quote Originally posted by GraterFang: True, compressed gases will flow faster but a bigger pipe will still allow for an overall equal or larger volume of flow, correct? As far as "breathing" is concerned a larger pipe will always have more potential. I may be wrong but that's how I understand it. However, I would agree that compressed gases are still better as they allow for backpressure which keeps air from rushing into the exhaust. In the end this is why too much pipe will start having negative results or so I understand.

Primary pipe diameter is far more important to ultimate engine power than the pipe length. Equal length means balanced cylinders. Header pipe size is a compromise between exhaust gas velocity and the pipe diameter sufficient to handle the mass of gasses flow of the exhaust. Smaller headers increase gasses velocity. This is an advantage at low and mid range rpm. A good muffler can actually increase mid rpm torque.

http://www.fastfieros.com has engineering documents from a Chrysler engineer that help design exhaust systems in 1994.

I am also a proponent of using a muffler with a 3" inlet and agree with darkhorizons assessment in that anything smaller will choke the 3800's horsepower. My 3800SC uses a Flotech Afterburner muffler. It is a very non-restrictive muffler and has a 3" inlet with dual 2 1/2" outlets and its small enough (13") that you can design an exhaust system that will fit with no trunk modifications.
The muffler is loud and throaty sounding but with the edition of Hedman Hot Tips resonators and some extra sound insulation ( under the deck and on the firewall) the sound is passable on the highway.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

That sounds quite good. Did you notice a significant change in the exhaust sound from the 1.9 rockers?

quote Originally posted by Jrgicehc: here is my exhaust setup, i used a flotech afterburner and did not cut the trunk http://www.youtube.com/watch?v=jVORSX0fzsk

the 1.9 rockers were my starting point so I dont really know how much of a difference it made. in my opinion it did make it sound like it had a little cam lope. I have an XP cam now and I think my rockers sounded better.

The resonator tips might be a good idea, I get hassled with my car alot.

quote Originally posted by GraterFang: That sounds quite good. Did you notice a significant change in the exhaust sound from the 1.9 rockers?

None from rockers.

A cam typically does not change the sound of wide open or part throttle, only idle.

I just realized that the manifolds are actually a bit less than 2.5" ID. In this case, does a 3" exhaust from here to the muffler really provide ANY advantage over a 2.5" pipe? If so, does this advantage come from less restriction at the inlet for the muffler? Aftermarket parts sometimes show up in 3" but is there an advantage without them?

Also, if yes, can a 3" flange be used with a ~2.5" manifold? I'm assuming this is where the size change begins...as then later a different manifold or headers can be added. Is this a correct assumption? OR...would one use a 2.5" flange with a pipe that goes from 2.5" to 3" and then to the muffer?

Thanks to everybody for the info so far

[This message has been edited by GraterFang (edited 08-08-2009).]

quote Originally posted by GraterFang: I just realized that the manifolds are actually a bit less than 2.5" ID. In this case, does a 3" exhaust from here to the muffler really provide ANY advantage over a 2.5" pipe? If so, does this advantage come from less restriction at the inlet for the muffler? Aftermarket parts sometimes show up in 3" but is there an advantage without them? Also, if yes, can a 3" flange be used with a ~2.5" manifold? I'm assuming this is where the size change begins...as then later a different manifold or headers can be added. Is this a correct assumption? OR...would one use a 2.5" flange with a pipe that goes from 2.5" to 3" and then to the muffer? Thanks to everybody for the info so far

Consider that you have TWO manifolds feeding into one pipe. Thats why a 3" exhaust is benefical. You can buy a flange that will allow attachment of a 3" pipe to the 3800 exhaust flange.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Consider that you have TWO manifolds feeding into one pipe. Thats why a 3" exhaust is benefical.

Even though the manifolds collect before the flange? Regardless of how much is feeding into that point there still seems to be a restriction there that would limit the usefulness of a larger pipe following the flange. I believe you and think that you are right I am just trying to make sure I understand properly.

quote Originally posted by Dennis LaGrua: You can buy a flange that will allow attachment of a 3" pipe to the 3800 exhaust flange.

Would this be like the 3", 2 bolt flange that zzperformance sells or would I be looking for something different?

http://www.zzperformance.co...php?id=776&catid=110

Thanks for the help

The "exhaust" as far as anything after the header/manifolds go, the bigger the better. Even if the outlet of the system is small (stock manifolds outlet to 3inch), adding on extra size behind that DOES increase flow.

IMO anything less than inch on a 3800SC is a restriction, and bigger could most likely show some gains.

I guess I'll take it on faith.

Any pointers for what 3" flange I would need?

quote Originally posted by darkhorizon: The "exhaust" as far as anything after the header/manifolds go, the bigger the better. Even if the outlet of the system is small (stock manifolds outlet to 3inch), adding on extra size behind that DOES increase flow. IMO anything less than inch on a 3800SC is a restriction, and bigger could most likely show some gains.

Hot Rod Magazine did an article on this over the last year or so, larger was always better. The rule of diminishing returns certainly applies, but their conclusion was that bigger had no performance down side.

Borla might be another choice.

Essentially any straight through muffler is great for sound, low backpressure, and durability, as long as they're not fiberglass. Magnaflow and Borla have stainless steel wool, which is much more durable than fiberglass flakes.
Flowmaster tends to be more restrictive, and in climates with a lot of salty air, the welds inside, on the baffles, tend to crack over time.

Remus, while similar in construction to Flowmaster, tends to have a nice European sound.

Having owned a Borla in the past on my Mazda, I would say, I really loved the sound of it. I liked how the sound changed to very European when flogged, much higher pitch.
Magnaflow sounded more mellow and deeper.

You're right, I've always heard nothing but good things about Borla systems. It's definitely a consideration but so is price.
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Still no leads on what 3" flange I need? Is this something a generic will take care of like the zzperformance link I posted above?

[This message has been edited by GraterFang (edited 08-10-2009).]

Good luck getting a Borla muffler for our cars... Used is the only thing now from them - private party... Borla said that we have to have an order of 50 cat back systems for them to even consider making them again for our cars. 700-800 dollars is the ballpark...

I still think that if you had a 502 or 440 or even a 383 cid, yeah 3" is the way but I think it's over kill for our size engines... the gasses would get loss and stay in the pipe because of expansion. They would eventually get out... Don't get me wrong.... Just my thought. Now if I were running a turbo or a SB it would be a different story. get the gas out quick with a shorter pipe and cat only for a dump out... no muffler.

I haven't seen this mentioned in this thread yet, so here is the setup I went with:


(found in lildevil's thread)

Tips:


No trunk cutting involved. My system is 2.5" before the cat and 2.25" after. I've very happy with the look and sound of this system. Its fairly loud, but I've had several people tell me they thought it would be louder. With the 3.6" pulley the SC whine is more noticable than then exhaust inside the car under heavy acceleration

I'll see if I can get some video later this week.

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http://www.raceme.cc/helmet/

quote Originally posted by GraterFang: You're right, I've always heard nothing but good things about Borla systems. It's definitely a consideration but so is price. . . . . Still no leads on what 3" flange I need? Is this something a generic will take care of like the zzperformance link I posted above?

I got my flange at an exhaust shop, *shrug*