Rear muffler delete

[campbeam]

On 9/2/2020 at 4:07 PM, Metal_Head said:

the specs are the same. 16" x 5" x 3" and will be fitted with 2" pipe along with a pair of decent sized tips.

Interested to know how you selected your specifications. Did you use any detailed exhaust sizing calculations?  We all make pricing and availability trade-offs or compromises so just what came into consideration. 

I had my Aurion jacked up yesterday to check out the rear brakes and rotors plus a brake fluid flush etc. So took the opportunity to have a more detailed look at the rear muffler and actually measure various dimensions. I particularly noted that the exhaust pipe has reduced down to 44mm for the inlet to the muffler. Just thinking that it would have been easily done to increase the inlet exhaust pipe to 2.5" or 3.0" and be less restrictive for exhaust gas flow. 

At the moment, I am more likely to consider fitting a high flow stainless steel muffler with larger inlet/outlet pipes.

Definitely would like to see an update of your real world experience with using resonators as replacements for the rear mufflers. 

 

[L4WL3SS]

Well I read in another thread "exhaust ripped off" here someone replaced the rears with straight through supercat mufflers and it basically sounded stock & they were very unhappy. So I had to assume those mufflers were the typical wide body versions which even though straight thru, do a very good job of cancelling sound..... The bigger the better as the old saying goes..... But as these aurions already have 3 cats & a middle resonator, there's alot of noise cancelation done before the rears. 

Another thread mentioned the use of hotdogs, and complained that it was still very loud. No good

So I figured fitting a small long resonator (but not toooo long) would do the job. I am supremely happy with the sound. I admit I would like to hear more in the cabin, but that would come at the expense of drone, so I'm happy with the trade off. It has a deep muted tone outside, and even my 70yo dad gave it a nod & said it wasn't too loud. I only had 2" pipe fitted as they're twins & more than enough for flow. I can't comment if larger pipe will change the sound for the better.... Or worse

Edited February 8 by L4WL3SS

[L4WL3SS]

Looked into it, and it seems that an ideal exhaust for a 3.5l with 270hp would be a single 3" or 2.5" duals. 

So to keep things simple, an ideal aurion exhaust would require the last cat be replaced with a 3" version and run that size tube all the way to the rear, and split into dual 2.5" tubing

DISPLACEMENT/HP/SINGLE/DUAL

Edited February 8 by L4WL3SS

[campbeam]

4 hours ago, Metal_Head said:

Looked into it, and it seems that an ideal exhaust for a 3.5l with 270hp would be a single 3" or 2.5" duals. 

So to keep things simple, an ideal aurion exhaust would require the last cat be replaced with a 3" version and run that size tube all the way to the rear, and split into dual 2.5" tubing. 

DISPLACEMENT/HP/SINGLE/DUAL

I have thought that dual 2.5" would be ideal for the Aurion more based upon posts by Corolla Sportivo owners and the following YouTube video.

I will also have to have a good look at the attached videos in this URL.

https://m.roadkillcustoms.com/determine-proper-exhaust-tubing-size/

End of the day, my hip pocket nerve is more likely to determine my final choice.

 

 

[L4WL3SS]

Since there's already a single running down the middle, seems more practical & alot more cost effective to use a single 3" pipe until it splits into 2.

[campbeam]

39 minutes ago, Metal_Head said:

Since there's already a single running down the middle, seems more practical & alot more cost effective to use a single 3" pipe until it splits into 2.

Absolutely agree as to practicality and cost effectiveness of using a single 3" pipe until it splits into 2. That is when it would be ideal to then have dual 2.5" exhaust pipes for improved exhaust gas flow.

At the moment, I am more planning ahead and considering options if I had to replace the rear mufflers only.  

[ZZT86]

@Metal_Head  Do you have any audio clips for our listening pleasure ?

[L4WL3SS]

Yeah will do a couple today. But better wash the car first ha

[L4WL3SS]

Not a great video as I didn't want to drive like an idiot past my neighbour's, but u get the idea. Will need to hear it thru something better than phone speakers to pick up the sound

 

[ZZT86]

Looks like a rippa car, very clean. Exhaust is pretty tame which is nice. I'm guessing it's got a nice burble @ idle once it gets hot ? Almost sounds like an RB str8 six.

[L4WL3SS]

It had an audible burble inside the cabin when I dropped the mufflers, not anymore at least from inside the car. I might make another video another day as my video was ****. A tamer note is what I was looking for. Picture the "stage 1" exhaust upgrades in a grand turismo game, similar sound haha

[campbeam]

Actually, I thought that your video was great. Nicely records the exhaust sound so demonstrates what noise levels to expect. 

As a comparison, following YouTube videos show the initial muffler delete on a similar Aurion and then one which has a straight pipe exhaust. Not a fan of the last video, Just makes the Aurion sound like an angry wannabe 4 cylinder with all those exhaust pops.

 

 

[Tony Prodigy]

1 hour ago, Metal_Head said:

It had an audible burble inside the cabin when I dropped the mufflers, not anymore at least from inside the car. I might make another video another day as my video was ****. A tamer note is what I was looking for. Picture the "stage 1" exhaust upgrades in a grand turismo game, similar sound haha

Haha, Nice one Adam. I like that sound. Has a tame burble at idle and a bit of a throaty whoosh. I could live with that.

Thanks for taking the time to capture and upload. 

Thumbs up from me.

[Tony Prodigy]

12 minutes ago, campbeam said:

Actually, I thought that your video was great. Nicely records the exhaust sound so demonstrates what noise levels to expect. 

As a comparison, following YouTube videos show the initial muffler delete on a similar Aurion and then one which has a straight pipe exhaust. Not a fan of the last video, Just makes the Aurion sound like an angry wannabe 4 cylinder with all those exhaust pops.

 

 

Cool videos but cringe worthy in the first watching that guy working underneath it with no axle stands only the jack. Very brave man.

[KAA]

Thanks for the video Adam, has a nice sound and looks good mate, Keep Safe up there in my homeland..

Stay Safe

KAA

[L4WL3SS]

.

Edited February 8 by L4WL3SS

[campbeam]

On 9/7/2020 at 8:18 AM, Metal_Head said:

Looked into it, and it seems that an ideal exhaust for a 3.5l with 270hp would be a single 3" or 2.5" duals. 

So to keep things simple, an ideal aurion exhaust would require the last cat be replaced with a 3" version and run that size tube all the way to the rear, and split into dual 2.5" tubing. 

DISPLACEMENT/HP/SINGLE/DUAL

Like a dog with a bone, I have been busy looking on eBay at different exhaust size resonators and mufflers and taking some more measurements of the exhaust pipe at various stages of the exhaust system.

I had not previously thought about replacing the last catalytic converter probably being more focussed on post cat systems and free flowing mufflers.

Finally come to a conclusion that your suggestion of replacing this last catalytic converter with a 3" version would make an ideal starting point for an improved flowing exhaust system.  

http://www.surefloexhaust.com.au/exhausts/ballistic_cats/ballistic_cats.htm

Most of the original exhaust system from the headers to the exhaust tip could be retained or changed using a staged approach depending upon the budget. 

[KAA]

Ash as always a wealth of knowledge ..Thanks mate..certainly as always it is budget based but makes sense to start at the back and work forward as dollars these days are hard to earn 

Keep safe Mate

KAA

[campbeam]

Actually, the real wealth of knowledge is locked away within this Forum.

Highly rate this thread because Metal_Head did his research and achieve the desired end result.

Just for comparative purposes, following YouTube video is of an Aurion with a catback exhaust system. 

 

[L4WL3SS]

Thanks. The last cat is about as far as u can go without throwing codes.

It was a lucky result as I didn't recall seeing any definitive recommendations for modding the exhaust whilst avoiding drone. It was either too quiet or too loud, or no specifics given regarding size of mufflers. Can honestly say if I tried to make it any louder outside, then would start droning again in the cabin.... This combo is just right. I'm sure there's a way to get some burble back with smaller resonators & avoid drone by using j-pipes, but it's all theory until it's tried & tested.

Edited February 8 by L4WL3SS

[L4WL3SS]

43 minutes ago, campbeam said:

Just for comparative purposes, following YouTube video is of an Aurion with a catback exhaust system. 

 

Hard to tell if it's dual all the way or what exactly has been done. But it just sounds like the rear mufflers have been dropped & replaced with hotdogs that have large tips welded straight onto them. Loud pop & burble sounds great outside, but that car would drone bad inside

[L4WL3SS]

After driving around with the custom rear section for awhile, I've decided to do a front resonator delete to gain a bit more sound. Booked in tommorow for $150.

Inside the car u can hear it fine as it is, but I had somebody drive the car while I listened outside, and it sounded damn near stock apart from a slight hum. I'm hoping deleting the front rezzie won't bring back drone

[L4WL3SS]

Success!!! 

After hearing stories from others that deleting the front resonator does nearly nothing, I was a bit worried..... But... It seems once the rears have been opened up, the front resonator was holding back the sound. I'm tempted to replace the last cat with a 100cpi version, but its about as loud as I dare take it without getting resonating drone through the cabin. This is the sound I wanted all along, and some of the engine burble can be feintly heard over the hum. 

[campbeam]

17 hours ago, Metal_Head said:

Success!!! 

After hearing stories from others that deleting the front resonator does nearly nothing, I was a bit worried..... But... It seems once the rears have been opened up, the front resonator was holding back the sound. I'm tempted to replace the last cat with a 100cpi version, but its about as loud as I dare take it without getting resonating drone through the cabin. This is the sound I wanted all along, and some of the engine burble can be feintly heard over the hum. 

Excellent that you have achieved the sound that you have wanted.

Nothing unusual for me to be skeptical so always nice to be proven wrong again. I was certainly expecting more drone with the removal of the resonator. Looks like the recently replaced rear resonators/mufflers are able to deal with/eliminate the expected extra drone. 

Interested to read a follow up on whether you have noticed any change with more torque at lower rpm or in the higher rpm range.

[L4WL3SS]

Can say there's a noticeable improvement how it drives. Goes to show how much a bottleneck can hold back & negate other exhaust mods. 

Regarding drone, well my definition of drone is vibration in the cabin at certain rpms/load. This car has a boomy sound now, but nothing extreme. 

With the rear section done, and rezzie deleted, I would bet theres nearly a 10kw increase over stock, it honestly feels so much more lively at full throttle, and is so much more effortless at medium throttle around town.

Edited February 8 by L4WL3SS