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Thread: Cold air intake (CAI)

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Posts: 11-19 of 19
2012-05-21 19:27:26
Before you decide what you want, you first need to figure out what your goals are. Performance (which type), looks or just a nice sound.

Here are the theories:

Cold air is better than warm air for intake charge beacause of the increased density of colder air.

Long piping is better for low and bottom-end power/response.

Shorter piping is better for top-end power.

Narrow (2.5") piping helps with air velocity and will help you with that bottom and mid-range power you are after.

Wider piping (3" and above) will have a slower air speed but will allow more volume of air to move through the pipe which will help with top-end power as the engine is craving lots of air at high revolutions.

Bigger filter is better than smaller filter.

Smoothing the air turbulence at the beginning of the intake cycle (with velocity/flow-stacks) helps with accurate MAF reading of air flow. Long-tubed CAI's don't have as much of a need for velocity stacks as the air molecules have an opportunity to "line up" or straighten out before entering the MAF. Short-ram intake setups usually have more of a need for flow-stacks for the opposite reason. In most of these setups the MAF is right sfter the air filter. If the air is too turbulent and the MAF can not read the air-speed (flow-rate) properly, the ECU may read the MAF voltages inaccurately and cause a lean or rich condition that will cause a power loss. All things being equal the MAF takes a "guess", the ECU "guesses" as to how much fuel is needed and then the O2 sensor readings force the ECU to make fueling corrections. It is a harmony of sorts.

Slapping on any 'old' POS on to your car may cause you to lose power where you want it for many of the reasons I have listed above. Keep in mind that many dynos will show that this intake setup makes more power than the next one but the truth of the matter is that a set-up that is designed for your needs will always work the best. There is no such thing as a cookie-cutter intake set-up that will work the best on every type of engine.

The first 'intake' mod I did to my Nissan over 11 years ago was drop a K&N high flow panel filter in to my stock air box. The results? I felt like my car was faster but in reality it probably wasn't. Maybe 1 hp? . The next mod I did was rip out the factory setup and install a big cone-type filter right after the MAF. The results? I noticed increased throttle response and it sounded cool! The next mod I did was to install an AEM CAI that was designed for my engine. The results? I loved it! Increased power all over, especially in the mid-range. It also sounded awesome. All of the results were monitored with my trusty butt-dyno, of course!

In my opinion the best of all of the worlds would be to have.....whatever matches your goals. You say you have cams, header, exhaust, etc. etc. etc. Do you spend time aove 7000 rpm? In my opinion you might want to look at a medium lengthed set-up. Keep the piping as long as you can within the engine compartment, make a box for the engine compartment to keep the warm air away from the filter and to alow cold air to make it's way into the box from the wheel-well area or other areas depending. Use a flow stack/velocity stack and go with 3" tubing. If this is too much work and you are set on getting a CAI, then just get a CAI set-up that is designed for your engine. Injen, AEM, DC sports, place racing, weapon-R, there are lots of them out there. You can't go wrong with Injen or AEM. Just make sure it is 3" in diameter as you have other mods but more specifically, upgraded cahshafts. It may be hard to get theses kits in 3" and they tend to be over-priced so a do-it-yourself 3" CAI setup with a flow-stack or JWT pop-charger might be your best bet.

Also, you don't need to worry about hydrolocking your engine from water ingestion form your cold air intake. Unless you plan on driving you car in the ocean, I wouldn't worry about it. Water droplets and moisture will not hurt anything. A puddle splash, while not ideal, WILL NOT hydrolock your engine! I drove for years with a vent in my front bumper so the air filter could get direct air flow. I had zero ill-affects from this and the filter did get wet from highway driving in the rain. Now, I would not reccomend this and I would not do it again but all things worked out without any issues. If you are still worried about hydrolocking your engine from water ingestion, get a bypass valve. They retail for between $20-$60 on ebay. Problem solved. The AEM bypass valve will not hurt performance either. I went without one on my setup but had the opportunity to try one out for a few weeks and I noticed zero difference in power. The bypass valves that are designed properly will not ingest air unless the main filter is submerged under water and no air can pass through it.

My next setup will be a medium length CAI with a flow-stack and 3" piping.

Not sure why I decided to type this much?? Hope I helped.

Here are some links you missed on EBAY.

sr20 cold air intake | eBay

Cold Air Intake 97-01 Sentra 2.0L,200SX 2.0L,SER 2.0L | eBay

sentra cai | eBay

nissan sentra cold air intake kits | eBay

nissan sentra cold air intake bypass valves | eBay
Last edited by B15NEOVVL on 2012-05-21 at 19-46-57. Reason: Spelling!
2012-05-21 19:32:22
Now thats a great,informative post!!
props to you for doing all the work .
2012-05-21 23:10:14
Great info on cai vrs wa intakes. I liked mine i bought years ago. I paid $300 for the damn thing . But i also had my ecu tuned for it and other mods . Like b15neo said dont worry about the bypass . Ive never had issues with mine going threw puddles.

Sorry to thread jack ..
If anyone is looking for a full 2.5" aem cold air system for a lowport DE then member "fubar102" has one for sale not posted yet .
2012-05-23 19:40:37
Thanks for the great information ! ill look into trying to buy an aem cai and if i cant find one ill go injen.

does anyone know where to get aem cai ? if soo please link me

thank you for your cooperation appreciate it !
2012-05-23 20:09:08
Here ya go

dang it looks like he sold that one.

2012-05-23 20:17:49
Get you some piping, and buy this........http://www.sr20-forum.com/naturally-aspirated/58085-stillen-popcharger-de-maf-w-fair-cond-filter.html
2012-05-26 03:11:19
2012-05-26 03:46:28
Here's my current one with some research: http://www.sr20-forum.com/sentra-se-r/54538-62-00-autozone-semi-cold-air-intake-pic.html
Last edited by Storm88000 on 2012-05-28 at 20-40-23.
2012-05-26 03:56:17
A well-respected Nissan tuner recommends stock-intake box with for instance a K&N-filter element and from the box a hose to a duct at the front of the car. This way colder air will always reach the intake directly. I had everything, WAI, CAI and different makes. I´m sticking with what the tuner recommended as it gives me torque and high-end power and no loss compared to CAI and WAI. The latter btw, in the warm climate I live in, caused a lot of heat soak.
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