: ::HAI:: for Better WINTER MPG

12-20-09, 11:15 AM
HAI = Hot Air Intake.
CAI = Cold Air Intake.
Optimal Air Temp ~50-60deg

CAI works well in the summer when the outside temp is above 70deg.
HAI works the other way around by bumping the engine intake temp closer to that ideal temp for fuel combustion.

My observations for summer use go as follows.

OEM Summer City MPG ~18
OEM Summer Hwy MPG ~24.5

OEM Setup returned MPGs much lower then the OEM Specs with outside air at 32deg.

OEM Winter City MPG ~14.5
OEM Winter Hwy MPG ~21

Thats a drop of around 4mpg on either driving conditions.

Improvements with the HAI Have been as follows:

HAI City ~17.4
HAI Hwy ~23

Other noticeble differences have been the difference in air temp and intake temp wtih OEM and HAI set ups.

OEM is always 10deg above outside ambient temp.
HAI returns around 30deg hotter intake air then outside temp.
Example: at 32deg outside air temp the two intakes reveal the followign readings.

OEM IAT 42deg
HAI IAT 65deg

Also note that when moving cold air rushes under the hood and often the IAT drops below 60deg but in general the air receives warmer air and the following results occur.

Engine warms up 30-40% faster due to air filter pulling air from above the right bank exhaust manifold.
Air temps have never been above 68deg even at idle, which is close to the underhood temps.
MPGs have been improved across the range.
HAI Set up cost me 10$ for the filter and 4$ for a 3" pipe.
Installation time took under 2min.
No issues with underhood clearance.


12-20-09, 02:03 PM
Is there any fire hazzards to this installation? Also, do you notice any smells or fumes from the engine compartment? Seems like a great little mod, if any of the issues I asked about are not present. How long have you been running the HAI?

12-20-09, 02:09 PM
I don't think 97-98s would have that problem- they are equipped with IAT sensors... Which should actually cause the problem, and the 99-up shouldn't have it. Go figure. Also, keep in mind the probably longer warm-ups.
P.S. CateraMV6, I think your MPGs dropped due to your TCS being disabled and rear tires spinning faster than the front ones... lol :D
P.S.S. CateraMV6, I am in Chicago area til next Saturday :)

12-20-09, 02:40 PM
Hey I almost bought a set of those shielded wiper blades, but the weren't available in 19" for pass side, so I didn't purchase. How do you like them?

12-20-09, 02:44 PM
I actually think I'm having an IAT issue right now, it's been -10*C here for the last 4 days, and I've noticed extended cranktimes, as well as last night I didn't run the car all day and it wouldn't start, and required a jump. R, do you know where this is located?

12-20-09, 04:03 PM
As far as the MPG goes, I have been monitoring that closely on the ScanGauge II. Also the filter has been on the car for a good 5 days now, since last Wednesday. I have noticed at lower speeds the under hood temps go up, and the intake temps can get as high as 100deg but only until you get moving then they drop back down.

Water temps are not affected in any way. I did notice that at 30deg and cold start the water temp takes around 50sec to reach 100deg at which time the heater starts to give off warm air... at 120 you get warmer yet, and at 140 its almost hot... so to me 1min warm up time in cold weather is awesome...

OEM set up took around 3-5min to get decent heat. Of course a lot less when you start driving.

I haven't experienced any fumes or smells from the set up. No rattles either, its been a blast to drive it too, since you get some insane resonant sounds above 4000rpm. Sounds like a V-Tech...

I can reverse the set up within 30sec with a small screw driver.

This set up is not for power, its for MPGs, since hotter air causes the ECU to lean out the air mixture.
Cold air is more dense and the engine uses more fuel which explains the decrease of MPG in the cold weather.
The car doesnt feel slower, it drives no different then before.
I would recommend this mod to anyone looking for better gas millage in the winter.

I read a lot of info on a page called Car Bible < Google it.

PS. R-Caddy I am also in Chicago until the end of the year so if you want to meet up for a cup of coffee that would be sweet.

BTW The wipers I have are 24" and either 20" or 21" on the passenger side. That size fits well and increases the sweep area of the windshield. The two wipers are almost touching when they are at the bottom of the windshield. Also you dont get that little triangle in the middle of the windshields from the two wipers overlapping.
My wipers were bought at Meijers and I think they were 3.99/pc < Which is why I got them.

12-20-09, 06:52 PM
here is a cool place to read more on the WAI - Warm Air Intake.

12-20-09, 07:01 PM
So I'm assuming your Sport mode is a little compromised by this mod...

12-20-09, 07:05 PM
Well from what I understand overall power will be reduced but engine efficiency will be increased and thus the better MPG.

As far as how much power is lost, I would say maybe 3-4hp, its not too noticeable in every day driving conditions. I do notice that the RPMs seem a bit more jumpy, the engine seems to be able to rev more freely but thats due to the filter and its reduced air restriction.

The engine also makes a roaring sound almost like V-Tech especially above 4000rpm.