Cutting the airbox

[Kofkof_00]

I have heard that it allows more air to flow in. Is this a worthy upgrade? Has anyone done this?

[Aaronbrook37]

Absolutely worthwhile. I have yet to do it myself. I'd most recommend getting a hard piping setup from the TB to the MAF in it's stock location. Some people seem to have a real grudge against the flowing capabilities of the stock filter... it's not really the piece of the puzzle causing restrictions as of yet, so keeping it is advantageous.

If you DO decide that you want to upgrade to a cone filter, ensure that you have it protected from the engine bay's heat as well as providing one of the below solutions for it.

There seem to be two main sorts of airbox upgrades:

1) Drilling holes in the bottom of it. (Less expensive and less effective)
2) Feed pipes... which come in two main forms:

a) Dryer Hose which is routed down to the front bumper. (Ram-air Intake)

http://www.bmw-m.net/TechProc/diy_ram_air.htm

http://www.dsmtuners.com/forums/articles-intake-exhaust/195667-diy-ram-air-duct-cold-air-intake.html

http://www.8thcivic.com/forums/introduction-pictures/139048-my-custom-diy-r18-ram-air-intake.html

b) PVC/Plastic rigs to the grill.
Posts 6+7: http://www.fordfestiva.com/forums/sh...ad.php?t=23751

[manxbuggy1]

I cut the whole bottom out of mine and it def made a difference. It also made it sound different, meaner and a little louder. Then when I put the cone filter in it was better yet. Whether you just drill holes in the bottom or cut it, you will notice a difference in seat of the pants feel for sure.

[TominMO]

Right, it lets more air in at higher RPMs (therefore more gas is injected too); has no effect on gas mileage at lower RPM if you drive for economy. Probably does most of what a cone filter would do.

[ejp2fast]

i cut mine out too.. got rid of the whole oval snorkel, and cut the airbox about a 3" square....
my exhaust is cut anyway, so its loud regardless- and can't say it made it louder, but i think it pulls a hair harder above 3K rpm..

[Kofkof_00]

Wow, thank you all. Aaronbrook37' i'm thinking of ordering a generic 3" inter-cooler piping kit from ebay,
I would have enough for 2 cars... Interested?

o.O .-(I wonder if 2 1/2 is better suited to this?)

[Aaronbrook37]

Wow, thank you all. Aaronbrook37' i'm thinking of ordering a generic 3" inter-cooler piping kit from ebay,
I would have enough for 2 cars... Interested?

o.O .-(I wonder if 2 1/2 is better suited to this?)

Do you mean for the pre-filter piping or the post-filter ram air? I'm definitely interested in the package... shoot me a link via PM first though... just a couple of issues to sort out.

For the pre-filter intake pipe:

1) We're going to need to drill out two vacuum fittings for the brake booster / crankcase.
2) I'm unsure about how much underhood clearance the hood gives for round piping.
3) The OEM throttle body and VAF are both 2" to my knowledge, so a 2.5" or 3" pipe would not really do much in my opinion. Remember... if 1.8L/2.0L Civics and are using 3" piping, we'd probably be fine with 2". It will be easier to fit, and the noise wouldn't be as bad.
4) We won't need VAF adapters or extra couplers for filters if we keep the stock airbox.
5) This pipe could be insulated from the heat of the valve cover and exhaust manifold with intake heat wrap from Home Depot.
6) 2" piping will completely minimize pressure loss.

For the Airbox itself:
Any grooves/imperfections/flow impediments can be straightened down and sanded - a dremel comes to mind. Because of how much larger the air filter is in comparison to the rest of the system (both stock and modded), it's flow is better than the remainder of the piping. The airbox can be wrapped in heatshield, or shielded from the remainder of the engine bay, but this isn't really necessary because it's plastic and fairly far from the exhaust. They're also much cheaper to replace and keep clean than aftermarket panel/cone filters.

You can go cone filter if you like, but then you have to work out a properly-functioning filter shield.

For the post-filter ram air, it depends on which method you're choosing. DOING BOTH WOULD BE RIDICULOUSLY AWESOME!

1) The dryer/vacuum piping is super effective if doing a lower grill/bumper ram air. Even though it is significantly larger than the rest of the piping, it doesn't matter. The bottleneck at the VAF will be there either way. At 3", the ridges/restriction of the piping may significantly restrict airflow, but not compared to a crush-bent or mandrel 2.5" or 2.25" respectively. Just have to pop in a big hole in the bottom or side of the filter and route it from there. Plus, it's cheaper, often made of heat-resistant aluminum, and much easier to work with and shape into the front end of the car. After it's placed into the bottom of the airbox, it can be siliconed to reduce pressure loss.

2) For the "Type B" grill-fed system, the heat from the engine bay would make the aluminum piping a better option, probably with some sort of junkyard-produced air box as an end piece to fit in the grill and provide high quality airflow. Considering that the OEM radiator takes up only half the grill, it may be smart to get an airfeed source from here instead of the lower bumper. The other half of the grill (non-radiator) could be shaped to divert all of the air into this feed pipe to increase positive pressure - the entire purpose of a ram air pipe in the first place.

The entire purpose for intake upgrades is to reduce pressure loss and increase flow. Think of it this way... an intake is like a straw, and a human is like an engine. In order to get anything through the straw, you have to create a low pressure system in your mouth. The more restrictive and tiny a straw is, the harder you have to work in order to get the Coke or water on the other end. However, if you had a straw that used sufficiently large piping without too many impediments, the design would make drinking much easier. The difference here is that the intake pipe on a car has the assistance from airflow passing through/over the car, which is why you don't have to run giant piping the whole way. With amazing work, elements of the intake (especially the post-air feed pipe) can actually become positive-pressurized... also known as boost.

[fastivaca]

I've drilled several large diameter holes in the bottom of my airbox which makes a "throatier" sound. I've also adapted the K&N filter originally intended for a Chev Beretta. It's actually about an inch shorter than the stock Festiva filter but the Beretta is over 180hp so I don't think it's a problem. There used to be an article a looooong time ago on how to do that mod, I'll see if I can find a copy and post it (with permission of moderators of course).

One concern I would have for "ram" air is the possibility of sucking up to much water and forcing into the intake system.

[1990festiva]

One concern I would have for "ram" air is the possibility of sucking up to much water and forcing into the intake system.

A solution to this would be to drill one or two small holes in a low part of the intake (like the stock air box). This would allow rainwater and road spray to drain out but wouldn't be so large as to negate the effects of the "ram air". Like this you would be fine unless you drove into deep standing water, at which point you would be in trouble anyway.

[Kofkof_00]

Wow, again, tons of good info! I will order the 2 1/2 kit then, I don't think they carry 2". I definitely want to try both. Sounds like it would be a super fun project.

1) We're going to need to drill out two vacuum fittings for the brake booster / crankcase. I presume you want to drill / plumb these in the tube that goes over the vc? There was a bp that used a bmw e30 angle, that came with 2 holes / fittings molded in.

2) I'm unsure about how much underhood clearance the hood gives for round piping. I'm rocking the fms, but I don't even think it would be an issue.

4) We won't need VAF adapters or extra couplers for filters if we keep the stock airbox. I agree. I'm hoping to keep it in the stock location as well.

I own a dremel. Any mods that require this "ghetto" approach DO sound ridiculously awesome.

pm sent!

[Aaronbrook37]

Wow, again, tons of good info! I will order the 2 1/2 kit then, I don't think they carry 2". I definitely want to try both. Sounds like it would be a super fun project.

1) We're going to need to drill out two vacuum fittings for the brake booster / crankcase. I presume you want to drill / plumb these in the tube that goes over the vc? There was a bp that used a bmw e30 angle, that came with 2 holes / fittings molded in.

2) I'm unsure about how much underhood clearance the hood gives for round piping. I'm rocking the fms, but I don't even think it would be an issue.

4) We won't need VAF adapters or extra couplers for filters if we keep the stock airbox. I agree. I'm hoping to keep it in the stock location as well.

I own a dremel. Any mods that require this "ghetto" approach DO sound ridiculously awesome.

pm sent!

1) Yes.
2) Scott (leapin) has a pipe on his... I bet it's 2.5" or greater.
4) Awesome... I'm with you.
5) Dope... let's hit it up for sure! I'll PM you back later tonight about the situation - we'll need some reducer couplers, but those can be found on Ebay too.

[graywolf_14]

I made my own somewhat CAI using the stock piping and a cheap apc cone filter. I got rid of the airbox took the pipe apart flipped the one that attaches to the airbox turned it around and it bent down so it would fit behind the grill area. I wish I had a festiva I could take pics of what I mean