3inch exhaust .How to make it quieter ?

[Mark351]

As Monty says, the track is the best measure. Bum-o-meter is sometimes distracted by new noises and the subconscious justification of money spent but the ETs don't lie as I found out when I gained 6 tenths out of a Bluepower tune plus some tweaks.

Leaks suck, just had a leak in one of my header gaskets fixed on my new truck, ticking gone which ruins an otherwise sexy engine note.

Goat rocks, the Mitre tav in the Melb CBD has it on tap, beautiful stuff! Pick up a six pakc of the hightail ale from the bottle shop, you won't be disappointed.

[Stav]

I wonder if I can grab some of this Goat stuff here? Give it a go .. :
Yer I agree.A good tune is worth around .5 of a second down the track.

[JC]

Originally Posted by Stav

If anything,the 3 inch cat is to restrictive. I am going to see if I can fit a 4 or 5 inch cat.I had the car turning both wheels off the mark.Maybe the tune needs adjusting. The extra performance was from a 2.5 inch with a leaky cat to a 3 inch with a leaky cat. There was a big performance increase.This says leaky cat or not the gains are there to be had.The car stll feels much quicker than the 2.5 incher. So whoever doesnt back the 3inch just hasnt really done enough work on them.

From what I read in one of your earlier posts, you don't actually have a 3" exhaust Stav. You have some 3" and some 2.5", so overall, the 2.5" is going to be the effective diameter as it would be restricting the whole exhaust at some point.

[Damage]

Originally Posted by JC

From what I read in one of your earlier posts, you don't actually have a 3" exhaust Stav. You have some 3" and some 2.5", so overall, the 2.5" is going to be the effective diameter as it would be restricting the whole exhaust at some point.

hmm : I am thinking the cardboard book again here, if you read all his posts you can work out he removed all the 2.5", after trailing the 2.5" with the 3" cat, he also never fitted a rear resonator with the 3" system, well that is how I quickly read it. Am I correct Stav, or am I the one needing a Mr Men book?

[The Monty]

Originally Posted by Damage

hmm : I am thinking the cardboard book again here, if you read all his posts you can work out he removed all the 2.5", after trailing the 2.5" with the 3" cat, he also never fitted a rear resonator with the 3" system, well that is how I quickly read it. Am I correct Stav, or am I the one needing a Mr Men book?

Thats what I read also.

[JC]

Originally Posted by Damage

hmm : I am thinking the cardboard book again here, if you read all his posts you can work out he removed all the 2.5", after trailing the 2.5" with the 3" cat, he also never fitted a rear resonator with the 3" system, well that is how I quickly read it. Am I correct Stav, or am I the one needing a Mr Men book?

I read the same, but I didn't make assumptions about what I read:

Originally Posted by Stav

Put a 3 inch cat,muffler and left the rest at 2.5 inch.

To me, that means all the pipework is still 2.5", with ONLY the cat and muffler being 3".

Originally Posted by Stav

Recently I ditched the rear 2.5 inch resonator and piping.

"Ditched" does not mean replaced with 3".

Your book is in the mail.

[TE205]

Interesting times you ran with both systems. If you take away the difference in the reaction times, it looks like faster times were on the 2.5" system. Reaction time is dead time. According to the temperature too, it was 5 degrees hotter when you ran the slower time. The cooler and denser the air into the car, the more power it will make.
I don't think this really answers the question as to what system makes more power or torque.

[ratter]

reaction time does not affect the et


the et timer does not start until the reaction time beam has been broken

[The Monty]

Exactly, hence why you see the rotaries with huge as turbos, sitting there trying to spool up and have reaction times of 4 seconds, but still run 7's.

As for track conditions, 5 degrees I doubt would make that much of a difference.
Also, there was an hour and 8 minutes gap between the run before the 15.379, and on the 14.971, there was 56 minutes, Id say the extra 10 minutes of cooling down would counteract the 5 degrees ambient temp difference.

[Stav]

Originally Posted by JC

From what I read in one of your earlier posts, you don't actually have a 3" exhaust Stav. You have some 3" and some 2.5", so overall, the 2.5" is going to be the effective diameter as it would be restricting the whole exhaust at some point.

Yer I got a bit slack and havent updated the stingray build thread.I have had the back 3 inch added a few weeks ago just like the much bigger injectors I am running since May .I just have been plodding away in my garage and with spare time up the side of the road. Trying this n that.

The 2.5 inch remainder is sitting in my garage on the floor.

[gozza]

Originally Posted by The Monty

If you bothered to do any research at all, and pulled your head out of your crack, youd realise that three inch is a great option for the 6. OED666 runs 13.8 - 3 inch
XTC is a BA with twin 2.25's - 14.4's
I ran 15.379 with 2.5, 14.97 with 3 inch.
If you cant be bothered to do any of your own research dont bother giving your opinion.

OED ran the 13.8 with 2.5Inch

Now has BBM and 3 Inch gained 11 rwhp

[Stav]

Originally Posted by TE205

Interesting times you ran with both systems. If you take away the difference in the reaction times, it looks like faster times were on the 2.5" system. Reaction time is dead time. According to the temperature too, it was 5 degrees hotter when you ran the slower time. The cooler and denser the air into the car, the more power it will make.
I don't think this really answers the question as to what system makes more power or torque.

Timing starts at the track from when you break the first beam.The car did pull those times down a full quarter excluding reaction time. I have ported my own head from a book and got a bigger cam. The car has issues which will leave me stranded if I dont fix them. It doesnt really matter if I give you the cold hard facts as some people choose to belive what theyve been told by the "experts" . I can tell you that the experts are no less human than myself and arent always prepared to go the extra mile as a car enthusiast. I love the au's. Most experts dont because they havent been able to make em go quick. Now the ba's are the flavour of the day.A standard ba with a xorst has alot more power than a modified au six on dynos. At the end of the day I dont care because dynos pretty much suck!!!

[FS5]

was just reading those time slips and realised i'm car number 576.

[5L]

3 inch on a 4litre should be ok, lol ive got 5 inchs of pipe to fill on my 5 litre. mine is probably not the best option for power but for how it sounds its definately the best option.

as for dronning i found that the twin 2.25 to a single 2.5" that the exhaust shop put on first in error droned twice as much as the system now.

[The Monty]

Originally Posted by FS5

was just reading those time slips and realised i'm car number 576.

Yes you are, thats the only race I won all night, and only because you red lit, lol.

[StealthAu]

This thread is a joke, how many of you guys saying a 2.5" is the be all end all and 3" exhausts are crap have had one? How many of these "professionals" have actually done the R & D to determine that the 3" is inferior to the 2.5"? I'm guessing no one here has the answers I'm looking for.

[Damage]

Originally Posted by stockoau

This thread is a joke, how many of you guys saying a 2.5" is the be all end all and 3" exhausts are crap have had one? How many of these "professionals" have actually done the R & D to determine that the 3" is inferior to the 2.5"? I'm guessing no one here has the answers I'm looking for.

If you have the dosh try both, but to be fair use basically the same mufflers, bends etc in both sizes, sell the one that didn't work for you to someone in here as they will know it has little work.

Back in the 90's they used to say 2.5" was to big for a 6, they also said 3" was to big for a 351 Cleveland, weren't those tosses proved wrong.

[JC]

Originally Posted by Damage

If you have the dosh try both, but to be fair use basically the same mufflers, bends etc in both sizes, sell the one that didn't work for you to someone in here as they will know it has little work.

Back in the 90's they used to say 2.5" was to big for a 6, they also said 3" was to big for a 351 Cleveland, weren't those tosses proved wrong.

I guess nail and hammer have connected here. Though, to me, It's not really an issue of whether a 3" is actually too big for an I6 (despite the fact that I did say that earlier, and stand by it). The real issue, is whether a 3" exhaust, at roughly twice the price of a 2.5", actually gives you the extra $$$ benefit over a 2.5". I guess a time saving of 0.3 sec over 400m may be worth the extra cost to some, but not to me.

Also, does a 3" on an I6 really sound that good? I'd doubt it, and the fact that Stav is getting headaches from his tends to suggest it's not - by the time you muffle it so it is at an acceptable (and legal - by EPA standards) noise level, you've probably muffled out/restricted any extra power gain over your run of the mill 2.5" mandrel bent redback or lukey system.

Lastly, to say any I6 with a 3" sounds better than a V8 is ludicrous - nothing sounds as good as a V engine, whether it be 8, 10 or 12 (and yes, even V6). You cannot get the same clashing of exhaust pulses from a straight motor (boxers aside) that you get from a V. But everyone has their own opinion I guess, and some are entitled to it.

[OED666]

i have 2 mufflers in my exhaust. the one in front of the diff is 11x8 and the rear is 9x6 IIRC. Its probably quieter than my 2 1/2" with 2 mufflers and a 3 1/2" dump tip.

For a reasonably worked I6 3" seems to be good. I havent lost any bottom end power, even with my BBM stuck on short runners at the moment. I was told that fitting the BBM I would lose top end, but I gained.

I havent been back out to the track yet, but it will go better I believe.

[XRCIST]

I have a twin 2.25 inch on mine which is equivalent to a single 3.18 inch exhaust. Didnt get a before or after dyno run but i did run the car at the track after i got it done. My PB is 14.91 and i ran that back in june (no spare, low fuel and in cool temps) I went again a few weeks back with the exhaust being the only change and ran a best of 14.97 ( half a tank, spare included and MUCH hotter temps). I have no doubt that if i ran it in the same conditions as when i ran my PB it would have run an easy 14.7/14.8 Lots of people have had success with the twin systems and it also winds up being alot cheaper.

And the sound..........love it......couldnt have asked for a better note, sounds old school with an awesome snap, crackle and pop on the over-run.

With the BAs alot of "experts" were syaing that a 3 inch cat is not necessary that a 2.5" is the biggest you need and that even the stock cat is fine and a good unit. Well i think they would have been a little embarrassed when people were gaining 16rwkw over a 2.5inch hi-flow with the fitment of the 3inch and a retune.

Dont see it being any different on an AU, especially one with a considerable amount of work. Remember, professionals built the titanic and amateurs built the ark!!

[The Monty]

Originally Posted by JC

I guess nail and hammer have connected here. Though, to me, It's not really an issue of whether a 3" is actually too big for an I6 (despite the fact that I did say that earlier, and stand by it). The real issue, is whether a 3" exhaust, at roughly twice the price of a 2.5", actually gives you the extra $$$ benefit over a 2.5". I guess a time saving of 0.3 sec over 400m may be worth the extra cost to some, but not to me.

Also, does a 3" on an I6 really sound that good? I'd doubt it, and the fact that Stav is getting headaches from his tends to suggest it's not - by the time you muffle it so it is at an acceptable (and legal - by EPA standards) noise level, you've probably muffled out/restricted any extra power gain over your run of the mill 2.5" mandrel bent redback or lukey system.

Lastly, to say any I6 with a 3" sounds better than a V8 is ludicrous - nothing sounds as good as a V engine, whether it be 8, 10 or 12 (and yes, even V6). You cannot get the same clashing of exhaust pulses from a straight motor (boxers aside) that you get from a V. But everyone has their own opinion I guess, and some are entitled to it.

That wasnt the issue at all. Money was NEVER bought into it, the issue was is it a worse option than having a 2.5 inch.
Im guessing you havent heard an i6 with a three inch, you are just seeing whos buttons you can push. Stav's was loud because he had a cracked cat, if you read the thread youll find that now that it is welded up, noise level has been deemed as appropriate.
I run one muffler, at the rear, no res, and I drive past the police at this time (2-3am) every single morning, coming onto the highway, on the highway, at lights, and not one has ever given me a second glance.
But in saying all of that I do prefer the sound of my old Lukey, it felt so warm and refined, where as the 3 inch is rough and barky, which has grown on me a hell of a lot, especially at idle.
I have mates that are ricers, they say its the most evil sounding six theyve heard, and I still have no cam.
I have an idea JC, go do some research, and come back or even look at a few posts on the last page, and really sit there and try and determine if you believe what you are trying to tell yourself, or if you are just trying to stir everyone up.

[Damage]

Originally Posted by The Monty

I have an idea JC, go do some research, and come back or even look at a few posts on the last page, and really sit there and try and determine if you believe what you are trying to tell yourself, or if you are just trying to stir everyone up.

I say stir due to he can not think out of the box, hey if someone was to have told me the same thing without time slip proof I would probably think the same thing.
I believe time slips way before dyno read outs, dynos can have problems or be in many cases fudged, fudging is commonly done by workshops to get the outcome the owner was expecting from them .i.e quote 175rwkw, basically left the business with that on a dyno sheet but time slips and other dyno's could not reproduce it.

[OED666]

here's a link to a vid of my car at powercruise. having a bit of a play with Rollins 370RWHP Turbo ED.

http://www.youtube.com/watch?v=Zj6TULQrfhQ

[Stav]

Thats sounds really good .There we go for 3 inch sound..

[FS5]

Originally Posted by The Monty

I run one muffler, at the rear, no res, and I drive past the police at this time (2-3am) every single morning, coming onto the highway, on the highway, at lights, and not one has ever given me a second glance.
But in saying all of that I do prefer the sound of my old Lukey, it felt so warm and refined, where as the 3 inch is rough and barky, which has grown on me a hell of a lot, especially at idle.

i have heard monty's car in the flesh ,sounds nice like an i6 should .from my veiw point theres no way its excessively loud.
you can hear that thump at idle and when he gives it some ooooh yeahh .
but i'm one that likes the more (louder zorts)

oed666 ,once you get the bbm to close to the long runners look out.
i drove my car for a while on the short runners due to a tune issue.but once that was sorted and i hooked the bbm back up it WAS a completely different car to drive. you'l have more then a smile on your face.

[JC]

Originally Posted by The Monty

That wasnt the issue at all. Money was NEVER bought into it, the issue was is it a worse option than having a 2.5 inch.
Im guessing you havent heard an i6 with a three inch, you are just seeing whos buttons you can push. Stav's was loud because he had a cracked cat, if you read the thread youll find that now that it is welded up, noise level has been deemed as appropriate.
I run one muffler, at the rear, no res, and I drive past the police at this time (2-3am) every single morning, coming onto the highway, on the highway, at lights, and not one has ever given me a second glance.
But in saying all of that I do prefer the sound of my old Lukey, it felt so warm and refined, where as the 3 inch is rough and barky, which has grown on me a hell of a lot, especially at idle.
I have mates that are ricers, they say its the most evil sounding six theyve heard, and I still have no cam.
I have an idea JC, go do some research, and come back or even look at a few posts on the last page, and really sit there and try and determine if you believe what you are trying to tell yourself, or if you are just trying to stir everyone up.

For a start, I said the issue to me (and where I am coming from on this whole 3" vs 2.5" thing) is one of expense vs performance, and I can tell you, that as far as my pockets are concerned, a 3" system is not worth the extra $$$ over a 2.5". That is my opinion. If you could show me that you would chop a second off your ET, and add 20% power for double the cost of a 2.5" system, then I'd be mad not to jump at that - but you can't.

Also, sound of an exhaust is a personal preference, and as much of an animal as rollin's (turbo) car is, sorry, but I prefer the sound of a V8 anyday over an I6 when the I6 sounds like that. A fart in a tin can I think describes it best.

[StealthAu]

So you think an extra $300-500 would not be worth an extra 0.3 seconds? If you were upgrading a decent 2.5" to 3" I'd agree, but if you need a new system I don't see it as being a bad investment.

[Mark351]

What times are you running stockau?

[OED666]

Originally Posted by JC

Also, sound of an exhaust is a personal preference, and as much of an animal as rollin's (turbo) car is, sorry, but I prefer the sound of a V8 anyday over an I6 when the I6 sounds like that. A fart in a tin can I think describes it best.

If your referring to the car in the video that you can see, thats my car. The video is taken from Rollins car, hence he starts pulling away with an extra 150RWHP.

[StealthAu]

Originally Posted by Death351

What times are you running stockau?

I've never been down the quater, and at this stage I've got a 2.5" with a sqaushed hi-flow cat. I think I'd be lucky to get down the quater in less then 16 seconds