Author:Harrell, Rick
Publication: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>

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

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

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.

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

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If your reading this, then good for you, your saving some gas because your here.

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

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

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...

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)

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2008 EPA adjusted:
http://www.gassavers.org/gaslog/sig.php?id=249
http://www.gassavers.org/gaslog/sig.php?id=414
Distance traveled by bicycle in 2007= 1,830ish miles
Average commute speed=25mph (yes, that's in a car)

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.

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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.

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Top ten prediction

FE for the Brain

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

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.

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Top ten prediction

FE for the Brain

See if I can post a picture.



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

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FE for the Brain

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

What is with the alluminum foil?

__________________
2008 EPA adjusted:
http://www.gassavers.org/gaslog/sig.php?id=249
http://www.gassavers.org/gaslog/sig.php?id=414
Distance traveled by bicycle in 2007= 1,830ish miles
Average commute speed=25mph (yes, that's in a car)

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!

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If your reading this, then good for you, your saving some gas because your here.

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

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.

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Top ten prediction

FE for the Brain

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.

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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?

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Top ten prediction

FE for the Brain

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

I'm gonna try that...

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.

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[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.

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Top ten prediction

FE for the Brain

[quote=zpiloto]
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 ??

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.

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Top ten prediction

FE for the Brain

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.

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.

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.

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,

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.