The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 05-04-2021, 12:58 AM   #1
jumpsoffrock
Senior Member
 
Join Date: Apr 2014
Location: California
Posts: 341
Quiet non-restrictive exhaust?

My truck has a 402 and two new flowmasters(or something) with true dual exhaust.
I don't mind loud sports cars, but a truck IMO doesn't need to deafen you. I want this to be a comfortable truck I can drive for hours and not go deaf. I'm not trying to scare people.

Would the stock mufflers be too restrictive? Are there any options that sound essentially stock, but offer a little more performance?

Is there any horrendous reason I should absolutely not go to stock mufflers?

Thanks for any advice.

P.S. Part numbers for what I could/should order are appreciated.
jumpsoffrock is offline   Reply With Quote
Old 05-04-2021, 07:57 AM   #2
Mike C
Registered User
 
Mike C's Avatar
 
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,511
Re: Quiet non-restrictive exhaust?

Walker SuperTurbo 20 case
__________________
44 Willys MB
52 M38A1
64 Corvette Coupe
68 Camaro 'vert LT1 & TH700
69 Z/28 355 12.6's @110
69 Chevy Short Step 4 1/2"/7" drop
72 Jimmy 4WD 4spd 4" & 35's
02 GMC 2500HD 4x4 Duramax
Mike C is offline   Reply With Quote
Old 05-04-2021, 08:31 AM   #3
sick472
Registered User
 
sick472's Avatar
 
Join Date: Jul 2015
Location: Sedalia Mo.
Posts: 831
Re: Quiet non-restrictive exhaust?

I just put these on my 72 that sports a 350ish HP 400 (Pontiac motor)...

Dynomax Performance 17749 - Dynomax Super Turbo Mufflers, from Summit Racing (67$)...

https://www.summitracing.com/parts/WLK-17749

These 20" case length mufflers have the offset inlet and outlet and fit nicely where the General originally put them. They should compare very closely to the Walkers that Mike suggests. They are quiet and have great reviews for not being restrictive. The only complaint I have is that my exhaust system does have a short drone at about 2500 rpm in second gear (35 mph), not at highway speeds in third however. I think this is due to the pipes just off the manifold having to be 2-1/4" diameter to fit the manifolds. These pipes necks up to 2-1/2" within 2 feet of the motor and continue out the back at 2-1/2". I'm not very versed on exhaust systems, so the drone may be due to something else, but I doubt that it's on the mufflers. My duals are traditional and do not have the X or H pipe.
Attached Images
 
__________________
He who is without oil shall throw the first rod. Compressions 8.7:1
sick472 is online now   Reply With Quote
Old 05-04-2021, 09:32 AM   #4
jumpsoffrock
Senior Member
 
Join Date: Apr 2014
Location: California
Posts: 341
Re: Quiet non-restrictive exhaust?

^^^Dude you put a pontiac 400 in your chevy truck????

If so, BADASS

Thanks for the leads, guys.
jumpsoffrock is offline   Reply With Quote
Old 05-04-2021, 10:00 AM   #5
Steeveedee
Senior Member
 
Steeveedee's Avatar
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 6,201
Re: Quiet non-restrictive exhaust?

When I go to do my exhaust, it'll be a couple of '70s Cadillac mufflers. If one flows well enough for a 500 CI engine, two ought to be OK for a 400 CI engine. And when is the last time a stock Cadillac of that era "roared" by you with loud exhaust?
__________________
'70 Chevy 3/4T Longhorn CST 400/400/3.54 Custom Camper
Steeveedee is offline   Reply With Quote
Old 05-04-2021, 03:48 PM   #6
SCOTI
Registered User
 
SCOTI's Avatar
 
Join Date: Apr 2001
Location: DALLAS,TX
Posts: 20,140
Re: Quiet non-restrictive exhaust?

Quote:
Originally Posted by sick472 View Post
I just put these on my 72 that sports a 350ish HP 400 (Pontiac motor)...

Dynomax Performance 17749 - Dynomax Super Turbo Mufflers, from Summit Racing (67$)...

https://www.summitracing.com/parts/WLK-17749

These 20" case length mufflers have the offset inlet and outlet and fit nicely where the General originally put them. They should compare very closely to the Walkers that Mike suggests. They are quiet and have great reviews for not being restrictive. The only complaint I have is that my exhaust system does have a short drone at about 2500 rpm in second gear (35 mph), not at highway speeds in third however. I think this is due to the pipes just off the manifold having to be 2-1/4" diameter to fit the manifolds. These pipes necks up to 2-1/2" within 2 feet of the motor and continue out the back at 2-1/2". I'm not very versed on exhaust systems, so the drone may be due to something else, but I doubt that it's on the mufflers. My duals are traditional and do not have the X or H pipe.
x2 on these mufflers.

I have the 3" versions on my Squarebody dually based off of internet research of muffler flow vs. sound testing. The testing was w/2.5" units but these mufflers tested almost @ the top spot for flow (straight-thru exhaust & a race only muffler ahead in flow) & were the most quiet after a stock muffler.

My set-up is:

461bbc w/true dual set-up.
1.75" full length car headers w/a 3" collector
3" head pipes to 3" H pipe into 3" In/Out mufflers
3" tubing out of the mufflers immediately reduces to 2.5" tubing
2.5" tail-pipes to the rear bumper

It's stockish quiet until my foot is into the throttle.
No drone.
Attached Images
 
__________________
67SWB-B.B.RetroRod
64SWB-Recycle
89CCDually-Driver/Tow Truck
99CCSWB Driver
All Fleetsides
@rattlecankustoms in IG

Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.

Last edited by SCOTI; 05-04-2021 at 03:55 PM.
SCOTI is online now   Reply With Quote
Old 05-04-2021, 04:06 PM   #7
MikeB
Senior Member
 
MikeB's Avatar
 
Join Date: Jul 2000
Location: Justin, TX
Posts: 2,408
Re: Quiet non-restrictive exhaust?

I've used Dynomax Super Turbos with the 20" case on at least two vehicles over the years. They're not a heck of a lot louder than OE-type mufflers, but they are less restrictive than Flowmasters according to tests done by David Vizard.

If you decide to use OE-type mufflers, keep in mind that they reduce sound by "restriction", so they typically "neck down" 1/2" or more internally. Good for quietness, but bad for power and efficiency. An option is to buy OE-type mufflers that are 1-2 sizes larger than your pipes, and connect them with adapters. For example, 2.5" mufflers on 2" to 2.25" pipes.
__________________
Mike
1969 C10 LWB -- 1989 to present
1982 C10 SWB -- 2013-2020
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 20 years! This is the very first car/truck Internet forum I joined.
MikeB is online now   Reply With Quote
Old 05-04-2021, 07:58 PM   #8
jumpsoffrock
Senior Member
 
Join Date: Apr 2014
Location: California
Posts: 341
Re: Quiet non-restrictive exhaust?

Probably gonna go with dynomax super turbos, maybe 3" and have a new exhaust made? IDK might just stick them on as is and do full exhaust when pigs fly. lol
jumpsoffrock is offline   Reply With Quote
Old 05-04-2021, 09:05 PM   #9
jimijam00
Registered User
 
Join Date: Apr 2009
Location: PNW
Posts: 213
Re: Quiet non-restrictive exhaust?

I recommend you get the 2.5 super turbos. 3.0 is probably too much if your 402 doesn't put out a lot of power. Besides, put a 2.5 on the left and a 3.0 on the right, the 2.5 will be quieter just about always.
__________________
1969 C10 Custom, 427, TH400
pics here
jimijam00 is offline   Reply With Quote
Old 05-04-2021, 09:27 PM   #10
jumpsoffrock
Senior Member
 
Join Date: Apr 2014
Location: California
Posts: 341
Re: Quiet non-restrictive exhaust?

OK, that's great advice. I'll stick with 2.5"
jumpsoffrock is offline   Reply With Quote
Old Yesterday, 12:49 AM   #11
Richard
Registered User
 
Join Date: Dec 1999
Location: Southern California
Posts: 1,301
Re: Quiet non-restrictive exhaust?

If you like the Flowmaster sound just make sure to use the "big block" or 70 series muffler. Larger muffler pretty much always mean less sound. Have a single Flowmaster "Big block" 3" on my 94 get compliments all the time. Nice low tone, not to loud. Recently replaced it with the big block II as it had holes in it after 26 years. BB2 is a little narrower but same length. Friend put a 2.5" on his 2002 Chev truck and it sounds almost stock at idle to me. The 40 and 50 series were to loud then and are way to loud for me at this point in my life. Unless your are looking for every last hp. Really do not think muffler choice matters much on a DD. Looking at many muffler shootouts in the past I would guess the loss from running open exhaust on your set up to stock type mufflers would be less than 20 hp. See myself thinking about the Hooker Aero Chambers on my new build, I don't have a specific reason.
__________________
Richard
1972 K10 Custom Deluxe SWB Fleetside
My build https://67-72chevytrucks.com/vboard/...d.php?t=800746

Last edited by Richard; Yesterday at 01:07 AM.
Richard is offline   Reply With Quote
Old Yesterday, 10:34 AM   #12
MikeB
Senior Member
 
MikeB's Avatar
 
Join Date: Jul 2000
Location: Justin, TX
Posts: 2,408
Re: Quiet non-restrictive exhaust?

I second the comment above about the 70 series mufflers being much quieter than 40 and 50 series. They are super expensive though!
__________________
Mike
1969 C10 LWB -- 1989 to present
1982 C10 SWB -- 2013-2020
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 20 years! This is the very first car/truck Internet forum I joined.
MikeB is online now   Reply With Quote
Old Yesterday, 03:38 PM   #13
Big Kev-O
Registered User
 
Big Kev-O's Avatar
 
Join Date: Mar 2014
Location: Simi, CA
Posts: 289
Re: Quiet non-restrictive exhaust?

Just about any 2.5 inch "turbo" muffler is going to give you plenty of flow while keeping things quiet. I installed some on a C3 Corvette and they have a nice deep idle although quiet, cruise without drone but show some power when you hit the pedal. There are even some affordable options in stainless that will work great. The difference in power between straight through, turbo & chambered mufflers are usually less than 10hp on anything under 500hp, typically around 5hp difference which is negligible. I found the Engine Masters muffler videos very informative. Check out Engine Masters "$40 Muffler Shootout" and "Cheap VS Expensive Mufflers" Episodes for some cool dyno tests and reviews. IIRC there are some nice quality stailness turbo style mufflers that are really affordable.


https://www.youtube.com/watch?v=Od3f_N-59Jo

https://www.hotrod.com/articles/engi...rs-episode-17/
__________________
Made in America by Americans

Last edited by Big Kev-O; Yesterday at 03:45 PM.
Big Kev-O is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:01 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Copyright 1997-2020 67-72chevytrucks.com