Switched Hot/Cold Air Intake

[markweatherill]

Is there anything inherently *wrong* with the wax pellet or bimetal vacuum-door air mixing system referred to earlier?

[lunarhighway]

my car's carburator air intake is equipted with this system ( bimetal vacuum valve controling air temperature by mixing hot and cold air with a butterfly valve). as far as i can see it's working nicely.even after 20 years. i don't know it it's opperationtemperature can be adjusted though or if it changed over time but it's still opening and closing. if i can find a suitable thermometer that i could place in the airflow but read from inside the car some it would be interested to see what the temperature does

the only downside i can see is that this system will take time to adust to temperature changes... electronics with a thermometer will work much faster.

also i think this system is linked to the trottle ... letting more cold air in at higher trottle pressure...though i'd have to look up how eccactly... i'm still amazed at how clever some things are engineerd with 20 year old technology.

[rh77]

Originally Posted by markweatherill

Is there anything inherently *wrong* with the wax pellet or bimetal vacuum-door air mixing system referred to earlier?

The problem is precision and speed. It is a simple system, but here's a problem I foresee (please correct me if my assumption is incorrect):

15F, Cold Start at work. 100% HAI input off of the exhaust manifold / 0% Cold Air. The engine warms up and intake temps hit 100F after 10 minutes of driving in the city. 110F is reached and the machanical system opens the cold air tube and closes the hot: a rush of cold is introduced. IATs are now down significantly. The mechanical system takes a while to change back to a warmer mix. The result is a wider swing of temperatures and a potential for a low temperature average.

An electronic system would recover more quickly and precisely control actuators to instantly keep the temperature range in check. A threshold of 85 low and 95 high would be programmed to keep those servos busy, especially during higher engine speeds. With luck, 80-100 maximum range would be realized.

Basically, here's what I've come up with so far:

2 throttle bodies from a "U-Wrench it"-type place, and rubber tubing from perhaps a used vehicle as well (for the cold air especially and to fit the throttle body; hot air will utilize a metallic end source into a plastic or rubber tube. Both outputs will terminate into a 'Y' directly to the airbox. I'd like to run it farther up the flow, but the airbox contains the filter and is the only way to provide clean air.

Now the tricky part: control. At first, I'd like to try wiring a knob that, for example, ranges in motion from 9-o'clock to 3-o'clock. The "Noon" position will allow 50/50 mix where 7-o'clock gives 70 hot/30 cold and 9 = 100 hot/ 0 cold (and the same on the Noon to 3 on the cold side) -- or if that's too complicated, 2 knobs at first for each source.

To control the throttle bodies, servos or actuators will move the valves based on current from the knobs. Someone mentioned using actuators from an old fax machine. If that doesn't work, I could find a (recommended ) company that sells servos cheaply. Then badda-bing controlled intake temps.

The final stage: full automation. If this proves to be work, I'd like to use Red's example using products similar to those from Parallax to program a range from the IAT to move those servos without thinking about it

Carlos-

That is quite some system -- good work! Unfortunately for my setup, if temps go higher than 120F, then detonation, power loss, and an overall loss of FE will occur. I hear Saturns love high temps, though. For the Integra, this may be impossible in the summer when the CAI is in full ops and it'll get what it can, but for the remaining parts of the year, the mix should help.

Keep it coming folks -- good stuff. I can't go to sleep without brainstorming about this first. Call it what you will, but it's a version of cabin fever: not easily being able to modify the car in Winter!

RH77

[GasSavers_Red]

Random idea from a sleep deprived brain, some throttle bodies on newer engines have an IAC servo strong enough to move the butterfly of the throttle body. I don't know the range of these servos but something like that would at least simplify the opening of the throttle body

[larryg]

Don't a lot of the luxury cars have a climate control system that adjusts the heated and cooled air to maintain the exact temperature you set to keep your car toasty in the winter? seems like the bulk of what you need could be found in the dash of a junk yard caddy- you could could even adjust the temp as you drive and use the mpg guage to get the correct setting-

[rh77]

Originally Posted by larryg

Don't a lot of the luxury cars have a climate control system that adjusts the heated and cooled air to maintain the exact temperature you set to keep your car toasty in the winter? seems like the bulk of what you need could be found in the dash of a junk yard caddy- you could could even adjust the temp as you drive and use the mpg guage to get the correct setting-

Hmmm...you may be onto something there. First, a vacuum-controlled ventilation system that directs air to the floor, vents, defroster, etc. could be the mechanism that directs the air. Eventually, I'd like to fully automate the system thru electronics if possible -- but to start, this auto-luxo system could be hacked. That's a good idea.

I need to find a Pic-n-Pull place and go "shopping"

RH77

[jeff88]

I was thinking about this idea and found it in a search. I just wanted to know if this went anywhere. At this point I have the "Y" intersection with a cold and hot air side and a "wastegate" of sorts to switch between them. At this point, the only part I don't know how to do is attaching a "computer" which will take inputs like engine temp and engine revs and use the data to determine which intake side to open/close.

I would like the HAI open during engine startup/cold op until the engine is at proper engine operating temp and the CAI open during high revs/accelerating. I want the computer to determine based on temp and revs which to do.

Any help would be greatly appreciated and I just wanted to know what came about of this.

Thanks!