Matt400

Ok...I think I get the deal. Fleetpride is simply a distributor and buys the muffs from Nelson and in the process of boxing the product leaves room for error in addition to the fact that many are so close in design.

At the moment for my wishes I am trying to find out what the difference's are in the Nelson:
86740M
86514M
86534M

as dimensions all look the same. Plus what the difference in a vertical muffler vs horizontal is and why they specify the application.

Lots of good info in this post and you are really doing homework doug...thanks!

Big Bob

I'll call Fleetguard tomorrow and check on the direction of flow on the 86713M.


Matt,

One thing about the vertical muffler is like Doug has stated in a previous post, one end is coned, this end goes up allowing water, snow and whatever to run off and not build up on the top of the muffler.

Matt400

If you think about it Bob, ask them about the vertical/horizontal thing.
I understand the cone but don't understand why the Donaldson Quiet Partner quoted it as Vertical only.

I can see why you wouldn't want to run a horizontal muff in a vertical application but not the other way around.

doug

yes, that and the obfuscation produced by having their own part number means that we really don't know what specs are behind it. sometimes they may fill those specs with a std Nelson number, sometimes not. at least thats what I'm seeing.

Here's the Nelson data on the muffs you listed. All three of the following are domed for vertical install and CFM numbers are at 2" Hg backpressure:

86740M: 1500 CFM. Economy muffler. no applications listed

86514M: 1375 CFM. Used on Caterpillar, Cummins, Detroit Diesel, and Mack engines (singles) up to 375 HP

86534M: 1560 CFM. stainless steel simliar to 86514. used on a few Macks and Detroits up to 350HP

The only reason I can think of that they specify the application is just to show what is supplied as OEM equipment for certain engines.

I honestly dont' know what "domed for vertical" means in terms of muffler construction, unless it has something to do with snow or water running off instead of accumulating. must be purely an exterior thing. pretty much any muffler with a baffle is going to have a flow direction I think.

Matt400

That's interesting considering those have a 5" outlet I would assume they would flow better since db rating looked similar. Must be some more baffling in there.

With M090544 flowing 1638 and the Nelson 86131 flowing 1670 at 2" It makes me have to ask.. why bother with a 5" tail pipe other than the visual effect.

Thanks Doug for working those CFM numbers.

doug

yea, good point. But remember that the CFM numbers are for the muff itself. The pipes themselves and all their bends, contribute to the backpressure as well. Its not hard to see that 5" pipes are substantially less restrictive than 4" pipes, but when I ran the 1st order approximation numbers, I came up with the fact that the muffs we're considering present equal to or less flow restriction than the (4" pipes themselves. So there's not a whole lot of point in going to a higher flow muff. Seems to me the next opportunity is the 3.5" downpipe on the 305.

remember guys we're talking about Mack, Navistar, Detroit, Cummins, etc engines up to 475 HP using this muff. My target design point is overkill (hottest possible WOT condition 3000 rpm targeted at 2" Hg back pressure). The only problem is, you won't be able to spend all kinds of money on technobabble. I mean, you're stuck in dullsville spending $75 or less on an ordinary high-flow diesel truck muffler. no quasi laminar flowing spiro nitro turbo sucking pseudo rocket guiding resonating nonscience. dern.

Matt400

I contacted Steve Burnette in Service/Engineering at Fleetguard and here is a quote:

Most all Nelson mufflers are baffled in some form or fashion. Our 86514M
is baffled in a way that you could not look through the muffler. I do not
know of any Nelson muffler with a straight through design.

So that leads us back to the Donaldson if in fact someone can vouch for a see through design.

AK RAM

My muff, M085171, is 4" wide open all the way through. The last 4 inches of the exiting side of the muffler is an empty sound chamber. The gasses pass thru the "straight through" part, then dump out into an empty cavity, then out the other end. Make sense? Wish I had a picture of it so you could see what I'm trying to explain. Kind of like a built in resonator. Anyway, yeah, wide open all the way through.

RTillery

The Donaldson M090544 has a crimped, cone shaped baffle in it down about 18" from the inlet. By the way, the inlet is marked on this muff and the outlet is domed for vertical installation. I suppose someone could knock out the baffle if they wanted, but I was after a quiet straight through design. Outside the truck, you can hear a little big rig rumble but inside, going down the road with the windows up it is quieter than stock. If I have the right side windows down, you can definitely hear the Cummins at work, but you have to be bouncing it off a fence, wall, ricer etc.

Matt400

Interesting...built in resonator thing.

Now that you all got me researching I see that the Donaldson M090544 @ 51” long is more loud @ 13/18db vs the shorter M085171 @ 40” rated @ 8-12 db?

I would think the longer muffler would be quieter. The shorter one flows more which makes sense but not the lower db unless its due to that empty sound chamber.

100 Proof

Actually Matt, those dB numbers are for attenuation. In other words, the higher the number, the quieter the muffler.

100 Proof

Matt400

Oh!

Kinda hard to compare the attenuation db to the db measured at 50 feet on the Nelsons.

Big Bob

Well guys, here's the latest on the FleetPride M4490.

I called FleetGuard (Nelson) for the directional flow of the 86713M (with 1 coned end), they said it was definately a directional muffler and it need to be installed with the cone end as the outlet. Of course mine is installed backwards!

I figured if I going to have to take the muffler off, I was going to get the right muffler (Nelson 86131M) and put it on!

I called FleetPride and had them cross over Nelson part numbers 86131M and 86713M, both crossed over to the FleetPride M4490! I explained that I specifically asked for a Nelson 86131M and was sent a 86713M which flows 250 CFM less at 3"HG. I told them that this was not the muffler I ordered and asked them to check stock for the 86131M. They didn't have the 86131M. They agreed to allow me to return the muffler and would refund my money.

Tomorrow, I will go to Cummins Northwest and get the Nelson 86131M and have it installed, which I will have to pay for again. I am also going to call FleetGuard again to find out if the 86131M is also a directional muffler. I don't understand why Nelson doesn't indicate on the muffler or have instructions explaining the direction the muffler needs to be installed in!

If you are thinking about adding one of these mufflers, FORGET FLEETPRIDE!

Big Bob

Matt,

I asked FleetGuard (Nelson) about the 86713M with the cone at one end. They told me that the muffler would work in either Vertical or Horizonal position as long as the cone end was the outlet. I don't know about the Donaldson Quiet Partner.

Matt400

Thanks Big Bob