Are you guys running catalytic converters on your EJ22 swapped cars? I was thinking of gutting them to simplify the system.

 

Will I loose much of my lowend doing this?

 

CEL?

 

Gain much in the top end?

 

 

Thanks

Since I live in a non-emissions county, I always gut my catalytic perverters with a piece of pipe and a hammer.

It doesn't really simplify the system to remove the cat as the cat case is the merger of the Y pipe. Gutting them doesn't really change anything either, the volume the cat can flow is probably larger than the header pipes can flow so it's not an issue. You won't set any codes with an OBD1 car as there is no oxygen sensor after the cat.

 

I just don't see what you gain by gutting it... It's not hurting anything and the car is louder and smellier when you do gut it. Mabe if you drive in tall dry grass all the time? A proper set of heat shields should protect against most fires though.

If the cat is in good shape, you will not notice it is there. I have left the first cat in place on all my EJ swaps - no reason to add more work.

If it's good, leave it; unless you drive near redline more than 90% of the miles on the road, then I could see a tuned exhaust; but who drives race cars on the street?

Ive been curious how and when a cat goes bad. I have 200k on my car with the original california cat and i wouldnt know if its hindering anything because the car runs so bad anyways.

Cats usually go bad from too rich of a mixture and they get too hot (Usually a sure sign is rotten eggs smell.) and melt down the catalyst grid in them causing a blockage which makes the exhaust accellerate and heat up more which makes it hotter and volia! Blocked cat. When it goes you'll get a whisle under full throttle and when it fully plugs, the intake noise goes WAY up. But by then, the power will be so low, it takes 2 miles just to get to 55!

Assuming the engine has been properly tuned up, here are a few experiments to try: Feel the exhaust pulses coming out of the tail pipe: does it have a slight pulse to it or is there practically nothing coming out?

Disconnect each exhaust pice and see how it drives. Start with the mufler section: no difference except loud? Good, move on to the center section and go for a test drive, still no difference? Then the front cat/y-pipe is the problem. Remember, you will get some performance boost since there is less piping for the exhaust to work through, however, you should mainly just have more noise.

I've also read that if you leave the exhaust plugged for too long it tends to burn exhaust valves.

I read about people gutting the cats but leaving the stock exhaust. It has alittle more rumble but not as annoyng as running mufflerless. How can i gut a cat on the car. Cut out the bottom remove the bits then have someone weld it back up.

I guess I will leave it as they (2 cat style EJ swap) are fine. It just seems like a good idea to remove unnecessary items.

 

 

 

 

 

FYI to gut a cat you just bust all the ceramic honeycomb out with a bar.

 

same procedure works for these ones too lol