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View Full Version : creating a true cold air box



Simonhla
06-29-2008, 12:06 AM
SO i know this is a topic that has been thrashed to death but in all my searching I have not seen one of the biggest issues addressed and that is the susceptibility of piping to transfering heat to the incoming air.

A lot of people have cold air intakes on here that they have either modified or custom fabbed, and I have to say they are all ingenious and look fantastic but one thing that concerns me is that any air going through the aluminium piping is considerably warmer by the time it gets to the engine.

One alternative i was looking at was just modifying the original system. My engineering background is next to none so i do warn you that i may be talking out of my brown starfish on this one.....anyway bear with me:

I was looking at purchasing some a Large thermal Hose sleeve which I would then stick over the stock rubber intake hose. I would then modify the air box to accept a cone filter and somehow (not sure how yet......suggestions very very welcome) heat shield the airbox. Then I would run a hose from the airbox either into the fender or preferably down to the front bumper (also with a thermal sleeve on it). By my reckoning this would give a true cold air intake provided the thermal hoses and heat shields installed were effective. Any thoughts on this?

There is also a little plastic box or bubble that comes of the hose about the size of a small apple, I am assuming this is the resonator? What does that do? Is it for the sound? I was thinking of removing this. Assuming my reasoning is sound there are advantages to this approach. not least maintaining oem reliability and perhaps an evern better functioning system. With the filter still in the airbox hydrolock is also an almost guarnateed impossibility.....

I'd love some feedback on this. I already have a civic cold air intake sitting in a box thta i was going ot make a minor mod to to put on but i look at the thin aluminium piping and wonder if the air is likely cooked by the time it gets to the TB.

METDeath
06-29-2008, 01:47 AM
You are aware that we basically already have a cold air intake? you could just wrap the piping in exhaust wrap to lower intake temps... it'd be kind of silly though... also, just get one of the K&N drop in filters, they achieve almost the same thing at a fraction of the cost of a CAI setup.

Ghosty
06-29-2008, 02:59 AM
A lot of people have cold air intakes on here that they have either modified or custom fabbed, and I have to say they are all ingenious and look fantastic but one thing that concerns me is that any air going through the aluminium piping is considerably warmer by the time it gets to the engine.

I'm not so convinced that there is a dramatic increase in the temp of the air as it passes through the intake system. My theory is that the air travels at a fast enough velocity that there isn't much time for the air to heat up.

Now, I have no formal test results to prove my theory, but I might suggest that you try some tests before putting all this time and energy into an intake system. Even if there is a dramatic increase in the stock design, you will want to have a system to see if your intake worked as designed.

Integrate some temp sensors at various locations in the intake, compare between stock and custom.



One alternative i was looking at was just modifying the original system.

The stock system is designed for quiet running and economy (typically for a torque that comes in low, at the expense of horsepower that comes in high on the rev band). You'll see much better results with smooth, custom tubing with gentle bends.



I was looking at purchasing some a Large thermal Hose sleeve which I would then stick over the stock rubber intake hose. I would then modify the air box to accept a cone filter and somehow (not sure how yet......suggestions very very welcome) heat shield the airbox. Then I would run a hose from the airbox either into the fender or preferably down to the front bumper (also with a thermal sleeve on it). By my reckoning this would give a true cold air intake provided the thermal hoses and heat shields installed were effective. Any thoughts on this?


This thermal hose sleeve- in what temperatures was it designed to operate? Temps under the hood can be very high, and it would be bad for this thermal sleeve to degrade. Then again, you might be talking about some very high-grade material, I don't know.

Modifying the stock airbox seems like way too much work, especially when you can fabricate your own box from a wide range of materials. I've often wondered if fiberglass would be a good material to fabricate intake systems with, given that you can mold it into any shape and given that fiberglass isn't as thermally conductive.

Yet, I don't know if it is terribly efficient to contain a cone filter in any kind of box. Most all applications of cone air filters have been at the very front of the intake. I believe the purpose of the location is to capitalize on the cone filter's ability to pass air from a comparatively large surface area. Containing a cone filter in a box, I think, would almost negate the point. If you want to keep the airbox design, I would look into keeping a "flat" filter, but manufacture a box that can hold an even larger filter, for even more surface area and thus better airflow.




There is also a little plastic box or bubble that comes of the hose about the size of a small apple, I am assuming this is the resonator? What does that do? Is it for the sound? I was thinking of removing this.

It would be hard for us to speculate about this part without an actual picture, but I think I know what you're talking about. I believe it's some kind of baffle (for the lack of a better word) in the intake system, the purpose of which is to deaden the sound of the engine to the occupants.

Removing the component would most likely result in better airflow, and consequently, a louder engine.



Assuming my reasoning is sound there are advantages to this approach. not least maintaining oem reliability and perhaps an evern better functioning system. With the filter still in the airbox hydrolock is also an almost guarnateed impossibility.....

I'm pretty sure you'd still be at risk of hydrolock if your system, if your system is closed and airtight. Hydrolock occurs when the opening at the front of the intake is submerged, so long as there is an airtight connection between that opening and your throttle body.

There are only two safeguards I know against hydrolock. One is to build an intake system which is higher than the level of water that you might be unfortunate enough to drive through. The other is to integrate some kind of "breather" filter high up in the intake system. The breather works because if the front of the intake is walled off with water, the air will pass through the intake via this small filter, rather than trying to suck up the H20.

Simonhla
06-29-2008, 07:15 AM
Thanks, that's a really informative response.
The thermal hose sleeve I was talking about was designed for an air intake and i believe was resistant up to 1100 degrees. That said you can get heat shield tape which is resistant to 200 degrees for $20 a pop. Candidly i am not sure how far a roll would go though.

I did think that perhaps the air flowed pretty quickly through the rubber hose so I understand what you were getting at there. I'm really enjoying experimenting with things right now so not bothered about putting th work in. I might have a fiddle with it and post my findings......

BlackGt92
07-01-2008, 06:32 AM
I do have a CAI for my 92 and i went to my local parts store and bought exhaust heat wrap. It is a fabric material that works really well. I wrapped my intake all the way down to the filter and it works great from what i can feel.

Here is a pic from before the wrap.

http://img.photobucket.com/albums/v737/trixfourkids/DSCF1183.jpg

I believe this is what he above is talking about as far as the "Bafal"

http://img.photobucket.com/albums/v737/trixfourkids/DSC01555.jpg

Simonhla
07-01-2008, 06:48 AM
Yes that is exactly what I am talking about. What is that weird thing shaped like a plastic jockstrap attached to the tube? I am assuming it is the resonator. Wonder if anyone has just taken that off or replaced the rubber hose with an aluminium tube wrapped in heat wrap (but still going to the airbox) wonder if that would make a difference....

I like what you have done there with the CAI but is it staying in place with what looks like a zip tie to the battery strap :laugh: That's brilliant.

I bought...not sure why but it was recommended to me.....a CAI from a 96 honda civic. Apparently with minor or no mod it should fit fine. Haven't had the courage to try yet.

geebes
07-01-2008, 05:06 PM
You could hook up your a/c to the cold air and really make a cold air intake! :p

H8PVMNT
07-01-2008, 05:58 PM
You could hook up your a/c to the cold air and really make a cold air intake! :p
That is really funny... :bigthumbu

I have an ebay SRI and I switched to the K&N high flow flat filter with the stock airbox today. I'm going to try to feel the difference. I noticed a clear decrease in power with the hot weather on the highway lately.

Simonhla
07-02-2008, 01:00 AM
That is really funny... :bigthumbu

I have an ebay SRI and I switched to the K&N high flow flat filter with the stock airbox today. I'm going to try to feel the difference. I noticed a clear decrease in power with the hot weather on the highway lately.

So how about making a true test and swapping out the hosing to the airbox for some aluminium piping and wrapping it in heat shield?? I'd love to see the results on that.

CollapsedNut
07-02-2008, 04:27 AM
You could hook up your a/c to the cold air and really make a cold air intake! :p

Thats an awesome idea....(stumbles to find a drill, aluminum piping, duck tape, small child non jew, fire bear, jeff goldbloom, and another beer)

Conrad_Turbo
07-02-2008, 06:17 PM
Why not use stainless instead of aluminum piping? Thermal conductivity is much (almost 10x) lower with SS. ;)

H8PVMNT
07-02-2008, 06:47 PM
So how about making a true test and swapping out the hosing to the airbox for some aluminium piping and wrapping it in heat shield?? I'd love to see the results on that.That is a good idea...* So I got to drive with the freshly installed K&N in the stock airbox and ducting, here are my driving impressions:* First off, I would like to say that the SRI I was using was better off line than the stock setup with a paper filter, however, I was losing highway hill pulling power as soon as the weather started getting hot, presumably because of the really hot underhood temps. It did sound really cool though.* My top highway speed was 122 mph with the SRI.To my suprise though, the K&N filter in the stock airbox feels even better off line!* The biggest shocker though is that my car did 131 mph on the same stretch of highway that I could only do 122 with the SRI.* I didn't even top out, I backed off because I got to a corner! I guess that cool blast of air crammed into the intake really does make a difference.So for me, the K&N in the stock airbox is better than the SRI.The paper filter must really suck in the stock airbox to see this much difference.

ciento44
07-02-2008, 06:59 PM
That is a good idea...* So I got to drive with the freshly installed K&N in the stock airbox and ducting, here are my driving impressions:* First off, I would like to say that the SRI I was using was better off line than the stock setup with a paper filter, however, I was losing highway hill pulling power as soon as the weather started getting hot, presumably because of the really hot underhood temps. It did sound really cool though.* My top highway speed was 122 mph with the SRI.To my suprise though, the K&N filter in the stock airbox feels even better off line!* The biggest shocker though is that my car did 131 mph on the same stretch of highway that I could only do 122 with the SRI.* I didn't even top out, I backed off because I got to a corner! I guess that cool blast of air crammed into the intake really does make a difference.So for me, the K&N in the stock airbox is better than the SRI.The paper filter must really suck in the stock airbox to see this much difference.


Strangely enough.... i get the opposite results with the stock w/ K&N vs my 4" long short ram w/ cone filter.

H8PVMNT
07-02-2008, 07:10 PM
Results seem to be different for different cars. I've been wondering if there isn't some other factors that make this difference. Does running that hood isulation make a large underhood temp difference? Maybe ignition timing, different ECUs, elevation, who knows!?

Maybe all SRIs aren't created equal. Mine is a real cheapy. Which one are you running? Ebay keerap or sometning nice? The filter could make a difference too.

I saw this thing in a magazine where some miata guys tried out several different ECUs and they were all different horsepower/tourque on a dyno.

SRI sounds cooler though!

ciento44
07-02-2008, 08:17 PM
Results seem to be different for different cars. I've been wondering if there isn't some other factors that make this difference. Does running that hood isulation make a large underhood temp difference? Maybe ignition timing, different ECUs, elevation, who knows!?

Maybe all SRIs aren't created equal. Mine is a real cheapy. Which one are you running? Ebay keerap or sometning nice? The filter could make a difference too.

I saw this thing in a magazine where some miata guys tried out several different ECUs and they were all different horsepower/tourque on a dyno.

SRI sounds cooler though!


I cut all but the elbow off of the stock piping, and clamped a filter on it lol.

I don't have hood insulation, i have no clue what my ignition timing REALLY is... it's all kinds of screwed up and i've been too lazy to take the time to fix it.

Lonestag
07-02-2008, 08:21 PM
I just keep thinking, if you didn't mind doing a bit of body work, could you just place a hood scoop right about a SRI and maybe box off the area right around it? Then you could grab a bit of cold air with the short ram design, and if you did it right, look sweet in the process...

Simonhla
07-02-2008, 08:48 PM
I just keep thinking, if you didn't mind doing a bit of body work, could you just place a hood scoop right about a SRI and maybe box off the area right around it? Then you could grab a bit of cold air with the short ram design, and if you did it right, look sweet in the process...

My wife banned me from hood scoops......it is her car too after all.....bah humbug!

Simonhla
07-02-2008, 08:49 PM
That is a good idea...* So I got to drive with the freshly installed K&N in the stock airbox and ducting, here are my driving impressions:* First off, I would like to say that the SRI I was using was better off line than the stock setup with a paper filter, however, I was losing highway hill pulling power as soon as the weather started getting hot, presumably because of the really hot underhood temps. It did sound really cool though.* My top highway speed was 122 mph with the SRI.To my suprise though, the K&N filter in the stock airbox feels even better off line!* The biggest shocker though is that my car did 131 mph on the same stretch of highway that I could only do 122 with the SRI.* I didn't even top out, I backed off because I got to a corner! I guess that cool blast of air crammed into the intake really does make a difference.So for me, the K&N in the stock airbox is better than the SRI.The paper filter must really suck in the stock airbox to see this much difference.

That's really interesting. I'm glad you did that. I might tinker with something similar myself. I'll let you know how it goes.

Simonhla
07-02-2008, 10:18 PM
I have just been outsidefiddling with my custom CAI, trying to get it to fit. Fusebox is in the way. If I move it I think I can make it happen. How easy/hard is that for a novice?

Also the intake piping I bought (originally designed for a civic) has the beveled hole for the Air Intake Temp Sensor but it alos have two inlets about an inch apart which are raised up as if to fit two tubes onto them. I am assuming these are pressure hose fittings of some sort but I don't see anything comparfable on my current stock intake. Should I just loop a small hose between them or block them up or something?

H8PVMNT
07-03-2008, 05:06 AM
I've seen these little rubber caps on those fittings before. I think you can get them at a hardware store or maybe an auto parts store for that purpose. I just crushed the fitting on my SRI pipe flat to close it off. It would be nice to weld up the hole but I'm not set up to weld aluminum.

Let me know what happens with your CAI setup. There has to be something that's the best of both worlds for these intakes.

Simonhla
07-06-2008, 05:27 AM
A quick question..........I am looking at a number of CAI designs. Maybe looking to come up with something new.

A lot of guys on here have routed piping and filter into the fender well through a hole already present. When I removed my airbox i didn't see that hole into the fender well. There was still some tubing going to behind the headlight that I hadn't removed but on quick inspection I couldn't see the hole anywhere. Am I missing something? Is my car certain to have it? I have a 92 GT automatic coupe.

Ghosty
07-06-2008, 07:45 AM
I'm pretty sure they made the holes themselves.

Cutting the chassis gives me the creeps :(

Galcobar
07-06-2008, 08:32 AM
There actually is a stock cut-out between the engine bay and the fender well. The stock air box is not connected to it; the connection is on the intake section which runs from behind the headlight and along the engine bay wall.

This leads to a fairly large box in the fender well which is the primary resonator for the air intake. People who've removed their entire stock air intake system can route their piping through this hole and position their filter in the fender.

Simonhla
07-06-2008, 09:42 PM
Thanks Galcobar. I'll put it apart and have a look later today.

wrongboy
07-07-2008, 06:37 PM
There actually is a stock cut-out between the engine bay and the fender well. The stock air box is not connected to it; the connection is on the intake section which runs from behind the headlight and along the engine bay wall.

This leads to a fairly large box in the fender well which is the primary resonator for the air intake. People who've removed their entire stock air intake system can route their piping through this hole and position their filter in the fender.


Anyone have pics of this?

Simonhla
07-07-2008, 08:42 PM
Anyone have pics of this?

I should be going back to finish the job today or tomorrow so I'll take some pics for you.

caneman
07-08-2008, 02:34 AM
In the sixties, those of us who wanted a performance car, but couldn't afford one, used to pull the air cleaner off our massive, take-no-prisoners, Chevy Impala two-barreled carburetor, straight-sixers, and drive around town, going "Whaaammm, whaaammm, whaaammm (the actual sound made by a three speed automatic inline-6 without its air cleaner).

Looking back on that period of self-deception, I am embarrassed to admit that I was briefly one of those Baldwin Motion Chevy-wannabees that tried to excuse our behavior by saying (okay, maybe whining), "Well it sounds faster..."

I've compared what I've read about the various modern, 5-bucks-worth-of-plastic-and-aluminum, short-to-long, hot-to-cold and all over-priced air intakes and the only claim that I think the buyer of one of these scams can honestly make is, "Well it sounds faster..." BWUUHHAHAHA! ;)

Simonhla
07-08-2008, 10:00 AM
I don't doubt you are right. I also think it is fair to say that colder air can deliver better performance to your engine. But on these engines is it really worth the time and trouble? Probably not. I think most of the discussion and effort that goes into little projects like this is because we are natural tinkerers. We like to have things to work on and we like the sense of pride and achievement that accompanies a successful custom project. I know I do. I would love to have more money and access to a better and bigger engine, alas I don't. My job's crap and I have other financial priorities, therefore I relish the welcome distraction and sense of achievement I get every time I work on my car. It's not much but it's what I got.

Someone once said that the best reward for a job well done is having done it.

Now with all that said I should point out that my latest effort....the custom CAI........has been an utter failure. I didn't have access to a drill or any proper tools to fabricate things properly so I tried to use an old civic intake I had acquired for $10 (whoever said you get what you pay for must have sold me this) and mod it to size along with some plumbing parts. The 3" pipe was a nightmare to work with and in the end I just gave up as it was all too big and I would have had to relocate too many things. It didn't seem worthwhile just for air possibly a few degrees cooler. I was annoyed though because I only figured this out once I had the wheel off, the wheel liner out and the battery removed.

As it currently stands I have managed to make some improvements which all things considered I am quite happy with. The big resonator box from inside the fender has gone, I tightened up the fit of the plastic conduit between the airbox and the fender hole to ensure an airtight connection and replaced the stock rubber airtube S bend (complete with baffle/resonator bubble..whatever that is) with a lightweight aluminium tube of the same shape. The first half from the box is 3" and the second half 2.5".....don't laugh coz it's all I had at the time. But it does look good and I am hoping the slight funnel effect might increase velocity a little going into the TB.

Anyway to perfectly dovetail the post above I do have to say that it now sounds faster. Because it really does. Removing that crap from the wheel well and replacing the hose seems to have removed some of the restrictions on airflow just a tad. It seems to respond a little better. I will probably try and attach some tubing to the front of the plastic air conduit behind the headlight and extend it down to the front bumper. Once I've done this I really don't think the air will be much if any cooler than one of the CAI designs. I will most likely pick up a drop in flat panel K&N filter for better air flow and in the future if I feel really fruity I might try and modify the airbox to take a cone. But no promises.

CollapsedNut
07-09-2008, 05:24 PM
I think most of the discussion and effort that goes into little projects like this is because we are natural tinkerers. We like to have things to work on and we like the sense of pride and achievement that accompanies a successful custom project.

This is why I love the celica and CelicaTech. Mainly us ST/STX owners because we dont have alot of options for cheap addons on the 4afe so we get to kinda play and experiment. I know building my CIA was the most fun project I've done to my celica yet, its the little things like getting that 3" AdvancedAuto exhaust tubeing and trying to get a 90degree elbow to fit thru the fender hole and still fit the battery. Not to say that 3s owners are any differant just they have a whole world of parts to work with. Working on the 4afe makes me feel like Im back in the day when you couldnt just order a part, you had to draw it up, make it, test fit it, trial and error, and then remake it.

Hookecho
07-09-2008, 10:47 PM
there's a common misconception with cai's. this being that if you introduce the cooler air to the filter then surely this cooler air will carry all the way to the combustion chamber. the reason this won't happen is due to heatsoak. all the heat from the engine bay will heat the metal air intake and then radiate that heat into the air stream. thus, raising the tempurature of the air stream significantly. this is one reason why automakers use plastic. the best thing to do is wrap the cai with insulation. duct wrap works well and you can buy it at home dept on the cheapness. it works wonders.

here's a link to the one i made. i have it insulated now.
http://www.celicatech.com/forums/showthread.php?t=22870

Simonhla
07-09-2008, 11:21 PM
Regular duct tape? Presumably it won't melt under there. I am going to wrap my intake tube to the airbox and maybe even cover the airbox itself and the plastic conduit into the fender. I think this'll be as good as any CAI. Maybe even better.

Galcobar
07-10-2008, 02:58 AM
Not duct tape, duct wrap -- typically a foil backed with foam for insulation.

Think he means something such as this:
http://www.lowes.com/lowes/lkn?action=productDetail&productId=28929-1410-FV516