A Quest for 35mpg (Subaru Outback Limited Sedan 2.5L auto)

[Zerohour]

Nice Mcrews! That grill block is sweet.

I know Brucey has a Subaru almost identical to mine, and his whole front bumper is blocked off. I'm considering closing in some of the squares on the grill or pulling a hat trick from the New Chevy designs. If you notice all the new chevys have a wide bar in the middle. If you look they are all angled upwards. In the aero videos around youtube you can see the smoke trail fly up from the grill. It almost seems like some of their vehicles they are only making it look like a has a big grill. I'm considering making a "wide bar" in the middle of my Subaru grill to see if it helps at all. But need to finish up these projects first.

Oh a sad note, I've killed another power tool...this is my third orbital in 5 years. This time the internals actually melted and the metal block that held the shaft in place was no longer aligned for the motor to work properly. :-/ puts a damper on my cost savings for the mod, but on well. Partly I can sand with an orbital for four hours and the orbital can't! Worst part was I was bouncing between the Wheel deflectors and bumper block. So there were cooling cycles between. I had even been keeping it clean internally with the air wand! But alas, another one bites the dust.

The last one I killed was from clogging it up. And it sucks even more cause I ended up buying the same exact one that melted because there's nothing close but a walmart where I live. Probably will take this one back and get a better grade model or different brand all together.

[brucey]

I know normal convention says to block off the top grill first, but the stock lower bumper intake is roughly 5 times the size of the top. It was a no brainer for me.

Also, I have a trophy case on my garage walls of burned up power tools. I believe we're at 3 dremel (or dremel knock offs)

[Zerohour]

I was so sad when my first dremel died. :-( I have a new one, and I have a multi-speed one, but I got it for free. Someone had it and the cord has a bad wire in it. So it will randomly not work for a while.

I've also gone through two angle grinders, some screw drivers, a hammer, ball joint puller, tie rod seperator and some other ones along the way.

Brucey while you posted in here. You have a header on your Subaru? Do you think it helped with acheiving better MPG? I really want to get one, but if its going to do more harm then good, I don't want to buy it just yet.

You're in WV so you know what I mean with the loss of speed and downshifts on the hills. I have a feeling a header would help keep the engine in top gear more often.

[Zerohour]

Ahh I also have a 2nd question for you buddy! I know you've played with the Boattail, but have your played around with a straight end on the rear end of the Subaru? Something like they mention in the Chevy Volt videos. Reason being, I notice my Subi builds dirt on the bumper. And its only getting there one way, air pull it back behind the trunk. I was thinking of trying to make some sheet making edges to get the air to lift off end the car, and not wrap around that round Subaru bumper/trunk design. Have you had any considerations to this? Maybe mine is different because I have the Sedan.

[brucey]

I'd have to see a picture of what you mean on the bumper question? Like creating a kammback would help, if that's what you're asking.

My intake and exhaust is stock. Well, I did remove some of the piping recently to make room in the engine bay, but other than that it's stock. That being said, my engine has been bored .040 over when it was rebuilt a few years back, but that should be returning me slightly worse economy.

As far as the transmission downshifting, a couple things:

Do NOT use cruise control. As soon as the cruise control is engaged, the transmission goes into a different mode where it shifts way sooner than necessary. I'm not sure the reasoning behind this, but it does. It also tends to unlock the torque converter way too early too. I don't get it. But whatever.

Also, you can "train" the 4EAT somewhat to stay locked and in 4th. I can keep mine locked on 85% of mountains around here. As you're going up the hill, use your foot to control it. As soon as it unlocks (scangauge helps here too, but the tach also shows the difference) let off of it and wait for it to lock again. You'll probably lose a few MPH but it should lock back up and you can put your foot down again more. After you do this enough, it should start to stay locked forever it seems. I've gone as high as 45 on my TPS before it unlocks going up a mountain, while cruise control will do it as soon as 20TPS.

As for the header, meh. If you want it go for it, but I wouldn't expect a major increase in mileage from it. Do it for the fun (:

[Zerohour]

I have noticed that if the Subaru is ready to shift up hill, All I have to do is lift and tip the throttle back in, How the ECU and trans relays signals must tell it not to shift when it's at closed throttle. I have timed it right, and it will stay in fourth, but I'm not sure how healthy this technique will be for the transmission in the long haul.

As for an update, I have primer on the bumper block, and I still stopped to fill one few tiny bits. Its not perfect, and I could do better, but it's too damn hot and I don't have enough time if I ever want to get the block on the car. Mounting points are done, and I should be getting a call this afternoon to get Subaru color match paint from Napa. I have a feeling It's gonna be a hell of a test run tomorrow morning going to work. lol I don't see getting the paint in time to get the bumper painted, dried, and install and then still giving the car a half an hour test run tonight. So tomorrow morning will have to be it.

I have held off on the wheel air deflectors, I have them sanded out, but I am not happy with the way they are fitting or with the seam quality I'll have if I install them. I need to build a better mounting tab system and revamp the edges somehow.

So for now, focus in on getting the front block done.

[redpoint5]

Great project Zerohour. This is an interesting post to follow. However, I think 35mpg is unrealistic unless you make some drastic changes (removing AC/PS/Alt, boattail, etc).

I had a 1996 Legacy MT that would sometimes get 32mpg if I happened to do a lot of mountain miles. Strangely, my normal driving conditions would only get about 29mpg. I bought a 2007 Outback auto but sold it after 1 month because I would baby the thing and only get 25mpg (made $1000 in the sale).

Kudos for the effort you are putting into this. If it were me I would have sold the auto and bought a manual since that is the single greatest and easiest thing you can do to improve fuel economy.

[Zerohour]

Well Brucey (posted above) has achieved 38 mpg with his. And his is bored .40 from a rebuild. Now I don't expect to get the car to 35mpg city, but I do hope I can get up to 35mpg with highway driving. Which will bring the overall average of the car upward and maybe get the average up to 30's consistently.

My eco sig lies since I put in data from previous summer when I had a different commute. The car got 24-26mpg on gasohol with long stretches of Hilly two lane highways. And I did that without ever trying to conserve fuel. Right now my commute which is worse than that I got in above 26mpg on the last three tanks (26.5, 28.25, 27.5 respectively). Getting improvements that make 10-15% improvement would put me nearing 30mpg! Which is still better than half the massive transit vehicles use to go to and from work.

On a side note, no paint tonight. It is sitting primed. I ordered Color matched paint from Napa, but the store neglected to order caps/sprayers for the aerosol cans. So they have three cans of paint but no way for me to spray it. :-(

So tomorrow night I'll be painting if the weather holds up.

Pictures should be on their way shortly.

[Zerohour]

Pictures:

[Zerohour]

Test Fitting on the Car: