Big Block Sleeper Exhaust

reidsrods · Posted: Sun Feb 20, 2011 11:55 am Post subject: Big Block Sleeper Exhaust

Hey guys,
I have a 68 firebird with a mild 454 roller motor. Should be making approx 520hp. The exhaust is a set of ceramic coated Hooker street headers, 3" Torque Tech pipes, and 3 chamber flowmasters. I do not have a crossover pipe. The tails exit behind the wheels.
The combo is not terribly loud at idle, but the drone at cruise is terrible. Jump on it and it sounds like a racecar. I am looking to quiet things down. Any suggestions are appreciated.

jeep_406 · Posted: Sun Feb 20, 2011 4:23 pm Post subject:

Is it 3 inch all the way back? I'd think an x pipe will quiet it down some but all complete 3 inch systems I've heard have been on the loud side.
I have a 3 inch system with Hooker open chamber mufflers and it's louder under power than I really like but I was looking for performance.

reidsrods · Posted: Sun Feb 20, 2011 4:49 pm Post subject:

Yes, it's 3" all the way back.

MufflerBearings69 · Posted: Mon Feb 21, 2011 3:15 pm Post subject:

I have 3" duals with the same flowmasters on my galaxie- a crossover pipe (h-pipe) wont help any, I have one on mine.

Same problem- drone. I am hoping to try some other mufflers and see how it goes.

I honestly think my race bullets were much quieter in the car... Have considered welding them in and seeing how I like that setup.

10sec.et · Posted: Mon Feb 21, 2011 4:27 pm Post subject:

flowmasters are great..... if its 1987 and you have them on a bone stock mustang. way better choices in mufflers out there now. we use borla straight through mufflers with an x pipe and 3" tubing on all our exhausts. with a properly built system, the drone is minimal to nonexistent.

af2 · Posted: Mon Feb 21, 2011 7:40 pm Post subject:

Magnaflow is quiet! From my useless intro, the dynomax works also.
Nice quiet mufflers!!!

Skunkworkx · Posted: Mon Feb 21, 2011 9:16 pm Post subject:

My FlowMasters used to be bad about the resonance inside the car.... new cam changed all that Very Happy

http://www.youtube.com/watch?v=w8anGSYf1Xw

reidsrods · Posted: Thu Feb 24, 2011 10:05 am Post subject:

The Borla x pipe approach is too rich for my budget. Will likely swap out for a set of magnaflows. The cheapest/easiest way would be to add a set of glasspacks and leave the flowmasters as resonators, but I don't know how well it would work.

Paul P · Posted: Thu Feb 24, 2011 10:09 pm Post subject:

I have had the 3" Torque Tech system on my car for years with Stainless Steel Dynomax Super Turbo mufflers. It has a drone like all 3" systems. The only time it is a bit of a nuisance is on the highway. I'm not sure you have room for them but resonators might be the answer with an X pipe.

clay · Posted: Fri Feb 25, 2011 10:40 pm Post subject:

I second (or third - whatever) ditching the Flowmasters and going with a Dynomax muffler (I think they call them welded ovals now). I made switch and they are much better. One thing I have never had the chance to try is an idea from Ford. On the factory exhausts on the Mustangs I believe they used two different length mufflers to put the sound waves out of sync and help cancel the dreaded drone. Maybe try replacing one muffler at a time and just see what difference it makes. Maybe a Dynomax welded oval on one side and a Super turbo on the other. I have a friend with almost the same exhaust as Paul P and a decent 454 in a Monte Carlo - his mufflers aren't stainless, but still the same muffler and I'll have to say, it's a pretty quiet exhaust overall. Clay

reidsrods · Posted: Wed Mar 02, 2011 9:40 am Post subject:

Thanks for all of your inputs. I will post some db readings before and after. It will be a few weeks as the car is currently in storage.
Reid

10sec.et · Posted: Fri Mar 04, 2011 10:51 pm Post subject:

something else to consider is adding sound deadener like Dynamat. i drove the Willis we built today (see link in "new job" thread) and it was damn quiet inside (considering it has a 700+ HP Hemi) while going down the road. it has 2 1/2" headers, 3" exhaust, X-pipe, and Borla mufflers. the exhaust goes all the way to the back of the car but turns down just before coming out of the back. you cant see the exhaust looking at the car. i figured this would be loud as hell but the interior guys said they "put a sh!tload of Dynamat in the car".

SMOKEmUP · Posted: Mon Mar 07, 2011 12:33 pm Post subject:

The downside of dynamat is it's heavy.

MufflerBearings69 · Posted: Tue Mar 15, 2011 2:07 am Post subject:

Clay- the stagger the placement of the mufflers by a few inches on the 5-oh cars and I have heard thats what it was for... However, I have had some staggered muffler dronemobiles so I cannot say. Waiting for a reason to put my gf's 04 bone stock GT on the lift and ill throw a tape measure on the cases and see... Intriguing.