I just put back my Catalytic Converter on my car, for emission purposes, I was told that the cat was cracking inside and that its almost heading south, anyhow I have it on and I have a downpipe in place to replace the precat and I have an aftermarket exhaust. I just got my turbos rebuilt and have a new motor with about 45000K on it. Should I keep the main cat in? atleast now I dont see spikes!!!!!! and does a bad main cat pose a threat to the new turbos and motor? I will be getting a ecu and an intake for my car in a couple of weeks

 

anyone?

 

A clogged cat will cause too much backpressure and will cause your motor and turbos to get too hot. You shouldn't drive around with it like that for too long.

 

Oh by the way I am talking about the main cat not the pre cat here

 

Either one being clogged isn't good.

 

plus if its really clogged your car will be slow as a dog

 

It doesn't sound like your main cat is clogged. If it's just cracked inside, you'll probably get a lot of rattle noise. The broken pieces inside could clog your cat and restrict flow so I wouldn't just ignore it completely. You can always put the MP back on and take care of the spike.

 

What happens is all the little honeycomb pieces break apart and lay loose inside the cat. When you get on it the exhaust pushes all of them back against the rear of the cat clogging the opening. Boost spikes are hard to control. Porting the wastegate and a good boost controller are needed.

 

A hi-flo cat is a happy medium between the stock cat and MP - gives you about 10-15 rwhp over stock and more overall power throughout the powerband - plus it weighs about 25-30 lbs less - keeps you legal and helps with boost spikes over a MP. A clogged stock cat can really cause a lot of heat that could damage the turbos and engine if not addressed soon.

 

I just installed an N-tech Hi-flow cat and the sucker flows TOO well! Before I installed it I was able to control the boost just fine with needle valves. Since the N-tech went in I'm getting crazy spikes. Even with 2 restrictor plates w/ 2" openings before and after the cat I still get boost creep. Porting the wastegate is gonna cost $600. Ouch!

 

Not to sound ignorant, but i was always curious, isnt getting an aftermarket wastegate cheaper? I mean, i know the FD with hard inter. pipes have em, but whats the main reason for porting the wastegates, as opposed to getting per say, an HKS wastegate or something?

thanx ahead of time.

 

Well, then you'd need an aftermarket exhaust manifold too. Big $. Porting just takes a couple hours to remove the turbos and grind out the hole.
~Tom