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Emissions 101

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So you want to remove your emissions pieces because you were told it would yield you more horsepower. Well I’m here to tell you that is pretty much wrong. This statement would be true in the 1970s when emission pieces were new and in development but recently in the past 20 years, OEMs have found a way to side-step the emissions equipment killing your horsepower.

THE CAT

The first thing everyone does when they want to tear out their emissions is to: punch or remove the cat with test pipes. This is god awful to the environment but it is the ONLY emissions removal mod which will yield an increase in horsepower. You remove the honeycomb restriction in the cat and you will effectively allow exhaust gases to exit your car a lot faster. For those who are curious, the cat is a platinum coated device which creates a chemical reaction that breaks down the HC and COs emitted from your motor. So if you have irregularly high HCs and CO during your emissions testing, the cat is most likely the culprit.

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PCV VALVE
The second thing I see people doing is eliminating their PCV valve and running both the PCV and the intake PCV (side of valve cover) to a catch can. Boy is this ever STUPID. The PCV effectively and simplistically takes out unwanted, harmful blow-by in your crank case and removes it via vacuum in the intake manifold. This feature is not in function under WOT. In fact once the intake manifold reaches 1psi, it is theoretically closed and not in use.

Now, another misconception is that the PCV intake tube is really an exit tube. If you have oil and air blowing out the PCV intake tube on the side of your valve cover, you have motor problems. In most cases it’s just a tired and worn out motor but this isn’t something that is supposed to happen. The PCV intake is designed to suck in fresh air when the PCV opens and draws in the gases which had previously slipped past the rings. Taking out the PCV system seems pretty dumb to me.

(NOTE: Image D below is for N/A cars. Once boost hits, the pressure gradient will force the PCV closed.)

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EGR SYSTEM
The EGR is another system which many people eliminate. Now, other then dirtying up the intake manifold with a little extra carbon, the EGR does not affect the performance of the car in any way. It’s closed at WOT and idle. It’s only open at partial throttle w/ no boost to be precise. If you are doing your emissions and you are failing miserably in the NOx department (FWD only), your EGR is not functioning correctly. To understand this, you have to understand that NOx is not created by the burn of the motor but by the heat of the motor. At around 2500 degrees F, nitrogen and oxygen in the air effectively combine to create NOx, a harmful gas. The EGR re-circulates inert exhaust gases back into the intake to cool down the hot burn and reduce the NOx being formed.

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CHARCOAL/FUEL TANK VENT
The charcoal canister is an over-glorified device which simply consists of a few valves, filters and carbon. Excess gas vapors in the tank are vented out to the charcoal, where it is stored, mixed with fresh air and then purged into the motor via a throttle body port. Simply removing the system and blocking off the line coming from the tank will create a lot of gas tank pressures. Though the gas cap has a pressure release valve built in, it’s a backup system and only opens up under a lot of pressure.

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If you decide to remove this charcoal device, make sure you leave the tank vented so it does not over-pressurize.

I hope this provides the knowledge to those blind ones who try to remove their emissions.
 

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