In the ever constant quest for that one or two more MPG I took a couple bucks I had layin around and got some insulation to try and cool the intake box, I6 snorkle and tube to the TB per Project MPG. It was easy and I figured Ide test it out over the next month or two and see if its worth keepin that shiny gawdy crap under the hood. In doin some research today I came across a couple sites talkin about warm air intakes and how they are actually BETTER for MPG. They do seem to be bad for power, but better for MPG so Im wondering if everyone who downed the open filter under the hood so hard in all the MPG threads should eat crow or if its only good for smaller cars. I for one will NOT run a hot air intake as I need power to get my heavy *** around, but i do wonder if anyone around these parts has tried it. Might have to try a stock filter/K&N drop in/open filter MPG shootout sometime and actually see what happens.
Matt

 

Cold air, warm air , there never going to bring in any colder air than the ambient outside air temp , once you are at cruising speed the underhood temp by the fender is the same as by the grill , i did a test on both with a digital thermometer inserted into the air intake tube before the TB and both were the same , one had a open element filter , the other stock air box that draws outside air , the insulation will help keep the tube cooler , i think it has more to do with air flow , the motor needs as much air as it needs with no restriction , and i have never seen a stock air intake system that can't be made to breath better JMO.....Let us know how it goes...

 

Yeah, Im not really thinkin Ill get anywhere but Im ALWAYS up to tryin somethin out. With the mods I have I usually see high 12mpg winter and low 14mpg when the weather is nice. I would like to try and hit 15 consistently but I STILL havnt figured out my code 41 and Im sure the C6 aint on my side either.

As for the actual, "hot air intake" If you check out some of the hypermiling sites (which are annoying to us big land barge drivers by the way lol) they are wrapping intakes to keep heat in and in some cases add MORE heat and have shown some AMAZING gains in MPG. Im not crazy on the idea of adding heat to the intake but would like to know if someone has ever tried it in somethin other than a rinky dink 4 banger.
Matt

 

The theory behind what you're saying is the warmer the air, the eec will see this through the iat sensor and due to the warmer air mixture, the eec will adjust the a/f ratio slightly above 14.64 afr making the mixture leaner. That is the same reason you shouldn't put a colder thermostat on the truck, the ect picks up the cooler temperature and richens the mixture (just the opposite of what you are trying to achieve). So warm air, warm thermostat in theory should offer slightly better gas mileage due to the leaner a/f mixture as adjusted by the eec. This would also cause the "slight loss of power" because the motor is going to make more power with a richer than 14.64 mixture. 12.5:1 or so is ideal target for max. horsepower with gasoline.

Also you could just take the iat out of the airbox and modify the iat harness to add an adjustable potentiometer that is mounted in the dash to "trick" the motor into thinking it is getting hotter air than it really is. It would still lean the mixture and you wouldn't have the motor sucking in the hot air.

FYI....my wife's '07 Yukon comes from the factory with a 210 degree thermostat compared to our '03 Yukon that had a 185 degree thermostat. I think the mfg.'s are running the motor's hotter for the same reason, to squeeze every bit of mpg out of these trucks and suvs.

 

It depends on the ambient temp. I have an SC2 on my 2005 Escape and it seems to get it's best mileage when the IAT is about 75F. I was thinking about trying to rig up some kind of flapper valve that would decide between outside air and underhood air based on the IAT temp but have not thought it worth the trouble so far. Maybe something using one of those flapper valves they used to put inside the air cleaner snorkel on 70s cars.

 

I'm getting the stuff together for a true CAI....I have a MAF 302 Intake Y tube....Gonna pipe it down, and use a 45* elbow and a open element filter behind my valance...

 

This will do nothing for mpg, may see very slight increase in power. Also, to save yourself some trouble just get a intake tube from a 460... I have the part # lying around somewhere, but its basically is as good as it gets.

 

I have the I6/460 intake already....Just really wanting to clean the engine bay up a bit...

I grabbed the 302 intake Y off a truck going to the scrap yard...

 

I'll take your 460 intake tube if you don't want it.

 

k man...No prob....I'll give you a holler when I get it off and the CAI on...

 

cool...thx!

 

Back in the day when we ran carbs warm air intakes gave us better MPGs and cold weather performance. Most warm air systems were set at about 100 deg to allow better vaporization of the AF mixture. Some systems were adjustable and many would set it at 50-70 deg. The last warm air stock system i had was on an Astro van with the 4.3 and TBI. Excellent gas mileage (20-24) and power.
The system in our trucks is a CAI with the computer making adjustments via the intake temp sensor.
My 95 4.9 SD 5 Speed 3.08s, 4200lb SC sb with 235/15/75 tires gets about 17 mpg overall. The best I've gotten has been 20 @ 60 mph and it drops to 18 @75.
YMMV
rikard