Quiet 3" Muffler

[markw]

RMCBRONC how do they fit? Would you post a pic of your setup? I'd like to quiet my NORRA racer a little. 427. Thanks, Mark

 

[rcmbronc]

I will see what I can get for a pic. I have fender well headers and the mufflers are each mounted under the seats on each side outside the frame. Fit great with a couple of 45 elbows after the collector. Then a 90 degree turn down. Would love to run exhaust out back but no room with the four link set up.

 

[markw]

Same setup we have on my Bronco. Exiting before the tires and it's LOUD. I don't know if we can fit out the back 3" but it would reduce the fatigue of 1300 mile race that's already rough.

 

[DirtDonk]

I always loved the way that the original builder of mtfit's red Bronco buggy tucked his exhaust in tight all the way to the back with coil-overs and 4-links at both ends. Very slick indeed.
He cut up a set of Hooker Super Comp headers so they tucked more inward (tight up against the engine and bell housing), crossed over into a single 3" (or was it 3.5?) and ran it down the center, through a single Flowmaster 40 (or maybe a 50, not sure) and then out through a hole in the bumper. Great sound, great clearance.

Not that you can do the same when already running fenderwell headers of course, but felt like mentioning his work.

Paul

 

[rcmbronc]

Mine had the same set up with chambered mufflers and yes loud. These mufflers are much better

 

[B0neCrush3r]

Same problem here. Mine is too loud, not happy with it because it drones on the highway at 2100 rpms. Around town it's fine.

Switched from smaller magnaflow, 2- 2.5" to 3" to larger magnaflow, I believe 24" from bcbroncos.

Ford racing Coyote engine.

How can I get rid of the drone?

 

[rcmbronc]

I am not sure the best way to get rid of drone. Best I can tell is maybe longer tailpipes but not sure. If I wanted quieter still I would probably add a second muffler each side but lack of room for me.

 

[nvrstuk]

Mark, you have drone with the Ultraflows? That's why I recommended/like the Ultraflows....no dang drone! Hmmm, my pipes are run out the back with my 4 link so maybe that helps but I don't see how...

Sorry you're dealing with drone now.... Personally, I hate it. Guys that run Flowmasters seem to drive their rigs for about 10 minutes...maybe less, and aren't on a trip for hundreds of miles. Had a buddy loving his flowmaster around our tiny town, he followed me for a 70 min drive on 40 mph dirt road to a wheeling expedition and said, "You're right, Flowmasters SUCK, I hate the drone"... lol

Can't help ya, ...

 

[bcmbcmbcm]

I have been running Dynomax Super Turbos for years in various car projects. If you look at the cutout it has an s bend to improve flow vs flat walls of stock type mufflers. Granted this will make it louder than oem replacements (such as Walker) but the sound is ‘smoother’ if that makes sense.

Drone sucks.

I have run magnaflows and taken them off because of drone. Sounds great in the driveway but when on it they droned like crazy at 2-3k rpm.

After much trial and error (and expense) I looked at what made a stock 87 Mustang sound so good. I suspect it is the fact that it had headers( factory, though not the best with crimp vends) , a dual exhaust, and SMALL DIAMETER PIPE.

Exhaust and air filter upgrades are the gateway drug for people beginning to mod cars of all types, so the industry tells everyone you need larger pipe. I don’t think this is correct.

A stock 87 Mustang 5.0 has 2.25 diameter pipe front to back. That’s what I have on my EB.

I know this is off topic but unless you are pushing serious (400,500hp +) you may want to consider smaller pipe. Marginal cost is not much for a local exhaust shop to make it, particularly if single.

Again, hard lesson learned for me. On a 1996 road master wagon with 350 LT1, I attempted to get rid of the drone and quiet down a very nice mandrel bent 2.5 exhaust system made by a B Body specialist. I switched mufflers 3 times, eventually ending up with Walker stock type quiet flows. They were not much quieter than super turbos, but sounded much more ‘choked up’

That’s when i realized I should have reduced the pipe size from the get-go.

 

[nvrstuk]

Mark's running a 427... agreed with what you are saying about pipe dia being a major contributor to NOISE tho. 100%

...but a 427 needs at least 2 1/2" dia to move over a third more cubes out the back.

 

[blubuckaroo]

I question the need for full 3' duals, even with your high revving 427.

With 3" pipes, it's going to be loud.

One option is to add an "H" or "X" pipe ahead of the mufflers. It quiets things down considerably, and improves exhaust flow too. It's a win-win.

 

[nvrstuk]

Agreed the crossover really helps quieting things down. Hard to run a crossover with mufflers outside the frame rails... ask me how I know...

 

[Pa PITT]

I didn't have time to read all the responses .. We're heading out to eat with friends.
But I've got to where when I need a New Quite muffler I Just go to the Muffler shop . & He puts me on a new, pull off from a new truck. Kids buy new truck & head to the Muffler shop .

 

[68ford]

I question the need for full 3' duals, even with your high revving 427.

With 3" pipes, it's going to be loud.

One option is to add an "H" or "X" pipe ahead of the mufflers. It quiets things down considerably, and improves exhaust flow too. It's a win-win.

A 427 that turns 6500 moves more than double the air a 302 turning 4500. Large displacement engines also rely more on scavenging do to not having big block size heads. Exhaust becomes extremely importing.
My old 427W went from 525HP to 560HP from simply switching from 1 5/8 headers to 1 3/4 headers while on the Dyno. And that engine had peak HP at 5800.

 

[nvrstuk]

There are several charts for estimates on pipe dia...

68 Ford only mentioned primary header tube dia increasing the power, I didn't see anything about a big increase of power with larger tube size... not sure where that came from??

 

[bronconut73]

Delta 50's are quiet and being Flowmaster they will have a 3" version.

 

[68ford]

There are several charts for estimates on pipe dia...

68 Ford only mentioned primary header tube dia increasing the power, I didn't see anything about a big increase of power with larger tube size... not sure where that came from??

That's because my example was on a Dyno and headers went straight into very large flexible exhaust. The point I was trying to bring accross is the increase volume and flow importance in larger displacement small blocks. Was in response to him questioning the need for dual 3in exhaust when stating he has a "high reving 427"

 

[nvrstuk]

Agreed, that's what I said... Primaries made the HP difference on your post above...

 

[DirtDonk]

Engine Masters engine dyno test between 2.5 inch, 3 inch, and open exhaust.

Engine is a 454 BB Chevy in the 600hp range
10.25:1 cr
Holley 950xp
Cam (obviously!)
2" primary headers

Power numbers:
With full length discrete dual 2.5" Magnaflows:
554tq 601bhp

With full length discrete dual 3" Magnaflows:
569.8tq 614.2bhp

Open headers, no exhaust extensions:
582tq 620hp

Side note:
No changes made to jetting or timing between the three setups.

In the "expected but needed to be commented on" category:
2.5 was notably quieter even through the dyno room walls.
The higher the rpm, the more the HP spread.

In the "that's interesting for most of us" category:
The 2.5 made more torque below 3200 rpm than either open or 3" exhaust.

The "in case anyone cares" category:;D
The full exhaust added 72lbs (2.5") and 82lbs (3")

So now 'ya know...

Paul

 

[nvrstuk]

Yup...big cubes=big air in = big air needs out.