Quite muffler that doesn't kill power...

[VMC]

You guys are awesome !

I do recall hearing about how a cam with too much exhaust duration was like a built in EGR.

Yep.
I found that out in the 80's when a lot of local short tracks started mandating mufflers.
I figured, I'd just take the cam that was working well without the mufflers, and increase the exhaust duration. All that did was kill the power and make the intake runners black.

Did you change anything in regards to the centerlines/LSA's or just add duration?

Hope I'm not asking too many questions, I'm just trying to learn--I have my own theories on the subject but lack practical means to test most of them, and since others have already been down these roads...

Eric

[CamKing]

Did you change anything in regards to the centerlines/LSA's or just add duration?

At first, I just added duration.
Then I pull the lobe seperation apart to keep from increasing the overlap. That helped with the reversion, but the earlier exhaust opening hurt the power.

[hurstoldsracer]

Sorry to hijack your thread Grits & Gravy.

[econo racer]

I have this theory! I thought about trying 2 large case 3 inch inlet mufflers with dual 2 1/2 in outlets any good

[crazyman]

Just even machining a bevel at the combustion face of your valves fights reversion, and helps it sound and idle like a lesser cammed engine.

David Vizard writes a good book about this, called how to hotrod small block Chevy heads.

An engine doesn't know who makes it or what size it is, it's still an engine.

In the last two years or so, the internet has shown me so much that would have taken me at least 25 years to learn on my own.

One word for internet learning. Discernment.

[Ron Golden]

Randy,
I regularly add collector extensions when I dyno an engine, usually after all the tuning is done. One 406 SBC picked up 96 lb/ft @ 4500 rpm and 6-8 hp above peak TQ when I added 18" of collector. The same engine lost TQ when I added just 8" of collector extension.

I've seen TQ increases on every engine I've added collector extensions to. Minimum of 20 lb/ft on a mild dirt track engine to a max of 96 lb/ft. Drag, street, dirt engines all seem to respond to the extensions.

I've seen much less TQ/HP change when the header length/size was changed. Kinda follows what David Vizard found in his testing.

Ron

[Grits & Gravy]

Sorry to hijack your thread Grits & Gravy.

Wear it out big guy.

I'm learning even if it isn't the original context.

[moneymaker]

anyone used these....SPINTECH MUFFLERS.....http://www.spintechmufflers.com/spintec ... hindex.asp


Inlet Size: 3 1/2 Inch oval Center
Outlet Size: 3 1/2 Inch oval Center
Case Size: 3 X 10 1/4 X 14

Description:
Our pure breed race muffler used extensively in Southwest tour,Craftsman Truck, and Winston West. Its a proven winner able to meet decibel levels where required. Description

[cv67]

Primary size being too big maybe?

Joe were those magnaflows the straight through or turbo type?

Spoke at length with Walker this morning really had my heart set on the 20 in hemi super turbos
He insisted that

Their 2.5" versions are good for 400hp/pair

Their 3" verisions are good for 450hp/pair

2.5 Ultraflows can handle 455 per muffler.
3" have fun.

Still want the large case supers....stealth mode in L. A. is the way to go .
Just too restrictive.

They are discontinuing a number of them.
Kinda bummed....really wanted a set but dont want to give up what would be a LOT.
One person suggested running them plus cutouts if need be

Giving the Ultra flows a shot. No flow issues there, 20 in case also.

Hope this helps.

Know that some of those hemi turbos neck down inside....some dont.
Call Walker directly to find out which.

[swatson454]

Randy,
I regularly add collector extensions when I dyno an engine, usually after all the tuning is done. One 406 SBC picked up 96 lb/ft @ 4500 rpm and 6-8 hp above peak TQ when I added 18" of collector. The same engine lost TQ when I added just 8" of collector extension.

I've seen TQ increases on every engine I've added collector extensions to. Minimum of 20 lb/ft on a mild dirt track engine to a max of 96 lb/ft. Drag, street, dirt engines all seem to respond to the extensions.

I've seen much less TQ/HP change when the header length/size was changed. Kinda follows what David Vizard found in his testing.

Ron

I've seen this personally as well. My 383 picked up quite a bit with 20" extensions. Once in the truck, it was noticably faster with the extensions, terminator boxes and full exhaust on the way home from the exhaust shop than it was with open headers on the way to the exhaust shop.

20 x 2.5 inch extensions into the terminator boxes with crossover pipe
out at 3 inch and into 3 inch, center/center Hooker Aero-Chambers
3 inch all the way back


Shawn

[ZIGGY]

it was noticably faster with the extensions, terminator boxes and full exhaust on the way home from the exhaust shop than it was with open headers on the way to the exhaust shop.

What kind of times did you turn each way?

[Orr89rocz]

Very old thread but some of you guys must have different definitions of "quiet" or have much worse hearing than me

I had a ~480-500 hp 383 at 11 to 1, street pump gas motor. 1 3/4 long tubes into 3" collectors into a Y pipe that was 4" outlet all the way back to the axle then splitting into dual 3" to the bumper to give dual tips. Had a Dynatech Split flow in there before the axle split, in the intermediate pipe section they call it.

DEFINATELY NOT QUIET like some say in here. Not any quieter than open Y pipe.

Replaced with a 16" Dynomax Ultraflo round. 6" round case, 4" inlet/outlet. Alot quieter than the other muffler and open pipe but still pretty loud. WOT was deafening. Could hear that car miles away. Sounded awesome tho.


My turbo motor... 9 to 1 comp 401" EFI motor. old combo had small heads, smaller Jones hyd roller, twin 60mm then 70mm turbos with same hotside, and first had the same single 4" as the 383 car did with the ultraflo. It was pretty quiet. Couldnt hear it down the track like the 383 when you stood in the stands.

Switched to dual 3" with bullets....still quiet on that car. SO thats good for a street car.

New turbo combo is larger heads and bigger cam, new hotside with same 70mm turbos. Its once again very loud not sure why. I guess heads/cam moving lots more air. Bullets were too loud. So now I have the 12" long case/ 16" overall length dynomax ultraflo stainless mufflers with 6" round case. Look like little Fart cans but they did a good job quieting it down but STILL much louder than the old setup. So I'm putting the bullets on the car behind the ultraflos.


If you guys have 800 hp all motor cars and cant hear them, then something is wrong with you

[jet1]

Here is a different type of mufler if you have the room. Just a 8" dia tube going crossways with two inlets at about 28" on center with two out lets on the opposite side with outlets 12" on center. No baffles. It is ridiculously quite with no lose of power. Each inlet gets to breath through two outlets creating and odd three mufflers design. If you want it louder just move the outlets closer together.

[Orr89rocz]

Any pics of that setup? 8" tube is massssive. Think that would be hard to fit

[MODNROD]

Here is a different type of mufler if you have the room. Just a 8" dia tube going crossways with two inlets at about 28" on center with two out lets on the opposite side with outlets 12" on center. No baffles. It is ridiculously quite with no lose of power. Each inlet gets to breath through two outlets creating and odd three mufflers design. If you want it louder just move the outlets closer together.

Kinda like this set-up?
http://www.vintagespeed.com.tw/Exhausts ... -main.html
A quiet exhaust that matches the power output of an open megaphone. Kinda cool........ina street racer sorta way!

My 2.5TT Supra used to be LOUD, gave me a headache when highway cruising (yeah, I'm not 20 any more ), and it had the usual 90mm head-pipe, followed by the usual 3" exhaust, into a cat, then a 5" case straight-thru truck muffler, then a stoooopid boomer cannon muffler at the back. I would have thought the truck muffler would have helped a bit, but nope.
I fixed it by fitting a Hooker Maxflow at the back in 3", and into a tip welded to it, went with one of these things (really, really clever, and they work too)......
http://apexi-usa.com/shop/index.php/exh ... encer.html
The Hooker Maxflow worked so well on it's own though, that if I hadn't already had the Apexi ATS on order, I wouldn't have bothered with it, that Hooker muffler is really quiet. Unfortunately, now I can hear the rattles.

It's also very irritating to the import guys that I have a V8 race muffler on a turbo whizz-bang!