Warm Air Intake System -- Heater coil or core?

[rh77]

I'm tweaking the temperature of the air coming into the vehicle's intake and I can't decide what to do as winter is approaching.

We know air is a poor conductor of heat, so what to do?

*Draw air from the catalytic converter, but it's a ways away from the destination, so temps (especially on cold days) would possibly be robbed.

*Get a heater core and fabricate a box close to the intake. (I don't want a junk one because who knows what crud is in there, so a buy a small, new one)?

*Would a small intercooler (like on the top of Subaru's turbo engines under the hood scoop) work? I'm afraid that the coolant would be to caustic for a device designed for air only.

*Somehow electrically generate the heat. A cigarette lighter makes a bunch of heat -- maybe on that prinicple. like wrap a wire around a metal pipe and use the car's electrical current to somehow draw heat that way?

Any ideas would be appreciated...thanks...

RH77

[SVOboy]

My vote is draw from the cat, thing is like 800 F outside and insulate your hose. The car doesn't actually lean that much over 110 - 130 degress, other than that, electric would be the best. Measure your temps first to see if it is needed, I say.

[beatr911]

Yeah, use heat from the cat or the exhaust manifold whichever is easier to fabricate a good heating stove around. Make the air have lots of contact time with the hot parts and minimize the chances of any non-heated air being pulled in, and seal the whole thing really good to minimize cold air leaking in during the course to the air cleaner.

On my wifes old Caravan I used 2" automotive hot air hose to the stock manifold stove and insulated it with 3" dryer duct, also secured to the manifold. It got good and hot at the throttle body, I'd conservatively estimate 200-250F I wished I had a thermometer in the airflow. Doing this I picked up 1.5mpg on a long trip, but keep in mind this was a TBI system so there is more time for vaporization than a port injected system, if that is even really a factor.

Let us know at what air temps you see what kind of gains.

[rh77]

My last setup was drawing-in hot air, until the weather turned cold. I found the best place was the exhaust header, which consistantly draws-in 140-150 degrees (see the how-to section on pics). Long-Term fuel trim is way down in the -5% range, so I hope the benefits will yield a consistant increase in fuel economy. I had a bad round of cold air slipping-in and a significant drop in economy. The gaslog shall tell...

RH77

[Matt Timion]

Originally Posted by rh77

My last setup was drawing-in hot air, until the weather turned cold. I found the best place was the exhaust header, which consistantly draws-in 140-150 degrees (see the how-to section on pics). Long-Term fuel trim is way down in the -5% range, so I hope the benefits will yield a consistant increase in fuel economy. I had a bad round of cold air slipping-in and a significant drop in economy. The gaslog shall tell...

RH77

I'm actually excited to see your results. the WAI is a mod that is very exciting for those of us who live in winter states. It is cold between November through April here in Utah. If the WAI helps, I'll be more than happy to do it

[kickflipjr]

I have my intake sucking hot air off the header, but i think it is getting lots of cold air in right now.


Here is a tip: You can by an electric indoor/ outdoor thermometer for $10 and place the outdoor sensor in the intake track. Then you can tell air temps easily.

^
i'm going to put that in right now. (when i used to have a cold air intake for performance it would bring in air within 5 degrees of regular air temps).

[rh77]

My datalogger is recording 140-160 degrees constant air intake temp with the current setup (sucking air between the header and heat-shield). I had a different setup that drew too much cold air (it's getting into the 30s outside at night, so intake temps were down in the 80's) so I moved it (check the how-to section for the location). Unfortunately, the mileage is back into the high 20's -- probably the Winter fuel switch. I was up to 33, now back to 28-29 (still better than the 26 baseline). I'd like to get back into the 30's, but I'd have to guess that the Winter fuel mix and longer open-loop segments on cold starts are killing the mileage. The next mod is the hotter thermostat...

RH77

[CruiseControl]

Back in the 70s I had a Ford LTD station wagon(74?), that had a bimetal valve that channeled hot air pulled off of the exhaust manifold. Don't ask me at what temps it opened or closed, however finding one of those big saucer shaped air intakes could yield the perfect gizmo for this as well as the hardware (the hose was an aluminum foil covered steel spring) and perhaps the exhaust manifold intake plenum. To the best of my knowledge ALL of the vehicles with old fashioned carburettors and air filters used this system, in the 70s and 80s. The 4 cylinder imports used the same type of system. Is the idea here to overcome the wind chill factor induced by injecting the gas into a speeding stream of air, so that it vaporizes better?

[rh77]

Yeah, my 77 Olds 350 V-8 had the same thing. The air-cleaner had a special opening that led to a flex tube down to the exhaust manifold that would open when it was cold out to decrease start-up emissions. The theory is that warmer and denser air requires less fuel to acheive the best air/fuel ratio. I hooked up a rudimentary warm-air intake on my current car and instantly started getting much better mileage until the crappy winter gas change-over hit. I consistently get around 140 degree air, which leans out the mixture (as shown on the fuel-trim data log). For modern cars it reduces emissions on cold starts by heating up the incoming air and goes from "open-loop" to "closed-loop" a bit quicker (rich vs. lean).

RH77

[SVOboy]

Open loop/closed loop isn't rich versus lean, just not monitoring o2 sensor/monitoring it. You can run open loop on a good tune better than most cars closed loop and stock.

[diamondlarry]

I have heard that there is a way to set your long term trim levels so that you can get better mileage in open loop than in closed loop. On my Saturn, there are about three or four throttle settings/ranges that the trim can be set for. Idle, foot barely touching throttle, cruise, and just below WOT. I tried to do this once and I didn't have much success. :-( I either didn't follow directions right or my car is right for the method.