355 cat replacing

I have a set of 5.2's at my mechanics in Fullerton. I actually hope you produce the 2.7 set up because that's what I need for my '95.

 

Thanks for offering the 5.2's Ralph. I have a set of 5.2's but still need a set of 2.7's you got a PM!

 

Hey mpodgor (michael) Hows the car coming along running well? Having aftermarket cats should help reduce the temps in the engine bay and help with the longevity of the headers. I was blown away by how much damage the OEM headers go through under the factory heatshield! Have you done anything else to the car since the last mod?

 

Glad it's working okay. I've seen that code from the 02 sensor and it goes away after a reset... Not sure if it's the sensor itself. I had a similar problem happened to me when I replaced headers on my car and after a reset it hasn't given me a problem.

 

FYI--I just had a major on my 355-installed fabspeed headers and sport cats with secondary by-pass y pipe and capristo exhaust.

It passed smog on the first on the starting sequence. I was pleasantly surprised.

 

That's a very nice setup you have.

 

I have some data (from a CFD engine simulator) that I could share with you.

After looking at the factory, Tubi, FabSpeed, and the custon 348 header Ernie did a few months ago; the engine simulator said A) the exhaust tubes are too narrow, B) too short, C) exit the heads at the wrong angle (90 degrees rather than 73 degrees), and D) need proper merge collectors.

The simulator indicates that the header tube sizes would be more optimal with more conventional American V8 tube sizes (1.75" OD rather than the 1.58" OD factory) and longer (by about 3 inches) finally the merge collectors need expansion cones to properly extract all the exhaust gass energy between the primary merge collectors and the secondary merge collector. The expansion chamber at the end of the header was pretty close to optimal.

 

Thanks Michael! I can't talk too much about it right now as I am not a sponsor but I will be one soon =)

Thanks for your input Mitch! I ran also some numbers through an advance header design software and was surprised with what it recommends as well. I believe there's power to be gained over the factory headers. The merge collectors look terrible on the OEM headers! I am a firm believer in a properly built 4-2-1 header design. A well designed 4-2-1 header will produce better low and mid range power which is what most street cars see. On a 4-2-1 header design the primary and secondary lengths play an critical role in power production and where it peaks.... I personally like the long tube designed custom 348 ernie header but too bad we couldn't see a before and after dyno! =)

 

This is not quite the case. Given 3 different header designs, a proper 4-1, a proper 4-medium-2-medium-1, and a proper 4-long-2-short-1 headers; all properly tuned for the same top end power band:

The difference in the TQ curve is all down in the 2700-4300 range. The band from 4300 through 9000 (simulated) is indistinguishable (that is less than 1 lb-ft difference at any point.)

The trick is that all three designs were properly optimized for top end power. Properly optimized means I tried at least 100 designs of each kind before declaring it the best I could do. One can optimize the 4-medium-2-medium-1 headers for more midrange at the expense of top end--but this does not HAVE to be the case.

 

Hi Mike, I am looking to purchase some high flow cats in the near future and was wondering if you are happy with the prospeed cats on your car? Any issues? I am considering this brand and hyper-flow.



Jimmy

 

Thanks Mike for the response.


Jimmy

 

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Excellent =)

 

Received my high flow cats on Friday from Prospeed. They appear to be made well. Brian was very good to deal with. Between the cats and Bradan's y pipe, all I need are some good headers and my exhaust will be done. Thanks Brian.


Jimmy

 

Thanks Jimmy! enjoy!

 

Picked mine up from Brian and they look top notch, installing this weekend

 

How did it go? Hope it went well!

 

Sure did passed CA emissions with them and no CEL's, I added new 02 sensors also to give iut a good start

 

That's awesome! Congrats. =)

 

Just curious how did they fail,I have hyper flow from ricambi and there 5 years and 8000 miles. My only problem was check engine lights occasionally but seem to have that sorted now.

 

Mike, did you contact Brian about this? These have a lifetime warranty on them, for what it's worth. I haven't installed mine yet, but will be putting them on with my new headers when I do my major sometime this year. Hope this is just a rare defect and will not effect all cats produced.

 

Keep us up to date on this