Big Honk'in Muffler (AKA: BHM)
05-30-2007, 12:35 AM
#18
Registered User
Join Date: May 2007
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
Newbie question, does the formula take into account the amount of boost a turbodiesel is running as opposed to a gas engine? With atmospheric at 14.7 psi, a turbodiesel at 30 psi boost would have an efficiency factor of roughly 3, not 1.4. The 1.4 would assume roughly 8 psi over the naturally aspirated efficiency of 0.85. The higher efficiency in the formula would yield a CFM requirement of 2481, which really changes the backpressure ratings of the muffler.
06-01-2007, 10:23 AM
#19
Registered User
Join Date: Jul 2006
Location: 29 Palms, California
Posts: 55
Likes: 0
Received 0 Likes
on
0 Posts
So on the complete opposite end, in both quality and noise control, I put a small 1.33 gallon beer keg on as my new exhuast tip.
I did it just for the humor(and maybe the beer) but it actually improved the sound of my straight pipe, more of a deep rumble now w/ less high frequency noise. Go figure. I'll try to do pics.
I did it just for the humor(and maybe the beer) but it actually improved the sound of my straight pipe, more of a deep rumble now w/ less high frequency noise. Go figure. I'll try to do pics.
06-02-2007, 03:11 PM
#20
1st Generation Admin
Thread Starter
Newbie question, does the formula take into account the amount of boost a turbodiesel is running as opposed to a gas engine? With atmospheric at 14.7 psi, a turbodiesel at 30 psi boost would have an efficiency factor of roughly 3, not 1.4. The 1.4 would assume roughly 8 psi over the naturally aspirated efficiency of 0.85. The higher efficiency in the formula would yield a CFM requirement of 2481, which really changes the backpressure ratings of the muffler.
WELCOME to our forums!
I don't know the answer to that question. I would think the figures used would put one in the ballpark for the sake of comparison. Along the same lines, what figure would be illustrated in the diesel with a scavenger?
Beats me.
IIRC my primary purpose with the equations was to help place all the mufflers one can choose from on a somewhat level playing field. My interest was a quiet, high flowing muffler. With that, the same numbers you suggest would present similar in comparison with the other mufflers using the same equation.
I can't help but agree though, the more air in, the more air out. Anything in the way is gonna run up the restriction.
10-02-2008, 01:24 PM
#21
Registered User
Join Date: May 2004
Location: Golden, Colorado
Posts: 2,867
Likes: 0
Received 0 Likes
on
0 Posts
OK i've decided that I would like a muffler as the drone while pulling a hill at 35mph can get old after a while, so i'd like to get some opinions on mufflers.
Searching the donaldson website i've come across a couple options that should work. I would really like this one:
https://dynamic.donaldson.com/webc/W...tml?item=22723
but it won't fit as it will be too close to my air tanks and frame, so I need one that has the inlet offset so I can get the body of the muffler down and away from the frame.
So I find this one:
https://dynamic.donaldson.com/webc/W...22&item=150816
and it looks like it should flow more than enough, compared to the real BHM, and still provide some noise reduction, about the same as the first one listed here.
Now if the previous one doesn't provide enough flow, I can step up to a 5in inlet/outlet and adapt down to 4in, and get more than enough flow from this one:
https://dynamic.donaldson.com/webc/W...73&kiosk=false
So basically i'm thinking I should get the M101168 unless it won't provide enough flow, then I should get the M120748.
Opinions?
Aaron
Searching the donaldson website i've come across a couple options that should work. I would really like this one:
https://dynamic.donaldson.com/webc/W...tml?item=22723
but it won't fit as it will be too close to my air tanks and frame, so I need one that has the inlet offset so I can get the body of the muffler down and away from the frame.
So I find this one:
https://dynamic.donaldson.com/webc/W...22&item=150816
and it looks like it should flow more than enough, compared to the real BHM, and still provide some noise reduction, about the same as the first one listed here.
Now if the previous one doesn't provide enough flow, I can step up to a 5in inlet/outlet and adapt down to 4in, and get more than enough flow from this one:
https://dynamic.donaldson.com/webc/W...73&kiosk=false
So basically i'm thinking I should get the M101168 unless it won't provide enough flow, then I should get the M120748.
Opinions?
Aaron
10-02-2008, 05:38 PM
#22
1st Generation Admin
Thread Starter
Aaron,
That 1st muffler is the same one that AirFlow offers ~ http://store.airflo.com/m085171.html
While it offers very high flow numbers it doesn't do much for noise control. It's at best a really big glass-pac type straight-thru muffler. It'll take some off the high frequency sound but very little for the low rumble.
The second one is rather restrictive in terms of flow (as compared to a straight-pipe).
The third appears a good selection as it offers reasonably unrestricted flow with much better noise attenuation as compared to the first (the higher the attenuation number (in db), the quieter.
M/N xxx171 = Attenuation (dBA): 8 ~ 12.
M/N xxx748 = Attenuation (dBA): 12 ~ 18.
The 748 (3rd choice) will be a little more than half as loud with low rumble, and about 1/4 as loud in the high whine, as compared to the 171 (1st choice).
Hope this helps.
That 1st muffler is the same one that AirFlow offers ~ http://store.airflo.com/m085171.html
While it offers very high flow numbers it doesn't do much for noise control. It's at best a really big glass-pac type straight-thru muffler. It'll take some off the high frequency sound but very little for the low rumble.
The second one is rather restrictive in terms of flow (as compared to a straight-pipe).
The third appears a good selection as it offers reasonably unrestricted flow with much better noise attenuation as compared to the first (the higher the attenuation number (in db), the quieter.
M/N xxx171 = Attenuation (dBA): 8 ~ 12.
M/N xxx748 = Attenuation (dBA): 12 ~ 18.
The 748 (3rd choice) will be a little more than half as loud with low rumble, and about 1/4 as loud in the high whine, as compared to the 171 (1st choice).
Hope this helps.
10-03-2008, 07:36 AM
#24
Registered User
Join Date: Sep 2007
Location: new bedford,ma
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
10-03-2008, 07:44 AM
#25
Registered User
Join Date: May 2004
Location: Golden, Colorado
Posts: 2,867
Likes: 0
Received 0 Likes
on
0 Posts
Yes justin, please let us know how that 171 works out for you.
Fireman, I did come across the resonators on the donaldson site, but they don't have any specs as far as flow and noise deadening. But it looks like they are straight through so they should flow plenty.
The only problem with them is the body diameter is so large that it won't fit. The body will hit my frame.
BC, I agree with you that the 748 looks to be the better choice for flow, its just too bad that they don't have one in a 4in that flows the same. I'll have to check on prices.
Just FYI, my local donaldson distributor quoted me ~$80 for the 171.
Aaron
Fireman, I did come across the resonators on the donaldson site, but they don't have any specs as far as flow and noise deadening. But it looks like they are straight through so they should flow plenty.
The only problem with them is the body diameter is so large that it won't fit. The body will hit my frame.
BC, I agree with you that the 748 looks to be the better choice for flow, its just too bad that they don't have one in a 4in that flows the same. I'll have to check on prices.
Just FYI, my local donaldson distributor quoted me ~$80 for the 171.
Aaron
10-03-2008, 08:05 AM
#26
Registered User
Idle volume is overall down, thou near the tailpipe you can hear high freq turbo whine... and the exhaust brake is MUCH louder (especially when its on at 1100rpms for warm-up).... The tone when driving is a little higher than cat only, but quieter... I haven't towed with it yet, but so far I am guessing it will be a little quieter than cat only... and it sounds like a big rig... and it now smells better...
Also looking at that CFM chart I think it is lacking some info... A 5.9 at 3K making 12psi boost will flow much less air than one making 35psi...
10-03-2008, 09:18 AM
#27
1st Generation Admin
Thread Starter
Certainly, a higher flow into the muffler will present with a higher back-pressure, a lower flow the opposite.
In the format Donaldson uses, one can make comparisons on a somewhat level playing field.
10-03-2008, 09:31 AM
#28
Registered User
Keep in mind, 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.
Certainly, a higher flow into the muffler will present with a higher back-pressure, a lower flow the opposite.
In the format Donaldson uses, one can make comparisons on a somewhat level playing field.
Certainly, a higher flow into the muffler will present with a higher back-pressure, a lower flow the opposite.
In the format Donaldson uses, one can make comparisons on a somewhat level playing field.
10-03-2008, 10:20 AM
#29
1st Generation Admin
Thread Starter
Yup, it is a little vague ...
Efficiency = .85 for naturally aspirated engines
Efficiency = 1.4 for turbo-charged engines
Efficiency = 1.2 for engines with scavenging blower
I would imagine varying boost/turbine back-pressure would change (vary) the efficiency number used in the equation.
Toss in a compound turbo set-up and . . . . . . . . ?
EGT's impact the outcome as well.
Efficiency = .85 for naturally aspirated engines
Efficiency = 1.4 for turbo-charged engines
Efficiency = 1.2 for engines with scavenging blower
I would imagine varying boost/turbine back-pressure would change (vary) the efficiency number used in the equation.
Toss in a compound turbo set-up and . . . . . . . . ?
EGT's impact the outcome as well.
10-04-2008, 01:25 PM
#30
Registered User
Join Date: Jun 2007
Location: exeter,ca
Posts: 409
Likes: 0
Received 0 Likes
on
0 Posts
Got the donaldson on. Still have the vibration at idle when stopped,overall noise is down. More turbo noise and alot quieter going down the road. Gained some low end grunt also. APwatson,you can check ryder fleet products for the muffler. I paid $66 plus freight and shipping. I am happy with it. 