Cataletic Converter-modified! - BMW Forum

Bimmin'88 · 10-25-2004, 11:01 AM

First of all I wana thank you guys for your imput on my "Hi flo cat" thread.

I gutted my Cat this Saturday and I am amased at the performance improvement. Best of all it cost maybe $5.00. Welding wire, two cut-off wheels and a little spray paint.

My car used to be sluggish till 2500 rpm and then it would open up. Now the excelleration is far smoother and the sluggish lagg is almost non existent I would say 90% cured. I feel the gain is around 5Hp. Not bad 5hp for $5.00!!

The SOUND!!....from inside the cab its a little funny and somewhat tiny. The hollow cat resonates and without the insulation layer around the cat its pretty loud. But from outside the car sounds RADD!! and THROATY!! Its a raw performance sound, like a tuned RACER!

"NOT JAPISH AT ALL!!!"

I'm very pleased with the outcome of this mod!

Thanks again for the responce! I love this place!

theratdude64 · 10-26-2004, 02:42 AM

lol what was the spray paint for?

used

sean · 10-26-2004, 02:51 AM

nice if you ever get bored, try and get a sound link on here of that

Aether · 10-26-2004, 06:03 AM

So all you need to tear its insides out are some fiberglass cutting wheels?
That might be fun. What'd you need to weld?

Bimmin'88 · 10-26-2004, 10:29 AM

SPRAY PAINT- Makes it look nice and keeps the welds from rusting.

WELD- You need to weld the Cat back together.

theratdude64 · 10-26-2004, 08:23 PM

ahh I see
LMAO we did this to my friends IROC, and today the freakin streightpipe fell off cause we havent welded it quite yet. sounded like we bottomed out

ghead but got nice n wicked soundin after

bimsupreme · 11-02-2004, 01:04 AM

The sound is great! I would like to hear yours if you could get a sound clip because I want to see if it is similar to mine?

87 325iS · 11-02-2004, 11:03 AM

I hope you welded a pipe in the cat, and didn't just leave a big empty case.

alfamitch · 11-02-2004, 01:12 PM

Did that way back when I had my LT1 T/A. The sound was raspy as hell, and daily driving turn into shit, do to a nice loss in bottom end. Fuel milage went straght to hell, especially once I got the medium stall converter installed. There was one up side. Well, two actually. Sound at WOT. It was off the hook. Sounded nice as hell, even flowing through a stock muffler. Second upside was the performance at WOT. Pulled really well past 4k rpm. Seat off the pants difference. Eventually I had to put the cat back on, since it was time to smog the car, so I installed Car Sound cat from magnaflow. It felt like I lost about 2 wheel hp up on top, but I got so much torque back, it did not matter anymore.

Lesson of the story is: replace cats with either high flow cats, or bullit resinators.

seandaly · 11-02-2004, 02:01 PM

That's cool. What do you plan to do for smog checks though? Do you have another cat you'll bolt on just for smog checks?

Speedy-325is · 11-02-2004, 02:32 PM

Bimmin88, we should go for a drive next Monday!!! Jamez is prolly coming up to work in my garage, and we can talk to Spiff and see if the 'rents will let him out of his cell for a bit!!! we'll bring a few cameras too!!!

Mark
btw, call my cell if u r down!

spiff325is · 11-02-2004, 05:02 PM

Mark, im hosting a drive this coming saturday, call me for the details.

bimsupreme · 11-02-2004, 08:59 PM

To smog go to a junk yard and find a smashed e30 pull the exhaust and when time comes to smog just pull the gutted cat off and put the one from the junk yard on

Bimmin'88 · 11-03-2004, 10:43 AM

LOL....no I did NOT weld pipes into the cat...its a big open void and grawls like its on steroids WOT!!! Was thinking about going back into it and putting some pipe in.

I don't need to smog till May and I will get a new Cat by then.

Also thinking about insulating the exhaust to improve flow.

Mark...I'll PM or call you.

guywithblack88e30 · 11-04-2004, 03:01 AM

so did you just open it take out all honycomb crap and close it back thats all?