Cold air VS Warm Air Intakes - what's the difference?

[MetroMPG]

Originally Posted by Beaver

I can leave the air horn running out through the front bulkhead, as is the stock configuration, and it won't help or hurt my mpg, though it may give me more hp at wot. Right?

Right! Maybe!

You'd think I would have returned my car to the stock intake configuration after apparently learning it didn't improve efficiency @ cruise. But I didn't.

There are other considerations - such as the fact that the heated intake air will help warm the engine more quickly, so you get away from fuel enrichment sooner after a cold start.

[MetroMPG]

Hey - welcome, oldschool. Feel free to post up a "hello" in the Introductions forum.

[MetroMPG]

Beaver: I moved the discussion about whether or not your engine is idling rough:
http://forum.ecomodder.com/showthread.php?t=548

[brucepick]

Low cost air temp readout:

For anyone who like me is driving a car that can't support a ScanGauge (pre '96), you can get an "Interior/Exterior" thermometer for about $10 that will do it. I got mine from Autozone. JCWhitney.com and Advance Auto also sell them. Probably most big box auto retailers so.

This past December I restored the regulated warm air intake in my daily driver, installing the thermometer was part of that project.

As my new route is drastically different from anything I've driven in the last couple years I can't comment on whether it actually helps FE however I'm very happy that when it's 20 deg. or less outside, the intake air temp is generally between 75-90 deg F. Darn close to the range some suspect is ideal. And as MetroMPG pointed out, I think it has to help get the car warmed up sooner.

I installed the sensor into the airbox after drilling a small access hole for the wire. The wire lead supplied with the unit was long enough for me to place the display on my dash, nicely mounted (Velcro) on a home-built bracket. I did need to cut the wire to get the sensor inside the airbox, and soldered the cut wire back together. You want maximum wire conductivity as the sensor's resistance is quite high.

Low effort, good result.

[Beaver]

You know, I have one of those temp gauges lying around somewhere; thanks for the idea! Back in the 60's the Detroit automakers put a "manifold stove" on many of their cars; some ductwork around one of the exhaust manifolds with a pipe running from it up into the bottom of the air cleaner airhorn. There was a temperature-activated butterfly that directed the air into the air cleaner from the manifold stove until it became warm enough to open the butterfly and block the hot air, opening up the other intake on the airhorn (which usually aspired underhood air that was often quite warm). I think they used a similar arrangement well into the 80's. Of course nobody thought much about fuel economy back in the 60's...
Beaver

[Coyote X]

To make everyone a bit more confused about the warm air, I am running a megasquirt and wideband oxygen sensor in my metro so I can compensate for practically anything on the computer since I have full control over it.

I tested warm air before running the megasquirt and with super heated air it made me drop ~10mpg. This winter with my car well tuned with the megasquirt computer I tried it again. This time I was able to redo my timing and fuel maps to match the intake air. This time at best it didn't change my mileage and at worst I got about ~10mpg drop again. I ran various configurations to regulate the intake air temp and really wasn't able to get it running right.

Of course I also am running 11.5:1 compression ratio so the engine knocks easier than a stock one would. I just don't think there is enough of a gain with warm air to actually improve mileage any measurable amount. It can improve warmup times though so that is worth hooking something up but it needs a way to keep the air temperature from getting really hot though or any engine will start knocking.

So feed as much hot air into the engine as you can when it is cold then turn off the hot air and let it pull ambient underhood air after it is warm is what I think an ideal setup is.

[jazzie604]

beaver and coyote already got to what I was thinking. for years automakers were using hot air tubes to help engine warm up. carbs of the 70s and 80s did not have good emissions when cold, so they had to find some way to start warming the carbs up. you guys could use a similar concept to get warm air on start up, that eventually opens back up to fresh air. depending on how creative you are, you could even have the system be able to switch from hot air/underhood air/cold air depending on intake temperature. that way the engine could be getting "ideal" air temp as much as possible.

[oldschool]

LMAO, now we can completely confuse the folks here Coyote, when I was doin my vapor carb building in the 80's we had an exhaust heated exchanger mounted directly on top of the stock carb so we could use both the carb and the vapor unit. This was a 74 Chrysler Newport with a 400 cu in engine. In stock form it got 12 mpg, runing hot air(265 degree air) in the stock carb it went to 22 mpg.

It could be that high compression effects the intake air temps viability to increase mileage.My truck is running a 10.75 :1 compression ratio and like you avoiding knock has been an issue. In the winter however I run a stock air cleaner with the heat stove off the exahust manifold and disabled the temp sensor inside the aircleaner, running the snout butterfly directly off manifold vacumn so when I am cruising I have hot air and when I am accelerating cold air; while I don't drive the truck enough to get any accurate mileage figures , I do know the hotair stove helps the trucks drivceability.

[oldschool]

Here is a pretty good overview of preheating fuel and intake air

http://freeenergynews.com/Directory/...ell/index.html

[Cd]

I'd like to test the idea of a WAI.
One concern that I have is whether or not it increases the engines emissions.

I would think that since less fuel is being added to the mix, there would be less pollution.