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Exhaust system performance
Posted: Sun Jun 13, 2004 5:03 am
by ellusion
How much of a performance gain should i expect from a cat-back mandrel exhaust system??
Does a high flow cat (eg. 8L) give any gain?
Posted: Sun Jun 13, 2004 11:05 am
by ruchi
Does this "exhaust system" include new headers too or just everything that is behind the headers?
Is this a custom job or off-the-shelf?
What gains has the supplier suggested it will give?
Who's doing it?
Posted: Sun Jun 13, 2004 11:27 am
by ellusion
Just a cat-back exhaust is fine and wondering if changing to a high flow cat will be even better.
I would like to get a custom job from a reputable exhaust workshop but just wanted to know if there are any significant gains.
Its a GX so i can't use the UAS front piping....
Whate gains are you guys achieving? 5-10kw atw??
Posted: Sun Jun 13, 2004 1:53 pm
by Boris
Changin to a high flow cat ofcourse will make it better...

But you see I think you will only notice the difference if you already have a cat back exhaust and a good air intake...
It's hard to say by how much with all the mods, it's not like it's maths

But ofcourse there will be a difference, more importantly the slight torque improvement...
IMO first concentrate on the air intake side...
Just me 2 c...
Posted: Mon Jun 14, 2004 2:47 am
by ellusion
i have got a k and n panel filter coz thats as far as my insurance will let me go. Now its the exhaust i would like to play with.
Does gaining power from an exhaust mean that the engine power has been increased?
Eg. in a gpx, the engine produces 147kw... and say 90kw atw. An exhaust simply gives more flow of air thus giving more useable power right? The engine would still be producing 147kw....
Posted: Mon Jun 14, 2004 11:32 am
by ruchi
To over-simplify the process, the induction system is like your lungs, the fuel system is like your stomach, the engine is like your heart and the exhaust is like your bowels

.
By upgrading your exhaust system you are increasing your ability to get rid of the "waste" but unless you're taking in more through your induction (lungs) and fuel system (stomach) the improvement won't be as great and probably not worth the money.
To get really graphic, a restrictive exhaust system is like being constipated. Because of the extra back pressure you will be more sluggish and won't perform too well. Alternatively if you go for too large an exhaust you will have too little back pressure (diahorea) and will also experience problems.
The key is to understand that your car is a "system" and as such you must "tune" each of the components that make up the system. Changing just one will yield little result if it doesn't relate to the rest of the system. Even worse, upgrading one component can actually make the rest of the system perform worse if it is not matched correctly.
If you can breath easier, you're getting the food you need and you can expel the waste without any issues, then your heart will be able to pump harder and more easily (i.e. put out more power). So yes, if you upgrade your induction system and exhaust system the KW output of the engine can also increase.
I am
very surprised your insurance company will let you modify the exhaust if you are not allowed to modify the induction system.
Posted: Mon Jun 14, 2004 2:41 pm
by Hellsmurf
love the analogy there ruchi

Posted: Mon Jun 14, 2004 7:51 pm
by RallyMad
I've got a great example of what Ruchi is talking about.
The laser TX3 (B6 1.6 non turbo) that I have at the moment was modified a little before I bought it, and has what the guys I bought it from liked to call a tuned lenght exhaust. A term I'd never heard before relating to the whole exhaust but only the extractors and I know that it means equalling the distance that air flows from the exhaust ports in an engine so that they all flow equally right, and therefore gain more power (from the bowels if you like_
But anyway my car has a full exhaust with extractors (which I don't trust) into a 2.25 inch pipe to a resonater and 2.5 inch back to a muffler with a 3 inch dump out, now I feel as does my mechanic that this exhaust system is way to big for the stock engine, I have lots of idle issues which I'm sure are caused by this as well. And I also feel that even though the car has great response high in the rev range and seem like it has good torque I feel that I'm losing power compared to if I had a system better suited to my stock engine and induction, which will also be suitably modified in the futuer

Posted: Mon Jun 14, 2004 11:42 pm
by G_A_V
if you get a high flow cat system ,you should be able to use the unique front pipe. the reason its not recommended for non mivecs, is because when installed on my car, we noticed the cat inlet was slightly smaller then that used on the mivecs (this may of been a doggy compliance place sticking on any cat, because the cat needs to be changed when compliance, and many doggy places weld together anything). So anyways when installed with the slightly smaller cat inlet it created a lot of turbulence and ended up loosing a kilowatt and a couple more when the ecu adjusted.
Basically the unique front pipe should work for non mivec (6 cyl) engines, because the front pipes on the mivecs, and non mivecs are exactly the same
So hopefully when the tax man pays me a visit i will invest in unique front pipes, high flow cat, and rear muffler. Then ill be able to show you dyno chart differences with these modifications done on a non mivec.
Posted: Tue Jun 15, 2004 1:46 am
by ellusion
whats the size of the piping going to the cat?
If it's 2.5" then it should fit perfectly with a 2.5" high flow cat right?
Posted: Tue Jun 15, 2004 10:37 am
by RichardH
ruchi wrote:a restrictive exhaust system is like being constipated.
Okay. Now I'm REALLY getting worried about you East Coast lads!!
- Rich
Posted: Tue Jun 15, 2004 11:03 am
by GPXXX
RichardH wrote:ruchi wrote:a restrictive exhaust system is like being constipated.
Okay. Now I'm REALLY getting worried about you East Coast lads!!
- Rich
don't mind him richard, he's only speaking on his own behalf...

Posted: Wed Jun 16, 2004 6:29 pm
by ruchi
Posted: Wed Jun 16, 2004 9:59 pm
by GPXXX
no, we don't want to hear about your sexual fantasies...
Posted: Thu Jun 17, 2004 9:18 pm
by hnm738
i got a sports muffler
i went to do my exhaust today
and the guy told me if i was to change to a 2.5inch exhaust from cat to my muffler it makes no power or performances difference
is this true?
Posted: Fri Jun 18, 2004 12:12 am
by Jono
hmm so wats a laxative then?
Jono
Posted: Fri Jun 18, 2004 11:23 am
by GPXXX
a chemical to ease anal exploits...

Posted: Fri Jun 18, 2004 11:26 pm
by YMY671
guys where can you buy aftermarket exhuast?
i havent seen any for fto at all...besides custom ones.
i actually want the hks superdragger/5zigen/apexi N1
but what is the 5zigen like?
Posted: Sun Jun 20, 2004 7:37 pm
by EURO
depends where u are from mate?
in melbourne places like hypertech stock the N1 apexi exhaust for FTO, and im sure there are many others....
or go to
www.perfectrun.com.au - they stock the n1 as well, at the best price ive seen. I think they are in syd.
Posted: Mon Jun 21, 2004 11:35 am
by GPXXX
YMY671 wrote:but what is the 5zigen like?
sounds like HEAVEN!!
