Is a near OEM quiet exhaust possible while still supporting 350rwhp??

92bird

Registered User
I've been through several exhaust combinations on my SC and have come to one conclusion:

A good sounding V6 is a quiet one.

I want a near oem type quiet exhaust. I have a nice sound system in the car and the exhaust note just ruins the sound.

Does anyone think this is possible while still supporting 350rwhp?

I currently have SCP midlength headers, and a dual 2.5" pipe setup with magnaflow resonter and mufflers. (18" res, 15" mufflers)

Here's my ideas:

1: Wrap the ceramic coated headers to try to reduce the "farm truck" sound the headers make.

2: Re-install catalytic converters

3: Use the longest magnaflow resonator I can fit in there

4: Build a 3" center section instead of the dual 2.5 pipes I have now.

5. Use two large OEM style mufflers out back, maybe something like what they use on the Lincoln Navigator or Escalade..

I just spent 8 hours detailing/waxing the SC yesterday. Its such a classy looking car, and it would be nice to add some more refinement to the car by installing a quiet exhaust, even if it cost me a few hp..

Thoughts?

Jeramie
 
1: Wrap the ceramic coated headers to try to reduce the "farm truck" sound the headers make.

May get rid of some sound at a cost of header life expectancy

2: Re-install catalytic converters

Definately will make a difference. I have found the higher flowing the cat, the less noise it removes

3: Use the longest magnaflow resonator I can fit in there

Go with a dynomax standard resonator and not an ultraflow or a magnaflow

4: Build a 3" center section instead of the dual 2.5 pipes I have now.

That will help immensely

5. Use two large OEM style mufflers out back, maybe something like what they use on the Lincoln Navigator or Escalade..

I'd two standard dynomax turbo mufflers in 18"

You may want to look into some good sound insulation. You can do the firewall and floorboards. That should make a substantial difference as well

And make sure the tips of the mufflers pass the rear bumper cover somehow
 
should be easy, you'll loose maybe 20hp. Converters will cut noise right now. Otherwise add a resonator for sure. You could add a couple Thrush or cherry bomb old school mufflers if you have true dual out back. They are small, and typically filled with fiberglass. Then run some long mufflers out back. Most of those are fairly quiet until you put your foot down.

For 350hp, most of your noise will be from the blower.
 
As far as motor noise..Insulate the hood better, insulate interior firewall better, use an airbox and if using a metal intake...WRAP IT
 
Given the number of fairly quiet super sedans making 400+hp, I'd say yes. My 320hp XJR made zero noise, AND it was spinning an M-90, too.

I'd add mufflers wherever they fit, and glasspacks wherever there's a straight enough section to put them. You should be able to do this without killing flow too much, but you'll pick up weight from the mufflers.

Which gas tank do you have? I'll be taking on the task of quieting a 5.0 this weekend, '91 style tank. All I'm going for is "tolerable" right now. :p
 
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Given the number of fairly quiet super sedans making 400+hp, I'd say yes. My 320hp XJR made zero noise, AND it was spinning an M-90, too.


On mine I drilled the air cleaner lid just so I could hear a little bit of something...anything !

Cheers
DD
 
I want a near oem type quiet exhaust.

Are you referring to the drone you get in the interior?
Are you willing to have an exhaust note when standing outside if the car?

I can tell you this. I have a 350 RWHP car and I now only have a small drone in the interior. I just put 9 hours behind the wheel driving it, I can sure live with what little drone I have. But the car does have a very nice throaty exhaust note at idle. I can thank DD for 99.9 of the exhaust work.

My car did have a very bad drone in the interior and I was able to quiet it down by adding a few inches to the exhaust tips (.1 of exhaust work).

I know Ken Wagner's car is capable of 350 RWHP and his car has no drone in the interior. I just drove it for 3 hours.

I believe one of the big secrets to a quiet (interior wise) car is having the exhaust tips exit pointing strait back from the rear of the car and not have a down turn at the rear of the car.
 
I believe I can hear your exhaust over your AR.

You don't hear anything but an MPx on mine, and that's at only 15% OD.

 
The supercharger can whine all it wants. I like the loud SC whine, that's the main reason I drive two supercharged cars. When I bought my GTP my first mod was a 4" fenderwell intake kit.

I'm referring to the drone, and overall level of noise from the exhaust.. I had cats on this setup before the auto swap, but had to remove them for a temporary solution until I can re-work the downtubes to clear the deep 4R70W pan. THe cats quieted it down quite a bit to where it was "tolerable"

My tips point at a 45* angle and extend about 3/4" past the exhaust cutouts on the rear bumper.

I'm trying to keep the sleeper appearance. With the raspy exaust, I'm attracting civics and riced out compact cars.

I do like the sound of a BMW strait 6 with a mellow exhaust, smooth and authorative.. I wouldn't mind having a smooth sound like that.

Jeramie
 
David,

Your exhaust is definitly louder than mine, but somehow sounds smoother. Mine gets this crappy burble around 2,300 rpm that's alsmost as bad as a fart pipe on a 4 cylinder.

90blkbrd, that MPX is much louder than my MP1. Holy crap, I like that :D

Jeramie
 
Anyone notice that the 5speed exhaust sounds sportier than the AOD? I like the way it sounds and its not harsh at all. Just a bit more rumble than my auto car's tone. So whatever Ford did for that setup might be worth looking into. One thing that comes to mind is the EGR vs. 3way cats.
 
For your listening pleasure.

http://s156.photobucket.com/albums/t18/mjmenke/2007 Lincoln dyno tune/

Rodney, Mike, and Paul are MPx. Rodney and Paul are at 25% OD
Ken is a MP112 (we now believe at the end of this run the blower started to seize)
Mike H is a un-ported early style (soon to be AR)

Here is my first attempt at removing the drone. I think the drone was almost non-existent, but this length looks horrendous.

rearview.jpg


DSC01486.jpg
 
i have really bad drone now and the tips kind of look like that, but i also need a resonator, so we'll see when i get the res.
 
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