True Dual Exhaust help 94 tbird - Page 2 - TCCoA Forums

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post #31 of 37 (permalink) Old 05-27-2016, 05:47 PM
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very exhausting
First off a good exhaust can give you more torque and more top end. Most people don't have a clue about firing order or tube size for torque, velocity, or scavenging. and the advantages of the H or X for pulse equalization.

The first thing you always need to remember is engine size and RPM because of a simple thing called physics you can calculate the volumetric efficiency of the engine and then you have a max flow in. Then you know spent combustion gasses going out will always be less than that amount. ( unless you supercharge or add NOS )
Any time you go larger than the volumetric efficiency you loose power as you are loosing the pulse of the exhaust to pull the charge into the next cycle.
If you go smaller you gain bottom end torque but too much you loose the top end RPM power.
Manufacturers build the exhaust for the base of the applications and make it emission friendly which also cuts on performance in most cases. They put a lot of research into the exhaust to get the performance to cost and emissions balanced out.
You can make a custom exhaust with 180° pulse cross under headers spiral collectors and tuned primaries to create the max for scavenging and mate it to a free flowing system sized to your needs but that takes time and money that most people aren't willing to spend. so we have to stick with the base mid line of performance that the afermarket manufacturers are willing to make hoping to make a profit without pricing themselves out of the market, SO choices are limited as to what you can just pick up.
As for function and reliability the factory exhaust is great but for performance going to a custom exhaust will help if matched correctly to application and engine demands.
The cast log manifolds are very restrictive but are great for being maintenance free, as opposed to headers which are great for torque and scavenging on upper rpms. but can be a maintenance nightmare warping flanges and blowing gaskets... so never cut corners on quality if you want reliability.

Sorry for rambling... I better stop or I'll get into the whole thing about stepping sizes and such to generate better pulse and help stop reverberation at lower speeds.
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post #32 of 37 (permalink) Old 05-27-2016, 06:55 PM
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Originally Posted by SCTbird1994 View Post
Its the same as any hobby .. making something your own and the experiences you create with it.

Im exactly the opposite end when it comes to "supporting" mods, I believe they are mostly to enhance after the fact instead of a pre-requisite. Take my SS Chevy for example .. almost 400 horses from the factory - and now I am considering the Borla cat back system. Mostly for the sound aspect to hear that 6.0 Liter motor leave Fords in the dust ( in reality, its been mostly WRX and STI's around here ) .. but its not necessary for the performance - its already there and can only be improved on. In the case of my Tbird, id rather put the money that could be spent on an exhaust, etc .. towards a better engine to have a real starting point.
I get that. I prefer suspension/braking before motor. Having more power is useless if I can't stop or get around something. The exhaust (unless you get headers) is one of the least expensive mods you can do, and has potential to help a performance build later (heads/cams/intake or a better overall motor) while still sounding better than stock.

But as you said, it's all about personal preference.

97 Thunderbird LX (The GT Bird)
2003 Explorer WAP block with Modular Head Shop "street ported" heads and Stage 2 PI NA cams, 75mm Accufab throttle body, C&L upper intake plenum, Kooks 1.75" primary/3" collector headers, 2.5" full exhaust with mid mount Magnaflow dual in/out muffler, 24lb/hr injectors, 80mm MAF, Tuning from Don @, CAI that feeds from fenderwell. Jmod, 3.73:1 TL in Mark VIII carrier, Mark VIII aluminum LCAs, 93 Mark VIII driveshaft, PBR brakes (soon to be Cobras), 18x9 wheels with 35mm offset, 255/40/ZR18 Tires, Front and Rear strut/shock bracing, GR-2 shocks, Eibach 1.5" springs, 1989 SC front and rear sway bars.
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post #33 of 37 (permalink) Old 05-27-2016, 07:30 PM
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I've never been methodical with this stuff, I just like upgrades and projects and I get/install them as opportunity presents. I'm not professionally racing the car, I'm not trying to meet some sort of rule book compliance, so so what if I do engine stuff before I upgrade brakes? I just need to get on them earlier until I do lol

Personally the way I go at things is spend absolutely little as possible, and do 110% of the work myself. With that strategy I'm sometimes faced with the choice between parts that fit my budget, and I pick the part or parts I think I'll have the hardest time getting later(for a good price) and focus on that as the primary project until it's complete. The whole "supporting mods" phrase is one I use but I personally don't follow, as it seems kind of silly - I'm MODIFYING a car, not building it from scratch afterall, I could argue that adding only power is a supporting mod to the v rated tires
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post #34 of 37 (permalink) Old 05-27-2016, 11:30 PM
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Originally Posted by steveg1988 View Post
I've thought about getting a true dual myself, but NJ does smog testing. On my car it ammounts to an OBD-II test.
What is the birth year of your car?

My understanding is, effective May 1, 2016, New Jersey no longer requires inspection of 1995 & older (gasoline powered) passenger vehicles with a GVWR of 8500 pounds or less. I had to look this up to get the specifics... But, don't take my word.

The New Jersey DMV sent me a notice stating that my 1994 T-Bird no longer requires inspection. YES!!!
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post #35 of 37 (permalink) Old 05-28-2016, 12:17 AM
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I too subscribe to the principle of doing things only once but with the exhaust you wouldn't want to install an exhaust system for a stock N/A engine that is more suitable for an induced engine especially if you don't have a tuner already. Sometimes though it's the deals we find in stores or online that dictate when we do certain upgrades.

Even though I can pretty much expect the nice shop I spoke to will still install a custom exhaust if I supply all of the parts, the local big performance exhaust shop insists that a tune is needed for any dual setup and that he would have to send it to Dallas. The asshole just has sooo much business and probably has something against MN-12s or only has boners for Mustangs, Chevys, or Dodges.

While I would love to go ahead and install a new complete exhaust I believe that there is such a thing as not enough restriction. I once owned a Kia Rio and I noticed a drastic decrease in low end torque after gutting the cats for the benefit of increasing the top speed by a few miles per hour. When it comes to my Cougar despite its gutted cats it seems to have a lot of low end torque and I have buried the needle long before I ever had the PI intake but I did have a chip with a tune installed. So, I think it's safe to say that the muffler and resonator are much more restrictive and I hesitate to replace the resonator with a strait pipe because of drone. Seeing as how the 3rd cat had been replaced with a Y-pipe back when I first bought the car all I really need are some turbo mufflers until new heads and cams are installed with the appropriate tune. I wish I hadn't hesitated to buy those ported stock headers that had been listed for sale because I assume they had taken out the ring that goes around the inside of the collector at the very least.

I'm limited on what I can do because my tune is one-and-done Jerry chip and I won't hit any need for a real tune until I do more than get the larger rear gears that are in this tune. I cannot justify any other upgrade if it requires a tune because of the added $250-400 minimum cost unless I happen to have at least a grand to burn because I'd want to install a newer PI engine in that case. That day will come soon enough but for now I need to save for that 3:73 built rear end with TL so my only drive wheel doesn't lose traction so easily and tries to kill me especially during a right turn or any WOT shift. I understand the true definition of being able to turn at intersections with just the accelerator or steering with your right foot.
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post #36 of 37 (permalink) Old 05-28-2016, 09:22 AM
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There's really nothing to be gained by getting a tune for just an exhaust system, headers yes(especially if you have a good cam).

Also gutted cats are not a viable way to increase flow in an exhaust and not at all comparable to a true O/R setup with real pipes in place of them, you've essentially created a couple big turbulence chambers right after the engine, and the cats themselves are not even particularly restrictive to begin with unless they're clogged. That turbulence is what you're noticing with the drop in low end torque, the loss would be virtually imperceptible if pipe of the same diameter were in the cat's place

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post #37 of 37 (permalink) Old 07-08-2016, 09:42 PM
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Originally Posted by TBird94 View Post
What is the birth year of your car?

My understanding is, effective May 1, 2016, New Jersey no longer requires inspection of 1995 & older (gasoline powered) passenger vehicles with a GVWR of 8500 pounds or less. I had to look this up to get the specifics... But, don't take my word.

The New Jersey DMV sent me a notice stating that my 1994 T-Bird no longer requires inspection. YES!!!
August 1995. But NJ does by Model year not year of mfg.
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