I have longtubes and 2.5" exhaust through the mufflers. Wondering if I should expect much change by up-sizing the tailpipes (from 2 to 2.5). My exhaust w/ Flowmasters is a little quieter than I expected. THanks.
DesertCoupe5.O
2.5" is far larger than a smallblock needs. That said, 2.5" exhaust feeding 2" tailpipes is pretty strange. Your problem (if you consider too quiet to be a problem) is the type of muffler you have. A 2" exhaust can be loud or quiet. I knew people back in the day that got noise tickets from running 2" glasspacks.
To answer the question no you will not notice a different in sound with that change. On another note send me a message with your email so I can see some pics of your coupe please
Dropping down a size as you go back isn't that bad actually because the exhaust volume shrinks due to cooling. If you consider how hot it is at the manifold and then at the tail pipe you can stick your hand in it you realize it cools a lot in that short trip. But I have to agree 2.5 to 2 is a pretty drastic change.
It will get louder and a bit "deeper". Not a whole lot, but noticeably. You can accentuate to effect by using three inch diameter tips.
I say this because I went through the EXACT same process doing an upgrade of an exhaust sort of paycheck to paycheck. Older Flowmaster 40's. I did the three inch tips too (not my vintage Mustang but a 302). With each stage it got progressively a bit louder and deeper toned. The tips gave it a...baritone sort of rumble.
I say this because I went through the EXACT same process doing an upgrade of an exhaust sort of paycheck to paycheck. Older Flowmaster 40's. I did the three inch tips too (not my vintage Mustang but a 302). With each stage it got progressively a bit louder and deeper toned. The tips gave it a...baritone sort of rumble.
If you have a drone issue at certain RPMS, it will likely help that quite a bit. I had 2.5" going into my flowmasters and 2.25 out. I increased the tailpipes from 2.25 to 2.5 on my 351 and it got a little louder and deeper on-throttle. At cruise on the freeway it is actually quite a bit quieter - enough so that I am considering a radio of sorts now. I also ran the tips 2" past the bottom of the valence to get the sound out from under the car. Used to terminate just past the valence about 1/2". I fabricated some custom Duals tips out of 2" pipes (dual 2" on each side) about a foot long which added a burble to it on throttle.
The other way to cut down drone is to drop to your output pipe size BEFORE the muffler...
One thing that made a huge difference was the tailpipe mount. I took a cheap autozone tailpipe/muffler universal mount - strip of recycled tire about 6" long x 1.5" wide with holes every inch and a mount rivited to the bottom to clamp to the tailpipe (~$5). Drilled the mount off and bent it in a U. Ran a bolt through one end and a ~2" piece of pipe then through the other end of the rubber, fender washer then through the tie down on the Mustang - another fender washer and nylock bolt. I welded a mount to the tip and bolted it to a convenient hole. Took an amazingly HUGE amount of vibration out of the frame. Before that I had a steel bracket with the classic muffler shop rubber washers on either side...
Good luck,
M
The other way to cut down drone is to drop to your output pipe size BEFORE the muffler...
One thing that made a huge difference was the tailpipe mount. I took a cheap autozone tailpipe/muffler universal mount - strip of recycled tire about 6" long x 1.5" wide with holes every inch and a mount rivited to the bottom to clamp to the tailpipe (~$5). Drilled the mount off and bent it in a U. Ran a bolt through one end and a ~2" piece of pipe then through the other end of the rubber, fender washer then through the tie down on the Mustang - another fender washer and nylock bolt. I welded a mount to the tip and bolted it to a convenient hole. Took an amazingly HUGE amount of vibration out of the frame. Before that I had a steel bracket with the classic muffler shop rubber washers on either side...
Good luck,
M
Yes it will get slightly louder. Been there done that. Years ago I had a muffler shop screw up and put 2" pipes after my mufflers when I had 2 1/2" up front. But it wasn't significantly louder.
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.
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. Up to 30" length unit will fit fine 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” to 2.5" 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 (which is very doubtfull you would see on a mustang).
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.
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. Up to 30" length unit will fit fine 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” to 2.5" 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 (which is very doubtfull you would see on a mustang).
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.
beech - You (or someone else) have written this before and I stumbled across it once in an archive search but was never able to find it when I built my tailpipes. BUT I followed these recommendations to the letter (by memory) and the impact was HUGE. My old tailpipes were designed as the antithesis of this and it was rude inside the cabin. Sill have all the rumble and noise I want but its outside the car. Cheers, M
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