
Don and Fe's 1995 Ford F-150s Eddie Bauer and Stock SVT Lightning.
After doing more reading than I really wanted to, I am going to try a 1/4 wave resonator. I just need to find the best location for it. I may wind up dropping down to 2.5" all the way back as Conanski recommends. Its so hard to believe that less than 18" of 3" pipe would cause this specific rpm drone. Also, EQCMCAT, gorgeous trucks!
My first thought that hot rodding isn't meant to be quiet. Once stock form is deviated from noise changes. From my experience any aftermarket exhaust that isn't stock or basically a stock replacement will drone or have interior noise in some way or another. Larger pipe and larger tips will usually increase interior resonance.
Walker has a muffler called Quiet Flow if I remember right, but that probably won't compliment your build very well.
The most mellow but decent performing muffler I can suggest is a Dynomax Super Turbo.
I've seen those J pipe or resonator pipes mentioned for years but never seen the results of using one first hand. It seems interesting.
I would not think that a short section of 3 inch pipe would be the factor.
I have 3 inch pipe with a single cat on my truck and it does have a small amount of interior noise but it doesn't bother me. I had interior noise on one of my old trucks with 2.5 inch pipe as well. Virtually no difference that I noticed.
Having pipes exit out the back corners works best in my opinion. I think the 2.25 inch tail pipes may work better than 2.5, unless the build needs 2.5 dual pipes. I have noticed this on Mustangs with both sizes. The 2.5 tail pipes always increase drone on them. I have 2.25 with larger tips.
Its so hard to believe that less than 18" of 3" pipe would cause this specific rpm drone.
It's not just about the 3" pipe it's about the total length of the exhaust. If there is no tailpipe section just a turndown after the muffler the resonant frequency of the system is higher, or if the muffler is moved forward it breaks up the pipe sections into shorter pieces which also raises the resonant frequency which equates to the engine RPM where the exhaust is loudest.
Moving the muffler farther forward may have some affect on the resonance due to breaking up the lengths into sections, but I have noticed that it seems the muffler placement matters for interior noise. The farther back it is the quieter inside seems to be. It seems when you are sitting on top of the muffler in a reg cab short bed with the same setup interior noise (not drone) is more noticeable.
Groundrat,
Thank you for the complement, you made my afternoon. Know if my Dad was still alive, he would give me heck (ribbing me) about the 95 F-150s. He used to refer to my 1979 F-100 as a "glorified contractor's wheel barrow". As my profile shows where I'm located at, Borla has a manufacturing plant here. Anyway, when I was getting ready to replace the dual exhaust on my 77 F-150, 400 cuin (6.6L) I called and asked if I could purchase two of there mufflers to install on my 77 F-150, they would not sell me any of there mufflers. I was wanting to get a sound similar to the mustangs.
I am also dealing with nearly unbearable drone on my 351w,non-overdrive. Long tube headers, 2.5" true duals straight out the back, no cats or crossover, but has a dual in/out flowmaster 44. Fine at idle, anything about 2k rpm, I can't hear the radio.
I battled drone on my '89 for the longest time with many different exhaust iterations. Shorty headers, 2.5" dual to a 3" Y to a Flowmaster 50 with a full over-axle and out the side tailpipe. Then with a 3" dual with 2 flowmaster 40 copies. Tried all kinds of tips, tried moving the mufflers upstream, down stream, etc. Tried replacing the mufflers with the longest "turbo" style mufflers I could find. Tried glasspacks. Finally decided to try a Magnaflow Tru-X muffler. More expensive than any other thing I tried, but problem solved. The muffler is a "straight through" design, but with a built in X-pipe. Could not be happier with the sound of the exhaust, and the lack of drone.
