Big Block muffler choice

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clementine

clementine

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Hey Fellas,
1967 Barracuda 383 4 speed. Dunno if it matters but its a flat tappet .250/[email protected] think. Anywho, this thing has somethin to say and I wanna quiet it down. its a 3" exhaust. The 14" summit mufflers (turbo?) aren't doing the job. My question to you is....

1. Whats the longest muffler you have run? 20"?

2. Did you choose a 'straight through' or chambered design.

3. I am looking at the dynomax 17233 ultra flo and the half the cost walkers quiet flow.

4. Does running a cat help the situation?

I dont want to kill the power, but rattling the neighbors windows every time I go out isnt cool by me.
 
Spend the money and go Borla - sounds really nice and controlled at idle, but at wide open throttle it’s a screamer.
Being a straight through design, there is virtually no power loss.

You could go Magnaflow too, but personally I like the Borla sound better (I’ve had both)

Chambered and “turbo” mufflers eat a ton of power
 
If I remember correct I’m running Dynomax ultra flow 17233. Before I put tail pipes on, it would shake everything around. I’m running 3” with x pipe all the way out on my big block Demon. Fairly docile at idle, but when you squeeze the skinny pedal it opens up. I will say interior noise isn’t exactly quiet even with sound deadening, but very tolerable to me. The tail pipes made a ton of difference.
 
I have used hooker aeros, long magnaflow straight thru, and giant flowmasters. The FM I'm using won't fit under an a-body, but I really like their sound the best (3 chamber, 5x12, 28"oal, 22 case. ) The aeros being a chambered muffler sound similar.
My theory for a quiet efficient exhaust is: get the right size pipe for the engine, and as big and long a case that will fit under the car.
In your place I would try dynomax or magnaflow straight thru, with the longest case that will fit.
 
I have Dynomax Super Turbos on my built 73 Sport 340. Sound at idle is nice and it sings on throttle, but the interior drone is terrible.
 
If you want it quiet and efficient. Straight-thru ovals. If you have room, run 2 on each side. My e-body ragtop is dead quiet, till it's eating. It doesn't hurt performance. I run magnafow stuff. It's well made and thought-out. If room is an issue, 3" bullets will work as resonators. I've done this stuff on many cars. I like quiet.

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My silver car has bullets at the axle kick-up, and mufflers at the bumper. Again, really quiet.

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18” resonators after the mufflers on each pipe. You can use small, straight through mufflers as resonators if you like. Then get some resonated tips.

This is exactly why I am running 2.5” duals on the 383 Swinger. I don’t want obnoxious, and I don’t want drone. The smaller pipe will make less noise, and less power depending on your combo. The small power loss from the 2.5” pipe and the extra mufflers will be worth the final exhaust tone. IMO, of course.

Jared
 
Im thinking I can get away with a 20" muffler, thats the body length. It would be like 25" including the in/out. Im looking now at the magnaflow and the dynomax. I have been using the V bands so no biggie on the disassembly/reassembly although Ill have to snip/weld for the longer body. If its still too loud Ill think about bullets. Space is an issue, but I flat bottomed the trunk and am running the shortened efi 68-70 tank so I have some room to play with. I was thinking that getting something that was 3"in and 2.5" out would be good but I already have the 3" pipe all the way back so since I feel like being fiscally responsible Ill use what I got.

If you care to weigh in, please post what length muffler body you are running. Most will be 14" on these floor pans Im guessing, but Im interested to know is anyone up in the 20" length? If so, how far forward of the axle is the body of the muffler? Or, is the body of the muffler under that low spot of the floor pan? (the low spot would be where the person in the back seat puts their feet.)

Thanks Fellas and Fellies if either of the ladies are reading. :poke::D:poke:
 
If you’ve already got the 3” pipe, then I would reduce to 2.5 after the mufflers. Or even after the resonators if you plan to run them.

The 3” pipe also explains the loudness, it’s quite a dramatic difference between the two. I also don’t think there will be much of a power loss when reducing to 2.5 after the mufflers if you consider the velocity of the exhaust charge as it cools in the pipes.
 
My FM's barely fit under my b-body, with a 22"case (thick and fat) but the 3" magnaflows are much thinner, smaller and lighter. I think they are 20"case (I'm a couple hundred miles away), and I can't tell if they would work on an a-body. Mine are hooked to fenderwell headers and run next to the rockers. Pic is the 3"magnafloww, and 3 1/2 aeros.

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Just curious if anyone has tried a single 3" instead of dual 2.5? I don't need dual 3" I got the idea from watching this... (without the catalytic though)..
 
Icetech said:
Just curious if anyone has tried a single 3" instead of dual 2.5? I don't need dual 3" I got the idea from watching this... (without the catalytic though)..
Click to expand...

That episode definitely made me want to add some electric cut outs to the Swinger. They give up a lot of HP with the full exhaust, I think dual 2.5” pipes would have been less of a loss, but it’s all speculation.

My final thought: if you have over 400 hp in a street car, the 20-50 hp you give up by having a full exhaust won’t be missed.
 
MidnightSwinger said:
That episode definitely made me want to add some electric cut outs to the Swinger. They give up a lot of HP with the full exhaust, I think dual 2.5” pipes would have been less of a loss, but it’s all speculation.

My final thought: if you have over 400 hp in a street car, the 20-50 hp you give up by having a full exhaust won’t be missed.
Click to expand...
i just like the idea of a nice quiet single exhaust.. then open.. had enough of loud cars non stop while driving
 
Excellent replies. Lookin for that magic muffler case (body) number. I'm thinking ill be ok with 20", but id like to verify before buying. I suck at returning stuff.
 
Icetech said:
i just like the idea of a nice quiet single exhaust.. then open.. had enough of loud cars non stop while driving
Click to expand...
Same here! I purposely put dual 2.5”, and will be adding resonators on my 383 swinger for that reason. I like the sound of a well tuned exhaust, not a loud on purpose exhaust. A single 3” sounds great on a V8, and if you have a cutout you don’t have any performance loss when open. Win/Win.
clementine said:
Excellent replies. Lookin for that magic muffler case (body) number. I'm thinking ill be ok with 20", but id like to verify before buying. I suck at returning stuff.
Click to expand...

I had flowmasters on a previous A body, just a hair over 20” with no issues. Wayyy back in the day I had a 30” glass pack on my 67 GT but I do remember that muffler removed itself at 60 mph on a unseen dip in the pavement.
 
There's also those "power sticks" that are basically really long glass packs that you install in place of the straight section of exhaust, ahead of the mufflers
 
I was never a fan of cutouts (most street cars with mild cams sound like ****, uncorked), and I have noticed that engine masters and power nations promoting cutouts have really shitty exhaust systems behind them (on purpose)
I would much rather have a good ,quiet, free-flowing exhaust, all the time, than a cutout, electric or not. Just my opinion.
 
33IMP said:
I was never a fan of cutouts (most street cars with mild cams sound like ****, uncorked), and I have noticed that engine masters and power nations promoting cutouts have really shitty exhaust systems behind them (on purpose)
I would much rather have a good ,quiet, free-flowing exhaust, all the time, than a cutout, electric or not. Just my opinion.
Click to expand...

I have never had cutouts, i just like the idea.. free flowing and quiet don't seem to go together.. i will probably just end up with 2.5 duals out the back
 
Icetech said:
I have never had cutouts, i just like the idea.. free flowing and quiet don't seem to go together.. i will probably just end up with 2.5 duals out the back
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Fair enough. I never tell anyone not to use them, if they want. I guess I'm just not into making noise. I like a mufflered sound better than open, I have raced for a lot of years with mufflers on, always.
As for free flowing. EM , the same people who choked a 700 hp motor to make the cutouts look good, tested four mufflers on a 1000+hp motor, and MADE horsepower with one of them, and the WORST one only cost 15hp.
 
33IMP said:
Fair enough. I never tell anyone not to use them, if they want. I guess I'm just not into making noise. I like a mufflered sound better than open, I have raced for a lot of years with mufflers on, always.
As for free flowing. EM , the same people who choked a 700 hp motor to make the cutouts look good, tested four mufflers on a 1000+hp motor, and MADE horsepower with one of them, and the WORST one only cost 15hp.
Click to expand...
Yeah, i never got the full open headers thing, i like to hear my motor and if any problems are starting.. I watched a buddy run 9's in a C5 with full stock exhaust.. didn't seem to need a lot of noise to do it :)
 
Icetech said:
Yeah, i never got the full open headers thing, i like to hear my motor and if any problems are starting.. I watched a buddy run 9's in a C5 with full stock exhaust.. didn't seem to need a lot of noise to do it :)
Click to expand...
I ran 9's through the hooker aeros in post #11. Plenty quiet for street cruising, probably wouldn't wanna go three hundred miles tho.
 
Id entertain reducing to 2.5" post muffler, but admittedly don't find a lot of 3"in/2.5out. So adding a reducer increases length that could possibly take away from the desired muffler length. Money is dictating using what i have in 3" and make a decision on a 20" muffler. See what she doubles like then adapt.
 
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