Subaru Outback Hot Air Intake Results

[theunchosen]

Originally Posted by SVOboy

Well, the troublesome think about intakes is that every car reacts differently to different temperatures. Some will pull timing with hot air, others won't.

I'm glad you did this test, but I hope others don't take this to mean that "hot air doesn't work" or that "hot air is debunked"

It's probably entirely based on how the car's ECU is mapped. If it is geared more towards HP output its just going to dump more fuel to try and recover that lost HP(lost air). If it's geared for economy or somewhere in the middle it would see gains. . .

which would make sense with the subaru not showing gains. Their systems are typically mapped for HP over FE.

[Nevyn]

Originally Posted by theunchosen

It's probably entirely based on how the car's ECU is mapped. If it is geared more towards HP output its just going to dump more fuel to try and recover that lost HP(lost air). If it's geared for economy or somewhere in the middle it would see gains. . .

So what would that mean for something like my beat-up piece of Detroit-us (detritus)? '93 Lumina Euro 3.1L MFI (not the 3100).

[theunchosen]

Originally Posted by Nevyn

So what would that mean for something like my beat-up piece of Detroit-us (detritus)? '93 Lumina Euro 3.1L MFI (not the 3100).

When you are driving do you feel the need to go faster? Does it look like it should go fast? Can it get to 60 quickly or very quickly?

lol. I do not know. Those questions won't really even answer the question. An outback doesn't really look like it should go fast but its designers are keen on mudding and four-wheeling so it needs hp.

The real question is what was your car designed as? A sports car or an econo car. Did it get good mpg to start with or lower end?

If sportscar just slap either no changes or a CAI. If it got really good for its weight class and trim might wanna look into it, although test the inake air temperature first and see if its really high to start with or low. low WAI, high, leave it alone, really high CAI.

[Nevyn]

It's not the "super-performance" package (which was the Z34), but it's the "Euro" package, also known as Eurosport. It's most likely set more toward the performance end than the efficiency end. I'll probably just leave well enough alone for now.

Thanks for the thoughts!

[bgd73]

the hot air maf worked wonders on a singular point injection subaru of the 80s. the giant intakes and increased stroke today with individual gadgets individualizing...hot air, cold air, who cares...it won't do much without changing to lean conditions by changing parts.
speaking of outback...
I heard an ej series engine run with higher compression and singular type plug fire, with a performance exhaust, non-turbo. It would be the only ej sube I would ever attempt, it was nice to see. The owner did admit the heads do not like to stay sealed. that is the shame of making it a "real" engine...I could only guess the consumption for power returned bringing a laugh while it lasted. Good ol days aint good ol stupid for some of us under the hood...

[metromizer]

Originally Posted by SVOboy

I'm glad you did this test, but I hope others don't take this to mean that "hot air doesn't work" or that "hot air is debunked"

Indeed... concluding the wrong thing from a test can be worse than no test at all.

This is a great post though, and puts a fine point on the fact that there is more to it than meets the eye, you need to test your car.

This makes me wonder if there is an optimal intake temp or temp range (to achieve max FE) for every fuel injection system and engine. If so, having access to very hot air, and very cold air in winter allows for mixing to maintain the 'sweet spot' if you use a flapper door controlled by some simple circuit and upstream temp sensor. As someone in another thread pointed out, most 70's and 80's cars came OEM with vacuum operated flapper doors <my daughter's '89 Honda Civic Si for instance>

[brucey]

I'm sure every car is different, thats what the scan gauge is for!

29 mpg driving regularly on trips to pittsburgh now, although I recently overhaulled the suspenion and my car got out of allignment and I got 13.8 under verys imilar conditions

[Formula413]

Originally Posted by brucey

With the cold air coming in, the torque converter locks up quickly. It locks up way more than I'm used to, it can lock up in 4th and still climb a moderate hill at 45 mph without a problem.

Any thoughts on why IAT affects TC lockup?

[JMags]

just a WAG but computer may monitor torque production, other idea is that the larger throttle opening required for the same speed with less power means the TPS sensor reads a higher range than is permitted for lockup. Performance calibration and all...

[RH77]

First, I would like to echo the sentiment that each engine model is different and reacts to intake air differently. Less than 90F and it's tough to attain optimal FE (with all other parameters equal). It has been tested and documented.

Originally Posted by Formula413

Any thoughts on why IAT affects TC lockup?

Have you noticed an increase in throttle input with the warmer air? TC lockup is often based on an increased throttle position (either electronically and/or through the kickdown cable).

Aside from that, my TC has me baffled. The TCM uses fuzzy logic to calculate speed, TPS, and change in speed to determine gear holding if ascending or descending a hill, and TC lockup (slight, partial, and full). Starting from cold (without EBH) in the winter, let's say the IAT goes from 25F to 100F during the drive. Coolant temps are well within full-temp range (195-200F, open thermostat), and it still won't lock up! Sometimes it requires a firm throttle press, then it engages. Other times, it just decides to kick in 20 minutes later. Only on cold startup. EBH starts, it engages no problem.

-Rick