Bell turbo finished
- Thread starter 20ESGUY
- Start date
Good question
I would suspect that the pre cat flows especially after a turbo would hinder performance immensly. But I have no scientific data to back that up just a very very educated guess.
I removed my second car and gained amazing power from it. Remember, turbos dont like back pressure.....so its safe to say that the primary cat does hinder performance. To what degree is the actual debate here.
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I have heard that the primary reason the first cat has flow issues is becuase the exit or part that goes into the down pipe is very small. The inside diameter of the pipe goin out the first cat is some 1.75".
So, if that is ture, that is the big bottle neck in the first cat. The inlet and exit sizes. If you make the hole larger, it'll flow better.
So, if that is ture, that is the big bottle neck in the first cat. The inlet and exit sizes. If you make the hole larger, it'll flow better.
Interesting!
I actually have my primary cat laying around somewhere. Perhaps I will try to find it, and measure the darn thing.
I dont think so. But you may want to give Corky a call http://www.bellengineering.net/. California emissions are tough. Sorry man..........
melicha8 said:
I took my exhaust all apart and reported my findings on the Protegeclub website. The Primary cat outlet is indeed small with the outlet on mine being only 1.710. It's cast, so I'm sure that there would be some that are slightly larger or slightly smaller. I enlarged it to 2.05 by using a die grinder and then final honing it the last .030 to make it perfectly round. That's a bit over a 30% increase in area. I then used a flange that I had made to fit our cats and built a replacement for the cast head pipe using 2.25" OD mandrel bent pipe.
The stock head pipe is also small (1.75" ID) and attaches underneath the motor to a stainless pipe going into the secondary cat. This stainless pipe is also small (1.9 OD) but is necked up to fit the cat. The secondary cat is slightly over 2" ID. I also built a 2.25" OD pipe that goes from the second cat forward to the pivot under the motor. The stuff I built hooks up to the factory brackets, has the heat shields on it and maintains the O2 sensor in the factory location. Definately breaths better than stock and will be even better when I get my header done. From the second cat back I used 2.5" all the way back including the stainless muffler. I'll be dynoing it again after I get the header done, probably later this week.
mp3_moran said:
I've spoken with Mr. Bell and was told that they aren't going to go through the cerification process due to expense and time. The reason that they built their system to retain all factory emissions though was to be able to get certification at a later date and not be liable for altering emissions equipment. They built the system to be able to be certified, but they aren't going to be going through the process.
