Gutting Your Cat

[legion]

This weekend I successfully gutted my catalytic converter without removing it from the car. A road test confirmed that the turbo is spooling much faster.

Items Needed:

-Shop vac with 1 1/4" hose
-4' piece of straight rebar
-4' piece of 1" box steel
-Angle Grinder
-Hammer
-Metric sockets and wrenches
-Floor Jack
-Jack stands
-WD-40
-A big, dirty blanket
-A wire clothes hanger
-A flashlight

Steps:

1)Jack up your car, place jack stands at jacking points that can hold the weight of the car, lower the car on to jack stands.

2)Remove the muffler. Position your big, dirty blanket under the muffler so that it has a place to safely be lowered when removing.

3)Sharpen a point on one end of the 4' rebar

4)Insert the rebar (pointy end facing away) to the end of the catalyic converter. Hit the rebar with a hammer until you punch a hole completely through the first layer of catalyst. This can take up to 10 minutes as your range of motion for hitting the hammer is severly limited.

5)Move the rebar to another place, repeat the step above. Keep repeating until you have punched 5-10 holes in different areas of the catalyst. Use a flashlight to check your progress and to position the rebar.

6)Take the 4' section of box steel, cut a 1/2 section out of it about an inch from the end. This is will be used as a hook for removing large chunks of catalyst.

7)When the first layer of catalyst is in big chunks, use your catalyst hook (made in the step above) to pull catalyst pieces out of the catalytic converter. If a piece becomes jammed in the end of the converter, twist the hook so that it crushes the catalyst chunk.

8)You may need to fashion a more precise hook out of a wire hanger.

9)Repeat steps 4, 5, and 7 until all of the layers of catalyst have been removed to the best of your ability.

10)Feed the shop vac hose into the end of the catalytic converter. Vacuum as much out as possible. Chunks of catalyst may become jammed in the vacuum hose or stuck on the end of the hose. It will need to be pulled out and cleared frequently. You may need to use the rebar to break up chunks of catalyst too large to fit out the end.

11)Use a flashlight to inspect the interior of the catalytic converter. When you are satisfied that it is clean, reattach the muffler.

12)Lower the car.

13)Take the car for a test-drive.

[928ram]

I sure hope the 944/951 doesn't use those stainless steel wool blankets to hold the ceramic in place, it's gonna suck trying to get those wads out of the muffler.

[legion]

I pulled them right out with my " hook".

[docsafi]

928ram said "WADS" huh huhh huuu hhh

[Slam]

Had this done to my old RX-7. Made a big difference.

With the 944, I

1) Had muffler shop use cutting torch to cut out cat.

2) Had muffler shop weld in pipe.

3) Had muffler shop bolt in stock muffler

4) Paid muffler shop about a hundred bucks. New pipe, ya know.

It helped.

And they didn't need a dirty blanket! Actually, I have some dirty blankets of my own but I needed a muffler put on the car anyway...

[livewirevoodoo]

Between all the timing belt murders and now you bragging(!!) about feline torture, its not safe to be a cat these days.

[CJFusco]

944s are killing too many kittens these days...

[speedracing944]

Very nice legion. How much more aggresive is the sound? I have an extra cat that came with the exhaust i bought. The muffler is straight through now and I have considered gutting the spare cat. meow!!

[legion]

The sound isn't that much louder, but the car already had a straight muffler and the turbo tends to block much of the engine noise at higher RPMs.

[Don 944 LA]

I had to gut mine in the past due to the material being worn and turned sideways totally restricting flow.

[legion]

I did a little test and found it was much easier to break up the cat sideways rather than head-on. Unfortunately, unless it moves like it did for you, Don, you're going to be hitting it head-on.

[CJFusco]

why bother gutting the cat... wouldn't it be easier just to bolt/weld on a straight piece of pipe that's the same length as the cat and same diameter as the exhaust pipe?

[legion]

1) My only expense in this mod was the 87¢ or so I paid for the piece of rebar.

2)With how the pipe from the wastegate joins up with the cat, it might be a difficult weld.

3)The whole reason I took this approach was because I was having trouble disconnecting the cat from the down pipe.

[CJFusco]

good answer.

[ChrisBennet]

I wouldn't recommend gutting the cat on a nonTurbo 944. I did that on my last 944S2 and it sounded horrible - like a riced out Honda.
-Chris

[Dougster]

It will sound better if you install a "test pipe"