QUIET down the strrroker... tried DynoMax, MagnaFlo and thinking of...

ntsqd · Sep 22, 2017

Was thinking about this while walking back to work from lunch today. 500 ci Cad OEM exhaust's all used resonators very close to the outlets. They were so quiet that tose cars could sneak up on you if you weren't paying attention. Worth looking at, I've no idea what those resonators looked like inside.

Broncobowsher · Sep 22, 2017

The big 500 caddy were big engines, but they had little cams and could not rev very much. HP and airflow are pretty low. Most were low compression as well and that helps make an engine quiet as well.

ntsqd · Sep 23, 2017

500 cubes at 3000 rpm is still 500 cubes at 3000 rpm. That may not be as high of an rpm as nvrstuk's revs, but the point is that Cad used resonators on a big displacement engine and achieved a quiet well below what I suspect is desired. Scale CR and rpm's and so will scale the exhaust note.

Something else to consider is induction noise. That is not insignificant. the air has to come from somewhere, and how it is ingested can be a good portion of the total noise signature of the engine.

5001craig · Sep 24, 2017

I'm pretty close to 94 db @ 2500 RPM. Not the most scientific test but somewhat close. Running 1.75" fenderwell headers, 3" mandrel bent exhaust and Super 44's dumping out just in front of the rear tires.

sykanr0ng · Sep 24, 2017

nvrstuk said:
http://www.mustangandfords.com/parts/m5lp-0212-ford-mustang-muffler-comparison-test/

I think these clips give you db levels...94 ain't very loud... remember, db like the Richter scale is logarithmic so sound volume goes up fast...

85db is considered the threshold for permanent hearing damage.

Broncobowsher · Sep 24, 2017

I don't think you will be able to fit it under a Bronco, but I just found the muffler part number for the big block I have in a truck. Walker 22822. Overall length 43" Dual 2½" in single 3" out. Should be in by the end of the year.

nvrstuk · Sep 24, 2017

Not sure I could carry that monster in the back of my Bronco!!

Cpt7576 · Oct 21, 2017

My 75 Ford highboy has 428 too loud!!! 3 inch. Looked on summet the Flowmaster HP is only 2.5 inch. any suggestions on how to quite his beast?

naneumranch · Oct 21, 2017

Brian your getting old lol

. Listen to the sound bites from black widow exhaust see if any of those fit your fancy

.

Sent from my iPhone using Tapatalk

nvrstuk · Oct 22, 2017

Thanks for the tip Brian! : ) We can't talk when driving unless you yell...gets old on 2-4 hr drives! lol yeah...getting up there!

I'm up and running...but you might have seen my post on the brake issue and the tranny issue last night... quitting early tonight at midnight!

ntsqd · Oct 22, 2017

Cpt7576 said:
My 75 Ford highboy has 428 too loud!!! 3 inch. Looked on summet the Flowmaster HP is only 2.5 inch. any suggestions on how to quite his beast?

This:

ntsqd said:
I've run this muffler: https://www.summitracing.com/parts/wlk-17698 on a couple 350ci sized engines and really like it. I have one for the Bronc-up as well. I run them 3" thru, but I know of one behind a 302 that uses a 2.5" tail pipe to keep resonance at bay.

Your comment about a larger displacement engine causing a system be louder was one that I've been pondering since spotting this thread.

;D;D

nvrstuk · Oct 22, 2017

Well, I haven't really "gotten on it" yet but the 50% longer case muffler changed the tone but did not significantly reduce the sound. I really wanted a cross over but there really wasn't any room...I'm not going under the bellhousing or something so it will get ripped off.

4 link, 4R70W and doublers don't leave you a lot of room.

ntsqd · Oct 22, 2017

Do it Mustang style and put it cross-ways somewhere behind the rear axle?

On the YJ from Hell (early LS1/4L0E transplant w/ that Warn links & C/O's kit with a HP D60 rear) I think we had even less room than you do. I ended up putting the turbo-type mufflers on edge right next to the fuel tank & directly under the frame rails.

74 Bronco Billy · Oct 22, 2017

Subscribed. I plan on building a 408 monster for the crawler, and it will need to be quiet in town. Sometimes the forest service will do sound checks, and the CHP loves to nail people, so, can't let them take away my fun. Be curious what you end up with in the end. ;D

Yeller · Oct 22, 2017

74 Bronco Billy said:
Subscribed. I plan on building a 408 monster for the crawler, and it will need to be quiet in town. Sometimes the forest service will do sound checks, and the CHP loves to nail people, so, can't let them take away my fun. Be curious what you end up with in the end. ;D

We put a single 70 series flowmaster sideways where the fuel tank would normally be behind a 408 in my opinion it's perfect

nvrstuk · Oct 31, 2017

I ended up with JBA short tube headers (8 yrs old) with the flanges cut off and 3 inch ceramic coated pipe welded on to them. Then used turbo clamps from there in 3 inch to ultra flow 20 inch bodied stainless mufflers 3" in and 3" out offset which are sitting directly under my seats with heat shields spaced 1/2" from the floor boards.

the tail pipes are down to 2 1/2 since the gases are pretty cool buy then and ran them straight out the back.

Definitely not whisper quiet, but noticeably quieter than before and what helps is the sound is a bit deeper-not as raspy sounding. Put 150 miles on it yesterday cruising at 70 and you could talk...talk loud but not almost yelling like before.

Here's a couple of quick pics before we left for Moab. They are high and tight. Above the top of the (within an inch) frame rails and I will end up with something under them to give them a little extra protection if ever needed. Might be one or two small pieces of inch and a quarter tubing running parallel to the frame space several inches apart or??

nvrstuk · Oct 31, 2017

People that haven't run the EXACT same exhaust on a SB have NO idea the difference 80-100 more cubes and and extra 250 HP make for NOISE!

You can't compare ANY SB exhaust to a built stroker exhaust for sound levels.

SSDDBRONCO · Oct 31, 2017

Why not run cats? It'll cut the noise down and even take all the fumes away too.

nvrstuk · Oct 31, 2017

With a doubler, 4r70w and a 4 link even with the extended WB there isn't any room for cats...I couldn't squeeze in a crossover and I tried hard. .

No way am I going to lose ground clearance by putting one in-won't do it and adding exhaust heat to my tranny doesn't fit well with my goals either.

But on a stock drivetrain vehicle that isn't sliding across rocks or loose logs/debis it would probably be fine. I have zero room and only hung mine where they are because I lowered the DS floor by 2" and raised the PS floor 2". Lot of work to hang my mufflers safely.

nvrstuk · Nov 2, 2017

Official results---

We like it. Did another 7 hr day in the rig today with some 65mph and literally hours of 1st and 2nd gear stuff climbing to 11,500' -several times on gravel trails.

Good tone, people can tell I'm not close to stock but not obnoxious, deeper tone, we can hear each other in the cab-face each other but that's OK!

Gotta remember I have a 1/2 cab with windscreen only from the top of the cab to the floor

QUIET down the strrroker... tried DynoMax, MagnaFlo and thinking of...

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