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I’m looking for advice on exhaust options. I’ve got a freshly built 460 in my 79 F250. Currently running 2.5” off of short/mid headers into a single 3.5”. I’m running the biggest oval Magnaflow I could find and it sounds great for normal driving but drives me crazy when towing (2500-3000 RPMs). It’s not a drone it’s just loud when I put the 460 under a load. What would you suggest to quiet it down? I have plenty of room to add another muffler in series or would a resonator help? Thanks.
I was having the same issue running a 3.0 in / 2.5 dual out Flow master which was on my '07 when bought, not huge loud, but annoying at steady highway on the up hill grades. I put a 28" long Cherry bomb with 3" core ahead of the other muffler, it helped a lot.
In 2015 I ripped it all out up to the Y and put a 100% stainless system on, same layout though, muffler was just like a FM, it was loud and dronish. I bought and installed another 28" long, 3" core, stainless steel, $70 Cherry bomb in front of it too, it again helped. It still droned though quieter. What absolutely killed the drone was 10-15 pounds of a steel weight clamped to the 3" pipe between the Y and the muffler.
Looking from front back towards the rear, 3" OD pipe with clamped on weights, SS Cherry bomb, the louder small FM chambered muffler.
I made my weight using some exhaust pipe weights from an old Crown Vic., Ford used to bolt then on at the junction of H pipe to the exhaust system after the cats. I had bought the system off a wrecked CV to convert our Mercury to factory duals, weights were laying in a box, Merc already had two.
Thank tbear. I was wondering if a glass pack might help but not sure.
I do have a 2.5” flow master sitting on the shelf but I’m torn on if the smaller inlet muffler would be a good idea or not. Maybe worth a try since I have it. I’d most likely put it after the magnaflow.
Just to be clear, do you mean that you have the two headers feeding into a Y using 2.5" pipes, then are running all that through a single 3.5" pipe to out back and that it has tjhe muffler, I guess it is a 3.5" muffler?
You've got two high velocity sets of exhaust feeding into a single long echo chamber.. Area of 2.5" circle = 4.90 Squ". Two of them are 9.80 Squ" Area of a 3.5" circle is 9.62 Squ". So size is OK, as exhaust gasses are cooling and shrinking. I'm like you, a single 2.5" in the long one would slow gasses, ... a 3" would maybe be better... not sure you can get one in 3.5"
I know it is gonna seam weird, but before cutting pipe, try just adding some weight clamped to the pipe about half way back. Two 3.5" U-bolts, some "scrap" steel .... as a test. Cheap enough & easy to do.Something, ... like an old brake drum even. If it works, then work on a prettier version.
Sometime, if there's room, just moving the muffler forward or back a few inches will eliminate drone. It changes the timing of the exhaust pulses going into the mufflers and it smooths the flow through them. I had a custom dual exhaust done on my Crown Vic with cheap cambered SS mufflers. It had horrible drone right around 40mph and a weird metallic vibration sound at higher speeds, but I chalked it up to buying cheap mufflers. Turns out, the guy mounted the mufflers about 4" forward, and lower than stock. I got them hung up a couple times, so I cut the mufflers out and moved them back and up into the stock location and the drone went away, along with the weird metallic sound. Also, moving the muffler forward or back drastically, like going from behind the axle up to the y pipe will change the whole tone of the muffler. Generally, the closer to the engine the more snappy it'll sound and the further back will give a more deep mellow tone
Just to be clear, do you mean that you have the two headers feeding into a Y using 2.5" pipes, then are running all that through a single 3.5" pipe to out back and that it has tjhe muffler, I guess it is a 3.5" muffler?
You've got two high velocity sets of exhaust feeding into a single long echo chamber.. Area of 2.5" circle = 4.90 Squ". Two of them are 9.80 Squ" Area of a 3.5" circle is 9.62 Squ". So size is OK, as exhaust gasses are cooling and shrinking. I'm like you, a single 2.5" in the long one would slow gasses, ... a 3" would maybe be better... not sure you can get one in 3.5"
I know it is gonna seam weird, but before cutting pipe, try just adding some weight clamped to the pipe about half way back. Two 3.5" U-bolts, some "scrap" steel .... as a test. Cheap enough & easy to do.Something, ... like an old brake drum even. If it works, then work on a prettier version.
Yes I have headers that feed into 2.5 pipes then they are combined with a y pipe just behind the engine. From there it’s a 3.5” (I think but I guess it could be just 3”) all the way out the back. My big magnaflow is about halfway between the y and the rear axle. I could move it back several feet but I thought maybe adding something else in series might work. I also contemplated getting a bigger muffler like off of a newer stock truck and trying that.
If I were you, I would try installing a bigger, longer stock style muffler as you have already suggested.
I've used a few different stainless magna flow mufflers on different applications over the years and they are loud. I've also experienced drone from their mufflers so I would be reluctant to used their products again.
My 460 powered F350 has a scabby looking dual exhaust cobbled together with two glass packs for mufflers. Surprisingly enough it actually sounds really good and is very quiet but the tail pipes have rotted off.
I plan on re-doing my exhaust this spring and after trying to find someone who can custom bend a new system for a reasonable price (the one guy I found quoted me $1500 ouch..... ) I have decided to just buy a bunch of mandrel bends and fabricate my own system. I'm a decent welder and have a mig so why not. As for mufflers, I'm gonna just go with glass packs again. They sound good, are reasonably quiet, and will more easily fit in that limited space along the the right side frame rail.
After watching some videos I ordered a 25” (overall length) glass pack for $40 on Amazon. I’m going to put it where my Magnaflow is now and then mount the magnaflow further back. The vids I watched where others did this type of setup and it still had a good idle but knocked the overall sound down a lot when under load. I’ll let you know how it works for me.
So I added the 25” glass pack directly behind the Magnaflow. Had to cobble together something that would work with what I had. I originally had a 4” tailpipe section from just in front of the rear axle to the end of the tailpipe. After some experimenting I figured out that 6 or so feet of 4” pipe was making everything louder. It was louder with the full tailpipe then just having it dumped right after the glass pack. So long story short is I made up a quick over axle dump. I think I can easily build a few more feet and get it out from under the truck but I need some more 3” bends. Did a quick drive and it is quieter on the throttle but idle and cruise sound much the same as before. I may do some more experiments and try putting the muffler after the glass pack but I just ran out of time for now. I need to hook up the trailer to get a real test because that’s the only time the old setup bothered me.
I know you have ordered parts already, so this is just for future reference if you need another option. I hated my Magnaflow system for the reasons a few other people mentioned above. The raspiness when passing through certain engine speeds was horribly annoying and the overall tone to the exhaust note was not pleasing in my opinion. I added an SLP resonator and it cleaned up just about all of my complaints.
Follow up: I ended up adding the 24” glass pack after my muffler and it’s definitely helping a lot. I didn’t get to tow with it until recently but I can confirm the effectiveness. The truck still sounds good but the addition of the glass pack knocked down the overall noise especially under load or high rpm’s. Idle still sound much the same if not a little deeper. I’m happy at this point and would recommend this to anyone that wants some noise reduction but still maintain the deep tone.
I originally had a 4” tailpipe section from just in front of the rear axle to the end of the tailpipe. After some experimenting I figured out that 6 or so feet of 4” pipe was making everything louder. It was louder with the full tailpipe then just having it dumped right after the glass pack.
Oh, so you once had 4" diameter open pie out back? ... be like a huge echo chamber. No wonder it droned.
Glad you found relief though.
Did you ever try weight just strapped on? ... it don't have to be fancy or pretty to test it.
Oh, so you once had 4" diameter open pie out back? ... be like a huge echo chamber. No wonder it droned.
Glad you found relief though.
Did you ever try weight just strapped on? ... it don't have to be fancy or pretty to test it.
I haven’t tried the weight trick yet. And yes that 6 ft section of 4” pipe was a big part of the problem for sure. I’m currently running it dumped over the rear axle and happy so I’ll probably leave it alone for now.
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