I'm wondering if anyone here would be interested in trying a HAI or Hot Air Induction to improve fuel economy.

I recently did this in my saturn along with a few other minor mods that resulted in a signifigant improvement.

results here post number #5
http://www.gassavers.org/showthread.php?t=1448

Basically the theory is the hot air is closer to actual combustion temp. I'm no scientist but I think it would work. I don't have my trusty old first gen to test with anymore .

My setup is basically 4" aluminum flex pipe from the airbox to just above the exhaust header. I adjust positioning to maintain airbox temps between 130-180 deegrees. Testing by a fellow saturn owner revealed 200 deegrees to the maximum usable temp for fuel economy and power. What this temp would be for a TD I don't know.

 

Don't think you can compare a gasser to a diesel.
My understanding is that an intake temp of 50-90F yields the greatest efficiency. If hotter was better why have an innercooler?
What I've read is that a fuel temp of 700F at the injector is the most efficient.

 

I would think the same thing. the hotter the air the less dense which means less power. Hotter fuel quicker combustion. Just my thoughts.

 

read up on your carnot cycle.

Power is produced by temperature change.

http://www.grc.nasa.gov/WWW/K-12/airplane/carnot.html

a decent explanation of the carnot cycle.

 

I agree, but what would be your explanation for a 610 that runs a tad faster at 90F compared to 50F? Surely the fuel temp couldn't vary so much with those ambients?

 

Could you be more specific?

... as related to an intercooled turbo diesel

 

The carnot cycle is the ideal 4 cycle combustion process.

the amount of work comes from a rise in temperature between the intake and exhaust cycles.
fuel burns at a certain temperature.
if the intake temperature is close to the combustion temperature you get less work.
This applies to gas, diesel, JP8, or what ever your fuel of choice.

 

Like I said before, I'm no engineer. But I will say this on a number of cars this has worked quite well. On my dodge I noticed better FE with the WAI(swiss cheese airbox). I did not run the HAI. Reguardless of reasoning I can get better fuel economy in my saturn with a HAI.

 

I think the turbo, especially in a non-i/c truck like mine, introduces enough heat on it's own. I wouldn't doubt my intake temps approach 300+ degrees during full-boogie. jmo

 

I'm not suggesting this mod would produce power. It certainly would not. It might increase FE.


Fronty thanks for your input. It would be interesting to know at what intake temp best FE is observed. Of course before and after turbo. I measure mine with a simple HVAC testing thermometer that cost $4. I would readily admit that the turbo preheats the air incoming even in off boost conditions. If optimal intake temperature is 50-90 deegrees then in wintertime for sure there is FE to be gained.

I would also venture to say that this generally only works in light load conditions.

 

One of your previous posts stated that you did "other mods" at the same time. one of those is the result of your higher gas mileage.

hot air takes up more space = less air (oxygen) in a given space
cool air takes up less space = more air (oxygen) in a given space

a given space being the combustion chamber, in this case.

more air (oxygen) = better fire = better combustion = more complete combustion = better efficiency = better MPG.

the OEM car makers have to meet a variety of noise levels, and routinely install sound mufflers/dampers/mazes to quieten the intake noises.

the LS1 camaro's gained almost 10rwhp from just removing the intake restrictions.

i would assume your HAI is doing the same, using smooth wall tubing, a K&N low restriction filter, and providing the gain.

now, IN ORDER TO FULLY TEST IT, you need to aim it at the front of the vehicle where it can get a fresh (cool) air stream, and run the same route of driving for a week,

then, you will realize a true gain.

GOOGLE "March Ram Air" for mustangs & see thier scoop.

here's another discussion:
in order to have a "RAM AIR" effect the scoop would need to be almost the size of the frontal area of a car to pressurize the intake tract @ 700cfm.

so, it's not the RAM AIR or the scoop - but the fact that you get cool air that is not heated by the vehicle.

 

You assume I want power. Wrong ,I want less. The whole point is fuel economy not horsepower. If I wanted horsepower I wouldn't daily drive a 100hp saturn. There are multiple saturn owners that use the HAI for increased fuel economy, it does work. Some believe for different reasons. I'm sure I could throw in a cold resistor and spin the hose around and make more power, but that is not the goal here. The goal is to do more work with less fuel and so far I've been successful. Maybe even lucky

 

that's even more indicative that the OEM saturn induction system is convoluted and restricts the flow.

where's the IAT in all this situation? (is it getting a true reading of the super hot intake air?)

are you de-screening & porting the MAF? (changing the MAF body changes the flow rate of air = changes temperature = changes ECM parameters)

changing to a FIPK or Ghetto CAI is a proven method to increase MPG,
based on "the motor is a pump" theory of removing restrictions to the pumping cycle.

i've done it on ~dozen vehicles with varied results. I've got a pile of 3 inch Thin wall PVC at the house now, if you want it. you buy it from ACE hardware to make Ghetto CAI's, it's the right size for GM MAF's & Throttle bodies. easily pliable when heated.

but a pump pumping less (hot) air more efficiently, just doesn't make sense,
than a pump pumping more (cooler) air.

 

Quote:

If optimal intake temperature is 50-90 deegrees then in wintertime for sure there is FE to be gained.

You are correct. A lot of the lower mpgs people blame on winter fuel actually come from colder temps. There is even more aerodynamic drag with colder temps.
I have a intake temp gauge on my truck and it's harder to stay above 50F than it is to stay under 90° in my climate. Almost always the intake temp is 20° above ambient (outside) temperature. My solution is a tube from the airbox that normally connects to the window cowl being removed and placed near the turbo in the winter. Keeps the intake temp in the optimum range even well under zero.

 

Your logic is in the wrong state of mind, I believe. The original poster wants MPG not HP. So in a sense:

More o2 = better fire = better combustion = better efficiency = more fuel = NOT better MPG

Remember gas engines have o2 sensors, tps, and a whole other slew of **** to make sure they get the right RATIO of A/F.

But you where on the right path with HOT AIR TAKING MORE SPACE, leave less to be taken up by o2 thus needing less fuel to keep the right A/F ratio's.