Supercharged Cat Delete

[Bodhi]

Hi All,
Any help in the following issue is greatly appreciated. I have read and re-read so many threads trying to find the answer myself that I’m just glossed over now. I have a whippled ‘13 with a whipple tune. I have stock manifolds and a borla s type cat back minus the muffler now (snow bank altercation). Everything has been running great up until 3 months ago when there was a slight rattle coming from the exhaust under load. As with all things it’s gotten really loud now and it appears to be a piece of the catalytic is rattling inside it’s housing between 1500 and 2000 rpm. Once past 2000 the exhaust gases push or hold the piece to the wall housing, thus stopping the rattling but when it drops to that magic range it so loud that driver always look thinking the exhaust is dragging. My question is, can I just cut out the cats and essentially have straight pipes other than the resonator and not need a new tune. We do not have emissions here in Vancouver and once this setup gets long in the tooth, I plan to go full 6.6 Livernois with full L/T’s (seeing as the engine is out anyway) so I’m trying to just keep it simple for now. I’m at 165,000 Kim’s and this has been my daily driver for the past 4 yrs and reliability has been great. Any and all experience or advice is much appreciated. Thanks, Bodhi

 

[Nex]

If you remove the cats, you might get a few check engine codes from your O2 sensors.

 

[FordTechOne]

Without cats you’ll get DTCs and a check engine light on all the time. It also stinks, which would be ok for a weekend cruiser, but as a daily driver the exhaust smell will blow back into the cab all the time.

You can get LTs with high flow cats, that’s probably the best way to go.

 

[Bodhi]

Thanks Nex, FTO,
I was hoping to get lucky and not have to worry about the codes as I’m sure I’ve read somewhere owners just doing it. My commute to and from work is 90% highway and I’ve owned a blown 5.0 with off-road pipes back in the day as well so if it’s anything like that, I’m okay with it.
My big issue is whether those codes will do anything strange with the tune or drive-ability as I do tend have a lead foot. I was hoping to not go L/T’s just yet and have it all done with the engine refresh.

 

[Nex]

Yes, it will adjust fuel mixture because of the readings seen by the O2 sensors. Not like back in the carburetor days...

 

[MTF]

@Bodhi

Once a cat breaks and starts to collapse, it can block the flow and seriously damage the engine,
especially when Supercharged!!!
You will need a revised Tune from Whipple to turn off the rear O2's, if you don't want to see the wrench light.
And best to do a data log, so you do not run into a lean condition.
I don't think Whipple charges full price for a Tune revision, give them a call see what the options are.

Having said that, if it were me, I would replace the cats!!!
It's your call, if you're really going to do a Livernois build in the next few months cut the cats out.
Buy a cheap muffler and a turn down, just keep in mind, it's going to be really loud!!!
But if you're going to wait a while or things in life change and you can't, replace the cat.

As a daily driver the Whipple needs a little back pressure,
to properly maintain the values that the PCM and Tune needs to correctly predict the next move.
Now, while having no cats does give more torque (40 to 60 ft-lbs.) and a little more HP (20+)
And that's it's basically only at WOT and that's with headers.
I'm running full stock exhaust and getting 561 rwhp without any issues.

 

[Bodhi]

Thanks MTF,
Doing more research now on getting headers and a new tune. Might as well bite the bullet and keep the ol’ girl happy.

 

[Nesc204]

If you remove the cats, you might get a few check engine codes from your O2 sensors.

Its easy to fix that. Just buy spark plug defauler for the O2 sensor behind the cat, drill it to fit sensor. What it does is pull that sensor out of the exhaust so it senses no change. Very simple to do

 

[MTF]

Its easy to fix that. Just buy spark plug defauler for the O2 sensor behind the cat, drill it to fit sensor. What it does is pull that sensor out of the exhaust so it senses no change. Very simple to do

That's not why you use the rear O2 extender.
The PCM is looking for the amount of time it takes for the rear O2 to reach a specified temperature. (AKA. heated O2s)
If it takes too long to heat up or heats up to quickly the PCM will through a code,
whether the cats are damaged, clogged or blown out or missing.

 

[Nesc204]

It has worked for me and many many other people. Especially people that drag race there modern muscle cars. Thats how I learned about it. Had to do it to a old Subaru I use to own and never had a problem with it