The Free Mod Series - Part II Adding Airflow

[Toysrme]

Background:
Ram air doesn't work, CAI doesn't gain anything more than the stock box and they both cost money. IMHO The only reaso to buy any of the *expencive* CAI setups is for the metal pipe bling factor. I can achive the same bling with sand paper and Duplicolor Engine spray paint, sorry...

Theory
The more air in a cylinder, the more fuel you can burn, the more power you have.

Instuctions
Two mods you can do by themselves, or in combination.

1) The stock box is already CAI, however there are two things you can do to improve it's function! When you take out your battey, and unbolt the relay and fuse boxes, you can see the CAI that goes behind the fender from the bottom of the stock box.

By taking that pipe out and replacing it with <insert cheap, large diameter pipe here> 4" dryer ducting, we obviously have an easier time drawing in air, especially around 3500-4000rpm and from 5000rpm on.

2) Cut the bottom of the original airbox out. While some may argue that it will then injest hot air, this is untrue. If you take the box out you see there is a huge path striaght to ground for air to flow. It's there, so you might aswell take advantage of it if you don't want to do any other intake mod.

I will also now say 100% that the sound from #2 is astonishing. (depending how much you cut out) It sounds IMHO better than any of my friends v6 Maxima, Accord, or domestic V6's, and I've gotten many compliments from them not only about how good it sounds, but that it's free.

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*Edit*

Even better... Remove the entire intake system. No filter box, No filter, No piping, No un-necessary restriction, NO PROBLEM












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Other Articles in the Series:
Part I Quicker Transmission Shifting
Part II Adding Airflow
Part III Taking Advantage of Intake/Exhaust Upgrades
Part IV Cheaply Monitoring the ECU & A/F
Part V How to pick up MPG, and sleep with her too!
Part VI Acing Aerodynamics
Part VII Cheap Water Injection
Part VIII Electronic Transmission Controller
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[dna59]

I have done #2 before and I didn't notice any gain in sound. Maybe it's just my bad hearing though. I guess i will probably try out #1.

[Toysrme]

Everyone should also clean the intake tract. This has previously been covered Here. You should clean everything from the throttlebody as far down the intake tract as you're comfortable with.

(This is really common stuff. I only wrote it so I can post part III)

[CrawlingEye]

No offense, but modding a stock airbox will never get you the same results as a real CAI.

1) The Radiator's heat will affect the temps of the air your intake sucks in. Want to do a test? Go drive on the highway while your car's heated up, while the radiator fans are blowing, stick your hand behind the radiator. Now take your hand and put it in front of the grille, realize the temp difference? Think of your intake as a huge vacuum, now imagine what it's getting from that, as far as density's concerned.

2) the stock filter is nowhere near the flow of a conical filter, this in itself will give you reduced throttle response in comparison to a true CAI.

3) the stock airbox is not a true CAI, it's a warm-weather CAI. It's also made of plastic which is more prone to abosorbing heat than an actual CAI, if done properly with being ceramic coated.

4) swiss cheesing (or cutting the bottom of the box out) just makes your intake a RAM-intake without the flow of a conical filter. You're still getting air that has been blown by the header(s) and radiator.


Don't mean to be a dick, just saying the facts. It may be true that there's nominal differences (although I've found with my 5SFE that the differences are comparatively quite good, for the money, not at peak power but before peak power there's a lot more pull and much better throttle response).

[bassthrive]

I could imagine an improvement if I replaced the lower piping with something wider and with less bends. Flow shouldn't be too much of an issue with my K&N drop-in filter. I think ill try this project next weekend.

[MadDawg]

my rubbermaid heatshield is a better idea out of all yours

[Toysrme]

CrawlingEye your arguement is clear and easy to understand.
The harder to understand retort is that if the car is moving at any rate, that particular part of the engine bay is also getting some fresh air.

If you would rather not admit to that; there is a point at which hot air and high flow can't match low flow and cold air. This is not the point at which that happens.

[CrawlingEye]

Originally posted by Toysrme
CrawlingEye your arguement is clear and easy to understand.
The harder to understand retort is that if the car is moving at any rate, that particular part of the engine bay is also getting some fresh air.

If you would rather not admit to that; there is a point at which hot air and high flow can't match low flow and cold air. This is not the point at which that happens.

I admit that the car is moving, however if you use my radiator test, you will realize how the movement does not add to efficiency behind the radiator. The radiator can clearly be felt to produce very hot air under turbluence (stick your hand behind the radiator fans while they're on). If you hold your hand far back, you'll still feel the hot air being transfered to the engine bay. This is not your only heat-producing item (as I'm sure you know) the header is also a huge heat source. Regardless of the transmission itself not producing heat, the heat itself is still going to grow through there. This may be obvious, but the way your cooling system works is by using a passive conductor (your radiator) and a fan to displace the heat that's transferred to it, where does the heat go? Heat's natural path is up and while it does leak down, it will clearly build up in the engine bay. Your average coolant temps are around 220f, which you can use to gauge the temperatures under your hood in general. Now think of what your intake (essentially a large vacuum) does when provided by this air?

There's a huge loss in efficiency from it.

[RED171]

toysrme? can you post a pic of this mod? thanks

[Xevuhtess77]

putting some kind of divider between the radiator and the intake could help to keep the air seperate. i think im gonna try doing it (i have a cai, but same idea since the piping goes to the same place) and also try to duct the air from the hole in the front bumper that you can see the cai/wheel well area from right at my filter

[alex86]

uhm ive been lookin at my engine bay and i tried taking off the fuse box but i cant anyways i can or how do i take off the silencer below the intake box?

[89SV21]

When your remove the bottom part of the airbox, you will see a few exposed nuts that look as though they shouldn't be there. These nuts hold in the silencer, as i remember there is another one or two underneath the fenderwell plastic trim. Once you remove these nuts there will be plenty of pulling and wrestling to get the silencer out, it's worth it though, that thing is a big restriction. I've got an el prototypes cai on my 89 gen 2 and it works far superior to the airbox method described earlier. I've tried both and have found that the airbox chopping method produces more noise than power. The cai gives the air a nice smooth path from the fenderwell to the t-body and it can't be beat IMO. No offense to the author of the air box post.

[alex86]

well ya it doesnt really give much air flow bak and of course it produces more noise compared to a cai but its all good for the pplz who are low on cash like me.

[alex86]

o and another thing how the heck u tak off the top portion of the intake do u have to actually take it off the tubing and how do u unblot the portion where the filter is at?

[Toysrme]

Just unclip the four clips on it. You probably want to take the rubber tube that runs from the throttle body to the AFM.

Most of them split on the bottom after a few years anyway so it's a good idea to check it. If it is cracked melting the rubber back to itself is more durable.