Project Veloci

[bigBADbenny]

Intriguing, is the central divider/brace bit perforated or...?

[MH3.0R]

Intriguing, is the central divider/brace bit perforated or...?

Yes, the central divider is perforated to let the rear chamber vent into the front chamber which then enters the outlet pipe. So the flow does a full circle before exiting.

We are going to try to fabricate a straight thru using the central divider to hold the straight through perforated stainless tube and then fill the remainder with stainless steel wool. The fibre glass wool will probably not be used.

Hopefully, get the straight thru flow performance but with a noise reduction on WOT (I hope).

Hey I see that Corsa is making mufflers with built in 1/4 wave cavities for specific vehicles, mostly BMW.

[MH3.0R]

There is some contention amoung us as to the muffling effect of a straight thru rear muffler when comparing to the OEM design, so instead of buidling it in 304 Stainless, we are going to experiment with mild steel and stainless steel wool packing as a starting point.I am only after another -6 dba in sound pressure level measurements, so will see hoiw that pans out. Should be ready by end of next week.

[Tradewind]

Can you handle further mind numbing input on this matter?

Have some ready if you like to hear it

[MH3.0R]

Can you handle further mind numbing input on this matter?

Have some ready if you like to hear it

Yes, need input please!

[Tradewind]

In the image I posted showing muffler installed reasonably close to Y section coming from engine it didn't clearly show that a large (long) resonator/hot dog style item was immediately following the muffler - apart from a small flex joint between the 2

[MH3.0R]

Some progress on the rear muffler mods. Internals gutted and new 2.5-inch inlet pipe is in place. Straight through section under fabrication and outlet will be resized as well but keeping the original chrome heat shield:



Should be fitted up on Thursday morning and will post the details on Thursday night.

[PUDZ RSC3.0RB]

Geez Mark ur going to some trouble with these. Hope it all pans out for you. GL

Interestingly subscribed.

[MH3.0R]

Geez Mark ur going to some trouble with these. Hope it all pans out for you. GL

Interestingly subscribed.

Thanks Grant,

It is all part of the stealth look and off the shelf rear mufflers tend to be more focused toward making more noise

[MH3.0R]

More progress today with the custom rear mufflers:


The new internal straight thru perforated pipe at 2.5 inch diameter.


Another shot, but with the new camera instead of the iPhone.


The modified outlet at 2.5 inch will also take the standard flared end piece and chrome heat shield to keep it looking stock


The stainless steel wool that will cover the perforated internal pipe. Shown here on the internal perforated pipe for the second muffler


The glass pack material that will fill the cavity next to and around the ss wool


The original outlet in front with a reduced neck size (about 1.25 inch) and the modified outlet in the background with a 2.5 inch neck.


Another comparison shot of the original and modified outlets


Close up of the new modified outlet.

Both mufflers will be ready and installed tomorrow with some more custom alignment and new flanges to the xForce Y pipe.

[bass_straitener]

This looks like a lot of effort to make a muffler that's easily bought from good manufacturers like Magnaflow.

Is this a cheaper alternative as that's the only reason I could think of for going through this effort.

I know when I was looking at rear mufflers it seemed there was sufficient data on the Magnaflow site to determine what the outcome would be in exhaust sound, noise reduction in decibels and the price was very competitive.

I hope you're happy with the end result given the effort and possible cost going down this path.

[<GB>]

if mine magna flow are anything to go by they will be loud as fuck ha ha

[bass_straitener]

if mine magna flow are anything to go by they will be loud as fuck ha ha

Yes but your tune has a lot to be desired.

A good tune with proper AVCS and timing tables will help manage this a little as well.

Plus do you have any cats? Or a resonator/muffler in your mid pipe.

You're a young bloke too. You like the look at me affect..

My whole system is magnaflow and it would be legal, I reckon, should a noise test be conducted.

[MH3.0R]

This looks like a lot of effort to make a muffler that's easily bought from good manufacturers like Magnaflow.

Is this a cheaper alternative as that's the only reason I could think of for going through this effort.

I know when I was looking at rear mufflers it seemed there was sufficient data on the Magnaflow site to determine what the outcome would be in exhaust sound, noise reduction in decibels and the price was very competitive.

I hope you're happy with the end result given the effort and possible cost going down this path.

Yes, it is a bit of effort. All the mufflers I looked at were going to increase the sound level at the rear end and given the extensive changes from headers back, I need more sound reduction while preserving the flow. Off the shelf sports mufflers were smaller cavities and therefore less sound reduction, so I am gambling the larger cavity of the stock mufflers, when given the straight thru effect, will still give a reduction in the sound pressure level at the outlet.

I will let you know tomorrow.

[MH3.0R]

if mine magna flow are anything to go by they will be loud as fuck ha ha

My Magnaflow front muffler does a good job cutting down on the sound pressure level and it is only a 4x9x18 oval. I am really hoping the large dimensions of the stock rear mufflers will provide the extra reduction I am looking for.