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T5 Expert Operator
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Discussion Starter #1
Yeah i'm thinking to get abit more power from my car by fitting a high flow cat. Will it give abit more power than standard cat???? Can anyone comment.

Myinterpretation of exhausts is that it makes more of a difference at the engine end then the back, ie if you change the back muffler it would do bugger all apart from noise.

This leads me to another thing about crappy exhaust noise. I hate cars that have these loud and a bad exhaust note.
Thats why i'm abit wiery of changing my exhaust. i want performance but i quite like the stock sound, cause while a good exhaust note is always better trying to get a good note is friggin hard.
We got a turbo exhaust fitted to our EB wagon the middle section of the exhaust and it sounded pretty crap.
 

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Pursuit Reincarnation Dog
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Matey!!!! The extractors, engine pipe and cat would be the first place I'd hit. To be entirely honest, the Ford exhausts on the EF aren't that bad for flow etc. The extractors will make a HUGE diff - trust me! Buy stainless components to the rear of the cat as a minimum so the cat doesn't get blocked up by corrosion particles.
 

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I wouldnt bother about a high flow cat, youd be lucky to get 5hp out of one.

Just go with extractors, 2.5inch pipe, flow through muffler and a resonator, with all that it will sound like a beast :D
 

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T5 Expert Operator
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Discussion Starter #4
Yeah as i said i don't want it to be loud, or sound like those ricers who try to imitiate V8's.
 

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T5 Expert Operator
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Discussion Starter #6
Chris,

I shouldn't effect insurance in the sense that i'm getting only a high flow cat. So it's pretty legal. Having a high flow cat will only increase power but won't change the sound of the car. I have already changed my exhaust from the cat back (only a replacement stock system with a tip).

I am after something that will give my car abit of power and a few kw here and there is what i'm after, as i cannot spend too big on go fast mods yet.
I still have to get a set of shocks for the rear, considering a tower brace and perhaps nolethene bush's.
:eek: :eek: :eek:

I'm still looking into getting a cold air induction setup as well. So all in all i'm targeting about 118kw - 120kw at the wheels.


:D :D
 
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EF
I think I owe you some prices and quotes, for the setup too, dont I. Correct me if I'm wrong.
 

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Pursuit Reincarnation Dog
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Martin said:
I wouldnt bother about a high flow cat, youd be lucky to get 5hp out of one.
Just go with extractors, 2.5inch pipe, flow through muffler and a resonator, with all that it will sound like a beast :D
I would definitely go for the cat only because the original would be stuffed after the kays your car has done (if there is anything left inside it :wink2: )
 

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T5 Expert Operator
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Discussion Starter #9
Doc,
Yeah i think i did ask you a while back. I went to ford muscle parts they quoted me $250.00 for the setup of coldair induction and that included a K&N filter. I'd like to know the price for the cold air induction setup only without filter as i already have one.
 

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$250 for a cold air induction setup? Like a high flow cat its just a waste of money. Just go to the harware store and buy about 2metres of stormwater pipe and some connections. Cut a hole in the bottom the airbox and hook the pipe up.
Total cost $50 or so for the exact same effect.


Why dont you just get a mild cam? It will boost power to around 135+ at the wheels and they are pretty cheap and easy to install on the 6.

Here are some pics from the NSWXRClub

 

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Australian ED XR6 Member
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IMHO
The way u should go is to fit a 2 1/2" sports exhaust system with a single turbo muffler. Have fitted this on my XR6, with a noticable lift in performance (Still with a nice, quiet, note)
After fitting this I also fitted extractors to the car (with no appreciable performance boost noticed - although the car is still running the standard CAT)
If you're interested in the note, I'll be taking the girl out to the carshow at Homebush this weekend.
 

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Pursuit 250 Member
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The first mod I did to my EF XR6 was a genie 2.5" exhaust and genie extractors.. The car has not been dynoed but I was told to expect around 15kw extra to the wheels.. After hitting the dragstrip against other XR's at a club event, there was a serious difference between my car and other standard cars...

The next mods I'd be doing would be camshaft and unichip for around another 10 - 15kw at the wheels...

Does anyone have any "accurate" or dyno figures regarding high flow cats? I have heard many mixed reports but nothing on paper..
 

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My Brother fitted a 2.5 inch system and replaced the 3 standard mufflers with one sporty one to his EB2 Fairmont Ghia 4.0lt. He also knocked the cat out completly and fitted a set of stainless headers, this is the same as my setup except he has no cat at all and his car sounds like crap, he wishes now he had left the cat in so it sounded like my 3.9lt EA Ghia. And on a closing note the headers have done nothing at all for the 0-100 times or 400mt times to the car but the setup has helped the top end speed by about 8km/h to 219km on the trip computer.
 

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Pursuit 250 Member
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My EF XR6 has no drone to it, sounds quite good.. I drive it all day every day (travelling computer network specialist) and prefer driving it to my EL2 XR8... HOWEVER you can't beat the sound of a V8... if you bought a 6 for the note, you bought the wrong car!
 

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CEO - The BSR Group
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Petrol Hamster said:
I drive it all day every day and prefer driving it to my EL2 XR8...
I am troubled, my son... please explain... :eek: :confused:
 

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Australian Ford Member
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I tawt I saw a puddy cat

Think of your exhaust as a lenth of hose pipe with water running through it. Now imaging cutting the hose pipe, plumbing one piece of the pipe into one side of a Coke bottle, and plumbing the other peice of pipe into the other side. Would it make any difference to how much water flowed out the end of the hose? Nah. That's what fitting a bigger cat will do to yur system. You need bigger hoses... but only if you have more water flowing through them. Silly example but it's all I can think of at 19.30pm
 
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One thing I have learned over the years, that is when your building rods, trial and error will win the day.
Take this as gospel, and ignore everything else you've read or heard. If anyone doubts me, ring a well respected engine builder, who has the knowledge, not your mate, or some pimple faced teenager who got a job at blair's tyre service changing mufflers at the weekend.

For V8's up to 351ci all you need is a 2 1/2 inch system, choice of mufflers is up to you, pay under a $100 a muffler, and your a mug.

For 351ci and over 3 inch is tops, maximum, same again with mufflers.

There must be a pulse and a scavenge effect for a muffler and exhaust to work in harmony. matched ports are important. by all means the headers can be slightly larger in the ports, than the heads, but not the other way around. Engines need back pressure to function properly and a larger exhaust, say 3 or 3 1/2 inch on a 5.0 Litre is a waste of time. granted it looks cool, sounds nice, when it's idleing. Put your foot down on the gas and you'll do the 1/4 mile in around 8 minutes. (flat).
 

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Exhaust Backpressure is a myth! After the headers/extractors bigger is better if the vehicle is tuned properly!

Heres just a few quotes from some extensive testing that www.Autospeed.com has done on exhausts.

In all but one test I have ever performed, the bigger the pipe, the better the power. That exception was on a Celica 2.2 FWD, where I'm willing to bet that if the management system had been slightly retuned (eg low rpm ignition timing advanced) the power at low revs would have picked up over standard as well (it was already improved over standard at high revs). Thus, after the tuned length section of the pipe is finished (ie after the first muffler/resonator/cat converter), in a naturally aspirated engine you should go for a large pipe. In turbo cars, go for a large pipe straight off the turbo. Incidentally, note that over the last 40 years, the pipe size regarded by some as "too big" has been getting larger and larger every year!
Bigger is best - unarguably so on a turbocharged car. Post turbine, these boosted engines need to breath as much as possible and - therefore - the largest diameter tube will be able to carry the gasses with the minimum of restriction. Three inch is presently the largest commonly available diameter you can get - though 3½ and 4 inch are now starting to make their debut. There is some argument that a smaller pipe diameter (and therefore more back-pressure) is required for optimal performance on a naturally aspirated engine. This theory, however, is unproven where the fuel and ignition has been optimised to suit the pipe, and where the large pipe is used after the tuned length part of the system
Not so long ago here in Australia, a "big bore" 2½ inch system was regarded as THE choice of exhaust. Sadly, many people still believe this when it comes to making big power. So when these people see a mere 2-litre turbo engine with a 3-inch system, they invariably snigger. Blissfully unaware of their mis-information...

The fact is ANY engine - especially turbos - will benefit from the highest flowing exhaust possible. This generally means the largest possible pipe diameter, with the least restrictive mufflers to boot. So long as correct air/fuel mixtures are maintained and there is no detonation, we are yet to see a genuine dyno graph showing the contrary - regardless of the theoretical reasons some people give. (In a naturally aspirated system, the large pipe should start after the tuned length part of the exhaust.)

And remember, you shouldn't have to drop off their entire exhaust system when you take your "street car" to the drags. The difference shouldn't be that big, should it? Is it?!


If your a member of Autospeed do a search for exhausts and check out all the articles and make up your own mind!
 
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I'm talking 2 1/2 and 3 inch systems, which is headers and extractors. what you do after that is up to you. I have this combo on my cusso. 3 inch extractors, port matched, reliable mufflers, then 3 1/2 pipe to the back, simple.
 
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