Anyone have exp with Hyper flow cats

When is the last time you passed ca emissions because I have never had a problem if o2's were working but last test was nov 2012. I also get occasional cel. Am trying the new mini cat as extensions for the o2's and so far they are better probably 20 drives no light yet.

 

During smog test, how would they know if u have hyperflow or not and could they tell by just looking at it and that it is not OEM cats?

 

Probably because originals say ferrari on them and quite bit diff but they wold have to have sme experience.

I forgot best reason for hyper flows is I think they were about 20 pounds lighter. In California that would mean you could eat 40 in and out burgers and they cars handling would be unaffected.

 

They may be 2 lbs lighter but not 20 lbs lighter. THe best reason is the sound of the exhaust.

 

I will re weigh them 2 pounds sounds way off but maybe? We're your cores still good when you weighed them? Maybe I'm going deaf as well because I do not really remember a big sound diff from the hyper flows cats.

 

I just did the emissions test last year and passed with no issue. Sorry if I gave the impression that it didn't pass. The only problem I've had was before I found the "right" place to have it tested. They did the visual test and couldn't find any serial numbers hence the issue but the car has always passed from an emissions standpoint.

 

Actually the car would handle better moving the weight from the rear to the center. +1 for In & Out!

 

Stock cat is 3Kg each, HF cat is 1.8Kg each, for a saving of 1.2kg per side, or about 2.5lbs.

 

I've had Hyperflow cats and semi-stock exhaust for over 2 years and no CELs.

1998 355F1 GTS

 

Holy crap I must be getting weak. In my defence though 40 percent is a lot lol. To bad the stock ones didn't weigh 40 lbs then we wold have saved 16 each side

 

Oh I understand there are exceptions to this, it is not a "universal" problem, but I personally know three 355 owners with good running cars, with recent major services and proper cam timing performed and they get CE lights for low catalyst efficiency with Hyperflows... Two of them ended up putting extensions on the post catalyst O2 sensors to eliminate the light. The third put a custom made restrictor just past each catalyst to offer a bit more back pressure, and that got rid of the light for him.

I am not saying there is anything wrong with Hyperflows, but from speaking with Mark G at FoS it would seem the Motronic on the 355 just has very tight limits it is looking for, and seems optimized to the factory catalysts. I experimented with rebuilt catalysts with high performance metallic cores, and got the dreaded CE light many months after installation. Had them rebuilt a second time, lights came back...gave up, when back to stock (found some good ones on Ebay), have had no issues since.

 

In my book Mark is right up there with Mr. Helms for knowing these cars. He has taken superb care of my dad's 328...even driving over to Wenatchee to make some minor adjustments after it was serviced in Seattle.

I don't have hyperflows, but do have aftermarket cats. Haven't thrown a CEL yet in 2 years and 4500 miles. Knock on wood...

 

Wow, NC? Mark's reputation precedes him!!
Both Dave and Mark have been invaluable to me in keeping my F355 ownership tolerable. I also have to throw in a word for Carlo at Alfa of Tacoma for helping on a few niggling problems that he masterfully corrected a few years ago.

All these guys I owe a sincere debt of gratitude, and for expanding my knowledge of the 355.