Well im installing my new 2.5 catco cat but its much smaller than the original one(the honey comb inside the original was in pieces just rolling inside the cat), and i don't know what piping i should buy to fit it in to weld myself im guesing i should get a 2.5 pipe with a opened wider end and maybe weld it to a flange, has anyone have experience with this

 

you could always have someone familiar with exhaust weld it up for you. That's what I did, I can weld pretty good so far but I opted to have a shop weld in my cat, it was quicker and they did a perfect job for like $50.

 

Are the catco cats any good? Hope your still running the precats cause that thing will go down in flames within 10,000 miles.

 

depending on your emissions requirements it's often desirable to remove the stock precats and run a single high flow catalyst. You might be able to install the cat, pass emissions and then hollow it out after the test. Or buy a better cat that will last longer in the high heat of the rotary exhaust.

 

They'll function as far as a cat is concerned, and last at least a few years. We recently put a 3 inch in/out Catco cat on a flowbench and lost something like 26% of flow. This was their 'High Flow' model to boot.

 

well emmisions here is strict so im goona still keep the pre cats they look good from the inside, and im gonna buy me some gaskets because it started to leak, when i decelerated it sounded loud it kinda made that bogged sound

 

Here is the shiznitz on catalytic converters. The term 'high-flow' is industry lingo for 'contains a ceramic brick'. The old style converters contained chambers of BB-sized ceramic catalyst coated *****. These were very restrictive. When the ceramic bricks came out, they were termed high-flow. This may have all occured before you were born.

Pretty much ALL cats these days are the 'high-flow' type. That does not mean that the will give high performance or last very long in a rotary engine.

If you want a cat that will last and will not give lots of back pressure, you should look at the engine size rating and you should look at the AREA of the front of the brick(s). These two things are related. A converter rated for a small engine will have a smaller brick and less frontal area on the brick, yielding higher brick temperatures and more restriction that a converter rated for a large engine. The larger brick will allow the heat of reaction to spread over a larger area and will last longer.


The cat I used on my 90 vert is as follow:
http://www.autozone.com/selectedZip,.../selectZip.htm

It's rated for 7000# or 7.7l (472 cu").

More details:
https://www.rx7club.com/showthread.p...&highlight=cat

 

one more question does it matter how far i put the new cat from the pre cats, would it be better to keep it closer to the pre cats

 

as close the the engine as possible, heat is your friend in this case.

 

Well installed my catco cat and noting bad so far runs way better than before because before it felt like i used more power to move now i gas it and feel the gain it should had been.
happy so far, i'll post if anything wrong goes with it