View Full Version : Fiberglass Cold-Air Box

Adrian Avgerinos
10-04-2006, 05:16 PM
A couple years ago I made a half-assed attempt at shielding the engine intake from the hot air of the engine bay:


After a track event last year, I recorded some pretty darn high intake temps:

For a cold-air box, that air ain’t so cold. About 11 months later I finally got around to building a new box. I believe the original box was flawed due to the lack of sealing. This time I inverted the box to create a bottom, and allow the hood to act as the top. This is the concept I came up with:

The second hole I intend to connect to a duct hose that will run under the radiator support to the front bumper.

I wanted to use a material that had low thermal conductivity so this meant no metal. I could have used ABS plastic sheets, but wanted to try my hand at fiberglass. After a failed attempt at molding an entire box into the aforementioned shapes with disastrous results, I decided to build the box out of multiple straight panels that would be attached by brackets and rivets.

So the first thing to do was mockup the basic shape using cardboard:
The toothpicks were used to locate the hood profile (plus they look festive!).

After that, it was time to build a large fiberglass plate:

This plate was constructed using 4 plies (weave/csm/csm/weave) and polyester resin. The glass surface acts as the mold creating a perfectly smooth surface with minimal effort. I made sure to wax the table 3 times before applying resin so that nothing permanently adhered.

After curing, a fiber-reinfored cutoff wheel and a Dremel made quick work of the plate:

(BTW, a respirator, shop vac, and nitrile gloves made the process extremely easy. I simply held the Dremel in one hand and the vacuum nozzle in the other while cutting. Piece of cake and no extraneous dust.)

I also found that using hot glue to temporarily tack together the sides works really well. I was able to get the pieces to line up perfectly without needing 3 more hands to hold the brackets in place for drilling. Corner brackets and aluminum rivets from Home Depot:

I filled in the seams with paintable caulking and then painted the inside with thick coating of Kyrlon Fusion. The outside got a coating of Dynashield spray insulation. Weather stripping completed the box and here is the result:

http://img.photobucket.com/albums/v232/sbcelicagt/Celica%20V6/Airbox/new_airbox_done2.jpg http://img.photobucket.com/albums/v232/sbcelicagt/Celica%20V6/Airbox/new_airbox_done3.jpg http://img.photobucket.com/albums/v232/sbcelicagt/Celica%20V6/Airbox/new_airbox_done4.jpg

All that's left will be to run the ducting hose to the bumper and to add some sticky foam strips in strategic locations where the fiberglass meets the chassis.

I've got a track event next week at Buttonwillow and will report back with some new data (if my OBDII datalogger decides to work).

10-04-2006, 05:53 PM
Very nice work :bigthumbu

Curious to see how it effects temps.

10-04-2006, 06:39 PM
looks great!

10-04-2006, 06:42 PM
Great work. Looks very good, almost store-bought. Im a little more interested in your V6 setup... Wat are the specs and wat engine did you use? What transmission did you go with? is it RWD or AWD? did it take alot of body MOD to fit the tranny under the GT? Please more info. Im really thinking of a V6 conversion w/RWD.

Adrian Avgerinos
10-05-2006, 02:44 AM
More tweaking:

I got home from work this afternoon and thought I'd quickly measure the temperature of the inside of the box using my handy dandy infrared temperature gun. I found that the vertical side measured about 120 degrees after my short 10 minute commute. I don't if this heat was due to hot air on the engine side, or hot air inside the box due to the gaping hole nearby (haven't run the duct hose yet). I had some foil-lined bubble wrap I bought at OSH last week and thought I'd give it a try. I'll test it again tomorrow to see if today's work makes a difference. It doesn’t look as professional anymore. Now it looks more like an under-funded NASA project. Ah well.

Mr. Ghost-

(I really REALLY need to get some sort of article written. Sorry for not doing it yet). To answer your questions directly:

Engine: 1997 3.0L 1MZ-FE out of a Toyota Avalon
Tranny: 1999 Camry Solara V6 5spd
No modifications to the chassis. Custom mounts are needed. Search around here for "1MZ" as I think I may have divulged more information in other threads.

10-05-2006, 02:52 AM
That still looks pretty clean though. I'm interested to see the numbers when you have them.

10-05-2006, 04:58 PM
Good stuff. Have you considered running a pipe through the inner wing effectively down from under where you have your filter to just behind the front bumper?

Very short pipe run and easy to install a scoop for cold air funneling from the airflow under the car ;)

Adrian Avgerinos
10-05-2006, 06:28 PM
Wing? I presume you are referring to something similar to this:

I had considered that solution, but wasn't ready to cut the splash guard or relocate the wires that already go through that hole in the chassis. I was also not keen about enlarging the hole as it looks a bit small for the larger engine. That and I may decide later to run brake ducts through that area.

10-05-2006, 06:39 PM
Nah mate, the same set up I have on my 185CS:


From the top left clockwise:
- 1st pic note the air filter position after relocation
- 2nd pic shows the pipe running through the inner arch to the scooped section just behind the bumper duct. If you look closely you can just see my foot at the bottom of the pipe (deliberate)
- 3rd pic shows where my foot is in relation to the front of the car to give you an idea where the pipe comes out
- 4th pic shows the air run from the duct to the scoop

Adrian Avgerinos
10-05-2006, 07:33 PM
So you cut a hole straight down then? Looks like nice work. It looks like your filter (foam?) sits right on top of your duct. Is that correct? Is the shiny wrap for your AFM?

If so, then something you need to think about is whether your duct provides enough airflow for your engine. If not, your engine will simply suck whatever air is available. Without a box to specifically "tell" the filter where to get the air, it's going to suck air from your engine bay since that requires less effort.

Similarly with my setup. I've got the stock ducts available (one behind the headlamp and one to the fender). If the flow out of the box (into the intake) is greater than the flow into the box (ducts), a drop in pressure is created. Unless the box is 100% airtight, it's going to leak in hot air from the engine bay. This defeats the whole purpose of creating a cold air duct. If the box was airtight, then you could hook up a vacuum gauge and watch for a pressure drop under high RPM WOT.

Simply put, it's not enough to simply point a duct at your air filter as it's not going to do a whole lot on its own. I’d suggest building a box around your filter so that your engine only receives air from that duct you built.

10-05-2006, 08:27 PM
It has a custom made box with insulation but as I'm running the standard ems with afm at the moment the box wont fit as it was made by the previous owner and designed without the afm there.

The insulation material is to insulate the air flow meter only. The straight intake positions the filter right over the duct and right next to the standard airboxes feed hole in the wing that would normally lead to the resonator box (removed).

The previous owner carried out most of the mods on the car, I'm now altering them to my way of thinking. The focus of the car is going to change as well as I get money together to move in the direction I want to go with the car.

Courtesy of the CS's better designed bonnet and bumper there is a lot less heat build up in the engine bay especially noticeable when moving at any speed. Temperature probe research has found after moving a few hundred yards the engine bay temps are down to within a few degree's of ambient. Since I have no interest in drag racing the car, that suits me perfectly.

Adrian Avgerinos
10-05-2006, 09:28 PM
Courtesy of the CS's better designed bonnet and bumper there is a lot less heat build up in the engine bay especially noticeable when moving at any speed. Temperature probe research has found after moving a few hundred yards the engine bay temps are down to within a few degree's of ambient.

Ambient? No shit. :eek: It would be interesting to see how that changes on the track. I've got a lot of heat under there and may add vents sometime if I find my coolant temps start to creep up.

10-05-2006, 11:03 PM
Yeah, the wide openings and vents help a hell of a lot, theres a very noticeable difference (apparently, I'm going on other peoples info) between normal alltrac bumper and scoop set ups and the CS/RC set up.

In a way I envy your set up because after getting cool intake air, your battle is pretty much won. With turbo'd motors in cramped bays with a charge cooler right over the engine block, our funs just beginning :hehe:

My main priorities with the CS in preparing it for track work are:
- weight
- brakes
- suspension
- heat management

Then I'll worry about power. Those 4 are the 185's arch nemeses, but like you showed above, bit of thought and DIY, they arent undefeatable.

Adrian Avgerinos
10-05-2006, 11:47 PM
More than once, I've given thought to tossing my FWD ST184 and picking up an ST185. The thought of having AWD is alluring. However, practicality wins out when I remind myself that my particular ST184 is lighter and makes the same power as a stock ST185 without the complications of a turbo. That, and it's damn fun to drive and cheap to replace if I crash it.

One minor concern I've had about the CS/RC bumper is the potential increase in aerodynamic drag due the increased size of the openings. It would be quite interesting to compare lap times between a car running a standard ST185 bumper, a series one ST184 bumper, and a CS/RC bumper. Then repeat with the CS/RC hood (or bonnet ;))

With the smallest opening, I'd guess a series one ST184 bumper with CS/RC hood would probably yield the fastest lap times.

Getting back to the ducted air, I'd love to run a duct similar to the one found on the SCCA World Challenge Cadillacs:


Adrian Avgerinos
10-06-2006, 01:26 AM
I found that the vertical side measured about 120 degrees after my short 10 minute commute.

Just got home from work. The scenario seems to be about the same as yesterday: same weather, same traffic, same distance, same valve cover temperature. This time the inside temperature of the vertical sides measured about 30 degrees cooler! :eek:

Looks like I did something right. Neat. :bigthumbu

EDIT: Some updates:

I picked up a new "duct" from the plumbing section of Home Depot today. The orange grommet is something I found at work and the green "pre-filter" is a Scotch-Brite pad.

I'll be testing different locations for the "scoop" this week to determine the best location.

10-06-2006, 02:23 AM
Nice work man, looks like a vent for your clothes dryer is commin out the bottom :D Hows the temp of the hose runing behind the radiator? Seems temps would be better if you went ahead and go through the side pannel..but good work, I love to see when people spend time and effort into something rather than buying and bolting it on!

EDIT: How do you plan to hold the ducted end on beside the zip tie?

10-06-2006, 03:19 AM
this is a really awesome thread Adrian! Cheers for the ideas.

10-06-2006, 09:29 PM
thats a good one

10-08-2006, 01:27 PM
how much better is a custom CAI then a ram intake ? whats the power difference like ?

10-09-2006, 08:45 AM
how much better is a custom CAI then a ram intake ? whats the power difference like ?

The ram air effect only works at high speeds. By high, I mean in excess of 100mph or thereabouts. Cold air intakes work, period.

Box in a cold air intake with plenty of feeds you'll get good results. Ram air effect doodahs on anything less than a race car is imho wasting your time.

10-12-2006, 02:19 AM
your "pre-filter" is going to get sucked back into the box if you dont have any support behind it.

but I would just say to remove it. Its slowing airflow and i would bet that it is going to get beat up by flying rocks/bugs/etc.

besides that, you did a good job with a cool idea.

10-12-2006, 02:21 AM
better it get's beat up than the filter, no?

has your battery been relocated to the boot, Adrian?

10-12-2006, 02:39 AM
with his design, the bugs and rocks wont make it all the way up the tube. Forget about them going in the filter. ALthough the piping behind the pre filter might get beat up.

a solution to that would be having a T connection in the tube. Imaging looking at the car from the side, and the bottom of the intake was an upside down T. Any rocks would pass safely through, and the intake would be able to grab all the air it wanted from the flow through the tube. hmm.. anyone see any flaws in that?

10-12-2006, 02:45 AM
nice sig :D

yeah that sounds like a good idea too. The chux pad should help keep water etc out tho.

10-12-2006, 02:59 AM

i personally wouldnt use the pad(I like to have everything free flowing), but it is ultimately his choice.

Adrian Avgerinos
10-12-2006, 08:47 PM
You bring up a few very good points, Mr. jakbauerctu. For what it's worth, there is some support behind the "pre-filter" but I'll probably pull it out at the track this weekend anyway. My main concern is having dust and debris pelting the fuse box that sits directly in front of the duct outlet. I may make a shield for the fuse box when I get back and then I should have less to worry about.

Mr. mtp_69_i, the battery was indeed relocated. It currently resides on the floor pan behind the front passenger seat but in front of the gas tank.

10-13-2006, 03:20 AM
Yeah, was obvious once I looked back at the photos. You've got it in the car tho, interesting.

Cheers again.

11-06-2006, 04:14 PM
Any updates in the last month Adrian?

Also, are you willing to sell another one of these boxes? I have NO experience with fiberglass and living in the city, I dont really have a place to do that part anyway. I would be most interested in the fiberglass parts, as I can source everything else locally

Adrian Avgerinos
11-06-2006, 04:50 PM
Updates: I got lazy about optimizing the scoop location, but did record the temperatures at the last track event and was happy to see this type of result often:

So intake temps dropped about 30 degrees on the track. :woot:

As for making the fiberglass and/or complete kits, unfortunately I don't have the time at this point. If the fiberglass is the only part holding you back, I recommend mail ordering sheets from a place like TAP Plastics (www.tapplastics.com). You might find ABS plastic to be even cheaper and work just as well.

11-08-2006, 12:28 AM
Thats an impressive difference in temperature! Do you think ambient temperatures were different or any other factors played into this?