Modification: Warm Air Intake

[SVOboy]

<p>Yup, you heard right: <em>warm</em> air intake. So basically, the idea behind this is to reroute your air intake to suck air from somewhere hot, and that hotairness will get picked up by the temperature sensor on the intake and the Engine Control Unit (ecu) will lean out the car's air fuel mixture, meaning you use less gas! Sounds pretty cool, huh? </p><p>The actual modification is pretty simple:</p><p>Take some hoses and duct tape and attach something to the end of the intake and run it down near the catalytic converter where it'll suck some really hot air.</p><p>&nbsp;This would make a great experiment I should think, and it'll be good to do it, but first it would be good to standardize to a degree the materials, tubing size, and placement first, as well as getting it done properly with some pictures posted to do a good DIY on it. </p><p>Whaddya think?<br /><br />

[SVOboy]

<p><img vspace="0" hspace="0" border="0" align="bottom" src="http://www.greenhybrid.com/share/files/1/5/0/HoseInfo.JPG" />
This first picture is of the hoses you need to go buy at your autoparts store. Should be under 10 bucks each, 30 inches per hose.
</p><p><img vspace="0" hspace="0" border="0" align="bottom" src="http://www.greenhybrid.com/share/files/1/5/0/HosesConnedted.JPG" />
Tape the hoses together like so to make one big ole hose.
</p><p><img vspace="0" hspace="0" border="0" align="bottom" src="http://www.greenhybrid.com/share/files/1/5/0/InstallationComplete1.JPG" />
Attach one end of the hose to your airbox and snake it around so that the other end of the hose can get down to your catalytic converter.
</p><p><img vspace="0" hspace="0" border="0" align="bottom" src="http://www.greenhybrid.com/share/files/1/5/0/Routing3.JPG" />
Here's a picture of the end of the hose sucking air from near the catalytic converter!

Pretty simple and quick and quick, if I do say so myself.

</p>

[diamondlarry]

I have even heard of plumbing a small heater core to fit in the air box.

[SVOboy]

I've never heard of that but later on I will post about creating an air damn behind the radiator to keep the engine compartment warmer. ^_^

[Matt Timion]

On one forum I saw a guy who made a WAI/CAI combo.&nbsp; It had a small sensor that read the temperature of the air.&nbsp; When the air reached a certain amount, it would switch between the warm air and cold air.&nbsp; My understanding is that the marginal benefits of WAI decline after the temperature outside is a certain level.&nbsp; This contraption that switches between Warm air and cold air depending on the temperature of the air is a cool idea of you ask me.

[SVOboy]

I imagine it has something to do with a something something. What are the called. Some sort of valve you stick on your CAI is you don't want to get hydrolocked. I dunno, something electrical, I can;t think how to fab up something like that offhand.&nbsp;

[SVOboy]

Anyone want to try it out?

[kickflipjr]

no, I could put the air temp sensor over my radiator hose. That way my car thinks its +100F. And it leans out the fuel a bit.

Well, that is what i hear.

[SVOboy]

You could do that also, but I figure it would be less bad to not move the sensor all over, but what do I know.

[diamondlarry]

On my Saturn, I just unplug the air temp sensor and stick some resistors in the end of the plug. On this car it is around 110 ohms or so. This way I can easily return everything to stock when necessary.

[SVOboy]

On my Saturn, I just unplug the air temp sensor and stick some resistors in the end of the plug. On this car it is around 110 ohms or so. This way I can easily return everything to stock when necessary.

I'm not really an electrical wiz, so do you think your could explain a bit of the theory behind this?

[dfoxengr]

just makes it think it is one temp when its not.

[SVOboy]

So then would 110 ohms work for all cars or is it something I need to figure out differently for my honda? That makes sense, I just wonder what temperature I should try to trick it into thinking it is.

[dfoxengr]

no clue

[Flatland2D]

Well the temperature is calculated by measuring the voltage drop across the sensor. The voltage drop changes with resistance of the sensor, and the sensor's resistence changes with temperature. It's a temperature controlled variable resistor of sorts.

You could use a potentiometer in place of a resistor (also a variable resistor, but controlled by a knob) so you could test a range of resistences easily.

[SVOboy]

That makes sense, I learned this last year. So then do you think there is anyway to ballpark what is too much or too little resistance or should I just get a knob and then try it out? Seems like something for your afr tweaker/instantaneous mpg gauge also.

[diamondlarry]

I was looking in my Hayne's manual for my Saturn about how to test the air temperature sensor for proper operation. That's how I found out that the sensor's resistance varied with temperature. I had a variable resistor laying around so I hooked it into the plug that went onto the sensor. I found that the potentiometer was very difficult to control but I did notice that, according to my Scaguage, when I varied the resistance to the equivalent of anything over about 250 degrees or so that the "check engine" light came on. I went to Radio Shack and bought some 1/4 watt resistors and started putting them together until the light came on. The combination I came up with was 1-100 ohm resistor in series with 2-22 ohm resistors in parallel. This is actually 111 ohms. It's hard to say whether this would be the same for all cars but it's worth checking out.

[SVOboy]

Well that solves a lot of my questions about intake stuff, haha, I'll have to try it out one of these days, mehbe since I've only got 92 hp I could wire the knob inside and then just heat it up a lot when I'm cruising and not when I am accelerating. Unless it makes no difference really. How much mpg difference was there on the scan gauge?

[diamondlarry]

I will have to get back to you on the mpg difference. I made the change back in April and forgot what the mileage was before the change. I'll do some runs with and without the mod to get the mileage difference. I'll do some runs on my favorite test route. It's a 10 mile trip on a county road(5 miles out and 5 back) with not too much traffic. I'll do 2 with the mod then 2 more at stock.

[SVOboy]

That sounds great, I'm interested to hear the results. By your method you'd have it running just under 250 degrees, right?

[diamondlarry]

Yeah. Even though they are fixed value resistors, the temp varies slightly. It seems to vary between 242 and 247.

[dfoxengr]

cool, get that testing done :-)

[SVOboy]

I know that the actual improvement numbers will have to wait for you to test, but I'm wondering. I think it was flatland I was talking about this with the other night, and he mentioned about the 02 sensor, and I was wondering how much the 02 sensor will realize the temperature is wrong and the burn is too lean and richen it up? It might be different since you're obd2 and I'm obd0, but I figure if it yours will still leave it lean than mine would be more likely to leave it even leaner.

[diamondlarry]

With my EFIE device fooling the computer into thinking the mixture is rich I'm able to overcome most of those problems. Without the EFIE the ECU would likely counteract anything I would try.

[SVOboy]

Good point, I forgot about that. I want to go looking for one now...Are you feeling a huge power drop because of the intake thing or something like that?

[diamondlarry]

There doesn't seem to be a huge power drop. I know this because if I'm not carefull when turning onto a crowded highway, I end up lighting up the tires. Not so much with the new tires though. By the way, in case anyone was wondering about my picture, it's what my piggybank looks like when I go to the gas station.

[diamondlarry]

Here are the numbers from my testing. I did two runs of 10 miles each with the mod and without. Since I had the mod in place I srarted with that first. Here are the numbers: with(mod)-56.5 & 57.1, without(stock)- 44.2 & 44.6. If I've done my math correctly, this figures out to be a little over 28% increase. A bit shocking for something so simple. It will be interesting to see what happens when the temps fall to around zero in the Indiana winter.

[Matt Timion]

Diamondlarry,

Is the mod you're talking about the warm air intake, or the little plug you put on your Intake Air Temp sensor to trick it?

Also, I'm curious to know if this type of modification has any long term negative effect on the engine (running too lean, etc.)

[diamondlarry]

Actually I just twisted the resistor combination together and shoved the ends into the plug. As far as any damage goes, I have been running this way since back in April and haven't noticed any adverse effects.

[SVOboy]

Actually I just twisted the resistor combination together and shoved the ends into the plug. As far as any damage goes, I have been running this way since back in April and haven't noticed any adverse effects.

Could you see a difference on the temperature gauge for the engine or anything to suggest it was running hot? That's a mondo increase. Think you could test with the mod but minus the EFIE also? I'd be interested to see hwo much correction there is.

[diamondlarry]

The temperature gauge seems to run just under halfway. According to the Scanguage the temp runs right around 195 degrees and goes up slightly when sitting in traffic on a hot day. I can disconnect the EFIE fairly easy so I'll try it that way a couple of times.

[diamondlarry]

I just went for a couple of runs. I disconnected the EFIE and got 56.3 mpg. I then reconnected the EFIE and went for another run. On the second run, I had to slow down for someone who was turning left in the middle of the run. On the second run I got 55.7 mpg.

[Flatland2D]

Wow, that's a monstrous improvement for something so simple, cheap, and easy. I'm glad to see the EFIE didn't help much as I've kind of given up on the tuning function of my AFR gauge.

[SVOboy]

Wow, I'm so down for trying these. Thanks for running the tests so soon, haha, you're amazing. But wow, that rocks. My temp gauge is always at 1/3rd even in the 90 degree weather, so I think I can take this. And without a performance drop too, how amazing. Got any pictures of the set up?

[diamondlarry]

Since it's already dark I'll try to get some pictures after work tomorrow.

[Matt Timion]

Wow, I'm so down for trying these. Thanks for running the tests so soon, haha, you're amazing. But wow, that rocks. My temp gauge is always at 1/3rd even in the 90 degree weather, so I think I can take this. And without a performance drop too, how amazing. Got any pictures of the set up?

you might want to think about just getting a warmer thermostat for your car. Get one that opens up at 195 degrees and your engine will run warmer, and will probably give you better mileage.

[diamondlarry]

http://www.filefarmer.com/cruisur/resistors.jpg

Here is a link to the picture of my tep sensor mod. Thanks SVOboy for the hosting.
Larry

[SVOboy]

<img src=http://www.filefarmer.com/cruisur/resistors.jpg>

There's the picture. You've just got to enclose that text in < and > to make it show up normally.

[Matt Timion]

<p><div class="quote-msg"><div class="quote-author">SVOBoy wrote:</div>There's the picture. You've just got to enclose that text in < and > to make it show up normally.</div></p>

A better way to do it is to use the tags.

[img]IMAGE URL GOES HERE

[SVOboy]

Yo, larry, where is the IAT on the saturn's? I'm going to hook up one of your resistor combo's for a friend to test it and I just wanna get an idea beforehand of where it is so I don't have to look too long (since I'd be doing it before school and all). Thanks.

[diamondlarry]

Off of the air filter box is a tube that runs toward the front of the car. This air filter tube runs parallel to the top radiator hose. the sensor is in the side of the tube near the opening. The connector may be kind of difficult to unhook. I have to pull up on the top part of the plug then use my pocket knife to push down on the other tab. Since everything runs so close to the radiator hose, you either want to let the car cool off or be real careful not to roast your hand.
Larry

[rh77]

My '99 Acura TL actually has a heater core that lies right under the air filter-box. They tell me it's there to help with startup emissions and fuel economy. There's a trap door with an open-close mechanism that draws the heated air under certain conditions. Some folks looking to add more horsepower actually removed it but found themselves with a big mess of coolant and a difficult re-route. Long-story-short, folks could find cars with this and purchase this device (or go to a junkyard)or rig up a heater core that heats the air using the coolant/anti-freeze and work it into the filter or pre-filter area.

RH77

[diamondlarry]

A friend of mine did something like that to his Saturn. He took a used heater core and modified his airbox to fit it in so he would still have his air filtered. I'll have to ask him how it turned out.

[rh77]

With the cylinder de-activation debunked, my focus has now been on drawing warmer air into the intake. Basically I routed it from the exhaust-header area into the airbox. Today's outside temp was 67. My datalogger showed a range of 80-150 deg. F., with an increasing negative Long-Term Fuel Trim percentage leaning out the mixture -- which will hopefully yield better economy. I honestly haven't noticed any seat-of-the-pants power loss, but the thing is loud at WOT!

Has anyone found a sweet-spot for temp? I assume the higher, the better -- but too hot probably means too lean, or would the ECU take car of it?

-RH77

[SVOboy]

If you go too hot, like larry did to find the max, the car will throw a check engine light or you'll be able to tell from crappy running, though I doubt you can get that hot with actual air.

[rh77]

The results are in from the warm-air intake...31.1 mpg, which is a huge improvement over 26. To keep the test scientific, I didn't modify my driving style, hit redline a few times and even had 2 passengers during one trip. My cruising speed on the highway was 70. The datalogger shows the difference -- Long-Term fuel trim went into the negative percentages with the increase in intake air temp (leaner mix, less fuel).

The setup draws air from the "Y" at the exhaust manifold using a clothes-dryer duct, into the airbox. Temps ranged anywhere from 90-150F.

So, with the understanding that air is a poor conductor of heat, I'd like to tap into the coolant line with a heater core closer to the intake point, to maximize the effect. Thanks!

-RH77

[SVOboy]

Damn! Take some pictures and do a little write up and post this over in the experiment section. I can host all the pictures you need! Wow, that's exciting, I might go for this since it gave such a huge increase without a whole hell of a lot of difference in temperature (compared to 240 degrees witht he resistors). Feel any power difference perchance?

[rh77]

Now my friends call me the Half-A$$ mechanic, since I kinda throw things together sometimes, and never have the right tools. My wife has the digital camera out-of-town this weekend, so I can't take any pics right now.

Just to see if worked, I ran the duct to header and fastened it there with coat hanger and holiday wire (you know that stuff that holds the holiday ribbon on the wreath). From my cold-air intake, I had a piece of PVC that was oval-shaped at the end that fit into the airbox. I duct-taped the pipe to the vent duct, and put a screw through the elongated end of the pipe, into the airbox (it kept dropping out). The airbox has some extra room as I have a cone-shaped K&N filter.

Long-story short, I travel for a living. Monday morning I leave town and then get back Thursday night. I have a video camera that takes still-pictures, maybe I can get that to work today...but getting them into the laptop is a grey area. I'll see what I can do.

-RH77

[SVOboy]

Sweet, excited to see this. Given your huge gains I'm thinking I'll put this as my number one next modification, in front of all the other crap.

[diamondlarry]

If I can figure out how to do it, I'm going to get some dryer vent tubing and try to draw some warm air from around my exhaust manifold. My thought on doing this is this: I know the ECU is leaning out the mix because of the resistors, but I'm thinking that the warm air will help the fuel that IS being injected to burn more efficiently.

[SVOboy]

If I can figure out how to do it, I'm going to get some dryer vent tubing and try to draw some warm air from around my exhaust manifold. My thought on doing this is this: I know the ECU is leaning out the mix because of the resistors, but I'm thinking that the warm air will help the fuel that IS being injected to burn more efficiently.

The closer the truth is to the lie, the better off you are.

[rh77]

I was concerned that tricking the ECU into thinking that the air was hot would lean-out the mixture too much, damaging critical components (This car is my daily driver, and it has to last me a few more years).

RH77

[diamondlarry]

The closer the truth is to the lie, the better off you are.[/quote]

I'm not sure I follow you on this comment.

[Matt Timion]

The closer the truth is to the lie, the better off you are.

I'm not sure I follow you on this comment.

For what it's worth, neither do I :(

[SVOboy]

I'm not sure I follow you on this comment.

Well, the danger with leaning it out by telling it air isn't that there is means that the combustion will act a little funky, which was my problem, burnt to oddly that my car smelled like melting tin plates almost immediately from the resistor mod. However, this is because I was telling it it was 240 degress when it was 60, the huge difference created the problem, whereas a 240 degree to actual 150 degree difference would be more accurate, therefore less problem.

[diamondlarry]

I've been thinking about your funny smell for awhile trying to figure out what it may be. Is it possible that 110 ohms is to small an amount for your particular car and the smell was things getting to hot? Just a thought.
Larry

[SVOboy]

Yeah, my thoughts exactly, which is why my next mod will be with actual hot air, and then hopefully I'll be able to crack into my ecu and mess with things a bit there. I can decrease fuel injection by 10% a lot of places, and it'll be 10% for sure no outside affects or any of that stuff, it'll be an absolute 10%, but I can also fool around by have the IAT return different values than it's reading and shutting of the ac at certain load levels and tons of stuff.

[SVOboy]

<a href=http://insightcentral.net/forum/viewtopic.php?t=2546&sid=5a6bd2d1a61e1487ba75ef93973921f4 target=_blank>Another WAI/HAI set-up</a>
<a href=http://www.cardomain.com/ride/581466/2 target=_blank>Another!</a>
<a href=http://www.cardomain.com/ride/581466/3 target=_blank>Another!'s update</a>

[MetroMPG]

the danger with leaning it out by telling it air isn't that there is means that the combustion will act a little funky

did some reading about WAI's today... and this is a good point that isn't mentioned often enough when just tweaking the sensor.

aside from just "fooling" the AIT sensor into thinking the air is warmer than it really is (with the resultant ECU response on A/F mixture), there are real efficiency benefits to warming the air itself.

another one that's not mentioned much, is that warm air is easier to pump (because it's less dense), so the engine experiences less pumping losses - less energy is spent drawing warm air into the combustion chamber than cold air.

so the benefits of WAI that i've been able to figure so far:

OBD ECUs will run the system leaner than at low IA temps
possibly contributes to better cold fuel vaporization
reduced pumping losses from lower air density
pumping losses further reduced by wider throttle opening for a given RPM to compensate for reduced power. (see this page (http://lists.osourcery.com/pipermail/bricks/2004-October/008698.html) for explanation)
contributes to quicker engine warm-up

so on my car today i moved from a "mild" air intake (snorkel to the stock CAI simply unplugged) to a WAI approach - additional snorkel length added to draw air from around the exhaust manifold.

the change raised my intake air temp from a max of 60F at 30f ambient to a max of 75F in a brief (20 min) city/hwy run. i may further shield the collection end of the WAI to improve this.

i'll run a thorough controlled-as-possible scangauge test to see if there's a measurable effect on mpg on my car... sometime... before spring...

[SVOboy]

Obd1 honda ecus will correct as much as 6% leaner or 24% richer from warm to cold intake air temperatures, just food for thought. I think the benefits dip off after 120 F, but I could check to be sure if you want me to. I'm pretty sure it'd be equivalent on most cars.

[Matt Timion]

let's not forget that this will also help warm your engine faster and will cut down on part of the mileage hit we all take during the winter time. I'd do this mod right now if I didn't have to plan for my engine swap.

[MetroMPG]

good points, both. i'll edit that (faster warmup) into the list of benefits.

the honda crowd is particularly sensitive to this mod since warm intake air is crucial for honda motors' ability to go into lean burn mode.

[SVOboy]

^^ huh? I'm prolly not thinking of the newer engines. Is this an insight trait?

[kickflipjr]

http://memimage.cardomain.net/member_images/3/web/2211000-2211999/2211872_2_full.jpg

this is my current setup.

Yeah, insights (maybee civic vx) go to lean burn with warm air. Some insight owners say they never go to lean burn during the winter months.

[SVOboy]

Civic VX lean burn is based on rpm, oil pressure, and coolant temperature. Not intake air temp, though that makes sense.

[MetroMPG]

did a bit more fiddling and went for a drive today. i was originally planning to do my controlled runs to test the effectiveness of the WAI with the scangauge, but i ended up driving around looking for a host car for EV conversion instead. focus... FOCUS!!!

but while driving, i did note that i've got lots of available heat with my current WAI set-up tweaked with an aluminum foil "shroud" to collect hot air around the inlet:

- ambient temp, 25F
- coolant temp 195F
- hottest intake air temp (IAT) 105F (idling in traffic)
- steady speed driving IAT, 95F
- after reverting back to stock CAI, the IAT slowly (10 mins) dropped no to lower than 39F (the intake tract obviously soaks up some engine bay heat and transmits it to the sensor or to the air passing thru from the CAI inlet inside the fender)

so this tells me i've at least got a wide temp range to experiment with. i'm going to try to get out again when the weather permits and do some controlled runs.

today i also got my first chance to calibrate my scangauge against a fill-up. it was 2% off (below) what the pump said. not bad, and within an acceptble margin of error for a small (10L/5gal) fill up (plus i splashed a tiny bit out).

also, the scangauge records actual volume consumed, whereas the pumps here are volume corrected to 15C, meaning it actually reported a higher volume pumped today than was in fact delivered, since the temperature is well below 15C. (i have read that not all US states use volume correction at the pumps, but it is canada-wide.)

i also returned to the same pump and parked in the same spot i used for my previous fill up to control for pump differences as well as car angle (i've found my tank fills to different levels depending on the slope it's on when fueling. as a result, i usually try to park with the car sloping basically forward and to the right so the filler neck is at the highest corner of the car).

[MetroMPG]

(edit: duplicate post removed)

[SVOboy]

May I poke at you to say some instantaneous gas mileage differences? Even if not totally accurate? :)

[MetroMPG]

of course i couldn't help keeping my eye out for a non-scientific "preview", but it was really too uncontrolled to be of any use. too soon to tell, sorry!

winds are supposed to be light tomorrow. i may get out for a proper test.

[MetroMPG]

went out for a little drive this afternoon (ev host hunting) and got some more figures on the WAI.

- ambient temp, 45F (alright, it's january thaw time!)
- coolant temp 200F
- hottest intake air temp seen (IAT) 112F
- steady speed driving IAT, 104F
- mpg for the trip 52.9 (US) - mostly hwy driving @ 80 km/h (50 mph) > 80 kms.

i know the mpg is still useless data, because i have no direct comparison yet in the same conditions with and without WAI. the last time i measured my mpg at that speed without WAI it was 10F colder out, and i recorded 48.6 mpg (us). so really it's not safe directly compare those or draw any conclusions.

but the temps are interesting (to me anyway). i heard the radiator fan come on at least once - 45f ambient is too warm for my full grille block. normally the temp averages 195.

i'm done a bunch of work i had to do on deadline for this week, so i will sneak out when possible for a proper test if the right (calm) conditions present themselves.

[MetroMPG]

proper test conducted...

results posted in 'experiments' thread (http://www.gassavers.org/forum_topic/wai_test_results.html)

[rh77]

I've found that the air needs to get hotter to produce a result for my vehicles. After they get to normal operating temps, my IAT is around 130-140F. Maybe you could get the air hotter, somehow...

RH77

[SVOboy]

I've found that the air needs to get hotter to produce a result for my vehicles. After they get to normal operating temps, my IAT is around 130-140F. Maybe you could get the air hotter, somehow...

RH77

Pulling off the cat should do this. That and insulating the WAI to not lose the heat.

[MetroMPG]

I confirmed this week that the IAT controls timing on my car (someone checked their shop manual). so any gains in temp may be offset by reduced ignition advance. though i don't know the exact relationship between the 2 variables.

last week i also attempted to run a second set of tests at much colder temps, but abandoned it half-way thru. the theory was: WAI benefits will be more pronounced the colder the ambient temp is.

but the ambient temp was slowly rising as i did the first 4 bi-dir runs (about 4F from the first run to when i quit) and this was reflected in the values i was getting in the control set (it could also have been the driveline continuing to warm up to operating temps - even though i had about 1.5 hrs of driving). ambient was around -16C /3F when i started.

cold-weather testing is just too hard. there's too much variability.

so i'll be waiting for spring to do any more scangauge experiments.

my conclusion on WAI: whether it helps depends on the specific vehicle and how it responds to IAT temps. The independent benefit of less dense air on reducing throttling losses is going to be very small as to be essentially undetectable. and in my case that density efficiency gain may have been offset by reduced ignition timing anyway.

[Compaq888]

Basically my setup is near the header the pipe is the hottest and the more it goes from the header the cooler the pipe gets. It seems to be working, my mpg went up like crazy. At 300 miles it hit the 1/4 mark. Don't forget I have transmission problems and I put those two mods when it was after 200 miles.