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About That CAI
by Tony (NastyBoy)
Well, it was suggested that I start a thread on intakes, to help those of you who have never had one, or dealt with them.

Disclosure: I am not, nor claim myself to be an expert.

Now, here are the basics...

An intake system is composed of an intake pipe, silicone hose, required clamps and hose fittings, and air filter.

There are two types of intakes: short ram and cold air. A short ram is an intake that is normaly no more than 2.5 feet long and it all rests within the engine bay. Where the cold air (CAI) has an extension that leads outside of the engine bay; its purpose is to obtain cold air from outside the engine bay's high temperatures.

Both intake systems replace your existing intake, and depending on the system you chose, it may require the removal all or some of your stock intake system (since a CAI is longer, it requires that you remove the lower "boxes" of your original system).

Which one is better? Theoreticaly, if an intake system is done correctly, the CAI is obviously better as it sucks in more colder air, rather than the hot engine bay air.

Why do we care if the air is cold or not? The colder the air, the denser it gets; the denser the air, the less volume it takes; the less volume it takes, the more you can pack into the allowed space for combustion; more air for combustion, more horsepower made. This is the same priciple behind turbos and superchargers; they both work on 'turbine' principles that 'force' more air into the engine.

Why would I say the CAI is better if done correctly? There are companies out there, like AEM and Injen, that actualy take their time in research and development, where there are others that will just copy their design to make a quick buck. For those 'inexpensive' intakes, they probably don't use the same material, or have the same bends or craftmanship to actualy gain the claimed horsepower amount.

Why does the material matter? Well, for one, if all they use is normal pipe and call it an intake, chances are that that pipe will get hot, and regardless of the intake being a short ram or CAI, it will definitly not produce its claimed horsepower. How can it if it sucks in all that hot air?

The bends also have much to do, as the smoother and fewer bends that an intake has, the better the air will flow into the engine. Ever notice that the 350Z stock intake is rather straight to the point?

Follow-up Article

Now, where do we go from here?

If you ladiez (or guyz) want to produce more power on a budget, these are your options:

1. Purchase a K&N 'drop in filter'. This is just a replacement of your stock air filter. It will work with your stock intake, and takes less than 5 minutes to do the install. Will it work? Of course it will, it's K&N, one of the most respected air filter manufacturers worldwide.

How will it work? First off, notice the opening by your radiator, on your radiator support. It's by the driver's side headlamp, and it looks like a square hole. Well, that is actualy the opening for your intake, designed as Cold Air Intake (one reason the 350Z makes more ponies than the G35). Well, if you replace the filter with one that has less restriction, then the air will flow smoothly, and if it flows smoothly, it will then produce more power.

2. You can always replace your intake system with a Cold Air Intake System. As of now, AEM and Injen seem to be the only ones available. Nismo, which was manufactured by AEM, is on hold, as there seems to be a problem with its rubber connectors. And K&N, although some 350Zs have them, I don't think they are available to the public... yet (I may be wrong).

So who do I chose, Injen or AEM?

I will do my best to give you my unbiased opinion, since I sell both, and have cars with both systems.

First off, you really won't feel or see the difference between both systems unless you are racing at the track. The difference between both is very insignificant, but both claim different numbers; unfortunately both use different dynos.

(picture of dyno http://injen.com/webpages/special/350z_testing/RD1985%20average%20gain.gif).

Injen is designed by having the intake filter in the grill opening area. It is composed of one aluminum piece inside the engine bay, and one rubber extension outside the engine bay.

The reason they use a rubber extension rather than all aluminum is because: 1. They need to fit in the stock Cold Air opening (the square hole previously discussed), and 2. The rubber will retain less heat; hence, it keeps the air colder. Not to mention it's easier to install the intake, given the odd place where the filter will sit.

Installing is not that difficult, as some of you may have found out, and it's easy on the eye when showing off your engine bay. Does it do its job? Of course it does.

(dyno http://aempower.com/pdf/dyno/21-547%202003%20Nissan%20350Z%20Dyno.pdf )
Also a Cold Air Intake, it's designed differently than Injen. Instead of sitting on the grill area, AEM decided to place its filter in the front lower corner of the car. This is the area in front of your front driver's side wheel and front of car. Their theory was not to catch all the air while the car is in motion, but rather have the filter isolated in a secluded cold area.

AEM's intake is composed of two aluminum pieces. Another reason for the final resting place of AEM's filter is because they figure it will remain as dry as possible when it rains, as it's surrounded by the splashguards; whereas, Injen will be exposed to the rain and all incoming water.

What do I recommend? I recommend both. Each has its advantages and disadvantages.

What do I have? I have an AEM CAI. Why? Because I didn't want the rubber extension, and didn't want my filter to sit in front of my grill area by itself. Also, at the time, Injen's trademark logo was only offered in RED, which will clash with my plans for my engine bay.

Have I tested out my intake? Yes, the first week I had the intake on, I raced a Track 6-speed 350Z and G35 Coupe at California Speedway; both with Injen Intakes. I beat both: the G35 by a car length, and the 350Z by 1.5 seconds. Then again, in a race, it also depends on the driver. The 350Z, however, also had the UR pulley set and the ever-so-famous grounding kit.

Anyway, I don't want to go off-topic, so I hope the information can help anyone out there who may have a question about intakes for your 350Z.

Please don't hesitate to correct me on any mistakes, or ask me any questions should you have them.


© 2003 Z Chickz
Last updated: Sunday, January 14, 2007 8:45 AM