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On a different thread, Andrew was commenting about why WAIs work. That was the starting point for this thought about how to improve FE with a WAI without paying the full horsepower performance penalty. I am planning to add significant material and flesh out the explanation with physics and equations as time permits. Without any further fluff, let me give you Andrew's thought starter:

Warm air is less dense. That means less oxygen in the cylinder. The O2 sensor reports this back to the computer. The computer reduces the fuel supply to maintain the optimum air-fuel ratio.

Basically, a warm intake makes it act like a smaller engine. A cold intake is like a larger engine.

Andrew is correct with this simplified explanation. I will attempt a slightly more complex explanation.

Think of an ICE (Internal Combustion Engine) as an air pump. In order to produce power, you have to combust a certain mass of air and fuel. Let us assume for the sake of argument that the efficiency of the reaction is relatively unchanged from the time that your intake valve closes until the reacted mass exits your tail pipe (I can provide the reasoning if you think it is critical). Therefor, the only significant change is between the ambient air and the filling of the cylinder.

If the intake air is cold, getting a given mass of air into the cylinder requires a greater restriction (less throttle) in the induction system. This results in greater pumping losses. If the air is warmer, getting a given mass of air into the cylinder can be done with less restriction (more throttle). The down side of a warm air intake is that you will have less ultimate power available to you.

I think there may be a relatively easy way to make this work great. If you have a split air intake with a volume actuated flapper valve, you could have the best of both worlds. If you have low airflow demand, the system will pull only heated air. As demand increases, the dp across the flapper will cause it to open flow from the cold air intake.

:D SHAZAM, I have me a hybrid intake!!! :D

I am thinking about using radiator exhaust or exhaust manifold heat to improve my WAI. Please comment on the idea and my take on the physics.

Please note that even though I have independently come up with this concept, it is NOT patentable because:1. There is prior art (see U.S.. Patent 4210115)
2. Any reasonable practitioner in the art of ICEs will be able to make the leap from the prior art cited in paragraph above (see KSR v Teleflex for obviousness exclusion)
3. I am claiming this concept as public domain property and it will also serve as prior art

I think it's a workable idea. I believe several old Volvo models used this concept.

Use to be used on tractors in the late 1800's, early 1900's and some cars too. It was called a heat riser.

Quick link for example: http://www.steinertractor.com/MMS002_HEAT_RISER_VALVE_ONLY

This technology is at least a 100 years old. Which means it probably would produce good results and not malfunction easily, unlike modern gizmos and gadgets.

heat riser science link: http://www.thebugshop.org/bsfqrisr.htm :D - Dale

Use to be used on tractors in the late 1800's, early 1900's and some cars too. It was called a heat riser.

Quick link for example: http://www.steinertractor.com/MMS002_HEAT_RISER_VALVE_ONLY

This technology is at least a 100 years old. Which means it probably would produce good results and not malfunction easily, unlike modern gizmos and gadgets.

heat riser science link: http://www.thebugshop.org/bsfqrisr.htm :D - Dale

I got a good :D at the heat riser science!! They actually said that the heat riser produces warmer, :eek:denser:eek: air to help you produce :eek:more power:eek:. This must be the new science they teach kids these days:p!

Seriously, most vehicles (mine in particular) would have 2 significant issues with an exhaust manifold heat riser:1. Whatever changes are made, they need to be easily reversed in order to not voiding the warranty. The donor vehicle for this case study is a 2009 Ford Focus
2. The plastic AIS (Air Induction System) would not tolerate the temperatures that it would see at idle on a hot day.

The best of both worlds is,,, WAI in the winter and normal OEM setup the rest of the year.

All the WAI does in the winter is help fool the ECU a bit when in warm up and help with the balance after warm.

I will be running a WAI on the HCHII come winter. Otherwise OEM intake.

Rev 3.0 of WAI is complete. If the camera was charged this morning, I would have posted the pictures.

I am now getting a +25F heating at low throttle. When I step in the throttle for the pulse, it drops it to about +15F. I think I am pretty close to what I need for the summer. I suspect there will be a Rev 4.0 for the winter ...

This sounds Very interesting...

Please show PICS!

Here is Rev 3.0 of the WAI in pictures:
1. Here is the business (Snorkel) end of my WAI. Please note that there are no flammable components in this aluminum dryer duct (the spring is steel)
http://www.cleanmpg.com/photos/data/522/WAI_Snorkel.jpg
2. The next image captures the transition as the WAI goes across the engine. Please note that it is touching several hoses that cannot handle the heat (PCV, fuel, etc.). Hence the reason for the next closeup. http://www.cleanmpg.com/photos/data/522/WAI_Transition_Across_Engine.jpg
3. This picture is a closeup of some high end house duct quality thermal wrap. It protects the areas it touches so well that I am able to use industrial duct tape and cheapo deluxe zip ties to hold it in place. http://www.cleanmpg.com/photos/data/522/WAI_Insulation_CloseUp.jpg
4. This picture shows the transition around and into the airbox. Please take note of how flexible the dryer duct is and how it easily conforms to the space available. http://www.cleanmpg.com/photos/data/522/WAI_Transition_Into_Airbox.jpg
5. Here I show the attachment to the airbox. This is ZipTie Engineering at it's best!! I ran zip ties around airbox at both the top and bottom of the inlet. Then I attached the mouth of the WAI to these ZipTie "Brackets". I do not show the original cold air inlet, but that was also (obviously) removed. http://www.cleanmpg.com/photos/data/522/WAI_Airbox_Attachment_Closeup.jpg

My plans for Rev 4.0 include the Y Pipe and flapper arrangement. This will be the most technically challenging part of the project ...

Inspiring! Great job. - Dale

Please upload your pictures to our gallery and link to there -- we have issues with links to Flickr (that's why not all of your images are showing).

Please upload your pictures to our gallery and link to there -- we have issues with links to Flickr (that's why not all of your images are showing).

Reconfigured using CleanMPG Gallery. How does it look?

Looks good!

Now if I could request a bit more info...
Can you show a picture from a little further out that shows how everything sits in there?
What exactly is going on at the snorkel end?
Do you have the dryer duct wrapped around some exhaust headers or is it simply taking intake from the vicinity of the exhaust?

Also, is that your brake fluid reservoir the duct is snuggled up against?

thx - Joel

Looks good!

Now if I could request a bit more info...
Can you show a picture from a little further out that shows how everything sits in there?
What exactly is going on at the snorkel end?
Do you have the dryer duct wrapped around some exhaust headers or is it simply taking intake from the vicinity of the exhaust?

Also, is that your brake fluid reservoir the duct is snuggled up against?

thx - Joel

I will add another picture when I get the chance.

The snorkel is just in the vicinity of exhaust shielding. I do not want direct thermal conduction between the WAI and the exhaust until I have active means to control the maximum intake temperature.

Yes, my brake fluid reservoir is in intimate contact with the WAI. This was one of the primary reasons for the insulation on the duct (VERY BAAAAD to boil brake fluid). I haven't thermo-coupled the insulation in that area, but it is comfortable to hold your hand on it at the end of 60+ minute drive.

I've been using a WAI for over a year now (use it for most of the year too). I once tried a similar setup with a plastic dryer valve (used for indoors to select dryer between blower out or into the house). But I was unable to get the valve to open just on high throttle, not easy to do, I gave up on it.

I'm thinking about changing my WAI... right now, the warm air comes from the exh. manifold, but I've thought about possibly adding a second heater (heat exchanger) run in series with the existing heater... so as you turn up the heat inside the car, you also turn up the heat to the intake air. This way, it would sort of automatically adjust to the outside air temp., as long as you adjust your inside temp. And if you want some added power temporarily, you can just turn down the heat.

I'm pretty sure the 81 Civic had something like this: a snorkel running across the exhaust manifold to a flap door on the underside of the air filter cannister. It was meant to draw warm air only during engine warm up, to prevent ice forming in the carburetor venturi. I remember because our's was malfunctioning.