rx7FDrider

iTrader: (16)

quick question.. if i remove the airpump... just drove it around the block.. would that be enough to clot the pre-cat?

dgeesaman

iTrader: (7)

It makes no difference to the precat.

The main cat is not as good without the air injection system, but simply driving around the block should have no effect.

That said, precats and main cats have a tendency to clog in general.

Dave

turbojoeg

Is it ok to remove the cats? If you suspect one clogged can you just replace it with a test pipe?? I dont have to pass emissions.

bajaman

Removal of the pre-cat is considered ESSENTIAL. Replace with a "downpipe" available from many places, I prefer the Pettit stainless steel unit because it has perfect fit.

gracer7-rx7

iTrader: (16)

Runing without cats at all presents some problems. Many times that is the reason a lot of people blow their motors.

It is generally accepted to be a good idea to remove the pre-cat and replace with a downpipe. This will give you some more power and remove a big heat source from underhood improving reliability overall.

However w/o the main cat in place, you loose a major source of boost control. The stock systems were designed with the assumption that a certain amount of restriction would be present in the exhaust. W/o that restriction in the form of the cat, boost control is just about impossible resulting in the car running more boost than the stock fuel system supports. An aftermarket boost controller sometimes helps but many times its not enough to control boost ALL the time in ALL kinds of weather. Cooler air builds boost easier especially in winter and cool weather.



Spend some time reading the FAQ thread stickied in this forum and the threads in the Archives so you learn this stuff.

dgeesaman

iTrader: (7)

Remove the precat and keep the main cat.

rx7FDrider

iTrader: (16)

thanks. i am going to do that.

Phread

The Main cat is an easy way for the back pressure to keep your boost in check.
Get a down pipe and and either wrap it with header tape or have it ceramic coated and get that heat out of your engine bay.......

Dudemaaanownsanrx7

iTrader: (23)

+1 on downpipe.

Main cat can be replaced with a hi flow cat. or a test pipe can be used with restrictor plates, or get the wastegate ported. It will open up some power and help spool a bit too. The exhaust will be much louder, and fire ***** will shoot out from unburnt fuel between shifts on the stock tune.