Honda Civic Forum - FAQ: Engine Components (Up to the Cat)

What do you mean by "cat"?

When we refer to a "Cat" on a car, we're referring to the catalytic converter. It's a part of the emissions-control system, and it helps to "scrub" some of the nasty stuff out of the exhaust before it hits mother nature.

Sometimes people remove it to allow for better flow though the exhaust system. Of course, the EPA doesn’t like this, so they decided to make it illegal.

Normal Aspiration (NA)

A normally aspirated engine is one which doesn't do anything to the external air before sucking it in.

1. What is a "CAI"?

: The term CAI is short for Cold Air Intake. It's premise is to suck in "colder" air from outside of the engine compartment. Because colder air is denser, you end up getting more oxygen into the engine. The O2 sensor sees this extra oxygen, and in turn, the computer adds extra fuel to the mix.

2. Can X CAI fit on Y model?

: The AEM CAI will *only* fit on the DX, LX, and EX with manual transmitions. Since the HX is basically the same as an EX the AEM CAI for the EX with manual transmition should fit the HX with manual transmition, but this has not bean verified.; The reason that this will only work on the civics equiped with a manual transmition is that the AEM CAI mounts to a bracket located on the manual transmission. Also, AEM did extensive tests and concluded that the CAI for automatics did not help in producing more horsepower. They will never make one for automatics.; The Injen CAI is more of a "true" CAI in that it mounts behind the bumper, and is completely outside of the engine compartment; unlike the AEM CAI, which sits rather low below the battery. The Injen CAI is made for all models; DX, LX, and EX. Again, no word whether it fits the HX.; The ICEMAN CAI has recently bean released for the 7th gen civic. There is no concrete information to report as of yet, but expect this to be updated in the next version of this FAQ.

3. What is the best CAI?

: There are various reasons to choose a particular CAI over another. Check the dyno sheets to see which CAI you prefer. You might chose AEM's CAI based on it's filter location and the fact that they also make a bypass valve for it that has bean tested to prevent your engine from injesting water when going over water that is deep enough to submerge the filter completely. You might chose Injen's CAI because the filter element is under the right headlight and is completely outside of the engine bay. You might also chose the ICEMAN CAI because it is made out of crosslink polyethylene which has the lowest thermal conductivity rating of any single-layered moldable material available on the market today. Then again, you might buy a no-name CAI and be just as happy with it as you would be if you had bought one of the brand name CAI's. The choice is yours.

4. What is a "SRI"?

: The term SRI is short for Short Ram Intake. Think of a CAI which has the lower pipe cut off. It allows for better flow to the engine, but it still sucks air in from the engine compartment since that is where the filter is. Sometimes a SRI is also referred to as a warm air intake.

5. What is a header?

: This generally refers to the exhaust header. Essentially, it's an aftermarket part which allows for better flow of the exhaust gasses from the exhaust manifold of the engine. There are several types of headers. A 4-2-1 header has four pipes merging into two pipes merging into one pipe and is generally beneficial from mid to high rpm's. A 4-1 header has four pipes merging into one pipe and is generally beneficial for high rpm's only, but it produces more power in the higher rpm's and less power in the lower rpm's than a 4-2-1 header. There are also two-piece designs as well as one-piece designs. One piece designs are more expensive, but lighter and less restrictive to exhaust flow.

Forced Induction

Forced induction is any mechanical method used to force more air/fuel mixture into an internal combustion engine at pressures above atmospheric. Why do we want to do this? In a word - POWER.

1. Nitrous Oxide, NOS, N₂O

a) What is Nitrous Oxide/NOS/N₂O?

: Nitrous oxide is a gas. One molecule of nitrous oxide consists of two atoms of nitrogen and one atom of oxygen. The laughing gas that is used for medical purposes is pure nitrous oxide, however the kind used for racing has some other trace elements in it that make it taste bad to deter people from using it as a drug.; NOS is a name brand of a nitrous oxide system made by Holley. Please DO NOT go around saying you have NOS unless you specifically have a kit from that company.

b) How does it work?

: Normal air is approximately 21% oxygen. So, when your engine needs oxygen to combust with the fuel, it doesn't get a whole lot from the atmosphere.; By injecting Nitrous Oxide into the combustion chamber (Which is 33% oxygen), you get the capability to increase the power of the explosion in the cylinder, hence creating more horsepower.; Nitrous oxide is typically stored as a liquid in a pressurized tank, so when it comes out of the fuel injectors it expands and cools. This raises the pressure and temperature within each cylinder before compression.

c) What's the difference between a "Wet" and "Dry" kit?

: A "Wet" nitrous kit injects both fuel and nitrous into the air intake. The "Wet" kits are generally dependant on a pressure-sensitive fuel regulator. Since the 7th gen civic doesn't have one, you're stuck with a dry kit.; A "Dry" nitrous kit only injects additional nitrous into the engine. The downside of this, is that it relies on the stock fuel system to deliver the additional fuel required to boost the power. It can also lead to a dangerous "lean-burn" condition, which will basically mess up your engine.

d) What's a "fogger" kit?

: A nitrous fogger mixes the nitrous and fuel together. It can be used to deliver the nitrous and fuel directly into the combustion chamber in what is known as a direct port nitrous injection system. In the movie TFATF the fogger kit was essentially a name brand kit made by Holley.

e) I saw "The Fast and the Furious", I really want NOS now!

: You should go and do a bit more research into the whole import racing scene and the nitrous scene before you even think about it.; DANGER: Nitrous can be dangerous to life, limb, and property when used to excess.

2. Turbocharger

a) What is a Turbocharger?

: Check out the following site for some really good information: Turbocharger Basics Plus The short answer is that a turbocharger is an air compressor driven by the exhaust gases of your engine. They can give significant power increases to your engine, but they're not cheap, you get turbo lag, there are maintenence issues, and much more...

b) Who makes a turbocharger for the 7th gen civic?

: As of the writing of this FAQ... NO ONE! There are plenty of rumors, and "My brother's uncle's cousin's sister's boyfriend got one", but as of yet, no one is producing a kit specifically for the 7th gen civic.

c) You mentioned "turbo lag". What's that?

: Turbo lag is the amount of time that it takes before the turbine in the turbo gets enough speed (from the exhaust gas, remember...) to actually kick in, and do the HP increase work. It's usually under a second, but still quite noticeable.

3. Supercharger

a) What is a Supercharger?

: Check out this link: How it Works The short answer is that it's an air compressor that is powered off of the accessory pullies of the engine. It's a parasitic draw, which means that it robs horsepower to make more.; They're generally considered to be better for the "daily driver" because they don't have some of the problems associated with a turbocharger. IE: No turbo-lag, no turbo-timer needed, etc...; The downside is that they're more limited in the amount of horsepower that they can produce. The upside being that they're more reliable than a turbocharger is.

b) Who makes a supercharger for my car?

: As of now: NOBODY. The latest word from Jackson Racing is that they're not planning to come out with one until at least a couple of years.

c) Which is better, a turbocharger or supercharger?

: The general rule of thumb is that for racing the turbocharger is better. For daily driving, the supercharger is better.; I guess it just depends on what kind of driving that you really do. If you're a hardcore racer, then go for the turbo. It allows for more fine-tuning than the supercharger, but it does require a bit more maintenance and forethought.; The Supercharger, can't really be tweaked easily, but it does make it a bit better for someone who just wants a bit more 'oomph on their way to work.