MK3Brent

iTrader: (6)

Definitely not the original direction intended for this thread, but I am more than happy to help with education.

Wouldn't it be logical to say that w/o the cat, the numbers you posted could only be improved?
It would be interesting to see two back to back runs w/ and w/o the cat to show no difference at all.

7_rocket

iTrader: (6)

Does the Bonez not reduce/eliminate most of the smell? I was thinking about going with the Bonez this fall because my car stinks (midpipe)

moehler

iTrader: (12)

I'm sure the cat reduces power over a midpipe. The point is that if want a cat (for smell, etc.) that you can still make good power with them.

moehler

iTrader: (12)

With an air pump, yes it eliminates 100% of the smell. W/o an air pump it eliminates most of the smell.

IRPerformance

iTrader: (41)

We have seen gains up to 20 hp at this power level by replacing the high flow cat with a midpipe and installing a better flowing exhaust than the Racing Beat, which is on the restrictive side vs some of the other offerings on the market. My point is you can still make solid numbers with a high flow cat, unlike some who post ignorant comments that you can't or shouldn't run a cat above a certain power level with no factual data. Some people are willing to give up a few hp to remain compliant or avoid the smell of running catless. I'm actually going to dyno another car within the next few weeks with a similar setup to the one who's dyno sheet I posted, but with a Magnaflow midpipe and a different exhaust. I'll post the results when I get them.

Hi Im Simon

iTrader: (6)

Damn I thought the Vibrant cat would work well. I was looking into the Vibrant and HJS high flow cats. Anyone have any experience with HJS? The BMW and Porsche guys seem to love it and they are expensive, $600-1000 USD. I was mainly looking to get rid of the exhaust stink.

Universal catalysts - HJS Motorsport & Tuning

David Hayes

iTrader: (6)

I may be the only 3 rotor guy to run a cat on his/her car. Wanted to get rid of the stink so tried a few units. Settled on the MBS 100 cell unit and have had it installed for around 3 years:

High Flow Catalytic Converters - Mandrel Bending Solutions

Holds up to the heat of the rotary and eliminates a good bit of the stink. The 200 cell would eliminate more of the smell but I was worried about the restriction. And yes, you can make good power using a high-flow cat. Here is my dyno at 20 PSI:



Made 716 WHP and 570 ft. lbs.

GoodfellaFD3S

iTrader: (213)

David, do you have any pics of that converter installed on your setup? Assuming it's mounted pretty far downstream. The price sure as hell is right, and they seem to be nice and compact based on the pics on the site you linked to.

I may have to change my tune on this subject, once you stop learning and growing you may as well be six feet under, right?

Happy New Year all

David Hayes

iTrader: (6)

Hey Rich. I don't seem to have a pic handy but will take one - once the car comes back from the body shop. A lady with a 1994 Buick Roadmaster station wagon backed into me a few weeks ago and it crunched the left side of my bumper.

As I recall, the converter is placed forward in the midpipe, not back, but I'd need to verify this as the work was done some time ago. Has held up well and cleans up most of the rotary stink. Zach at Addicted and I think there is little to no impact of the converter on WHP. If you were to use a higher cell count one (say 400 or higher) you'd definitely get a restriction so it's a matter of using a lower cell count and giving up some of its cleaning abilities.

cib24

People need to stop thinking that a cat is going to inhibit your ability to make power. High flow cats are not really that much of a restriction at all and like IR Performance says, at 450, 500, 600, whatever horsepower you aren't going to notice 10 or 20 hp. You probably wouldn't even notice that difference on a car with stock twins.

Manufacturers today have cars like the Corvette pushing 700+ horsepower and they have 2-4 cats. Set your exhaust up right and you will have plenty of flow and stay away from the headaches and poison to your lungs and the environment associated with running catless.

FEED AFFLUX v5

iTrader: (5)

Resurrecting an old thread here, but does anyone know if SMB are still in business?

The website either errors out or displays poorly whenever I try......

Thanks!

BLUE TII

iTrader: (9)

I read on this site that Marcus Read who sells FD parts on Facebook has contacts with SMB and might be able to get batches of exhausts made.

https://www.facebook.com/profile.php?id=527820134

I had to put my 3" resonated SMB highflow cat on my car to stop the boost creep with stock twins. It will run 12psi with the SMB high flow cat, but was creeping to 17psi with 4" downpipe back open exhaust. I tried a 3" resonated midpipe and even with that it was creeping to 15 or 16psi.

So anyone that says highflow cat flows well- not really; but it can be a useful restriction.

Problem is, I just looked at the SMB cat and its starting to lose its shape finally after running with no emissions (airpump). Don't know how much longer it will last with my abuse. It blows some big flames through it if I just wing it up to the 9,000rpm rev-linit which I was not expecting.

mikejokich

iTrader: (1)

I had an SMB cat for several years too. They begin to melt at the higher temps of our rotary exhaust. The deformation you are seeing in the honeycomb is the melting. The air pump is not necessary for a metal cat and this lack of an air pump did not affect the SMB cat per say except for it may have slightly decreased the exhaust temp from the pump air introduced. Likely negligible. After my SMB melted, I bought the newer Vibrant GESI UHO cat. Higher melting temp, 300 cell rather than the SMB 100 cell, and rated for 500 hp. Simply better.
Mike