Cat Removal

[Mopar Boy]

After reading the other thread regarding removal of the catalytic, it got me thinking.

What are the pros and cons to the removal?? Will I get more power? Will it sound better? What bad things are there to removal

And yes, umm, this car is only going to be used on the track as I am aware it is illegal to remove for street use.

Thanks!

Robert

 

[big-n-italian]

pro - much cooler side sills. no more burned legs.

con - alot more soot on back of car.

 

[KNG SNKE]

another con is running without cats its common for backfiring and it sounds horrible.

 

[dave6666]

You can get the sill heat taken care of whilst still having cats in them.

 

[95Viper]

You can get the sill heat taken care of whilst still having cats in them.

Sure is a lot harder to do so. If anything replace with high flow cats.

 

[99 R/T 10]

another con is running without cats its common for backfiring and it sounds horrible.

Maybe it's just me, but I think the "backfiring" is a pro. I love the sound of it

Lot cooler and you should pick up about 8-10 HP too

 

[Russ M]

Pro

Much improved interior temps
Footwell temps are like a normal car
Cool side sills
Side sills do not discolor anymore
More power 5-10hp
much better car sound
Louder

Cons
Wont pass smog
Louder(if you are old)
smell if you do lots of stop an go.

Some myths that are just not true.
No more exhaust soot than any other car
Sounds bad/popping If you car is popping its because of other issues cats dont have anything to do with it.
And last but not least there is NO WAY to cool your side sills like removing the cats. You can improve your sill heat by insulation/ventilation/hi flow cats but nothing you do will even come close to just removing the cats

 

[KNG SNKE]

to eachs own about the popping

whats weird is every car I have seen with cats removed have had backfire sounds coming from them. (including vipers)

 

[Bobpantax]

Don't underestimate the damage the sound from a catless Viper can do to your hearing. It is no joke It has nothing to do with age. It can also take a while for the damage to show up. You cannot drive on the road with plugs in your ears. If you do, and you do not hear an emergency vehicle approaching or a warning honk at an intersection, it could cost you more than just a bruised ego. It could cost someone their life.

 

[nkbrkr2]

Actually the popping noise on decel with cats removed is called after fire. Backfire occurs in the manifold. The after fire is just unburned fuel that ignites from being exposed to the atmosphere inside the exhaust.The excess gas would have normally been burnt by passing through a hot catalytic converter. To be quite honest I love the sound when backing off in second coming to a stop sign with a little rumble and pop!

 

[KNG SNKE]

Well I used the wrong term but you obviously knew what i meant. I was driving behind a catless snake the last cruise I was on and I was flipping out. The sound it was making reflected off the top right corner of my windshield and it sounded like a large rock was hitting the window. Didn't like it.

 

[dave6666]

Sure is a lot harder to do so. If anything replace with high flow cats.

Yup. It took some fabricating.

You must be registered for see images

 

[eucharistos]

Yup. It took some fabricating.

Bling Bling - nice workmanship as ususal

have you shot it with a temp gun yet?

thanks

 

[GTSnake]

I don't think it's worth it unless you go forced induction. If you're NA then you're better off just putting in high flow cats. My $0.03.

 

[dave6666]

I don't think it's worth it unless you go forced induction. If you're NA then you're better off just putting in high flow cats. My $0.03.

Did that too. R/T ceramic.

You must be registered for see images

 

[dave6666]

have you shot it with a temp gun yet?

Here are the temp measurements. I photographed each measurement, but we'll keep it to the data for now.

You must be registered for see images

 

[eucharistos]

Here are the temp measurements. I photographed each measurement, but we'll keep it to the data for now.

Wow!!

and your after temps taken on a cool, low humidity N. Tx day

cabin heat kills me on Houston summer days

installing hiflows over Thanksgiving, hope to get even some of that decreased temp

thanks

 

[dave6666]

Wow!!

and your after temps taken on a cool, low humidity N. Tx day

cabin heat kills me on Houston summer days

installing hiflows over Thanksgiving, hope to get even some of that decreased temp

thanks

Just to clarify, as the full details were on a prior thread, the before measurements are factory cats w/ Corsa cat-back rear exhaust, factory sills.

The after measurements are the RT ceramic cats, 3" side exhaust w/ Magnaflow mufflers, and the custom vented sills.

Both include the factory sill insulation, although I trimmed it after the conversion so it would not cover my vent holes.

 

[Bobpantax]

Yup. It took some fabricating.

You must be registered for see images

Impressive work. If you do not mind disclosing same, how many hours did this take to do and at what total cost?

 

[dave6666]

...how many hours did this take to do and at what total cost?

Since there are numerous ways to do this (use OE sills or go with Autoform, etc.) I'll break it down into tasks.

-> Fitting new Autoform side sills 5 hours per side at least. They are a good part, but needed some TLC for a premium fit.

-> Laying out and drilling large vent holes in bottom of sills (including cleanup sanding inside) about 2 hours total. Doing your OE aluminum sills would require a punch ($$$) as I would not use a hole saw on that thin metal.

-> Layout, cutting, finishing, drilling and riveting wire mesh screen about 4 hours total. Yes, each cut strand of the mesh is sanded to remove the burrs...

-> Trimming the factory sill insulation and re-seaming the edges with my custom SS wire staples about 3 hours per side. PITA.

-> Installing louvered vents in front of sills in wheel wells about 2 hours per side.

That adds up to 26 hours. Does not include many more hours spent just staring and figuring. You know, beer-lawnchair-clipboard stage.

Some $$$ figures:

-> Autoform sills $1100

-> Louvered wheelwell sill vents $70

-> SS wire mesh $20

-> Paint sills $330

Numerous tool$ and a few rivet$ too. And of course the Belanger headers and side exhaust conversion are above and beyond all of this, time and money. My short answer to the entire project is like $5 - 6K, about 3 months work nights and weekends.

Not rocket science, but not for the guy that has no skills or patience.

 

[Bobpantax]

Thank you for the data. Quite a project. $1520 plus incidentals plus 26 hours of your labor just for the upgraded side sills. Valuing your time at say $100 an hour brings the total to $4120 for the side sills. It's too bad that someone does not manufacture side sills with your improvements. I think that there would probably be a market for at least 200 at a price below $1600. Just a guess on my part.

 

[dave6666]

Thank you for the data. Quite a project. $1520 plus incidentals plus 26 hours of your labor just for the upgraded side sills. Valuing your time at say $100 an hour brings the total to $4120 for the side sills. It's too bad that someone does not manufacture side sills with your improvements. I think that there would probably be a market for at least 200 at a price below $1600. Just a guess on my part.

To mass produce (gty 10+), or to do even just one more set, would be a noticable reduction in time. The learning curve takes its toll on a one-off project.

My next step is to integrate an aluminum side splitter into the sills, and of course compliment it with a front splitter and rear diffuser.

 

[Frankster]

Nice work! I just removed my cats and have no more issues with high temps in the sills.

What I do notice is reduced HP. This is by a seat of the pants impression. I get allot more soot buildup on the rear than before the cat removal.

Also, when I gun the engine it's sluggish in response. With the cats it would rev-up or respond very quickly.

I think it maybe a fuel/air ratio thing but not sure about that.

Any thoughts?

 

[Russ M]

Nice work! I just removed my cats and have no more issues with high temps in the sills.

What I do notice is reduced HP. This is by a seat of the pants impression. I get allot more soot buildup on the rear than before the cat removal.

Also, when I gun the engine it's sluggish in response. With the cats it would rev-up or respond very quickly.

I think it maybe a fuel/air ratio thing but not sure about that.

Any thoughts?

Any modifications to the car besides the cats?

Did you reset the ECU?

How many miles on your o2 sensors?

Year car?

o2 sims?

I have never seen a car loose anything when it came to hp when cats were removed.

 

[Frankster]

Russ

It's a 96 RT/10 Venom 600 package, 520ci with big cam.

I didn't reset the PCU - Don't know how.

The O2 sensors are likely stock. There are no O2 sims in the vehicle.

I'm not positive about the HP loss but it sure revs sluggish like.

 

[Russ M]

Russ

It's a 96 RT/10 Venom 600 package, 520ci with big cam.

I didn't reset the PCU - Don't know how.

The O2 sensors are likely stock. There are no O2 sims in the vehicle.

I'm not positive about the HP loss but it sure revs sluggish like.

Frank,

On a car like yours you can't just remove cats without tuning. You have lots of mods and power output much higher than factory.

While on a stock car cats will only affect hp just slightly, on your car the difference can be big. Your cat's were most likely a huge restriction and now that its gone the engine wants more fuel.

Now you need to find out what your car has for fuel enrichment over stock, and how you can have it tuned.

Have you ever had the car dyno tested before? Numbers?

Find a tuner ASAP do not drive the car around as is, no need to damage anything before you get to enjoy it.

 

[jdeft1]

With no cats my sills are much cooler but it is LOUDER so I do wear earplugs.. You can still hear with plugs in but it may look a bit silly at stoplights.... Original exhaust w/ cats are standing in the corner of my garage.

 

[sdaddy]

Yup. It took some fabricating.

You must be registered for see images

That looks sweet! Much more venting to breathe and less visable than venting the ends of the side sill.

 

[Mopar Boy]

Wow Dave!! That is alot of work, but it looks great!!

I gather then, cat removal is mostly for the heat, a lot bit of sound, and a little bit of power. So if I gather correctly, high flow cats would be a better choice if I wanted to play a little, otherwise leave it as is.



Robert

 

[kennyhemi]

With no cats my sills are much cooler but it is LOUDER so I do wear earplugs.. You can still hear with plugs in but it may look a bit silly at stoplights.... Original exhaust w/ cats are standing in the corner of my garage.

Well I have an 06 coupe with the comp exhaust and while on idle is not loud at all. it is louder one you get on it but i guess all the years drag racing 7-8 sec. hemis is the reason I don't find it loud.