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Old 03-24-2015, 04:26 PM   #1
chris gilmour
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Default cat converter delete?

if i cut the cat out and replace with just a pipe, will the car work the same and not though a CEL? just wondering where the O2 sensor is right in it.

I was planning to build new exhaust for it with OEM mufflers and just leave out the cat. and put the O2 sensor in one of the blocked off bungs right before the cat.
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Old 03-24-2015, 04:29 PM   #2
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Model and year of car would be a big help.
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Old 03-24-2015, 04:32 PM   #3
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Assuming a 240 yes. That said there is no reason whatsoever for you to not run a catalytic converter.
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Old 03-24-2015, 04:36 PM   #4
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Given the choice of muffler and no cat, or cat and no muffler, I choose cat and no muffler. But I really want both, because I like driving long distances and hearing music, passengers, etc.
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Old 03-24-2015, 04:43 PM   #5
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I bashed out the innard of my car and noticed no difference in sound/power. I think it may have stunk a little bit though. You may be able to sell it for $20 as well.
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Old 03-24-2015, 04:54 PM   #6
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car is a '91 245 with a lh2.4 (its been a long day i forgot)

main reason for wanting to by pass the cat is simply money is a bit tight at the moment, but my exhaust is hanging in by a thread. so i figure two new mufflers and the pipe in between will fix it up. the pipe from the header to the first muffler (with cat built in) is pretty rusty. so i figure if i just use a piece of pipe to join the first muffler to the header, i can have solid exhaust system again. but with out forking out another 150+ for a cat.
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Old 03-24-2015, 04:56 PM   #7
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Quote:
Originally Posted by chris gilmour View Post
car is a '91 245 with a lh2.4 (its been a long day i forgot)

main reason for wanting to by pass the cat is simply money is a bit tight at the moment, but my exhaust is hanging in by a thread. so i figure two new mufflers and the pipe in between will fix it up. the pipe from the header to the first muffler (with cat built in) is pretty rusty. so i figure if i just use a piece of pipe to join the first muffler to the header, i can have solid exhaust system again. but with out forking out another 150+ for a cat.
Idk your rules, but places do a visual inspection here and if they don't see a cat (or at least the cat housing, they don't know what's inside..) they will fail it. YMMV

Rmoving the cat will have no affect on how your car runs and no CEL.
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Old 03-24-2015, 05:15 PM   #8
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theres no worries with that. My father has been the service manager for the local mercedes dealer for 16 years. and with the age of the car, getting an inspection is no problem.

So if i weld in a straight pipe and use an existing bung, all will still be good. question answered. thanks guys aha
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Old 03-24-2015, 05:52 PM   #9
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Originally Posted by mikep View Post
Given the choice of muffler and no cat, or cat and no muffler, I choose cat and no muffler. But I really want both, because I like driving long distances and hearing music, passengers, etc.
There is no reason to delete the cat on a street car, and it acts as a muffler too.

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Originally Posted by chris gilmour View Post
car is a '91 245 with a lh2.4 (its been a long day i forgot)

main reason for wanting to by pass the cat is simply money is a bit tight at the moment, but my exhaust is hanging in by a thread. so i figure two new mufflers and the pipe in between will fix it up. the pipe from the header to the first muffler (with cat built in) is pretty rusty. so i figure if i just use a piece of pipe to join the first muffler to the header, i can have solid exhaust system again. but with out forking out another 150+ for a cat.
Replace the cat. Skip one of the 2 mufflers and replace the cat. There's a reason they are on there, and the rest of the world wants you to keep it on there.
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Old 03-24-2015, 07:36 PM   #10
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Sold mine for $90. Paid for the new exhaust,the turbobrick way.
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Old 03-24-2015, 08:15 PM   #11
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Be a decent human being and run the damn cat, tell pops you want to drive a legal car and not be a dingleberry on society's ass
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Old 03-24-2015, 08:34 PM   #12
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sorry for the ignorance, but what does a cat do? i come from a diesel vw back ground, and Ive always used straight pipes on all my cars (no mufflers or cats). I guess what I'm asking is why does the world want me to have a cat? what happens with out one?
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Old 03-24-2015, 09:03 PM   #13
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cat burns up remaining hydrocarbons. I dig them, they make you exhaust minty fresh.

(carcinogenic hydrocarbons)
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Old 08-15-2018, 08:09 PM   #14
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I'm not here to promote removing a cat but I did give this thread https://www.thevolvoforums.com/threa...tomatic.11953/ a read and the guy who started the thread said that the power has improved. There are a few posts on this thread saying the opposite of that. Any thoughts about that? I'm curious to read them.

Thanks!
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Old 08-15-2018, 08:44 PM   #15
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Somebody posting about it does not constitute proof. There are plenty of articles around doing the tests. Even on a ****box tier stock automatic wagon one will be hard pressed to tell a difference unless the unit is clogged.
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Old 08-15-2018, 09:39 PM   #16
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Quote:
Originally Posted by Harlard View Post
Somebody posting about it does not constitute proof. There are plenty of articles around doing the tests. Even on a ****box tier stock automatic wagon one will be hard pressed to tell a difference unless the unit is clogged.
Thanks for your comment. Please provide links to these articles if you can.
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Old 08-15-2018, 10:29 PM   #17
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Of course a Cat restricts HP! Don't be silly.

Turbos work best with zero restrictions behind them. Even NA cars perform better w/o kittys and mufflers.

Now the factors are:
1. Is it legal?
2. Social concern or not.

Other than that, do whatever you want. I agree that a NA Volvo will see minimal change though.

https://www.youtube.com/watch?v=QjaK5n86IjY
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Old 08-15-2018, 10:31 PM   #18
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Quote:
Originally Posted by Pillow View Post
Of course a Cat restricts HP! Don't be silly.

Turbos work best with zero restrictions behind them. Even NA cars perform better w/o kittys and mufflers.

Now the factors are:
1. Is it legal?
2. Social concern or not.

Other than that, do whatever you want. I agree that a NA Volvo will see minimal change though.

https://www.youtube.com/watch?v=QjaK5n86IjY
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stupid you can get race cats for like $80
drive without one for a while and your car will stink to ****...

Idk what the deal is but carbed cars dont sell all that bad when running right

a EFI without a cat fuking stinks
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Old 08-15-2018, 10:33 PM   #19
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Originally Posted by Fred Gwynne View Post
I'm not here to promote removing a cat but I did give this thread https://www.thevolvoforums.com/threa...tomatic.11953/ a read and the guy who started the thread said that the power has improved. There are a few posts on this thread saying the opposite of that. Any thoughts about that? I'm curious to read them.

Thanks!
OP there are threads about the end of the world. Everything on the internet is true
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Old 08-16-2018, 07:26 PM   #20
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OP there are threads about the end of the world. Everything on the internet is true




Didn't the cat kind of kill off the muscle car thing back in 1972?


Is it possible that the fuel injection on a b230 can't be "tuned" like a carb can? Maybe the stock FI cannot modify itself to the new airflow at the oomph degree?


I put D&D silencers onto my triumph and the bike rode worse until a pro tuned the carbs which made a considerable improvement over the stock pipes.


This stuff is all Greek to me so excuse my rambling.

Last edited by Fred Gwynne; 08-16-2018 at 07:37 PM..
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Old 08-16-2018, 07:30 PM   #21
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Great video!
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Old 08-17-2018, 06:19 AM   #22
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Quote:
Originally Posted by Fred Gwynne View Post



Didn't the cat kind of kill off the muscle car thing back in 1972?
Massive drops in compression ratios due to octane changes killed the so-called muscle cars.

Catalytic converters converters made their way onto the scene in the mid-late 70's and the technology was primitive. Massive bead-filled containers that sucked the life out of an engine... but that was before we went to extruded ceramic core cats.

Converters today are efficient and cause relatively little power loss. I'm not sure why you bumped a three year old thread for this. Did the owner of the "catless" 240 have his car dyno tuned before and after or perhaps does his butt dyno need to be recalibrated?

Me personally after having NOT run catalytic converters for years can tell you the stink of a catless car outweighs any trifling power loss. I've used the spun-metal core cats for a couple years now and haven't noticed anything in the area of loss.

ymmv.
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Old 08-18-2018, 03:17 AM   #23
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Quote:
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I bashed out the innard of my car and noticed no difference in sound/power. I think it may have stunk a little bit though. You may be able to sell it for $20 as well.
Are you the previous owner of my car? Because that was done to mine. Was a nice surprise when I had my first emissions test.
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Old 08-18-2018, 01:25 PM   #24
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Originally Posted by 740atl View Post
I'm not sure why you bumped a three year old thread for this.
As stated in my post dated 8/15/18 at 8:09 PM, I bumped this thread because I want to read some comments/thoughts about the possible performance benefits of cat removal and the value of the post made on thevolvoforums.com.

Thankfully there were some pretty good responses and I learned a few new things. Give yourself a pat on the back because you did a good job.



And FWIW I'm not gutting or removing the new cat on my car that was installed this past May.

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Old 08-18-2018, 03:09 PM   #25
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Not sure if it applies here particularly, but I would unbolt and bolt-on the cat on my old 944 (Porsche) and there were definitely sound AND performance differences. Although louder without the cat bolted on, there was definitely some performance LOSS. I chalk it up to lack of back pressure since it was NA and basically open exhaust at that point.

I would venture to say with an NA engine, removing the cat would cause a loss of power, albeit very miniscule; with a forced induction engine, it makes sense there would be a slight gain. Obviously it's gonna be louder without the cat.
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