14" Magnaflows have me scratching my head...

[whtgmc68]

Ok, I have spent hours listening to sound clips on youtube and cannot figure out why my 14" oval magnaflows sound so much like glasspacks when everyone of the sound clips sounds much more aggressive. I have only been focusing on the setups with full length pipes.

The mufflers have about 2,000 miles on them and my new 383 sounds kind of wimpy. I realize that magnaflows are supposed to be fairly quiet until you are at WOT but mine aren't making the grade.

Has anyone else experienced this?

[b454rat]

What size pipe? Small diameter pipe will make an exhaust cackle, like a glass pack.

[whtgmc68]

2.5" from the Hedman headers turned out behind the wheels. They don't crackle and pop like glasspacks but the tone is very mellow. Even at WOT they don't have the aggressive sound that I have experienced with other magnaflow setups.

[crazy longhorn]

Agree, those are a 'packed " muffler...straight through, much like a glass or steel pack. Add the H pipe, to help with the glass pac "cackle", & give a little more power down low. Yes , pipe size....also muffler placing, will affect the sound More info on the system, will help....longhorn

[crazy longhorn]

How far back are the muffs placed? Just a thought, if you can move them forward....they will sound off more....longhorn

[whtgmc68]

Originally Posted by crazy longhorn

How far back are the muffs placed? Just a thought, if you can move them forward....they will sound off more....longhorn

They are a foot or so past the cab under the bed. I'm thinking about swapping to a set of JBA universal mufflers. I have a JBA catback on my Titan and it sounds much more aggressive at WOT and even part throttle than these magnaflows.

I knew these mufflers were pretty quite when it was still a stockish 350 so I chocked it up to a low compression engine with a very mild cam. Now I have a 400 hp 383 with a hydraulic roller .480”/.480” lift 212°/222° duration @.050” with 9.0 compression, not that it is a big cam or high compression, but I thought it would sound a lot meaner than the 350 with the same exhaust setup.

[crazy longhorn]

A neighbor, had a 67 camero (454/4spd)....had the exhaust done locally. He asks me to look, cause he knew that I did custom exhaust? Same deal as you saw.....he did not feel that it "barked" loud enough (fairlane tail pipes on the mix). It was one sweet job, end to end, with 14" body Magnaflows....awesome sound! The CID, of the 'mill", makes the diff, I have 50's Flows on my truck.....the 383, sounded like a shot gun cracking off when "lit'? The old 327 (new school LS), quiet down low? She does bark, when revved. I run 3 chamber Flows....Longhorn

[Marv D]

That looks like one of Edelbrock 'thunder' series cams?

If so keep in mind exhaust valve opening allows the gasses to escape the cylinder at supersonic speeds,, That's what makes the 'bang' in the exhaust port. With 222° exhaust duration,, and exhaust opening at a late 48° BBDC the gasses are loosing their 'pop'. More cylinder pressure (as in greater throttle angle) and earlier exhaust valve opening (say along the lines of the RPM cam with exhaust opening at 58° BBDC,, but the SAME exhaust closing as your cam)
That exhaust valve timing has a considerable effect on the exhaust volume and tone / 'pop'

[whtgmc68]

Originally Posted by Marv D

That looks like one of Edelbrock 'thunder' series cams?

It is Smeding Performance's custom grind that came in the crate engine I purchased.

[TJ's Chevy]

Dual 3 inch straight pipe. Problem solved!

[Marv D]

Originally Posted by whtgmc68

It is Smeding Performance's custom grind that came in the crate engine I purchased.

Cool, just close to the # of the Edelbrock / LT4 cam if it's a 112 LSA

Do you have the cam card? What's the 0.050 exhaust valve opening?

[whtgmc68]

Originally Posted by Marv D

Do you have the cam card? What's the 0.050 exhaust valve opening?

I dont have the cam card so I dont have all the particulars but I think I read it was a 109 LSA but cant find it on their website. It is Smedings 380 HP Cruiser engine but my dyno sheet shows 408 HP at 5500 and 458 lb ft at 3800.

The engine is plenty stout backed by the NV4500 and a blast to drive but I was hoping it would "announce" its presence a little more! The magnaflows sound good, just not like I was hoping. I guess it is time for some trial and error to see what sounds best.

[crazy longhorn]

Have your wifey, do a drive by....you can hear, what the rest of the world hears....carefull tho, my wife has a "lead foot" Longhorn

[whtgmc68]

Sorry to bring up my own three year old thread, but I finally bit the bullet and ordered a set of Spintech Pro Street 6000 2.5" mufflers and had them installed today along with an H-pipe.

All I can say is WOW! These mufflers and the H-pipe really made my truck sound like it means business. They are not too loud and only have a slight drone at 2K RPM. I just wish I hadnt taken so long to pull the trigger.

If you are in the market, then I recommend Spintech for a pretty unique sound.

[AcampoDave]

Thanks for the follow up. It would seem that the Magnaflows really were hushing the motor then.....hmmmmmm good to know, I might have to get me a pair of those, Unlike most people, I like 'em quiet.

[whtgmc68]

The Magnaflows sounded pretty good at idle, but when you got it up to 4K and above, they sounded too much like glasspacks for my taste.

[PGSigns]

That H pipe does a lot for changing the tone of any muffler. You magnaflows would have had a different sound with it.
Jimmy

[whtgmc68]

Originally Posted by PGSigns

That H pipe does a lot for changing the tone of any muffler. You magnaflows would have had a different sound with it.
Jimmy

Most definitely they would have sounded different, but I still dont think I would have been happy with them. I've had Magnaflows on a couple vehicles where I really liked them, but my GMC just wasn't one of them.

[Backpayne]

I've had Magnaflows before and did not keep them long. They were too quiet.

Black Widows have a mean sound. I have Hooker Aerochambers waiting for my 455 to be installed. Love their sound.

[toolboxchev]

How your engine sounds, in addition to what Marv says, has a lot to do with how the engine is timed. With Full Vac Advance at idle my silly 1 step over stock Comp Cams sounds wimpy but louder than normal. When I simply mechanically time the distributor using timed vac advance port it sounds like I have a very lumpy cam.

Timing again, done in a different way.