Dual exhaust question

[Gary H NC]

On my Chevy Tahoe 5.7 I had new exhaust run on it with high flow converters,2 new mufflers with no restriction and new tail pipes.So now it is true dual exhaust instead of 2 pipes going into one muffler with one outlet.
My problem is now it sounds like its spitting out of each pipe behind the truck.
I have read with this type of setup i need a X or H pipe installed.
I took it back to the exhaust shop and the old fart tried to tell me the engine is missing.I had a buddy with a very high end diagnostic laptop kind of reader hook it up and we drove it under load.It showed each cylinder was firing correctly.No codes,no problems.I even did a complete tune up,wires,plugs,cap and rotor..it was due anyway.
I'm ready to get out the saws all and cut those no name brand mufflers off!
Anyone ever hear of this problem because of no crossover or H pipe?
I'm looking at 2 series 44 Flowmasters and a Dynomax X pipe now.
The first 400 dollar exhaust job sounds like a helicopter..

 

[MikDee]

Re: Dual exhaust question

Hey Gary, We've discussed this before, yes an H-pipe, or X-pipe, will smooth out the sound, it usually gets rid of most of the popping. This idea has been around since the early 60's. What are you trying to accomplish? can I help you I've had a lot of personal experience with different mufflers, combinations.

 

[Gary H NC]

Re: Dual exhaust question

Thanks MikDee!
The exhaust guy that did the work said an X pipe is a waste...
It just sounds like its spitting out the pipes,kind of like header leak would sound.
All the welds are good,no leaks under the truck. I was wanting the Flowmasters but he was out of them,I found out what he sold me for mufflers are really resignators...or whatever they are called.I had another exhaust shop look at them.They look like glass packs but the second exhaust guy said they are even cheaper.
I can get the 44 series for 68 bucks each online and 83 bucks for the X pipe.
I know another shop that will weld it all up for me.
I like the sound of the 40 series on other trucks and thought it would breath better too...

 

[guy74]

Re: Dual exhaust question

Gary,
I agree that you need a X or H pipe to smooth out the sound pulses. I like large bore single exhaust systems just for that reason. I have a 1 ton chevy pickup, with 4.54 gearing, that has true dual exhaust (no X pipe). At 3500 rpms doing 65mph it resonates so bad that you can't hear anything in the cab. I have another pickup that is basically the same exept it has a 3.5" inch single exhaust, it is much quieter. I've been told that an X pipe would cure the resonating problem.

 

[Gary H NC]

Re: Dual exhaust question

Thanks guy74,Thats what i have been reading too.The more of a load i tow the worse it sounds also.I think those cheapo mufflers need to go.The guy that charged me 400 for them and the pipes will never get another dime out of me.
I have to drive with the windows up so i don't hear the spitting sound..It does have a nice deep tone though.

 

[VIPcole]

Re: Dual exhaust question

What size pipe did you run? And take a look at the magnaflow mufflers before you decide on the flowmasters.

 

[JB]

Re: Dual exhaust question

Exhaust systems are very sensitive to "tuning" to optimize extraction of exhaust gasses and minimization of racket. Guys like Stillen engineer those things as though they were engineering a sound system or a musical instrument.

Everything counts. Length, diameter, converter geometry, "muffler" geometry and. . .what you don't have. . .interaction of pressure pulses from different cylinders or different banks of cylinders.

I think you need Flowmasters, first of all, and you probably need and "H" or "X" crossover to allow the two banks to cancel one another's sharp edged pressure pulses.

 

[thefairlaneman]

Re: Dual exhaust question

Yo. I bet you can find the correct pipe on Ebay....

 

[Gary H NC]

Re: Dual exhaust question

Yea,I agree with the needing the X pipe.It makes sense to cancel each bank out.I originally had a single Flowmaster SUV muffler on it,2 pipes in and one outlet.It sounded fine with that until it rusted out.
I have the 2 1/2 inch pipes all the way back.
I had to have those 2 stainless tips hanging out the back... Should have put the single muffler back on it.

 

[MikDee]

Re: Dual exhaust question

All you need is a crossover pipe between the 2 otherwise known as an H-pipe, an X-pipe is even more effective but, first you need real mufflers on there, Flowmasters are Ok, but common, The New IMCO/Cherry Bomb "PRO's" are also a similar 2 chamber design, but make more of a Nascar sound IMO, and if you just want it abit quieter, but mellow, with very low restriction, a pair of Flowtech Afterburner Turbo mufflers, are the best of their type.

Here's a sample of the IMCO/ Cherry Bomb products, the "PRO" is like a 40 series Flow. but better, the "EXTREME" is like a 10 series Flow:
"http://www.cherrybomb.com/sounds-dynos/"

 

[cbear34]

Re: Dual exhaust question

Definitely install an "H" pipe. It will help balance the engine exhaust.

 

[JCF350]

Re: Dual exhaust question

I had to have those 2 stainless tips hanging out the back... Should have put the single muffler back on it.

Are you talking about out the back of the vehicle or behind the rear tires??

 

[GreatRiverDucker]

Re: Dual exhaust question

Hey JCF why did use the for the pipes out the back.

 

[JCF350]

Re: Dual exhaust question

Hey JCF why did use the for the pipes out the back.

This is an SUV. Tailpipes running out the back are no-no due to exhaust fumes. This why the manufacturers run the exhaust out to either just in front or behind the rear tires (the air turbulence breaks up and mixes fresh air with the exhaust). Not a big problem on pickups but with vans and SUV's it is, leave a rear window open or get a few years on the rear door gaskets and you'll be sucking exhaust fumes into the vehicle.

If I remember right they (out the back) are illegal (or used to be) in FLA on pickups, vans and SUV's even though the "LEO's" don't enforce it.

Of course there is always this on the noise issue:
FLA statutes
[SIZE=-1](5) NOISE ABATEMENT EQUIPMENT MODIFICATIONS.-- [/SIZE]
[SIZE=-1](a) No person shall modify the exhaust system of a motor vehicle or any other noise-abatement device of a motor vehicle operated or to be operated upon the highways of this state in such a manner that the noise emitted by the motor vehicle is above that emitted by the vehicle as originally manufactured. [/SIZE]
[SIZE=-1](b) No person shall operate a motor vehicle upon the highways of the state with an exhaust system or noise-abatement device so modified. [/SIZE]

 

[Gary H NC]

Re: Dual exhaust question

The tips are angled out just behind the rear tires,so it does not flow directly behind the vehicle.The truck has the barn type rear doors and the windows do not open.

 

[MikDee]

Re: Dual exhaust question

Here's a sample of an IMCO/PRO on a 2002 Silverado 5.3 V8:
"http://www.youtube.com/watch?v=zLP3wXr5wj0"

 

[Gary H NC]

Re: Dual exhaust question

Thanks MikDee,No sound on my work PC,will check it out when i get home.

 

[Benny1963]

Re: Dual exhaust question

hi gary i have run flowmasters bassani proflow and quite a few others
the flowmasters are quite loud if you run them strait out the back with tailpipes most of them will give you a slight popping sound like glass packs the x pipe or crossover tube will help in most cases and will also give you
some low end torque if placed right .borla makes a muffler that sounds really good ran out the back thanks for the help ya have givin me on some of my earlyer post
bennyb

 

[Caveman Charlie]

Re: Dual exhaust question

And, find a new exhaust man.

 

[Gary H NC]

Re: Dual exhaust question

Thanks Bennyb...I think i'm going to get the dynomax X pipe,looks like its the right size for what i need. Still have not decided on what brand mufflers.The Flowmaster 44s are on sale for 64 each with free shipping.
I'll need to save a few bucks first..

Cavemans got it right on the new exhaust man.
I'm going to drive 90 miles one way to get them put on by a muffler shop that has always done great work for me in the past.