Free flow catalytic converter

OK so turns out the flowmaster muffler will mostly only make more noise. How about if I just replace the catalytic converter with a free flow type and install a K&N air filter.

You do realize that none of these modifications come into play until you’re at wide-open-throttle? How often are you going to be at WOT?


Both your intake and your exhaust are capable of moving all the gasses that the engine is capable of inhaling and exhaling without difficulty. Any improvement will be imaginary.

If you want to say to your friends “may car has a XXX and an XXXX”, then go ahead and do them. But if you want any real performance improvement without tearing the engine open you’ll have to start by pushing more mix into the cylinders with an aftermarket supercharger or turbocharger. And you’ll have to suffer the reliability consequences. And the cost.

I totally agree with Tester; Save your money and spend it on things that do a lot more good such as the basic everyday maintenance stuff.

Is there something wrong with the car you are trying to fix? Is there something wrong with your catalytic converter or is there money burning a hole in your pocket?

Perhaps you should trade your Tacoma for a Camaro or a Mustang. Wouldn’t that make you happier than screwing up your Tacoma?

I say “screwing up your Tacoma” because a K&N air filter will need to be properly cleaned and oiled on a regular basis. If you don’t do it just right, it will screw things up. It also might not filter as well as a paper filter, which can harm your engine. I also don’t expect a K&N air filter to give you any noticeable improvement.

What is a “free flow catalytic converter?” Is that one that is shaped like a catalytic converter but doesn’t have the same equipment inside?

I suspect it’s a marketing term.

Any converter should have at least as great a CFM rating as the input, and then some. I say “and then some” because pushing the exhaust into an even larger capacity pipe slows down velocity and allows the NOx to “linger” more, allowing the NOx to more completely make contact with the catalyst and the CO more time to collect an extra oxygen molecule and the HC to “combust”. Velocity then picks back up as the gasses exite the converter into the lesser diameter pipe. Boyle’s Law (or was it Bernolli?) says so.

I don’t know this for certain, but I’ll bet lunch that converters are designed intentionally with greater CFM ratings than the pipes that they’ll support.

The real “enthusiasts” have two exhaust systems. The stock one, hung on the wall in their garage, to be used on “Emissions Test Day” and the “Race Truck Tuner Boy” custom system, no CAT at all, (I saved enough money to pay for the whole system) and a pair of 4" Glass-Packs to get that deep V8 rumble…Yes, your check engine light will be on, P0402, “Catalyst below threshold” but who cares about that stuff, right?? And YES, a K&N filter set-up…It must do SOMETHING for that kind of money besides creating an environmental disaster every time you clean it…And don’t forget the lift kit and huge tires…

Caddyman, it always amazes me that you’re not bothered by a constantly glowing check engine light. I would be.

I am grateful that height of the time of my most intense interest in modifyiny my street car came at a time where it was not only freely allowed to do it but the modifications actually helped the car. This era is by no means dead but a shift has occured in just what can be done.

Good friend with a wife and three kids built a stroked small block for a 70 El Camino he bought as a hobby, The car was so fast he sold it very quickly as he felt he had to remain on this Earth to take care of family.

I present just two examples about how things change and we just can’t so freely do as we once used too do.

Once you cross the threshold and remove the converter, CEL’s become meaningless…If you spend Big Bucks for a “High Flow” converter and K&N filter, getting the CEL to behave is likely to become a regular issue anyway. Black Tape…:slight_smile:

The idea that you can gain power by modifying the air flow of a modern car is about 95% wishful thinking. Back in grandpa’s time (yea I am a grandpa) the auto makers had not caught on that buyers were interested in performance. Today they know that customers want performance and better mileage. They also know that having free flow is going to help both.

The manufacturer has already milked the intake and exhaust close to as far is it is worth going.

[b] Note: K&N oiled filters (which if most of them) are known to cause damage to MAFs if they owner is not very careful about re-oiling them.  They also have been found lacking when it comes to how well they filter. [/b]

I respect your right to do this if you wish, but I strongly recommend against it for all others. Essentially eliminating your CEL as a warning device can leave an owner exposed to all form of serious problems that could have been caught and corrected had the owner had a functional CEL. IMHO this is a bad idea.

Intake and exhaust. Sure makes sense to modify to get the advertised benefits. But what about the CPU that is monitoring all of this? I just ask the dealer to flash my vehicles on board CPU for max performance. I married the dealers daughter so the garage guys have no problem doing this for me. Unless you control the brains of the operation, nothing else matters. Cheapest and easiest upgrade is a superchip flashpaq. You can argue about voiding the warranty, but the dealer won’t know (if you do it, of course they know I did it) cause you can restore it to stock codes before taking it in for service. Trust me, spend the $340 get the flashpaq, you will see instant improvement.

Things must be REALLY slow at Flashpaq to be digging up 6 month old threads that were answered correctly in the first reply…

Haha, actually I work in healthcare. Browse this sight at work and was reading throughout the posts. Thought I would offer my opinion.