I need to choose a muffler for the exaust system I'm building after the twin turbos. If they do quiet it a fair amount, I'll just use a Dynomaz bullit. If they don't really..then I'll need a quieter muffler, which will be much more expensive. It's a 4" exaust..so my options are fairly limited.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

they kill a huge amount of noise. The only loud exhaust sounds that come from a turbo car are from the wastegate.

Since the turbo kills all the wave pulses, then all you have to be concerned with is flow numbers which will be greatly increased over the non-turbo engine. A large straight-through type muffler should work fine... no need for a flowmaster though.

IMO

 

The exhaust will still be loud! Here's what we found out:

Car: 1993 GT Conv't. 351", T72 turbo
Single 4" exhaust, stainless
Borla XR-1 was LOUD.
Dynomax bullet was LOUDER.
Flowmaster 2-chamber HURT power, but was quieter.

Straight-through designs are loud, chambered mufflers hurt turbo power. I am still deciding what to do...

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Old: 1989 Formula, 383", DFI, built 700R4, TFS heads, Mini-Ram, Vortech S-trim 15 psi, 3.70 gears
Best ET: 10.796 @ 125.8 mph

New: 1989 T/A, 400" CNC Bow-Tie Tall-Deck, Accel Pro-Ram, DFI, AFR heads, HRC T76 Turbo, NOS 150-hp dry kit, TH400 w/GV overdrive, 12-bolt w/3.70 gears, 8-pt. S&W rollbar, Spohn suspension, 18" wheels, Baer brakes
Best ET: Spring 2001

Employed at:
Hahn Racecraft
Accel EMIC/DFI Tuning
Turbosystems & Custom EFI

Member of Midwest F-Body Association www.mfba.org

 

noway,
that is interesting.

how do exhaust pulses get past the turbo? if it is pulses then anti-reversion techniques would work to make it quiet.

what are your thoughts on it so far?

 

I still don't get that. Would it be because of the size of your turbo?

Even Randy Eakins huge turbo is quiet IMO

 

With my TTA I had the exhaust undone before the cat and pulled up next to a Va state trooper and he did not even look at me. I guess a stock single turbo is not that loud.

Pete

 

Well, Bill's vette has a 100mm also and it wasn't super loud but it was decently loud. he wasn't running a muffler though at all.

 

I heard Bill's vette i don't think it was any louder then my iroc with 3.5 exhaust and a 2 chamber muffler and his car has over 1400hp. I liked his exhaust it consisted of a pipe about 6 inches long that just turned toward the ground under the front clip.

 

You wanna know how quiet a turbo car is. Line up next to a T-type at the strip. Marvel at hwo you don't hear anything as he does his burnout and stages. Then admire the view as he does a wheelie and runs low 11s. Like ODB said, the only thing you will hear is the wastegates open after a few lengths off the line, the ungodly whoosh of getting smoked by a car that didn't make noise doing a burnout.
...ed (scarred by my first night at the track lined up against my old dream car)

edit, just wanted to add, like ODB says, turbos basically destroy exhaust pulses, so chambered mufflers like fromasters tend to eat HP cuz they derive their flow from the pulses causing scavenging in the various stages/chambers in the muffler.

[This message has been edited by Ed Maher (edited February 28, 2001).]

 

1648hp @ 34lbs of boost

best thing said at bristol

me: hey bill, you said you dynoed the motor at 34lbs of boost right?
bill: yeah, why?
me: your boost gauge only goes to 30lbs, how are you going to know if it creeps?
bill: it will just keep pulling

 

FWIW, Kenny Duttweiler built a 1300hp street car that dynoed through 2-chamber Flowmasters...

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1989 T/A, 400" CNC Bow-Tie tall-deck, JE 8.5:1, Eagle 6" rods, Crower roller cam, AFR heads, Accel Pro-Ram intake, 1200-cfm t/b, DFI, 72# inj., S/X fuel system, HRC T76 turbosystem, NOS 150-hp dry fogger, TH400 w/GV overdrive, 12-bolt w/3.70's, Baer Track brakes, 18X9.5 wheels, P275/35ZR18 Nittos, Spohn suspension, S/T springs, KYB AGX shocks/struts, Corbeau Targa RS seats, TeamTech 5-point harnesses, Sparco steering wheel, MacEwen white gauge overlays, Phantom gauges/tach, B&M Pro Stick w/carbon-fiber ****, REAL carbon-fiber dash/console kit (don't ask), S&W 8-point rollbar, Lonza aluminum pedal covers, Pioneer/Boston Acoustics stereo system, filled side markers, Audi clear fender marker lights, custom clear front turn signals, custom clear taillights, IMSA-style cowl hood (don't ask), custom medium Intense Blue pearl paint, tinted glass. Whew!

Best ET w/383" S-trim: 10.796 @ 125.8 mph
Best ET w/400" turbo, nitrous: Summer 2001

Member of Midwest F-Body Association www.mfba.org