How to build your own Warm Air Intake (WAI)

[Matt Timion]

Author:Harrell, Rick
Publication:www.gassavers.org (http://www.gassavers.org)
Date:11/17/05

Background:
The buzzword in today's engine performance is the Cold Air Intake. The rationale for this device is that the colder/denser the air coming into the engine, the richer the mix, creating more horsepower (and more fuel consumption). This device generally consists of drawing air from a cool source, someplace outside of the engine compartment and then into the engine's air intake.
With this in mind and studies done independently by this author and others, warmer/dense air allows the car's computer to cean-out the mixture, meaning it takes less fuel to complete a combustion stroke and fuel economy is increased. The common denominator is dense air, which is an independent variable of this experiment. Humidity determines air density. Humidity, unfortunately, was not recorded during this experiment. Lastly, air is a poor conductor of heat, meaning that it looses heat rapidly. This experiment is the groundwork for a heater-core system which will be described at a later date.
In this author's opinion, further experimentation was indicated, as there has been the ability to trick the intake air temperature sensor into thinking that the air is actually very hot. This implementation utilizes resistors input into the air intake temp. sensor to mimic a particular current, which translates into a higher temperature reading. This author has reservations using this technique, as the air may be too cold for a lean-mixture, and create detonation, pre-ignition, or spark knock, which can take a toll on the life-span of cylinder heads and related components.
Results:
Implementation of a rudimentary device using foil dryer vent pulling air from the Y junction of the exhaust manifold yielded a first-run fuel economy of 31.1 mpg on 268 miles of my normal driving style, which is pretty aggressive. The second run was over 33 mpg. The baseline was 26.0 mpg from previous tanks. This 15%+ increase has been considered significant, and further testing should be performed to support this increase. As the air at night became approximately 40-50 deg. F., it became increasing difficult to maintain a warm-air transition. During the test, it should be noted that the duct broke loose from the header and pulled cooler air into the engine as displayed by the data-logger collecting information on vehicle speed, engine speed, Long-Term Fuel Trim, and intake air temperature. My hypothesis, is that a easy-to-implement warm air intake will increase fuel economy.
Disclaimer:
You are assuming your own risk by performing modifications to a vehicle that is either stock from the factory, or has been modified within the scope of local laws; furthermore, this author and/or this website cannot be held responsible for damage resulting from experimentation.
Implementation:
Assuming you comply with the disclaimer, let's get started.
This author's vehicle is a 1998 Acura Integra 3-door, with the 1.8-Litre Dual-Overhead Cam, 16-Valve, Non-VTEC, 4-cylinder. It was equipped with a home-made cold air intake that drew air from a point behind the passenger-side turn signal, into the airbox, with a K&N-brand, low-resistance cone filter. (see picture 1) Also, the intake air silencer box was removed.
Basically find where your air filter is located. Mine is located on the passenger-side of the engine compartment with the air input from the bottom of the box and with filtered air running through a tube into the intake throttle body (see picture 2). Every vehicle is different – some may be out in the open others may be hidden. If you're not sure, consult your owner's manual. Take the filter out and see if you can remove the airbox (if necessary). Also, many models have anair silencer. This is usually large plastic box of some sort that quiets the sound of your engine's operation. My recommendation is to completely remove it, as it adds additional weight, and with our new setup, may not be needed to quiet operation, and free up some space in a cramped engine compartment. Consult Internet sources for your particular model to remove this, as models vary.
Secondly, find a source of considerable heat that can be sourced using ducting that won't choke-off the flow of air, and can be run without impeding the operation of fans, belts, etc. In my case it was between the heat shield and exhaust header (see picture 3). I used a foil-type clothes dryer-vent duct for my ductwork. Further experimentation of using a heater core is in the works, which will provide the potential for additional consistence (more on that later). Your ideal location may be near the radiator, catalytic converter, exhaust header, etc. Bear in mind that the longer the air has to travel, the more heat it loses.
Next put together an idea of where your ductwork will run. As you can see in this photo (see picture 4) outside air does not pass over the duct, which would cool the air; instead, the plastic baffle was forced down to accommodate the width of the duct. This, in turn, has created a situation where the plastic baffle easily bottoms-out on uneven road surfaces. The key here is to get a robust connection on the end of the tube, so when it does come in contact with obstacles, it doesn't break loose. Also, it may be necessary to remove or re-locate components to allow ductwork to fit. As you can see, the header's heat shield needed bending. (see picture 5).
The next step is to figure out how to get the duct into the airbox without sucking air from the engine compartment: a complete seal is needed from the airbox to the end of the tube's hot air source. As you can see here (see picture 6), a PVC pipe was slightly heated and bent to conform to the oval shape of the airbox's inlet. Since the pipe kept falling off, a screw was set into the box to keep it from falling off. The inlet has a rubber seal that aids in keeping our setup sealed from cooler engine compartment air. Again, your setup may vary. (see picture 7)
Route your ductwork. As this is technically a duct, duct tape was used to seal the PVC pipe to the dryer vent. (see picture 8). I know it's not pretty, but it does the trick to ensure a sealed system.
After running your ductwork to a hot source, ensure a solid connection. As my resources are limited, I used a coat hanger and hobby wire (similar to what is used to wrap bows on holiday wreaths) to secure the duct end to the header. The hobby wire was used primarily to angle the end to draw air directly off of the header.Conclusion:
Using my datalogger (OBD-II), I noted increases in temperature from outside air temperature/engine compartment temp (40-90 degrees) to a range in the 80-150 deg. F. range. I noted on my logger that as air intake temp increased, Long-Term Fuel Trim decreased, indicating a leaner mixture = fuel savings. This was especially helpful on my 80% highway travel. Bear in mind that power loss is to be expected. Lower-RPM power wasn't affected as much as mid-range to near redline power diminished. This small sacrifice, in this author's opinion, is worth the fuel savings. Good luck in testing, and let us know your results here at Gassavers.org. Please use the scientific method whenever possible, and do try to not let bias enter the equation (maybe have someone else drive the car after the mod., as this may effect mileage by using a more fuel efficient driving style). Happy motoring. </td>

http://www.gassavers.org/files/gassavers/WAI/Cone_Filter.jpghttp://www.gassavers.org/files/gassavers/WAI/Stock_Intake.jpghttp://www.gassavers.org/files/gassavers/WAI/Hot_Air_Source.jpg
http://www.gassavers.org/files/gassavers/WAI/WAI_Duct.jpghttp://www.gassavers.org/files/gassavers/WAI/Inlet_Closeup.jpghttp://www.gassavers.org/files/gassavers/WAI/PVC_Airbox.jpg
http://www.gassavers.org/files/gassavers/WAI/Duct_Route.jpghttp://www.gassavers.org/files/gassavers/WAI/Duct_PVC_Airbox.jpg

[Matt Timion]

more discussion here: http://www.gassavers.org/forum_topic/wai_test_results.html

[Murat]

Hello Matt

With all due respect, I suppose there is an error in the article concerning the warm air intake...

I have studied physics at college (thermodynamics etc) and worked as a flight dispatcher for 11 years (closely related to meteorology) during all these years I learnt that cold air is much denser than warm, both by means of oxygen and humidity (remember; dew point where humidity densens and becomes fog, is lower than ambient temperature)

I have been told by several saver/misers that cold air intakes improve economy. Furthermore I have been told that chip tuning improves economy given that you do not get tempted to "step on it"


I chenged my filter with a twin venturi cold air direct intake removing the filter box, removed the two mufflers (not the cat) and mounted a Remus glasspack.

Since I habitually do not step on the accelerator pedal, there is no excessive noise and I noticed thru the trip computer that the vehicle started reporting 4.8-5.2 liters / 100 km. from the usual 6.2-6.7 liters/100km. (from 35.10 MPG to 49 MPG) That is an average of a gallon saved every 200 kms (approx 130 miles)

I did not try any flush wheels, skirts and other aerodynamic aides as yet. I plan on getting a complete ground effect kit, lower the vehicle so drag is decreased. I want to prove that fuel saving can also go along with good looks of a car...

Best regards

[Sludgy]

Cold air intakes will produce more power, and will save gas if the engine operates only at Wide Open Throttle.

However, under 90% of driving, Warm Air Intakes are more efficient because the engine is throttled and under less than full load. WAI does two things:

1) Fuel evaporates more quickly, increasing combustion speed. Fast burn engines improves the amount of pressure generated and expansion work available for a given amount of fuel.

2) With oxygen sensors, engines run at stoichiometric air/fuel ratios. For any given amount of fuel, a corresponding mass of oxygen is admitted. WAI lowers the density of air, meaning that a higher volume of air must be let into the engine for a given fuel input. So with WAI, the throttle must be opened further for a given output, and this lowers the "pumping" work of pulling air past the throttle.

WAI is better than CAI for fuel efficiency imho.

[philmcneal]

man i want one! too hard can't i just pay some money and someone do it for me?

[SVOboy]

man i want one! too hard can't i just pay some money and someone do it for me?

Haha, I'll do it for free for ya.

See if my write up this evening or next makes it seem a little easier.

[Murat]

Well I guess you should know better than I do since you are further involved in fuel savings than me.

So I will follow your word...

Will test out your theory for a while...

[kickflipjr]

Hot air is probally seems like the strangest mod to the the typical car tuner. Someone who pays +$300 for a cold air intake probly would think you we are insane.

Hot air=better fuel atomization= better fuel economy (or so the theory goes)

[rh77]

I've had luck with the HAI (hot-air intake) for several months. It reduces power, and consequently uses less fuel. It takes more throttle input, so if you accelerate at a pre-determined level, say 20% throttle (from the ScanGauge), then you're doing so more slowly as well - then it's a driving style change = more economy.

Also, I have a new design from what's pictured above. The dryer vent was bottoming out and also deteriorating. I bought some hot-air (carb) flex-tube as reccommended by krousdb, cut a hole in the airbox, and ran it directly. (I may post some pics later...) I need to block the air flow as highway speeds cool things down. I have to use Premium fuel or I get continuous detonation, though -- It pays for itself.

[zpiloto]

Has anyone compared the HAI with the IAT mod. I tried the IAT mod using 260, 160, 125 with no luck.:? The OBDII just retarded the timing and my FE was actually worst. I'm thinking that the HAI might work because the temps would be lower and the air acutally thiner. I've got some dryer hose I think I'll rig it up and see what happens.:D

[SVOboy]

IAT sucks because it leans out the engine, for this reason I would not do it.

[zpiloto]

The WAI was a snap took 5 minutes wish I would have done this earlier. 3" dryer hose fit perfectly on the airbox ran the tube between block and exhaust manifold. My manifold has a heat sheild which I hope will keep the cool air from getting in.
Had a few stops to make so took it for a spin the temps were steady between 114 and 125 and the ignition timing seemed normal. I'll have to see what the temps do at highway speeds.

[zpiloto]

See if I can post a picture.

http://members.cox.net/zpiloto/101_0050.JPG

The end of the tube bends around 270 degrees and is between the block and the exhaust.

[kickflipjr]

That is a nice looking engine. It's so clean.

What is with the alluminum foil?

[philmcneal]

lol the alumminum foil is the warm air intake... the aluminum is a good heat conductor yes?

my intake is plastic, plastic does not conduct heat as well!

[SVOboy]

I think he means on the not intake. I imagine it has something to do with the heated fuel lines.

[zpiloto]

The WAI hose does stay warm after shutdown but I don't have enought time on it to have a good feel for it yet. Yes, the foil cover the heated fuel line that runs on top of the radiator hose to help hold the heat in.

[Compaq888]

I tried the hose thing with the warm air. I saw a solid 1mpg increase on the freeway but the problem was it lowered my power. As long as you're always driving on level roads this mod will be okay. But if you ride up hills like I do most of the time the engine will downshift the tranny which in result will require more fuel.

But the foil on the fuel lines is clever, it will bump up the fuel temps and make for better atomization which will increase fuel economy.

[zpiloto]

I've got a lot of rolling terrain so I'll see how it does. Our temps are alot higher down here also which should help with the IAT. I think I remember Compaq888 that you were have shifting problem until you reset the TCU, was it doing the downshifting before and after the reset?

[Murat]

Perhaps the key is "heat the fuel, cool the air" combo ???

I'm gonna try that...

[Compaq888]

I've got a lot of rolling terrain so I'll see how it does. Our temps are alot higher down here also which should help with the IAT. I think I remember Compaq888 that you were have shifting problem until you reset the TCU, was it doing the downshifting before and after the reset?

It wasn't doing the downshifting after I reset the ecu. Instead of downshifting it gains speed as it climbs, 2-3mph. Of course on huge hills it will downshift, that is no brainer.

[zpiloto]

[quote]Perhaps the key is "heat the fuel, cool the air" combo ???

I'm gonna try that..


I tried that with the dryer hose. I ran it to the front of the airdam so that it would be in the airstream so there would by a min supercharger effect at speed. Did A-B-A run at speeds of 30 and 50 over 2.8 miles with no effect on FE.

[Murat]

[quote]Perhaps the key is "heat the fuel, cool the air" combo ???

I'm gonna try that..


I tried that with the dryer hose. I ran it to the front of the airdam so that it would be in the airstream so there would by a min supercharger effect at speed. Did A-B-A run at speeds of 30 and 50 over 2.8 miles with no effect on FE.


I see... I heard of a guy building sort of an "electric supercharger" which is built from some aluminium flexi piping, a high rpm computer fan and a switch to regulate the fan on and off... I do not know if he achieved anything at all but it sounds a lot like your experiment with the addition of a forced flow... I am wondering of ways to suck some aircon cooled air into the air filter... Any ideas ??

[zpiloto]

I guess you could just "T" into a duct, but I don't think you would see any gain in FE. Running the AC is a FE killer. It can be as much as 3-5 MPG or more depending on the car.

I saw this on another site and if I was capable of doing it I would like to got to a junkyard and find the smallest turbocharger I could and install it. If it was small enough it would kick in about 2000 RPM and you could run about 4 pound of boost. I think you would get a good increase in FE if you didn't get carry away with the extra power. All for under $500 if you could do it yourself.

[Murat]

Well yes but you would need to mod your intake, reduce your comprression ratio and change the valve guides from (mostly)rubber or teflon to ceramic or chrome / vanadium... Otherwise you're likely to finish that engine in a short time. And to reduce the compression you' ll need to change the pistons and rings.

[psyshack]

I messed with a WAI mod yesterday on my 06 Civic EX Sedan, 5MT, w/Navi. The car is well ran in with around 11k miles on it to date. Its driven to work some days, putters around town and has been driven from the Tulsa metro area to PHX, Az. Its seen its share of redline shifts, Wheels spun and ABS action. After all it is a Civic. :) Its worse tank was 29 mpg, its best has been 47 mpg 25c/75h.

I have used WAI to improve FE in older big block and small block v8's in years past and some I6 engines. Always seemed to be good for about a 2 mpg increase across the board. These being carb motors it always took a major retune to see these results. Including, timeing change, cooler thermostat, idle air adjustments and higher octain fuel.

So armed with knowledge from the past and knowing there wont be any retuning for this run of test I go down to the local O,rilleys and purchase WAI alum hose commonly used on our old trusty v8's and I6's from years past. Cost $3.00 and some change.

This is a very complex install. Takes all of 30 secs. I opened the hood, yanked off the OEM rubber intake duct. Cramed it down and away from the filter box. Yanked on the alum. flex duct to increase its length. Pushed one end of the hose into the opening in the filter box, fourmed the hose around and set it next to the massive CAT right off the head and lodged in next to what acts like a exhaust manifold. Done! Ok it took a 1 min. sorry. :) The R18a motor in the new Civics dont have a exhaust manifold so to speak. Its all cast into the head. So they are very short passages if you will straight to a CAT.

My first run was with the WAI installed. Air temp was 95f. (was hot here in Okiehoma yesterday) Car warmed up in a flash. I set out one of my test loops around here. This is a 20 mile run thru my small town out to a hwy and back. Intake air temp with the WAI was 141F any time the car was moving up to 150f if the engine was off or at idle. I ran the loop came back, pulled the WAI slapped the OEM hose back on and did it again. OEM unit air temp was 101f with car moving and didnr flucuate much one way or the other. Then came back after that loop run and pulled the OEM duct off again and ran the loop with the filter box open to under the hood air temps. Max. temp in this mode was 121F on the hwy and it did flucuate alot.

I worked on this from the afternoon hours to early in the morning. I logged around 120 miles doing these test. As for night temp's. Just subtract 20f off the day time temps.

From all these runs and configs on the intake. I saw a soild 1 mpg increase in FE with the WAI. I had no pinging, water temps stayed the same. I didnt ever wrap the tach up. But I felt no loss in power in the range of 650 rpm to 3k rpm. I used my ScanGauge to look at the temps, mpg, timing and such.

Im going to leave the WAI on for awhile and see what it does. Im going to keep a very close eye on it. My guts telling me this may be a winter only mod and that I may end up running the inlet open to the air under the hood for summer. And then run the OEM CAI when I want to play. I do like to tackle the twistys from time to time. Theres always somebody that needs to be imbaressed by a little stock Civic from time to time.

It was a intresting test and there is something there to be had. Is it worth it and will the ECU with time adjust its self better for the mod. Only time will tell.

Theres alot going on in a r18a engine. Its not fully understood yet. The semi atkins low rpm head function. The normal function and then vtec. :) I dont know as of yet if when the engine is in low rpm idle to 3k rpm if the amount of fuel injected is less than a normal cycle or is it all in valve/cam timings that allow for the so called 1.5L compression stroke to happen. Is it chargeing the cyclinder like a 1.8L and then pumping some of the charge back into the intake manifold? Is there a lean burn component in this action? Theres alot to learn here.

Im not the best hypermiler. I have the skillz but tend to get lazy sometimes. That and I enjoy many driving styles. I do use low rpm shifting, steady foot, DWL, FAS, coast, light timing, engine off at light, will draft and surf also ride ridge in rain or follow trails.

My lmpg is at 39.6 with my high tank at 47 mpg, low at 29 mpg. OOO and the wife has never driven the car. :)

Hope this mess was a good read and that there maybe some useful info here.

psy

PS,,, we really need more 8th gen Civics in the game. I havent found a sole yet working with a non-hybrid Civic yet.

Im uploading a video of the last run I made at about 1am this morning. It nothing but 29 miles of the ScanGauge with the WAI installed. Its over 200 meg @ 640x480. Will post a link here when its done.

[SVOboy]

Wow, very good post, I suggest when you get the video up you create your own experiment post detailing this, to make it more accessible, very thorough. I can't wait to get my superMID hooked up so I can do this testing myself. Grr , I have to wait a whole damn week.

Anyway, I'm glad it worked with the newer stuff, sometimes it seems not to.

On the topic of the r18, does it use vtec-e or is there something different? I should read up on it at TOVA

[psyshack]

Wow, very good post, I suggest when you get the video up you create your own experiment post detailing this, to make it more accessible, very thorough. I can't wait to get my superMID hooked up so I can do this testing myself. Grr , I have to wait a whole damn week.

Anyway, I'm glad it worked with the newer stuff, sometimes it seems not to.

On the topic of the r18, does it use vtec-e or is there something different? I should read up on it at TOVA
I cant do a detail on the SG vid. My mind just dosent work that way. For hypermilers it will be very clear as to whats going on in the vid. Wayne, Bob, Cindy, Tara, Phil, Brick and countless others will know when gears are being ran, FAS, DWL, and other things are happening. I hope to have a better cam sooner with audio and beable to show and talk about what is going on.

Heres the link to sg http://www.psyshack.com/hm11.avi
Heres a link to another drive http://www.psyshack.com/okiefas.wmv
Heres a 0-60 run in the Civic. It will now do the run alot faster and 60 mph in 2nd gear is nothing. This is a a bad lauch and I didnt wring it out http://www.psyshack.com/MVI_4979.AVI
Heres a fish tank vid to calm you down before yeah flame me. :) http://www.psyshack.com/29gthemovie.avi

psy

Dont do they downloads unless your have a fast connect. Dialupers could have children and get them thru college before they see them.

[SVOboy]

As for detail I just meant you should repost this with links in your own thread in the experiment section, because it'll make it more searchable. Good evidence is always welcomed there, :p

[psyshack]

SVO

Go here. http://world.honda.com/CIVIC/1.8li-vtec/

It explains some of the mech. stuff,,, but nothing of injectors and ecu. Heck Hondadata it seems wants nothing to do with it at this point. theres alot going on here.

[SVOboy]

Eh, hondata sucks, and this i-vtec stuff, the i never means the same thing, grr, I'll get to reading though, thanks!

[SVOboy]

Reading this I have been:
http://vtec.net/news/news-item?news_item_id=376015

I don't know if you know anything about vtec-e, but it seems that this is very similar. vtec-e practically shuts off one set of intake valves on it's 16 valve head, but what this does is restrict intake air flow at the valve so that the throttle can be WOT while not sucking a ton of air. This is part of the idea behind the WAI, allowing the same air flow with a greater throttle opening, how great!

[psyshack]

The r18 is refered to buy Honda as a vtec-i. Its clearly not the k24 i-vtec in the Accord. which is a wonderful engine. To live with a K is a blessing. The Accord engine is a detuned monster in a very good way.

[SVOboy]

From what I understand there are 4 different types of vtec with "i" involved in them. I just don't bother mainly because I don't care, is the k24 in the accord the same as in the element?

[psyshack]

From what I understand there are 4 different types of vtec with "i" involved in them. I just don't bother mainly because I don't care, is the k24 in the accord the same as in the element?

Its my understanding that the Element, CR-v and Accord have the same engine in them. The TSX had the warmed up version. The Si has the smaller tuned version.

Another good mill in this class is the Mitsu 2.4L I4. Found in the Lancer Rally Art. Not the Lancer Oz or the EVO. Well the blocks basicly the same in the EVO.

My brother has a Laner Ralley Art. Its a wonderful car. the engine in it is wonderful. hp and tourge like the Accord engine and its own vtec copy head. not as refined a mill but a soild number 2 in the list. its a very fun car to drive. its late 90's sedan look is very dated but still yet a very good car. The best clutch of any car ive ever driven. The EVO short throw 5 MT is great. The mags have dished it. I see none of the glaring failures road test claim. Eric isnt a hypermiler by any means, nor is he a street racer. a autocrosser he is. The Lancer hasnt failed him yet. This from a guy that is building a Fiat X/19 open class ride. X/19 equals a underpowered Ferrari. After all Fiat owns the Prancing Pony.

[kwtorbe]

Okay, I bought a '97 Civic HX at the beginning of last summer. Once I got it running well I began to tune it and drive for fuel efficiency. The car had a cheapo 3" "Short ram" intake in the engine compartment that essentially used warm air. All summer I averaged 45mpg with a best of 47.7mpg. In mid-August I made a "cold air" intake out of 2"PVC piping and the cone from the ebay-intake---an awesome idea I need to Patent. My freind and I call them poop-poo shoot intakes. Since then I have commuted from Tulsa to Stillwater (~70miles) for school every weekend. My fuel economy dropped to about 41mpg but it does feel torquier. My driving habits before I began the Stillwater to Tulsa commute at 75mph had not changed and still netted the 41.5ish mpg. This last weekend I made a hot-air poop-poo shoot. I wedged the air filter between the radiator hoses (no kinks or anything damaging here) facing the exhaust manifold and plumbed it all in. I'll let you all know the improvements between hot or cold air in mpg for my highway crusin' HX. I know the theory behind hotter air being less dense makes sense for fuel economy and the PVC has smooth transitions for less pipe friction--especially if you have less degreed bends for better performance either cold or hot air involved.

Here's a how to Make a Poop-Poo Shoot Warm or Cold Air Intake:
To make a poop-poo shoot intake buy a 2"-2" rubber PVC hose clamp to attach to the engine (for civics anyways), a length of 2" PVC piping, PVC angled pipes, PVC primer and cement, a hack saw, drill, sand paper, scotch bright pad, flat black paint, duct tape, marker, tape measure, flat head screwdriver, and a 3" cone filter ( maybe some gasket sealer and dryer ducting ).
Remove old intake. Decide how you want to run the tubing--measure twices cut once. I wouldn't put the PVC within 3" of exhaust. Once all the pieces are cut, mock assembly and mark where peices fit and number the pieces 1-whatever. Also mark holes to drill in the piping for IAT sensor and PCV hose. (The IAT sensor fits in a small piece of 3/8" fuel rubber fuel line.) Drill out slowly while test fitting making sure to get a secure fitment. Then ruff up the outside of PVC piping and angles with a scotch bright pad if you want to paint it--don't take off the markings for assembly. Then, Use about 800 grit sand paper and lightly ruff up the connection parts for the pvc. Next, primer and cement pieces together one at a time with markings aligned. Use formagasket on PCV tube and sensor Hose if you made the holes to big. Then hang somewhere and spray paint it whatever color you want--I prefer flat black. Then wrap the filter end with duct tape until the filter is snug--only wrap to the edge leaving some overhang. Cut of the overhang duct tape with a seraded edged knife. Finally, install in the car with the rubber PVC 2" attachment piece and attach the IAT senor in front of the PCV tubing in the direction of flow. Pat yourself on the back for saving money on a cold air intake or saving gas for about $10 worth of PVC parts.

P.S. I plan on using the aluminum tubing you guys used to plumb it into the headers heat. It is pretty close already though.
You guys are awesome for giving me the hot air idea!
Kent

[kickflipjr]

I know that the top speed has decreased to 95mph from 120mph on the same stretch of highway at similar outside air temps.

SLOW DOWN! That is the easiest way to save on gas.

I am with you on the homemade intakes. I am constantly changing up my intake in search for a more efficient ride.

Stock, Cold, Hot, or somewere inbetween.

[kwtorbe]

I normally drive 70-75--the speed limit--but the long night drives to and from stillwater on the turnpike sometimes lead to top speed experiments---only the two mentioned actually

[jolt-tsp]

Does anyone know what the optimal air temp is? I don't want to get close to detonating, but this is too easy not to try. I'm thinking you can pull air from two sources (one cold, one hot) and use a Y with a flapper (Similar to what the HVAC unit uses to pull cold or hot air) to pull the right amount from both sources to reach the optimal temp. Using a cruise control style relay to adjust the flapper based on temperature could even automate it. It's late for me, so if I didn't make any sense, please excuse me. :D

[cfg83]

Does anyone know what the optimal air temp is? I don't want to get close to detonating, but this is too easy not to try. I'm thinking you can pull air from two sources (one cold, one hot) and use a Y with a flapper (Similar to what the HVAC unit uses to pull cold or hot air) to pull the right amount from both sources to reach the optimal temp. Using a cruise control style relay to adjust the flapper based on temperature could even automate it. It's late for me, so if I didn't make any sense, please excuse me. :D

Oooooh, this makes alot of sense, switching from "hot" to cold mode. I would probably be more primitive. One control for hot, one for cold, in order to have a "mix" that I can monitor from the Scangauge. For me, 100% cold would be the "stock" routing to bring my car back into normal running mode. Ha ha, maybe "hot and cold" faucet taps mounted on my dashboard!!!

Now where do I put the kitchen sink?

CarloSW2

[onegammyleg]

Hi jolt-tsp - ¨and use a Y with a flapper¨

This was a common arrangement back in the days of carburettors especially in the days just b4 the forced introducction of EFI.

A hot air riser tube would come off a heat shield on the exhaust manifold and either it would mix automatically via a big flap valve with the cool air coming into the air cleaner.
This valve was usually move by a diaphragm powered by vacuum which was switch by a temperature vac valve.
When the car was at full operating temperature the flap would be open all the way and when it cools down again a spring snaps it back.
It worked quite well unless some backyard mechanic had been playing around with the mess of vacuum hoses needed to make it work.

On some cars it was a manual change that needed to be done , by sliding a knob on the side of the air cleaner housing . it was usally marked , ¨winter / summer¨

Since EFI has come to be the computer is able to auto adjust to give suitable mixtures across a wid range of operating conditions and temperatures , so on many cars this intake preheater has been dropped.

As seen elswhere , warm intakes do have some benifit , but I dont think its the holy grail ,, the hotter the mixture the less air and less power ..its good , but up to a point.

We just need to find the happy compromise intake temperature by solid experimentation.

[Ted Hart]

To all the tinkerers out there :
Do you realize all this adjusting of the temperatures of the air, the fuel, both together, both different...for whatever reason... is really another way to "fool" the engine's ECU?
I don't deny the effects of all this ... but you must realize the effect you are having on the timing curve (for max. BMEP). Before electronics took over the chore of adjusting the timing, we had to "power time" for each change. Now, the ECU will do this for you...providing you remain within the limiting "window" for change! Some systems have a narrower window than others! You can find out how your timing window changes with an old-fashioned timing light (remember them?) and marks painted on your damper pulley (and some simple math to convert degrees to inches/circumference) for TDC & marks (2 degrees?) away from TDC, for advance.
Assuming you've got a Scanguage (or similar device) for showing the instantaneous MPG...a changeable intake (temp.) system can be activated from the driver's position. Later, the effect can be duplicated in the garage by revving the engine to the highway speed...to note where the timing shift ended up ... advance point. Only by doing this step-by-step approach can you determine if the ECU is within its own limits; ie, you won't be wasting your time with a "maxed out" timing shift(the window limit)!
Remember, too hot is dangerous (detonation) and too cold is bad for MPG ( does anyone remember carburetor ice?). -Ted Hart

[jthistle]

For a more professional look you could use a small intercooler sitting directly over the exhaust manifold. You would put one of the cone filters on one side of the intercooler and place the intercooler on top of the manifold then route the other side into the engine. A small intercooler kit like this might work.
http://img236.imageshack.us/img236/7223/intercooleroi1.jpg

[Project84]

this thread is 2 years old and HAI has been done about every way possible.... but spending that kinda loot on an intercooler kit for a 1mpg gain? Not very cost effective.

I'm fabbing mine tonight with a total expense of around $13

[theholycow]

Heh...yeah, we tend not to be about a "professional look" in our cars. :)

[almightybmw]

intercooler....haha, more like interfooler! anyways. I think the pressure change across an IC would actually increase your "pumping losses." It would take more throttle to pull the air across the IC than gains would show. You'd be better off custom building intake plumbing with radiator fins to absorb ambient air than use a traditional IC.

[cheapybob]

this thread is 2 years old and HAI has been done about every way possible.... but spending that kinda loot on an intercooler kit for a 1mpg gain? Not very cost effective.

I'm fabbing mine tonight with a total expense of around $13

The gain on mine was 15% initially. I agree it can easily be done well for a much lower cost. Mine was about $30.