Muffler selection. Magic solution needed.

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zKars
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Muffler selection. Magic solution needed.

Post by zKars » 03 Apr 2018 07:21

Well the question of the day relates to how to keep me quiet. Or at least the 71 510 I'm working on quiet.

What I'm looking for is the answer to the eternal question, "If I wanted to make carburetor induction sucking noise the loudest thing I hear, and I'm not interested in wringing every HP out of the motor, what muffler wouild you choose?"

Let's not consider resonators in line for the moment.

In my Z world, I think I've tried just about every Dynomax, Magnaflow etc performance muffler, with and without resonators, and they are ALL too loud for old ears on long trips.

I would love to understand more about exhaust systems. You see 300-400 HP minivans and SUV's running around with what looks like no more 2" exhaust pipes (often less) with essentially NO noise coming out of the tail pipe. Noise and the ability to flow the exhaust properly are NOT synonymous. I want all the good noises coming from the engine, and only enough "nice" noise from the tail pipe under high load and RPM conditions.

Even the answer to "what OEM muffler from some modern-ish car" have you found fits in the back in that constrained area and is on the quiet side rather than the "loud but lovely" side.

Maybe once the snow melts around here, I can go to pick and pull and look under a few cars for something that fits.

So if any of you have been on a similar quest and have something you are happy with, let me know.

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Byron510
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Re: Muffler selection. Magic solution needed.

Post by Byron510 » 03 Apr 2018 09:28

Jim, it's a great question - really.

I look at my family hauling Armada - I have four kids so that size of vehicle is necessary (and it pulls the 510 on the trailer really well as a bonus on track days!).

But to be honest, I just replaced the whole system from the cat back a few months ago. The pipes are less than 2 1/4", and the muffler is 4 times the size of that in my 510. Yet this truck achieves 380 ft/lbs of torque and 315 HP at a ridiculously low RPM.

The Bronze (my 510) with it's Nissan comp header, very free flowing 2 1/2" mandrel bent SS system through a 3" SS muffler booms like hell, and makes ear protection mandatory for anything more that 30 minutes and it only makes 150 HP..... yet this system is considered to be the bare minimum for "performance" orientated 510's.

Ok, but I have to interject here. My yellow 68 from years ago ran basically the same 2.2 L/Z motor(same head, cam and stock block combo) with a standard 510 exhaust manifold and a 2" steel pipe to a reverse flow turbo type muffler. It was twin 40mm side draft equipped, a freshened but stock valve size equipped U67 head and was your basic 90's build 510. But that car was much more sane than the Bronze, and although I don't have the official dyno numbers to back it up, my butt sensor tells me that this 68 car was hardly much slower, but way quieter when it came to exhaust boom.

So does the smaller pipe keep the velocity of the gas flow higher and direct the sound out of the car quicker - conversely does the larger pipe just add resonance to the exhaust by slowing gases down? So does the free flow really flow that much more freely? Have the back yard mechanics over thought this way too much and way oversized our exhaust systems without any real consideration to it's effects? Rob and I took a sound meter to Canby in 2011 - read 110 db on the highway inside the car! That's crazy.....

Back to exhaust flow - look at this episode of Engine Masters - the guy from Roadkill - it's entertaining:

https://www.youtube.com/watch?v=azPKIjxmmdU

They obviously proved that the header must be oversized because it took significant restriction before the HP started to fall - and it hardly fell at all.

So has the "norm" of 2 1/2" exhaust systems with 1 5/8" primary's done the same for our 510's (which don't run at 8000 RPM all day)? Is it just simply too much for hardly any gain?
Jim, Like you I'd love to put a 2" system back on my car as back this up with real numbers.

And BTW - SS pipe rings. I don't know how to explain it but from inside the car it just rings compared to steel pipe. Just a side note here.

I look forward to the discussion.

Byron
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James
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Re: Muffler selection. Magic solution needed.

Post by James » 03 Apr 2018 10:05

Me too - I would like real world experience on this issue. As I get older the exhaust noise is not as entertaining as it used to be.....
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RMS
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Re: Muffler selection. Magic solution needed.

Post by RMS » 03 Apr 2018 13:08

when the exhaust on the woman's stock L16 powered red rocket was replaced, we bumped it from the stock 1.5 to 1.75. and lost the resonator. we saw a 1mpg loss and I heard no end of complaints about the noise..... the car felt a bit more zippy but it might just be the extra noise.

on 6 inches of rust there was a big improvement in power on the stock z24 when the exhaust was bumped from 1.75 to 2.25 and a turbo muffler installed. with ss pipes, a large resonator and the turbo muffler she is quiet even at full chat.... well until the collector gasket failed and power and economy went through the floor.
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I think it could be a fine line between flow and back pressure to maximize power and economy.....hmm..... how much can cam profile and scavenging play in header choice and exhaust size ?

I cut up a vw toerag suv ss exhaust. its mean ID was 2in but as it joined the muffler it necked down to about an inch then back to 2in at the tail pipe.
Last edited by RMS on 03 Apr 2018 13:22, edited 1 time in total.
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Re: Muffler selection. Magic solution needed.

Post by Beegee2 » 03 Apr 2018 13:09

I also am getting to old for the excessive noise from our 3” exhaust. I am building another 510 (1600) at the moment and will be needing a full exhaust built so hope this subject gives some direction for us old, sonically challenged datsun enthusiasts.

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James
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Re: Muffler selection. Magic solution needed.

Post by James » 03 Apr 2018 15:23

What?
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TheHeretic
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Re: Muffler selection. Magic solution needed.

Post by TheHeretic » 03 Apr 2018 19:19

I don't know what motor you are running but most L-series below 150hp are fine with a 2" exhaust. Pair that with as long of a resonator that you can find and a Walker Quiet-Flow muffler and you should be happy.
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Re: Muffler selection. Magic solution needed.

Post by Three B's Racing » 04 Apr 2018 04:50

TheHeretic wrote:I don't know what motor you are running but most L-series below 150hp are fine with a 2" exhaust. Pair that with as long of a resonator that you can find and a Walker Quiet-Flow muffler and you should be happy.
Exactly!! I'm running a S14 SR20DE N/A with Tomie Poncams and 10lb aluminum flywheel through 2.25" exhaust, a Magnaflow 3" diameter resonator before the rear crossmember and a Walker Quiet-Flow out back. I'm 62 and drove the 510 from New Hampshire to Canby last year no problem. Is it loud? yeah when you step on it but @70-80mph for me its very tolerable. Driving to Road Atlanta in a few weeks also. This older guy just enjoys the ride :wink:
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Re: Muffler selection. Magic solution needed.

Post by abisel » 04 Apr 2018 05:30

I will be trying an Ermish Racing system in 2.25". With their headers too that has 2.5" collector. We shall see how loud it is or is not. May have to add a resonator if too loud. Or maybe a Thrush glass pack instead of a resonator. Thoughts?

Also looking into v-band exhaust pipe connections. Any thoughts on those?

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zKars
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Re: Muffler selection. Magic solution needed.

Post by zKars » 04 Apr 2018 06:37

Excellent advice, thanks all. Jsut getting the clue about the Walker Quiet-Flow mufflers is worth its weight in gold.

Quiet flow mufflers are OEM replacements, so finding a suitable size is a bit of a trick.
Looking through Walker listings on Summit Racing, shows the 21690 15 in long, 4.35 thick/8.8 wide seems to be about the only 2.25 Inlet/outlet choice that might fit. 53690 might work too, 2/2.25 13/9.75/? with a twin tip? Or 21503 2/2" 14/9/7 with a twin tip (Pontiac Gran Prix etc)

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Re: Muffler selection. Magic solution needed.

Post by datzenmike » 06 Apr 2018 23:34

I kept my stock 710 resonator and added a larger diameter inlet muffler using a 1 7/8" to 2 14" pipe adapter. The 2 1/8" ? outlet is just a 45 degree bend towards the ground. The muffler is physically longer and larger around too. My theory is the muffler has lots of internal room to allow the exhaust to expand and slow down before exiting, the internal baffles and holes are larger and more plentiful so less resistance, all average 'quiet' mufflers are tuned for the same basic frequency range resonances and the lack of a tail pipe is no loss anyway. The 45 degree down pipe just before the rear axle allows some of the sound back into the car so it's has a slight rumble but NO pops, bangs, raspy, throatyness or any other disagreeable ricer adjective to describe it. It's a quiet $40 universal muffler I got for $5 from a yard sale, brand new and shiny
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Re: Muffler selection. Magic solution needed.

Post by Chickenman » 07 Apr 2018 12:23

Let's not consider resonators in line for the moment.
Actually, the resonator is one of the first things you should consider. The " Type " of resonator is very important. You do not want a Bullet Style ot " Thrush " style of resonator. Edit Those are very IN-efficient at reducing noise.

With a resonator, the important part is giving the exhaust gases room to expand. That takes away energy and reduces the noise level. A bullet style has a small diameter. The small diameter allows less expansion of gases and can reflect the sound waves back. A much better solution is a medium size Oval muffler used as a resonator.

I find the Magnaflow Ultra series to be very good when used as a resonator. As is the DynaMax. You order a straight through Oval design. The straight though design offers no restriction to the exhaust gases as far back pressure, but it has much more Volume for the exhaust gases to expand. That greatly reduces noise and Drone.

For Turbo charged cars they often have a problem with melting the Glass Fiber packing in a straight though design. It is limited to about 1000 F. The solution is to go to chamber design or order a specialty muffler from a company like Burns Stainless Exhaust. http://www.burnsstainless.com/march2009newsletter.aspx

Once the resonator choice is covered, the rear Muffler can be chosen. For this I prefer a chambered Muffler from MagnaFlow or DynaMax.

I've used this combination on several cars. Including my Camaros and my 280Z. The Z exhaust ( 2.5" with headers ) is perfect. No drone at all. You can comfortably converse on the Freeway... but when you get on it all of that lovely Inline 6 howl comes through... just at a reasonable level.

BTW, I hate Flow Master mufflers. Very " tinny " sounding. The MagnaFlow and DynaMax has a deeper and more " Mellow " sound. Not " raspy " at all... YMMV
Last edited by Chickenman on 27 Apr 2018 12:35, edited 1 time in total.

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Re: Muffler selection. Magic solution needed.

Post by okayfine » 07 Apr 2018 15:57

zKars wrote:Well the question of the day relates to how to keep me quiet.

What I'm looking for is the answer to the eternal question, "If I wanted to make carburetor induction sucking noise the loudest thing I hear, and I'm not interested in wringing every HP out of the motor, what muffler wouild you choose?"
Take off the air cleaner(s)!

But seriously, look to smaller pipe sizes, as much as muffler types, to quiet a 510. Think about the tiny stock 510 exhaust pipe size, versus how loud an L16 can be once someone swaps on a 2.25" exhaust system?
zKars wrote: I would love to understand more about exhaust systems. You see 300-400 HP minivans and SUV's running around with what looks like no more 2" exhaust pipes (often less) with essentially NO noise coming out of the tail pipe.
Unfortunately, as Byron hints at, modern car mufflers are huge and designed to fit specific spaces underneath. There's no place on a 510 for a stock Armada muffler, except for (most of) the trunk.

You can muffle some with the small muffler that'll fit in the stock location. Adding a "resonator" (really just an upstream muffler) helps. Dialing down the pipe size will also help.
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Re: Muffler selection. Magic solution needed.

Post by SteveEdmonton » 07 Apr 2018 18:53

I'm running a 2" pipe with no resonator and a Magnaflow muffler on my L20B with SU's, and find this combination really nice. It probably has a little more steady-state noise than if I were running a resonator, but I think the smaller pipe offsets that somewhat. Just a bit of deeply mellow whoosh when I tromp on it-- otherwise, induction roar galore!
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Re: Muffler selection. Magic solution needed.

Post by Tedman » 25 May 2018 21:34

The Borla Pro XS muffler, 40657 (2") or 40658 (2 1/4") measures 14" long x 7 7/8" wide by 4 1/4" height with center inlet, and offset outlet and fits a 510 perfectly. They are stainless steel so a bit more expensive (about $100 from Summit), but worth it for fit, sound and durability, IMHO.

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