Straight pipe exhausts

[GauravSoni]

I had an issue in my last drive (sweihan) with lead @Asif Hussainwhere my car started withloud exhaust leak noise along with loosing power as it wouldn’t go beyond 5k rpm. 
Turns out that the catalytic convertor had broken substrate which created back pressure on engine forcing it to cut power ( smart engine!) 

On researching, I found info on how straight pipe exhausts allow for more engine power while

1. Introducing backfire noise ( gunshot sound) 

2. more pollution

https://mechanicbase.com/cars/straight-pipe-exhaust/

As an alternative ,its is also suggested to go for high flow cat from a reputable brand. 
 

any insights into this Mod. @Frederic @Gaurav @Vanessa8580

FYI , I drive the 2014 3.8 LWB PAJERO with 160k on the run. 

 

[Frederic]

1 minute ago, GauravSoni said:

I had an issue in my last drive (sweihan) with where my car started with loud exhaust leak noise along with loosing power as it wouldn’t go beyond 5k rpm. 
Turns out that the catalytic convertor had broken substrate which created back pressure on engine forcing it to cut power ( smart engine!) 

On researching, I found info on how straight pipe exhausts allow for more engine power while

1. Introducing backfire noise ( gunshot sound) 

2. more pollution

https://mechanicbase.com/cars/straight-pipe-exhaust/

As an alternative ,its is also suggested to go for high flow cat from a reputable brand. 
 

any insights into this Mod. @Frederic @Gaurav @Vanessa8580

FYI , I drive the 2014 3.8 LWB PAJERO with 160k on the run. 

IMG_7911.MOV

Removing the Catalytic converter on a "recent" vehicle will give issues in RTA passing, so i would not go that way.

It's a bit strange that the catalytic converter broke, as this is normally something that lasts many years. 

Straight pipes definitely a NO-GO, with Sharjah and Dubai now monitoring closely your decibel levels and serious fines are involved.

I would go for a scrapyard catalytic converter.

[GauravSoni]

@Frederic thanks  for the info.

I am now driving with an “open” CAT as part is unavailable. 
I do get a single gunshot sound when change from 1st to 2nd at 6k RPM. 
I hope it doesn’t start a 🐪 race on my next drive!

[Gaurav]

You can go with Borla and/or Magnaflow (esp hushflow) lower decibel but free flow product. I'm using these both brand and happy from last 5 years or so.

Beware that with loud noise Sharjah police can and will stop you to hand over 2,000 dhs fine. I recently got one last year when one of my flange gasket was leaking and making tiny bit extra noise, though well within 80 DB (allowed by RTA). So I fixed those gasket and went to Maliha police station to dance on cops tune to waive 2K fine.

Apparently I also installed a flexi joint in between as main culprit of broken gasket was high speed dune attack and on harder bumps it stretched my exhaust setup and cracked that gasket. So while at it, consider flexi joint too.

 

[Srikumar]

I have been running a straight pipe (no CAT) with a muffler at the end. I wasn't aware that a CAT removal in newer cars is a problem.

The easiest way to eliminate doubt is to just take your car for passing (even if not due) and see if they are passing or failing the car. 

[Frederic]

In above post some more information.

Let me throw a spanner in the whole discussion by asking myself loudly:

- How can a catalytic converter go bad on a 2014 vehicle ?

Would the Unichip cause a bad air/fuel mixture resulting in damaging the Catalytic converter ? 

[GauravSoni]

@Frederic I went over cross tracks at relatively high speed ( on 1st @ 6k) to gain momentum to get out of the bowl hitting the underbelly. The noise started immediately. 
On inspecting CAT at workshop after removal, the substrate was found cracked and broken in pieces. 
 M not sure if a fuel rich exhaust (due to unichip retune) would degrade the material for it to be brittle.  The attached pic is after they  hammered it, but it was mostly in big broken block inside to begin with.

 

[Frederic]

13 minutes ago, GauravSoni said:

@Frederic I went over cross tracks at relatively high speed ( on 1st @ 6k) to gain momentum to get out of the bowl hitting the underbelly. The noise started immediately. 
On inspecting CAT at workshop after removal, the substrate was found cracked and broken in pieces. 
 M not sure if a fuel rich exhaust (due to unichip retune) would degrade the material for it to be brittle.  The attached pic is after they  hammered it, but it was mostly in big broken block inside to begin with.

 

IMG_7913.MOV 5.69 MB · 0 downloads

If the guys can put back the catalytic converter you can always try get it passed in RTA (you might be lucky)...

[GauravSoni]

The CAT is refitted , without the substrate acting like a straight pipe! Not much change in exhaust sound unless I floor the pedal on traffic signal. 
@Gaurav thanks for the suggestion. Will try to get the Magnaflow CAT especially after knowing the recipe of  the sweet music on your car exhaust! Love that sound!!!!

[Reggie Landicho]

I am quite fascinated with the roaring sound of Magnaflow exhaust. And I am looking on the legality to install on my Wrangler. Anyone with the same dual exhaust? Will it pass the RTA test?