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Old 12-30-2010, 12:17 AM
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Default DIY GD cold air intake Custom Airbox

Well there I was a nice new ram air intake using the stock airbox and it was working fine. BUT me being me I couldn't leave well enough alone and had to see if I could improve things by getting rid of the stock airbox.

So in this thread we are going to pick off where we left off in this thread:
http://www.hondafitforums.com/showthread.php?t=1327

And I would suggest reading it before moving on to this DIY. You will need to use the pcv pipe installed into the fog light area from the first thread anyway so give it a read.

What we are doing this time: we will fabricating and installing a new intake system using turbo tubing, new air filter, and sheet metal.

What you will need: aftermarket air filter of your choice, two 90 degree 2 1/2 inch sections of turbo tubing, two 2 1/2 inch silicone tubing connectors, 5 screw clamps, a piece of sheet metal, sheet metal screws and nuts and bolts, cutting tools normal hand tools and a couple pieces of cardboard.

I started by removing the stock airbox and dryer tubing from the earlier system and saved them in case you want to change back to the other system.

Then I measured the area where the filter was going to be and went looking for a new filter and found this K&N one that fits in the space and even has a tapered end matching the area.



As you can see in this photo I have cut out section of the fender to make the opening larger for the other system but you could get away with the stock opening if you go directly to this system.

Now that we have the filter we need to build the tubing section of this system to see where everything ends up.

Here is the start of this section the tubing... and a warning I WAS going to use 3inch turbo tubing for the most air flow BUT it doesn't fit.



The radius is too big and you can't make it work unless you move your battery to another location. so back to the turbo shop to exchange the 3 inch for better 2 1/2 inch tubing.



Now all you need to do is connect all them together.... sounds easy but again there is a bunch of cutting and fitting you have to do so you hold it up check to see if it fits then cut a little more and try it again and back and forth until it fits. MAKING SURE TO CLEAN OUT ANY METAL PIECES OR DUST FROM THE PIPE BEFORE checking or installing

I found for me it was best to start at the TB and make the cuts with a hacksaw so the first pipe fits to the TB and is short enough the clear the battery where the 3 inch wouldn't.

And even with 2 1/2 inch it is fairly tight so cut carefully and start by sliding the battery as far to the right as it will go.

You should end up with the filter right next to the hole in the fender and everything connected with the silicone couplers in place leading to the TB and secured with screw clamps like this.



You will also have to take the stock IAT (intake air temperature) sensor out of the stock airbox and measure how far from the TB the sensor needs to be installed in the new system. It is best to mount the sensor the same distance from the TB as the stock system as moving it may throw off the calibration of the sensor. Then just mark the distance and drill a hole of the stock size in the new pipe and install the sensor using the stock rubber grommet that just pops out by wiggling it out CAREFULLY.



While I was there I also mounted the sensor for the indoor/outdoor thermometer I use to monitor intake temperatures right at the TB.



I ran it like that for a couple days and had to temporary install some of my favorite insulation to try it out.



I could have stopped right there but then thought why run with hot under hood air when I already had a ram air system in place that had nice cold air.

So I decided to fabricate a box to fit around the filter and take advantage of that cold air.

I started by measuring where the filter was and then started on the bottom of the new airbox first as that was going to locate everything and would hold the sides in place.

Sorry I forgot the photos of the bottom but it was made by taking the system out and then using some cardboard to make a pattern out of area before transferring it to the sheet metal.

It takes more trial and error to make it fit because the shape of the area by the fender has lots of curves BUT you want to make it as close as possible so you don't get air leaks.

WARNING: make the bottom so it fits but REMEMBER TO LEAVE 1/2 inch extra material on the back and engine side so you can bend that extra upwards into a lip so you have something to screw into to hold the box together.

This is the best photo of the bottom I have and you can see there is one sheet metal screw way to the right holding it to the fender. It is also held to the battery box by putting a strip of metal between the battery hold down bolt and another set of bolts on either side to hold it to the battery hold down. It rests on the fender also so it is quite sturdy.



Note how it follows the contour of the fender to make it air tight.

Then I did the same to the back that goes up against the battery. Not forgetting to leave the 1/2 inch to fold over to hold things together.




If you look close enough you can see the same system on this as the bottom where there is a piece of shinny aluminum between the battery hold down bolt and the battery which is screwed to this rear piece holding it in place.

The side toward the engine needed a little more work because of the tubing going into the box from this side.



And you also have to work around your radiator hoses and in my case the sensor block for my engine coolant gauge.

Then you just use some sheet metal screws to hold the sides together and start on the lid.



Simple just cut the sheet metal until you have a box............
Really it's not hard work but it is time consuming because you have to fit it, check it, make corrections and start all over again but you end up with some pieces like this.......



and end up with a box like this.....


So now we have a box but it LEAKS air and we have to seal it up.

I used my handy dandy foil foam insulation but you could use anything you have that is waterproof and air tight.



You really have to look around and fill in all the nasty places where air could leak out and just plug the up. You could even use duct tape or whatever you have hanging around as it's inside the box and won't be seen much.

But don't forget less obvious place either like this spot between the headlight and fender behind the hood support rod.



Just use what you have to stuff this area so air can't slip past it.

Ok so why have nice cold air when it could get heated by the engine heat. SOOOO out comes my favorite foil/foam insulation once again and the outside of the box gets a coat along with the radiator hoses that run in that area.



And the tubing gets a layer too.

Now that our airbox and intake system is built now we have to think about where the air is coming from.

The brilliant idea light came on and I thought HHHMMM we have a nice new ram air hole in the grille already so why not exploit what we already have?

So off came the wheel on the right side for more room to work and the front section of the plastic wheelwell protector was dropped to see what was up inside there. The first problem to solve was spotted....

In this photo from the ram air build you can see right behind the hose there is a large opening where you can see the motor mount inside the engine bay.

Sorry but no photos of this but this giant hole from the wheelwell leading to the engine bay has to be sealed off.



You can use anything a bit sturdy and WATERPROOF because if you drive in the rain this will get wet. It's very easy to do because this is inside the fender well and nobody will see it. I used some of my favorite foil/foam insulation so the hot air in the engine will not get into the front of the fender.

Now all you have to do is look around in this area for light or holes and seal them up with tape or something so the front half of the fender becomes a big air tight container (except the pcv tubing we will be using) the pcv tube already there lets cold air into the box which now leads to the hole in the fender which now leads to our new custom air box which feeds our new tubing intake system with cold air.

To seal the front of the fender from the back half I reinstalled the bolt holding the inner fender liner that is straight up inside the fender above the middle of the tire. Then I stuffed more insulation into that area around that bolt so air can't go from the front of the fender to the rear.

Put the fender liner back in place and presto air now comes in the front of the plastic grille housing through the pcv we installed last time but no hose is attached.

The cold air fills the front half of the sealed off fender and has to go out the hole in the fender leading into the engine bay into our new custom airbox.

Now you have a custom half short ram/half ram air intake system.

The engine sees the air as a short ram so there is no loss of power low down BUT the short ram has a source of pressurized colder air supplied by the big reservoir inside the fender which is supplied by cold air from outside the engine compartment. The best of both worlds.

The system works fine and supplies air at ambient air temperatures right to the TB.

The only drawback is when you need to add coolant you have to take the lid off but it's only 4 short screws and takes less than a minute. You can still check the level by shinning a flashlight on the container or looking up from the bottom.

Whoops almost forgot the "money shot"


Last edited by claymore; 02-28-2011 at 11:59 PM.
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Old 12-31-2010, 02:08 AM
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I forgot to comment on one more benefit of this particular system. you get nice cold outside air BUT very little chance of hydrolocking your engine. Since water would have to fill the whole front half of the fender then fill the airbox with about an inch of water the chances of that happening are slim to none. Unless you try to drive through water 2 feet deep playing submarine then you deserve to have it happen.
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Old 10-20-2011, 12:14 AM
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Well I had THE scariest "adventure" yet in my JAZZ today but now I know for 100% certain that even with my DIY opening in the bumper UNDERWATER FOR ABOUT 15 MINUTES driving through a flooded area the JAZZ made it through WITH NO PROBLEM.

I had to go to DMV today as it was the last day before my registration expired and I had been putting it off as the area around the DMV gets flooded every year.

Drove toward the place and was thinking not too bad a couple of puddles but no major flooding UNTIL just before the entrance of the DMV itself there is a little rise in the road because of the road passing over a small river I came over the rise and it looked like the flood from Noah's Arc water everywhere and no way to turn around to avoid it I was forced into going through the water.

And it was DEEP 2 feet in some spots. It was so bad that you had to maintain just the right speed if you went too slow there is a great chance of stalling out and when you go too fast YOU RAISED A BOW WAVE THAT CAME UP THE HOOD until I slowed down a bit and the wave of water ran off the hood. The area is rural and very open rice paddy fields and the DMV looked like a mirage in the middle of a flooded field just tall enough to be out of the flood.

The trip in took about 15 minutes of me sweating bullets waiting for the engine to hydrolock and die but it MADE IT FINE.

Then I had to think about how the heck am I going to get back to the dry main road again?

I switched out my cowl scoop that I had been running even in the rain for the closed stock cowl cover and gave a lot of thought to taking the cover off my airbox to allow the intake to draw air from under the hood but then thought about all the water rolling up the hood and how it had made it in and made the correct decision to leave it closed and drawing air from inside the fender.

Made like a submarine again for another 15 minutes of the hole in the front bumper completely under water and made it back to the dry road sweating it out all the way.

The only thing good on the day was making it through all that DEEP WATER and not causing any damage to the engine using my DIY system.
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Old 10-23-2011, 10:34 PM
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Just found one problem with my Jazz after playing submarine........... my horn is full of WATER. Tried using my horn yesterday and all that came out was a feeble meep instead of the great loud beep from the Accord horn I have installed.

Took it off and shook out all the water still trapped inside and put it back on and YAY back to normal. Guess I really was in DEEP WATER to fill up the horn in the stock location.
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Old 10-25-2011, 08:45 AM
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Playing submarine is not good for your car. today I found one of my red door edge reflectors was washed off not too bad while at the store found a 4 pack of them for a buck

BUT THEN my A/C stopped working..... Checked it late in the day when Mrs. claymore got home and could turn the system off while I watched the compressor and it's not even trying to engage the compressor so when I get a minute I will check the fuses first.

My fault .... while sweating it out trying to get through the water I didn't even think to turn off the A/C.
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Old 10-30-2011, 11:39 PM
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I hate to say it but Mrs. claymore "fixed" my A/C We went out last night to check the progress of the flood waters heading our way and normally we don't usually spend any amount of time driving around when it's dark but last night we had to check the flooding.

I had put off trying to "fix" the A/C until after the end of the month when my pay comes in and had just drove around with the windows down a couple of times.

She was disappointed that the air wasn't working but then said "it might work a little better IF YOU TURNED IT ON"

I must have turned it off while playing submarine and forgot about it. Normally the A/C is never turned off and runs 100% of the time around here as it's always HOT so in the day time so I never noticed the little green light was off on the A/C button.

But in the dark Mrs. claymore noticed the little green light was out and sure enough I just turned it on and it works FINE.

So much for basic trouble shooting as in "Check to see if the device is turned on before proceeding to step 2".

While it pains me to admit it on here you get the whole unvarnished story and I was a classic boob on this one but the good news is now I don't have to fix it.
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Old 11-02-2011, 12:15 AM
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found another problem caused by playing submarine. After giving my car a good wash yesterday I noticed my tint on the hatch window was looking a little "funny". It was hard to see but if you look at it from the outside it looks a little wavy on the bottom left side.

The only thing I can think that could cause it was while playing submarine I turned on the rear window defogger and it was on for maybe 1/2 an hour while I was busy rescuing myself from the flood.

Since I virtually never turn on my rear defogger since it's always so hot around here this was the first time it was turned on and it must have gotten too hot in that area. Lucky it's only in a maybe one inch tall 8 inches across area on the very bottom and it's not noticeable unless you are real close like when you are toweling down a freshly washed car.
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Old 12-01-2016, 08:59 PM
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haha, just after you installed and talked about no fear from water entering you post about the flooding near the DMV and driving submerged...haha, a great test, and an even better read. Please explain the following to this newbie. "Now you have a custom half short ram/half ram air intake system. *The engine sees the air as a short ram so there is no loss of power low down...*"
How does the engine sense whether its a short ram or CAI? how would it sense one or the other? Is it by intake air temp? Thanks again for the great read and the great DIY instruction. I may just attempt this in the Spring, after I replace my starter which will prob need replacing then.
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Old 12-02-2016, 11:44 AM
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The engine knows only the amount of pressure that is entering the intake. With a short ram the short length of the "tube" means the air moves quickly through the tube into the intake so there is no "lag" at lower speeds and you open the throttle the air can keep entering the intake at the newer rate without having to wait for the air in a long ram air system that is way far away just entering the long tube to get moving and travel along the longer tube.

With my system cold air is always entering the front part of the fender and collecting there so sufficient cold air is already there at the entrance to the new short "tube" rather than having to enter then travel inside a sealed long "tube".

Still working fine after all these years although I did have to replace some of the duct tape that separates between the cloth backing and the adhesive.

I can tell it's working because I have a thermometer mounted in the new metal "tube" right where the blue silicone pieces connect with the TB. While moving my intake air temp is normally 10-20 warmer than outside air ambient temps.
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Old 12-02-2016, 03:12 PM
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thanks for the explanation. On 'the other fit site' they're putting a little breather filter on a breather tube. Why are they doing that, and why are you not, or am I (likely) missing something?
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