Speaking of back pressure, I would have expected to see more low end torque if the cat is more restrictive.

 

This year is the first that evo owners will need to get smogged, isn't it? Wonder which cats will pass california smog.

Also wonder if those boost fluctuations follow a normal path or if they're random. If it's the former maybe they can be tuned out with the ECU.

Thanks for the post.

 

Did a new law get passed? I thought that if you bought any new car in recent years that you didn't have to get it smogged for the first 5 or 6 years of ownership? I was under the impression that you only had to get smogged every other year if your car was older or if it was purchased as a used car...

 

Razor..... excellent data. Thanks.

And this is why STU sucks!

 

This year 2008 - first year evo released in US 2003 = 5 years

I have a helix cat (200 cell metal) and I get those fluctuations in boost too I think. I'll check my logs and make graphs and confirm.

 

Was the actual timing advance (i.e., including any knock retard) and AFR the same with the test pipe and cat?

 

Both final tunes had no knock. A little bit of timing did have to be taken out with the high flow cat once I brought the boost back up. I think it was about 1* overall and about 2* at 5500.

AFR the same for both.

 

All HFC is illegal in CA. Even if they pass smog, they still fail visual.

 

For anybody that cares this particular cat will produce better emissions than the stock cat. No more black bumpers and legally probably one of the highest flowing cats available. I am really curious to see the 100cell cat vs this to see if it makes much difference.

 

Just looking at the apexi and the 100 cell, I can imagine the 100 cell flows better, the 100 cell core is like half the length of the Apexi and slightly less cell count.

but.. Looks can be deceiving.

 

Of course I'm biased, but prima facie evidence tells me that 30 more cells per inch + a length on the Apex'i that's twice as long = less hp than my 100 cell cat.

Hopefully we see a TP vs. 100 cell cat comparison in the near future.

I am also working on a CFM reading right now for the 100 cell to add to the available data.

IMHO, the 100 cell metal cat gives the greatest amount of flow next to a TP. For people who want a non-smelly high hp alternative, or have a conscience that doesn't allow running a test pipe the 100 cell cat is a great option.

 

Back pressure does help make low end torque thats a urban myth.

Low end torque from smaller exhaust systems is caused by phenomenon called "exhaust scavenging" this is where the exhaust pulse from the engine actually draws out fumes from the combustion chamber.

With a turbo car you can never really see exhaust scavenging in action because we have a large blockage in the exhaust track which disrupts the pulse called a turbo

 

Thanks for the comparison.

 

I have to wonder if these high flow cats really do anything for emissions. Some of these companies use guilt as a selling point by saying that there is a moral problem with not running a cat, but honestly how well do some of these 100 cell cats really even work?

An interesting test would be some exhaust gas analyzer readings on a car with the stock cat, high flow cat (different brands) and a test pipe.

 

These cats must be doing something because even my 100 cps stops the exhaust from stinking. Another guy in the UK (burgers22?) mentioned that he has no problem passing emissions using a metal substrate cat.