Extractors on AU

[StealthAu]

Already have mild steal 2.5inch system with extractors. Plan on upgrading after getting headwork later on in the year

[loxxr6]

Was speaking to rob herrod and a few other exhaust blokes and they reckon that our 6 cylinders will lose power with a three inch exhaust

Do a search, there's been plenty of discussion over whether a 3" exhuats will lose you power or not. Forum member Stiddy has one on his AU.

[The Monty]

And it is deffinately not losing power.

[sprjenkins]

how does stiddy's go, did a quick search didn't find anything on the 3 inch exhaust

[The Monty]

AU XR6 series 1 -
14.911@104.65mph (LOL go figure that one) 2.064 60ft! [I]
137.2rwkw on Autotech's Dyno

[sprjenkins]

that's pretty quick for the power no? Is he running big diff gears or a high stall? or is it that autotech dyno is really conservative?

[OED666]

well, i am also going a 3" exhaust in the coming months. i picked up a new 3" high flow cat for $90 at a swap meet. (yes, its definitely a high flow and brand spankers)

I am buying an off the shelf 3" tailpipe, and Rollin and I are making the centre from the extractors to the diff.

I am getting it all tuned now as it currently is, and then with the 3". if it makes more power then i am selling the old exhaust, which is 6 months old anyway.

[Stav]

Originally Posted by sprjenkins

Was speaking to rob herrod and a few other exhaust blokes and they reckon that our 6 cylinders will lose power with a three inch exhaust and that it won't help to replace the cat unless its stuffed.

Rob Herrod..I love his posts , his work and sounds like a top bloke but here I am openning a can of worms. 3 inch works well on a six.I was joking about a 4inch exhaust some time ago but I may well try that too. 3 inch exhaust will gain you power everywhere when done properly.
I was told by sureflo exhausts the same thing and I have proven them wrong!! Old wives tales like those are responsible for many a slow au fords.

Bring on the commies I say!!! out: :dr_Evil:

[Bucknaked]

Well I have an exhaust on my car. And the one thing I have noticed is that the car is louder, it really drones and it vibrates my jack loose. Apart from that, it's awesome. I haven't noticed any power increases, but its a 6 and how much can I really hope to gain that's worth noticing : Other thing is the car is thirstier.

[b2tf]

Originally Posted by Bucknaked

Well I have an exhaust on my car.

most people do bucky. difference is, theirs doesnt have stripes running down the pipe like yours. :

[JC]

Originally Posted by The Monty

AU XR6 series 1 -
14.911@104.65mph (LOL go figure that one) 2.064 60ft! [I]
137.2rwkw on Autotech's Dyno

Be interesting to see the same car as it did that run, but with 2.5" - I reckon there'd be bugger all in it. A 4.0 NA I6 just does not NEED a 3" exhaust. 2.5" is plenty. Of course, you can fit a 3" if you want, but I would guess that final rwkw difference would be max of 5rwkw, and there's better ways to get 5rwkw than spend twice as much on a 3" system when compared to a 2.5" - cam for example.

[jonbays]

Originally Posted by The Monty

AU XR6 series 1 -
14.911@104.65mph (LOL go figure that one) 2.064 60ft! [I]
137.2rwkw on Autotech's Dyno

Where did you get that TS from? 104mph ! the ET and the rwkw all make sense for an XR6 but not the mph thats got to be a mistake.

[Casper]

Originally Posted by jonbays

Where did you get that TS from? 104mph ! the ET and the rwkw all make sense for an XR6 but not the mph thats got to be a mistake.

It was done at WSID and even Stiddy knows the TS was some sort of timing error. Nothing uncommon, MPH timing errors happen a fair bit. I've had some interesting TS readings done on my car at some race meets too.

[private9]

Originally Posted by au2sw

im considering pacies and 2 1/2 system on my wagon, but local exhaust guy says the drone is terible, the ford cat is good enough (after asking for a hi flow cat) and that even putting resonators in, the drone will still be annoying? has anyone had this prob or is it just bs and the guy doesnt want to do it?

I've got a 2.5" Redback system (standard headers) on my AU wagon (with the optional second muffler) and it is not droney at all. It is a touch louder and deeper when cruising, but generally speaking most people wouldn't pick it as modified. Wagons generally do drone more than sedans though, hence the 2nd muffler option that I chose.

I've also got an EL sedan that had a Redback with just the single muffler and that was much louder, definite defect material, but the cat was gutted as well so that may have an impact on the noise levels (I didn't gut the cat, bought the car to wreck and found that when I pulled it out).

I've got another EL with Pacemakers and a Redback exhaust with the second muffler option, and that's very quiet, probably quieter than my AU.

Hope that's a bit of helpful info for you!

[Mark351]

Some of us with 2.5" exhaust are doing faster times than 14.91. I believe Terry's six has a DeFilipo/2.5" exhaust setup. and he's 14.2s.

[StealthAu]

Originally Posted by DeathXR

Some of us with 2.5" exhaust are doing faster times than 14.91. I believe Terry's six has a DeFilipo/2.5" exhaust setup. and he's 14.2s.

Yeah, but you can’t do a comparison with 2 different cars, with different drivers and presumedly different work done to them

[Mechan1k]

AFAIK Stiddy has the 3" exhaust ... diff gears .. and a strengthened manual and heavy duty clutch.

engine internals are stock.

[The Monty]

So whats the difference between the 4499's and the 4480's? Is there any difference in the max torque, and max power? What about the curves, and whats the midrange like?

[mattp]

You hear so much different stuff. I am mainly after low end torque if possible, not so concerned with top end stuff. The 4499's should suffice right?

[Mechan1k]

For more torque with basic mods ... get the 4499s (LPG model) ... they don't stick out as far as the 4480s.

I could only get the 4499s in as I have an LPG coverter in the way ... and it ONLY just fits too.

I found bottom end was the same ... but mid range punch was better (especially when it came to hills) ... also overtaking on highways and freeways it was better as well. Highway fuel consumption has dropped as well as it doesn't work as hard.

[99XR6]

i've just had the comps put on, and down low i can't notice any difference, but when the revs hit about 3000 it pulls much harder.

[jonbays]

Originally Posted by 99XR6

i've just had the comps put on, and down low i can't notice any difference, but when the revs hit about 3000 it pulls much harder.

This is what you would expect with the comps the tuned length working well in the engines peak power band which I find is more in the 4000-5300rpm range with the dev5 of course.

With stock cam I found the comps actually produced more low end and top end power but only marginally more in the mid range where I guess the BBM inlet and stock exhaust were well tuned to work from the factory.

Have a look at the before and after graphs in my gallery and you will see what I mean