Big Honk'in Muffler (AKA: BHM)
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From: Buies Creek, NC
Big Honk'in Muffler (AKA: BHM)
When I recently Bombed my heap, I planned to include means of keeping things quiet. I didn't want any low rumble at all. A sleeper's sound if you will. 
With the hot-rod turbo, manifold, injectors, 4" pipes, etc, I didn't want to restrict things.
So I did a little homework:
With the above, we're moving right at 1332 CFM through the exhaust system at 3000rpm.
In a perfect world, we'd be able to move all that through the plumbing with no restriction. The closest to that is the straight-pipe system.
As far as noise control goes, (note, I have no first hand experience with any of the brand-name systems), straight-through/glass-pack type mufflers (resonators) attenuate high frequency noise. They let the low rumble through. The baffled type mufflers attenuate the low frequency noise. While they do mute the high frequencies some, they also tend to contribute some with the baffles (it's weird science, do a Google). That's why you see both devices on the really quiet vehicles.
OK.
I've found that (outside of the brand-name packaged deals), many kits offer something like this; Muffler 4" In/Out 8.5" Diameter X 34" Body Length (Link).
Note: The rated flow shown, Low, Medium, and High, is at a given back-pressure (resistance to flow). That back-pressure is presented in Inches of Mercury (In Hg). 1 In HG = 0.4911541 psi, or just shy of 1/2 pound pressure.
In the Donaldson product line, that muffler is one of the highest flowing in a four inch pipe system. But it's also one of the loudest at only 8 to 12 db attenuation.
OK
Using the Attribute Search (Link) feature of the Donaldson website, I found one muffler to be the quietest while still maintaining a high flow with the least back-pressure.
This one: M110189 (Link). I call it the BHM (Big Honk'in Muffler)
The specs are:
As you can see, it flows the required volume with under 1 pound pack-pressure. AND, it attenuates the low frequency noise 19 to 25 db. A BIG drop in noise.
Now, it IS a Big Honk'in Muffler!
With a gross length of 45.5", and a diameter of just under 12", it's gonna be a close fit under my 1st gen (250 CC long-bed / Your mileage may vary). It's also a Round, Style 2 muffler, meaning it's inlet and outlet are not centered. With that, you'll most likely have to move your pipes a bit to get them to plug in.
Anyhoot, after installing THIS (Link) exhaust pipe kit, I installed that boy. I'm using resilient rubber mounts that I attach to the stove-pipe with regular U-bolt/clevice clamps. The stove pipe's connected with the band clamp deals.:
There's another mount right behind the muffler. Some custom cut 90's allow tight turns to get over the axle:
You can see the rear mount here:
There's just enough room to clear a full sized spare, and dump three inches behind the tire:
There's about an inch clearance between the top of the muffler and the bed frame rails. The bottom of the muffler sits higher than the transfer cases frame.
The system is VERY quiet at the exhaust outlet save subtle high frequency turbo sounds (see above homework) be it idle or WOT. The strongly predominant sound from the truck originates under the hood. In the cab, all you heard is the engine up front.
. . . . . . . NICE!
With the hot-rod turbo, manifold, injectors, 4" pipes, etc, I didn't want to restrict things.
So I did a little homework:
Originally Posted by BC847
Code:
CFM = Engine Displ (cu in) x Full Load RPM x Eff x (Exh Temp F + 460)
C x 941760
CFM = exhaust flow rate in cubic feet per minute
Efficiency = .85 for naturally aspirated engines
Efficiency = 1.4 for turbo-charged engines
Efficiency = 1.2 for engines with scavenging blower
C = 1 for two-cycle engine C = 2 for four-cycle engine
If exhaust temperature is not available, use:
T = 1200F for gasoline engine
T = 900F for diesel engine
In a perfect world, we'd be able to move all that through the plumbing with no restriction. The closest to that is the straight-pipe system.
As far as noise control goes, (note, I have no first hand experience with any of the brand-name systems), straight-through/glass-pack type mufflers (resonators) attenuate high frequency noise. They let the low rumble through. The baffled type mufflers attenuate the low frequency noise. While they do mute the high frequencies some, they also tend to contribute some with the baffles (it's weird science, do a Google). That's why you see both devices on the really quiet vehicles.
OK.
I've found that (outside of the brand-name packaged deals), many kits offer something like this; Muffler 4" In/Out 8.5" Diameter X 34" Body Length (Link).
Code:
Rated Flow LR (CFM): 1800 Rated Flow MR (CFM): 2546 Rated Flow HR (CFM): 3119 Back Press LR (In Hg): 1 Back Press MR (In Hg): 2 Back Press HR (In Hg): 3 Attenuation (dBA): 8-12
In the Donaldson product line, that muffler is one of the highest flowing in a four inch pipe system. But it's also one of the loudest at only 8 to 12 db attenuation.
OK
Using the Attribute Search (Link) feature of the Donaldson website, I found one muffler to be the quietest while still maintaining a high flow with the least back-pressure.
This one: M110189 (Link). I call it the BHM (Big Honk'in Muffler)
The specs are:
Code:
A - Inlet Diameter (Inches): 4 B - Body Diameter (Inches): 11 D - Overall Length (Inches): 41.25 E - Outlet Diameter (Inches): 4 Rated Flow LR (CFM): 1050 Rated Flow MR (CFM): 1485 Rated Flow HR (CFM): 1819 Back Press LR (In Hg): 1 Back Press MR (In Hg): 2 Back Press HR (In Hg): 3 Attenuation (dBA): 19-25 Product Type Description: Muffler, Round, Style 2 Primary Application: FORD MEDIUM DUTY TRUCK Gross Weight in Pounds 35.5 Gross Length in Inches 45.5 Gross Width in Inches 11.8 Gross Height in Inches 11.8 Country of Origin US
Now, it IS a Big Honk'in Muffler!
With a gross length of 45.5", and a diameter of just under 12", it's gonna be a close fit under my 1st gen (250 CC long-bed / Your mileage may vary). It's also a Round, Style 2 muffler, meaning it's inlet and outlet are not centered. With that, you'll most likely have to move your pipes a bit to get them to plug in.
Anyhoot, after installing THIS (Link) exhaust pipe kit, I installed that boy. I'm using resilient rubber mounts that I attach to the stove-pipe with regular U-bolt/clevice clamps. The stove pipe's connected with the band clamp deals.:
There's another mount right behind the muffler. Some custom cut 90's allow tight turns to get over the axle:
You can see the rear mount here:
There's just enough room to clear a full sized spare, and dump three inches behind the tire:
There's about an inch clearance between the top of the muffler and the bed frame rails. The bottom of the muffler sits higher than the transfer cases frame.
The system is VERY quiet at the exhaust outlet save subtle high frequency turbo sounds (see above homework) be it idle or WOT. The strongly predominant sound from the truck originates under the hood. In the cab, all you heard is the engine up front.
. . . . . . . NICE!
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Joined: Sep 2004
Posts: 4,053
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From: Tijeras, New Mexico, 7,000ft up
I love my SEMI sound! It's quiet enough if I keep my foot out of it. I would rather hear the sweet exhaust sound than the rattle of the valve train (makes me worry that I need to run the valves again, and I hate adjusting those things!).
I would like to hear more turbo whistle though.... that part would be cool.....
If I lived in town, and or needed to sneak home a lot, that setup would be nice. I guess I could do a cutout!
I would like to hear more turbo whistle though.... that part would be cool.....
If I lived in town, and or needed to sneak home a lot, that setup would be nice. I guess I could do a cutout!
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Joined: Jan 2005
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From: Buies Creek, NC
I can't recall exactly what I paid for the BHM, suffice it to say it was about $125. 
LOL! That diff cover is a girdle support type (has shoes that provide additional support to the carrier bearing caps). Perhaps a bit of over-kill in this application though I have broken a couple of teeth off the pinion gear once. See ~ http://www.ringpinion.biz/product_in...03ec6ed638c949
. . . . . . . and it looks cool.
And costs much less than what many are paying for the name brand stuff I've seen. I went ahead and filled it with synthetic oil. 
LOL! That diff cover is a girdle support type (has shoes that provide additional support to the carrier bearing caps). Perhaps a bit of over-kill in this application though I have broken a couple of teeth off the pinion gear once. See ~ http://www.ringpinion.biz/product_in...03ec6ed638c949
. . . . . . . and it looks cool.
And costs much less than what many are paying for the name brand stuff I've seen. I went ahead and filled it with synthetic oil.
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Joined: Apr 2005
Posts: 3,253
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From: Terre Haute,IN
In the $300 4" exhaust kit from www.bigexhaust.com you get basically the same 4" muffler, thats what I have.
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Joined: Oct 2005
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From: Ontario, Canada
Originally Posted by BC847
I can't recall exactly what I paid for the BHM, suffice it to say it was about $125.
LOL! That diff cover is a girdle support type (has shoes that provide additional support to the carrier bearing caps). Perhaps a bit of over-kill in this application though I have broken a couple of teeth off the pinion gear once. See ~ http://www.ringpinion.biz/product_in...03ec6ed638c949
. . . . . . . and it looks cool. And costs much less than what many are paying for the name brand stuff I've seen. I went ahead and filled it with synthetic oil.
LOL! That diff cover is a girdle support type (has shoes that provide additional support to the carrier bearing caps). Perhaps a bit of over-kill in this application though I have broken a couple of teeth off the pinion gear once. See ~ http://www.ringpinion.biz/product_in...03ec6ed638c949
. . . . . . . and it looks cool.
And costs much less than what many are paying for the name brand stuff I've seen. I went ahead and filled it with synthetic oil.
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Joined: Jan 2005
Posts: 4,601
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From: Buies Creek, NC
Originally Posted by bgilbert
In the $300 4" exhaust kit from www.bigexhaust.com you get basically the same 4" muffler, thats what I have.
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From: Terre Haute,IN
Originally Posted by BC847
Who's, and which kit?
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Joined: Mar 2006
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From: WY
Originally Posted by chrisjon76
Any idea if your BHM would install in a single cab 4X4 W250?
Grate artical....you'r allwas thinking
nice specs to paint the pitcher better!.......very cool
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From: Buies Creek, NC
Originally Posted by chrisjon76
Any idea if your BHM would install in a single cab 4X4 W250?
I don't know why it wouldn't fit under a standard cab as is pointed out above, the muffler's under the bed.
NOTE ~ As you can see in this image, the inlet falls right where the intermediate pipe can shoot straight into it.
BUT, being a type 2 muffler*, the outlet falls a little over toward the drive shaft side of things. That means you'll have to twist a couple of cut 90* ells to get over the axle and out.
* (meaning the in/out pipes are offset to one side with each at possible different locations according to a clock: RE In at 10:00 and out at 7:00 looking head on).
As this is not a kit perse, one will need a little imagination as to where things will go so as to make it fit. Hope this helps.
BC
