I think we have type 2s in there stock. keep in mind I haven't changed my exhaust (so no experience here) but I sense from my reading that a type 1 muff will fit with minor effort. A local performance shop told me that they fit a type 1 straight through muff in there and that things can be made to line up ok with all stock piping. But I'm like you I'll believe when I see.

I got drawings now but they don't really tell me much. The Nelson looks pretty complex inside, and I have only exterior drawing of the donaldson. We need to find out what Nelson part draebi has.

 

OK here is what I found out. The part # is M4490. The body is 9"diameter and 44.5"long. Overall length is 51". Has 4"in/4"out. The flow rate is 1750cfm@3"hg and 1450cfm@2"hg. So it sounds like it has little better flow rate than the one Doug is speaking of but not as high as the Donaldson. I think the sound is ideal so if my understanding of what Doug said is correct than it is plenty of flow without overkill. Doug when you say room to grow with Donaldson are you talking boxes, injectors, turbos, etc. or are you talking larger engine? If you are talking about bombs then what would be your guess to how far I can go with this muffler before it becomes the restriction?

 

Sorry but was posting when talk of type 1 or type 2 and installation was brought up. I do not what type 1 or 2 means but it is a straight through design with no offset like the stock one has. I watched muffler shop install with stock piping and it was no problem. I think it changed the direction of my tailpipe a little maybe little more toward rear and down but was no problem aligning it at all.

 

Cool! Think I found my next muffler. And the price is right!

MikeyB

 

thats not a Nelson part number -- its another OEM part number. the muff is no doubt made by Nelson but the origional equipment mfg is what we need. what other company name is on the package? that explains the 1750 CFM -- Nelson can't sell this muff directly because its an exclusive design that they mfg for someone else.

see this site for explantions of type 1, etc.

re: room to grow. Well, this is really just an educated guess, but looking at some flow restriction calculations I found on the web, I'd estimate that the Nelson muff itself presents just a wee bit more restriction as the 4" pipes themselves do. So I'd say you'd be good for whatever a 4" exhaust pipe is good for (somewhere in the 450+ HP region). by the time you want to exceed that power level you'll probably be changing pipes (5" pipe has about one third the backpressure as 4") and looking at a different muff (or no muff) anyway.

re: the donaldson , well, its restriction is about half that of the Nelson -- which means that at the very high power levels it would yield a small EGT reduction, but in the grand scheme of things it probably won't matter -- if you're really out to chase more power, you'll be changing pipes. In other words, if you were to go on a HP bombing quest, I don't think you'd ever say to yourself, "self, the donaldson would have taken me further". I think either of these muffs would get the circular file when you upgraded to 5".

sounds like we have two really good muff options. btw, did you keep the factory resonator and put in the 51" muff behind it?

 

I specifically asked if that was the only part # she had and she said that it was. I do not have the box since I left it at the muffler shop where it was installed. I came in a brown cardboard box with a sticker on the end that best I can remember only had the Nelson name and info about the muffler and no other company name. Maybe it is one they make specifically for FleetPride or something but I do not know any other way to get different part #. I think FleetPride is big company in other cities also, I know there is at least 3 here in Oklahoma City area so maybe others can get more info from there local one.
As far a factory resonator, I do not believe mine had one. There is just a straight 3.5" downpipe back to muffler and then muff and tailpipe.

 

ok, things are starting to make sense finally.

M4490 is a fleetpride number that crosses to a Nelson 86131M which crosses to a Donaldson M090544.

It looks like Donaldson updated their site and no longer show those extraordinary flow rates. see M090544


the correct Donaldson M090544 specs are:

1" mercury backpressure: 1158 CFM
2" mercury backpressure: 1638 CFM
3" mercury backpressure: 2006 CFM


the Nelson 86131M flow rates are:

2" mercury backpressure: 1670 CFM
3" mercury backpressure: 2000 CFM


The fleetpride M4490 flow rates are:

2" mercury backpressure: 1670 CFM
3" mercury backpressure: 2000 CFM

So draebi it looks to me like you and AK have essentially the same muff. In fact it looks like FleetPride puts "M4490" on to a Nelson 86131M. But I have no idea where the 1750 CFM flow rate came from???

AK I've been on the Donaldson site and witnessed myself the 2639 CFM rating. But this morning they are as stated above! I verified with Donaldson (they looked up hard copy reference) that the above numbers are correct.

FleetPride M4490 mail order price (plus shipping) $57.25 from Omaha, NB 800-441-4658

 

thanks Doug. Youre the man

 

This might explain it Doug. My Donaldson is a 34" muffler, part# M085171. Not quit as big as the 51" Nelson. I know a shorter muffler will be louder, but less restriction also? I took those stats from an old web site that I had saved some info from when I was looking for a muff upgrade. This is my muffler: http://shop.airflowonline.com/Mercha...egory_Code=EIO However, I paid $50 even for it at the local Freightliner shop.

Donaldson has changed part numbers this year, so technically this part number shouldn't exist any more. I would think they still make a 34" muffler though. That is the standard size for mounting with existing hangar points under our trucks. Did you run across any current CFM ratings for their 34" mufflers when you were looking?

 

yea, that does explain it. The M085171 muffler is a 3119 CFM device, 40" long and 8-12 dBA attenuation. The M090544 is a 2006 CFM device, 51" long and 13-18 dBA attenuation.

This is a difference of 6 dBA which is very easily detected. AK if you're happy with the shorter one, no wonder draebi was pleased with how quiet the long one was

 

doug,

how could you figure out the CFM on a BORLA XR1 Sportsman that is a 4 inch straight thru, just with offset inlet/outlet (a type 2)?
http://borla.com/xr1.sportsman.offset.mufflers/

40080 $179.99

http://www.northstarauto.com/BorlaPr...000.html#40080

i think that your previous posts indicate a 14 inch muffler will NOT quieten down our rigs, huh?

 

Doug,
Thanks for doing all that research and answering a lot of questions that I never could have, but basically all you research has just confirmed that I ended up about perfect since it flows about same as straight 4" pipe without overkill which keeps it as quiet as possible and still have optimum flow.
Everyone else that tries this muffler please give more feedback on your thoughts about the sound since it is definetely personal tastes, mine just favor great flow with reduced noise.

 

04cdt: I'm afraid I wouldn't be able to give a meaningful flow rate estimate on arbitrary muffler geometries. those numbers are carefully obtained at the factory by testing --- they stuff air through them and measure the backpressure. So I really have no idea how a short, staight through type 2 would do. the advantage of the big rig muffs is that they are tested and we have real data for them.

same for quietness specs. I got my numbers from the mfgs -- they declared the sound reduction in dBA. also carefully obtained by puttting them on real engines and measureing the sound level.

draebi: Actually I'm pretty pleased with the numbers on this Donaldson/Nelson/FleetPride muffler myself. just be careful about saying it is the same as a straight 4" system because it really isn't. I'm saying that the muffler itself presents about the same backpressure as all the pipes themselves -- about 1 psi at 1600 CFM. that means the pipes ALSO present about 1 psi backpressure (that was a very rough approximation). The reason I said that the muff is about the same as the pipes is to show that neither the pipes nor the muff is the dominant factor in the completed system. I'm out to say that (from a theoretical standpoint) this muff is a good choice system because it gives significant sound reduction with hardly any additional restruction beyond whats already there.

So a full straight 4" system (no muff) would in fact present less restriction, and theoretically would yield a lower EGT. but as I've said before, whether or not such a difference is a significant and practical benefit at the power levels you want to obtain with the stock turbocharger is a question worth asking.

 

Just bought my Nelson 51", OH My Gosh it is huge.........Was there fit issues underneath? I am a little worried about how heavy it is but can't wait to install it. They did not have an adapter so I am going to make a 4-4" adapter work with a few mods.

 

Mine came in today. I'll get it put on Monday.