XR8 cat back exhaust on a VCT XR6?

Cobra · 08-05-2007, 05:06 PM

Hi

I was just thinking today that theres no reason why an XR8 cat back exhaust couldn't somehow be made to fit on an XR6 VCT. If I remember correctly the XR8 exhaust is a twin 2" mandrel bent, which roughly would equate to about 2.75" diamater singally.

A 3" system may be too big, but a 2.5" system may be a little too restrictive for fairly serious mods (cams/headwork ect). Just like the BA N/A's, I think the twin system would make them sound tough while being a very cheap option if you can find a decent one.

galaxy xr8 · 08-05-2007, 05:55 PM

I've still got my cat back exhaust off my AUII XR8 in the shed.

Casper · 08-05-2007, 06:00 PM

Not worth it to be honest Eamon.. better off with a single exhaust setup. Looked into it myself. No apparent gains, twice the cost.

Cobra · 08-05-2007, 07:41 PM

Quote:

Originally Posted by Casper

Not worth it to be honest Eamon.. better off with a single exhaust setup. Looked into it myself. No apparent gains, twice the cost.

Twice the cost? Many people have them lying around (like galaxy xr8) and would sell it for next to nothing. Where does the "no apparant gains" come from? I would have thought a twin 2" system would have vast gains ovr a single 2 1/4" system? It just has me curious as the twin 2 1/2 turbo cat back has done wonders on our BA compared to the 2.5" redback system that was fitted to it previously.

Casper · 08-05-2007, 07:46 PM

The VCT's had twin 2" systems as standard, not single. The HP's had the singles. The engine wont use twin 2.0" pipes as the entire lot needs to go though 1 cat (no room to run twin cats). The end result is a single 2.5" system is easier, cheaper (single cat, single muffler, single resonator and single pipe), as efficient (no where near the number of flow direction changes) and simpler to replace/repair/maintain.

bodes-sh · 08-05-2007, 07:59 PM

couldn't you get extractors chopped back, then fit a 3" cat, then get a y piece made up to bolt/weld onto the cat, then onto the twin system?

Casper · 08-05-2007, 08:01 PM

Quote:

Originally Posted by bodes-sh

couldn't you get extractors chopped back, then fit a 3" cat, then get a y piece made up to bolt/weld onto the cat, then onto the twin system?

thats basically the VCT standard setup.. but its all going though one cat regardless.. the main restriction on the whole exhaust. Why split it, make it turn 5 times and then turn it all back to go out the drivers side (no twin system on an AU sedan.. fuel tank wont let you)?

bodes-sh · 08-05-2007, 08:07 PM

i guess it may benefit if you have your car dumped and turbo / s/c'd, if space is a restriction running a large diameter single pipe, or v8 supercar style, having twin outlets in front of the rear wheel....

HLC · 08-05-2007, 08:40 PM

i think it would work.

i think youve got things confused casper.

the BA twin system (ala the v8/xr6t exhaust- exiting on one side) on the NA6's is running through 1 cat.

so why wouldnt it work on an AU?

someone should try it. i am very interested in the results.

Casper · 08-05-2007, 08:48 PM

Quote:

Originally Posted by HLC

i think it would work.

i think youve got things confused casper.

the BA twin system (ala the v8/xr6t exhaust- exiting on one side) on the NA6's is running through 1 cat.

so why wouldnt it work on an AU?

someone should try it. i am very interested in the results.

yeah, its not like I own a VCT or anything.

stiddy · 08-05-2007, 09:00 PM

Waste of time, money, for what gain?
Really the only thing you will gain is bragging rights that you have a twin system like a BA does.. WOO HOO we all want that! pfft..

Stop pretending to know it all and listen to what casper is saying, its reality.. Go a single 2.5inch exhaust or a single 3inch exhaust..

HLC · 08-05-2007, 09:01 PM

Quote:

Originally Posted by Casper

yeah, its not like I own a VCT or anything.

heh.

ok but why wouldnt it work? its worked for the BA's and proven better than a single 2.5"

as far as i understood (my mums car is a VCT too) the VCT's had the twin system exhaust- the same as the xr8's only one pipe was blocked off. so it wasnt utilising both pipes in the exhaust.

how hard would it be to stick a dual flange on it and unblock the second pipe?

plext · 08-05-2007, 09:05 PM

Somebody should try a 1 into 2 into 4 into 8 system, it's bound to flow better as of course extra turns and splits are meaningless in flow terms, it's all about total area.

Backpressure? Who the hell needs backpressure? All the best race cars run without it.

Casper · 08-05-2007, 09:06 PM

Not hard at all. I was standard unblocked on the early VCT's just like the V8's. It isnt even close to the single setup. The simple fact is that 1 cat has to process all the exhaust. The cat is the main restriction. Why start twisting and turning it after that just to bring it all back to within 10mm of itself at the end?

As for the twin setup on the BA I6's being a proven benefit over a single exhaust.. I dont know about that either. Exactly how was it proven?

Hibbz · 08-05-2007, 09:12 PM

Quote:

Originally Posted by Cobra

It just has me curious as the twin 2 1/2 turbo cat back has done wonders on our BA compared to the 2.5" redback system that was fitted to it previously.

Has the twin system been compared to a 3" system??

FGII-XR6 · 08-05-2007, 09:28 PM

I would recomend the redback system it's engineered for the car and i belive they were developed with a dyno to get maximum gains i have one on mine and wouldn't change it

huggiebear · 08-05-2007, 09:38 PM

i just queeried blackers10 about this for my EA as i was after a unique sound. but he said there isnt too much power to gain and the cost isnt worth it... so ill stick to my 2.5 inch mandrel bent exhaust with extractors...

StealthAu · 09-05-2007, 08:48 AM

If you have a 2.5" inlet going into your cat, anything more then a 2.5" back exhaust wont provide any gains. Its that simple

Cobra · 09-05-2007, 05:45 PM

I didn't realise that the VCT ran a twin system also. My bad. Casper is right, there would be no point in doing this exercise.

Casper, as for proven, well theres isn't any before and after dyno proof as far as I'm aware. But seat of the pants proves a lot to me!

Casper · 09-05-2007, 05:59 PM

Quote:

Originally Posted by Cobra

Casper, as for proven, well theres isn't any before and after dyno proof as far as I'm aware. But seat of the pants proves a lot to me!

I have no doubt the twin setup on the BA is better than the stock exhaust or even some after market exhausts. I just find it hard to take that it can be called "proven better than a single 2.5" at the moment. I think thats just a bit too big a call to make just yet. It may well prove to be but at the moment the evidence one way or the other isn't there... yet.

bodes-sh · 09-05-2007, 08:28 PM

well depending on the cost of the exhaust for a ba, i guess it could be a "proven" bang for your buck mod over an aftermarket one, if it is in fact better...

Casper · 09-05-2007, 08:34 PM

Quote:

Originally Posted by bodes-sh

well depending on the cost of the exhaust for a ba, i guess it could be a "proven" bang for your buck mod over an aftermarket one, if it is in fact better...

thats the big question.. is it better?

bodes-sh · 09-05-2007, 08:36 PM

dunno, but if you could get a 2.5" single redback system for say $350, or an xr6t 2.25" twin for $100, which one would you take? surely the twin system couldn't have too many more bends than a single?

Casper · 09-05-2007, 08:39 PM

Quote:

Originally Posted by bodes-sh

dunno, but if you could get a 2.5" single redback system for say $350, or an xr6t 2.25" twin for $100, which one would you take? surely the twin system couldn't have too many more bends than a single?

On an AU it most certainly does. It takes a near on 90 degree turn straight after the cat and then does some serious loop de loops through the IRS at the rear. Then theres the long term costs of multiple mufflers and pipe replacement. Not to mention almost twice the weight (easy 10+kg's extra)

bodes-sh · 09-05-2007, 09:03 PM

seems like they didn't design it too well...you would think if they were going to put a factory twin system in they would at least make it more efficient than a single one...

Casper · 09-05-2007, 09:12 PM

When it comes to factory exhausts the Falcon's systems have almost always fallen into both the "cheap" and "nasty" categories.

bodes-sh · 09-05-2007, 09:56 PM

i guess with irs you could go wrx style and run a 4" pipe straight down the middle and under the diff, and have about 1" of height even at factory forte height before you scrape on anything, lol

FGII-XR6 · 10-05-2007, 12:45 AM

Quote:

Originally Posted by Casper

On an AU it most certainly does. It takes a near on 90 degree turn straight after the cat and then does some serious loop de loops through the IRS at the rear. Then theres the long term costs of multiple mufflers and pipe replacement. Not to mention almost twice the weight (easy 10+kg's extra)

I agree apart from the weight factor the redback system is a tried and trusted exhaust the perform well and sound GR8

Cobra · 10-05-2007, 05:09 PM

Well the clincher for me on the BA is the fact that the standard T system is twice the diamater as the factory one, it flows 560cfm with the restrictive centre mufflers still in place, and it can easily and safely flow 270rwkw on modified turbos without being a reall restriction at all. It does sound like the VCT stock system is rubbish though...

blu falc · 10-05-2007, 08:17 PM

I have a VCT Ghia which is a single system and has (3?) mufflers, is it worth upgrading to an XR6 system (twins)? I don't want to get a full "sports" system as I hate resonance and am not looking for it to be any louder, just free it up a little for a bit more performance and economy.