Gutting the Catayltics?

Well you'll have to watch out for one member from Austin, catalytic converters are his life's passion so he'll tell you all about how they don't cost power and you're destroying the environment for all our children and their children for your selfish, incorrect assumption that gutting them will help your performance.

Personally, if you're looking to do it just for "a little" more oomph, I wouldn't. Gutted cats can have unexpected resonances (i.e. your car can have funny new noises) and you won't get a lot of performance benefit. Plus, it's hard work! That substrate is surprisingly tough! The other concern is that you never know when they might tighten the emission standards on you. Here in Michigan, we used to have tailpipe sniffing for cars <10 years old (DUMB!), then they got rid of it, now they're talking about the need to go to a fullblown chassis dyno test.
On the other hand, if you're doing real hotrodding to the engine, then it'll be worthwhile to do something...

 

Get test pipes for a couple hundered dollars. They bolt in and you can reverse the change if emission rules change or you sell to another person who will need to get it tested. Cats can cose several $K to replace and that could be a sticking point on a sale rducing the price of the car.

 

Do not do it since the next guy that buys your car may need the full cat. Best bet is to get a test pipe installed.Check with our site sponsors. Nick has them for a good price. If you want the name, then Heiko has tubi test pipes as well.

 

I'll pass on my experience with the cats, etc., on my '92 512TR.

I had the cats removed and replaced with test pipes before I ever took delivery of the car as I had heard too much about overheating and fire danger with TR's. I kept the cats for the next owner, which hopefully is a long time off. Be certain the test pipes have the threaded fitting welded in for the oxygen sensors.

Next step after driving the car about 1K mi. was installation of a Tubi muffler. The exhaust was more open sounding and a little loud under hard acceleration but at cruising speed of 3000 rpm there was no objectional noise.

In a few months and following advise of a couple of other owners I decided to take the guts out of the pre-cats. The expanded area of the pre-cats is filled with a honeycomb type material that is bonded tightly in place. It takes to a magnet so is ferrous but would have to be very high quality to stand the heat. It appeared to be very restrictive in letting the exhaust pass through. You can only work through one end and removal is difficult. I drilled through the mass with a 7/8" masonry bit on an extention and then broke the honeycomb up with a large screwdriver. A large amount is in the outer diameter where you can't see it or probe with anything straight so we made a tool to get in there and remove it. I used a 1/2" steel rod about 2' long, heated one end, and hammered it flat on an anvil forming a spoon shape. I heated it red again and bent the spoon back toward the rod at about a 120 degree angle forming a hook. Using this tool, two of us were able to remove the rest of the honeycomb. The amount of material from both pre-cats nearly filled a gallon can. Don't leave any trace of the honeycomb inside or it might break loose later and cause a blockage.

The sound is much different and louder under hard acceleration but at cruising speed it seems no louder than with the stock system. I just completed a 250 mile drive resulting in a tired rear end, but no fatigue from noise. I'll anxious to hear it from outside the car and will have my son drive it sometime and pass me.

Emissions tests? We have none here and don't plan to sell the car for a long time. Maybe putting the cats back on and playing with the mixture would get through a test; I don't know and are not really worrying about it. The car is like I want it, the exhaust is free flowing with no restrictions, and any danger of fire from a failed cat or pre-cat is gone. And the sound is great, at least to my own ears!

Ron

 

Unless a person is a member of green peace or they live in california catylitic converters are useless IMO, especially on cars built within the last 15 years.