Project LegoWag'n: shooting for 28+ mpg, 35+ mpg highway on nonexistant/small budget

[97LegoBackWagn]

Might be a good time to start a build thread. I'm sure I'll have many a question in the near future

Candidate: One 1997 Subaru Legacy Outback 2.5l H4 AWD 4 speed automatic. Currently has 312700 miles and going strong. Running 205/65-15 Michelin Weatherwise II tires (iirc).

Current thoughts/possible future mod ideas:

-1.8l H4 engine swap
-Higher gear ratio auto trans with auto OD/manual lockup,
-exhaust mods (better flow)
-minor aero mods,
-weight reduction,
-synthetic fluids,
-roof rack delete,
-lighter wheels, LRR (run flat???) tires,
-ScangaugeII or similar (possibly CarChip fleet with wireless download to laptop)

Things completed (maintenance):

5/14/12 Purchased vehicle at 312,285 miles
5/14/12 Seafoam gas tank 16 oz 312,300 miles
5/14/12 Seafoam oil 8 oz 312,325 miles
5/15/12 Seafoam intake 8 oz 312,375 miles
5/15/12 Changed PCV valve 312,375 miles
5/16/12 Changed Oil - Castrol Edge (black) 10w30 full synthetic, Purolator PureOne PL14460 filter 312,425 miles
5/24/12 Changed spark plugs - Denso Platinum TT 312,615 miles

Things yet to complete (maintenance):

-Replace right front brake hub/wheel bearings, repacked with Lucas G3 Racing Grease (full synthetic)
-Replace front control arm rear bushings (possible solid aluminum or home cast polyurethane/solid rubber)
-Check and clean/adjust (or replace) handbrake and components
-Check brake calipers, replace/rebuild if necessary
-Flush brake fluid, replace with DOT 5
-Gravity flush transmission, replace filter, replace fluid with full synthetic

Goal: 28+ mpg average (grocery getter mpg), 35+ mpg highway while maintaining the all wheel drive capacity of the vehicle. Currently seeing 22-23 mpg combined, and estimated 29-30 mpg highway (currently untested). Also looking to do this on as little funding as possible, maintaining a strict DIY approach for as much as is physically and logistically possible.

More to be added as I figure out the rest of the plan. Starting with the lowest cost highest return mods first. Planning to pull as much as possible from junkyard donor cars for this project (saves money and is greener). Feel free to chime in with any suggestions/comments, would be very much appreciated

[97LegoBackWagn]

Sitting here thinking about this, and I have to wonder...

Most (if not all afaik) automatic AWD Subaru's have the option of running FWD by installing a fuse under the hood. Part of me wants to believe that running the car in FWD mode will increase mpg (due to less drivetrain loss and drag). However, part of me wants to believe that running in FWD mode will increase gas mileage, as it would make the engine and tranny work harder to pull the weight of the car. I'm also a bit concerned with the potential for increased wear/failure of the trans by running in FWD, seeing as said mode is usually only reserved for diagnostic purposes (from what I have been led to believe)...

Anyone have any thoughts on this? Any experience? Still somewhat new to the Subaru world, and I cut my teeth on the oddball one (the 92 SVX, with which I wasn't concerned about mpg ), so I'm a bit baffled when it comes to some of this stuff.

One more thing I should note, I have already adopted some hypermiling techniques, started them when I bought my Fiero about 4 years back (modified form of P&G, foot off gas downhill coasting, feathering the gas pedal, etc). And just recently started honing my DWL technique after researching here prior to registration.

[orangustang]

Only the auto trans models have the FWD fuse thing. I had a '96 and '99 Outback, both manual, and their drivetrains are fully mechanical (no electrics). FWD mode can also be used for 2-wheel towing. It was kind of a pain needing a flatbed the couple of times I had to have an Outback towed. I'm not sure if it would help mileage to run in FWD mode. The rear diff is still there to produce drag, and the driveshaft still spins with it, so there will still be some losses from that. The only place I think you would see a reduction in driveline drag is possibly at the center diff, but I'm not sure if it would be noticeable or not.

I never did any serious ecomodding to my Outbacks, mostly because I didn't have the budget or commute that I do now. I found in the 2.2L model ('96) that removing the intake silencer and installing a K&N drop-in element both helped initially, but it probably just leaned out the mixture because gains became less apparent after a couple of tanks. It also made the car loud with the throttle open. I was never able to get much better than 30 MPG at any point in those things, but I didn't have my SGII yet to help me out.

Maintenance note: Be sure to check/replace your timing belt soon, since you just got the car, unless you have previous owner's maintenance records saying it was replaced recently (assuming you're keeping that engine for a while). The EJ25 is an interference engine, and you don't want to deal with bent valves if that thing snaps.

As far as swap candidates, I think you're going to run into a lot of trouble if you want to mate an EA82 (or similar) to your stock auto transmission. I've played around with the idea of getting another Subie for serious ecomodding, and I think I would try and find a 6-speed manual transmission first (taller 6th gear), then wait and see if any of the new FB20 engines become available as people wreck their new 2012+ Imprezas. That's probably a little out of your price range and beyond your current goals, though. I just think you'll run into a lot of trouble either way, so you might as well save up a little extra and go all-out.

Removing the roof rack completely is pretty involved, but I did see a noticeable improvement from removing the cross-bars. I never got around to making a belly pan, but virtually no attention has been paid to aero under there from the factory. I think you'll see some good gains if you get your hands on a few sheets of coroplast and bolt it up there.

Good luck in your efforts!

[97LegoBackWagn]

Thanks for the reply

As far as engine swap and trans swap goes, those 2 options are definitely a future maybe. I know it is possible to swap the 1.8l OBDI into the car, but I am not sure yet if I will go this route. This 2.5 that I have now has been well taken care of, so there is plenty of life left in it. I am aware that it is an interference engine, and the timing belt/water pump was serviced by the previous owner about a year ago (~10k miles), and it shows when I remove the belt cover.

As for modding the intake, I haven't quite decided yet as to what I plan on doing. I do know that using a K&N filter is out of the question, as I would rather have a dry flow filter. It is my understanding, from the research I have done, the oil impregnated filters play havoc on the MAF sensors in these cars (and other Subaru's), due to the design of the MAF. So I am looking into using a Green or similar cone filter.

Aero mods are where I feel I will see the most improvement in MPG with this car. Thinking that when I remove my roof rack cross bars, I may design a coroplast/cardboard roof cover that keeps the angle of the windshield and stretches back over (and down around the sides) of the rest of the bars, then maybe put a small kammback on the rear. But again, the aero mods (like the engine/trans swap) are yet TBD

The spare tire will be coming out, and I will be carrying a bottle of green Slime, as well as AAA. I also am considering removing the rear seat and fashioning a sort of shelf to even out the space it sits in.

I'll have to post my fuel log book numbers when I get the chance. Keep in mind though that these numbers are affected by the bad wheel bearing/hub on the right front, and that I haven't actually done the math to get the actual numbers (estimated in my head by rounding).

[97LegoBackWagn]

Small update: Increased tire pressure from 30 psi to 35 psi at all 4 wheels. Door tag calls for 28 psi all around for normal inflation, with 33 psi for towing. Granted, this was done with 80 degree weather, so I will be checking them again at next fill up on a cooler day to get everything pegged down perfectly.

First thing I did notice was that the car seems to move easier (less rolling resistance). How much of an increase I will see is yet TBD

[orangustang]

In probably half a million miles on different Subarus with K&N filters, I have never seen the oil from the filters causing any MAF issues, but if that's a concern of yours, I applaud you seeking a different solution.

If you take down your mileage and fill amount, the fuel log on this site will calculate your exact mileage for you. I've taken to keeping a basic calculator in my car though, because the one on my phone is a pain to use and I'm usually really eager to see my numbers after a good tank.

The number on the door jamb is a recommended pressure for best ride quality according to the manufacturer. I always thought that number on Subarus seemed really low. You can go up to the pressure on the side wall without damaging the tire. Just ratchet it up to the highest pressure within that limit that you feel safe/comfortable with. Maybe find an empty parking lot and try a few panic stops and swerves to make sure it's safe. I always had trouble finding traction for braking and steering in those cars, which is why I never wanted to max out my tire pressure. The antiquated single-channel ABS in those things is not very good.

Strangely, I always seemed to get my best mileage in those cars with a lot of junk in the back. The hypothesis that I came up with was that it tucked the suspension up into the car more for better aero, but since I didn't really test it thoroughly, it remains a mere hypothesis. It could have been that I just drove more highway when I was carrying heavy stuff. I did notice when I removed my back seat and spare tire that the rear suspension rose a few inches. I measured 10" ground clearance at the lowest non-suspension point near the rear wheels (normal is 7").

[Neen]

I had a 99 Forester with the 2.5 and 5 spd...I would average 30 combined and maybe 32 on the highway.

The auto trans is your choke point on your Subi. I doubt mid 30s MPG on the highway (65mph plus) is attainable without serious re-gearing, trans swap with re-gear or engine swap to 2.2L with trans swap/re-gear.

Has the head gasket been replaced yet? If I recall the 97 2.5L is a problematic one.

[LeanBurn]

Auto transmissions on the highway are no problem for most car built in the past 15 years. Fueleconomy.gov confirms that it is within 1mpg of the manual version. Today's cars are often showing an auto getting better on the highway than a manual. The city mileage is more of an issue but driven conservatively can also net great numbers.

-1.8l H4 engine swap <-(I would save this one for last...$$ and complicated, the car is no spring chicken)
-Higher gear ratio auto trans with auto OD/manual lockup, <--(what about taller tires to test first?)
-exhaust mods (better flow) <--(because at low throttle you need more flow? Most stock systems flow enough for an additional ~40hp, stock is fine)
-minor aero mods, <-----(grill block, front/full belly pan, wheel covers/skirts)
-weight reduction, <-(tough one if you want to retain close to full ability of car)
-lighter wheels, LRR (run flat???) tires, <---(Are the OEM aluminium lighter..try to get to 40psi)
-ScangaugeII or similar (possibly CarChip fleet with wireless download to laptop) <--(I have heard good things about Utragauge as well less$$, worth a search)

[97LegoBackWagn]

As far as K&N and the MAF go, I am basing my info off of what I have learned with the SVX, so I may not be entirely 100% correct. However I would still prefer to run a dry flow filter over an oil impregnated filter...Something about it just doesn't sit right with me.

Where can I find the fuel log on the site? Still getting my bearings on the layout of the forum...

I do agree that the factory tire pressures on the door jamb do seem low. I've always been taught that regardless of what the door jamb says on any car, that I should run 32 psi for the best balance between comfort and mpg, and that by going this route I can minimize excess tire wear. Obviously this doesn't apply for larger, heavier vehicles (like trucks, etc). I chose 35 psi as it won't increase the tire wear much more, and should yield better mpg than I am already seeing (or at least help)

Personally, I'm not a huge fan of ABS, and would prefer just to have a power assist system instead. And as far as traction, I've not had an issue yet (however it certainly isn't the SVX in that department, which felt better IMO).

From the info that I've found in my research, the ground clearance is closer to 8". I plan to do new KYB struts (hopefully in the fall), and may consider bringing it down a bit. But I would rather not change the ride height if I can help it (again, shooting for full functionality of the vehicle). Also considering a heavier sway bar and possibly strut tower braces to reduce body roll and lean.

Originally Posted by Neen

I had a 99 Forester with the 2.5 and 5 spd...I would average 30 combined and maybe 32 on the highway.

The auto trans is your choke point on your Subi. I doubt mid 30s MPG on the highway (65mph plus) is attainable without serious re-gearing, trans swap with re-gear or engine swap to 2.2L with trans swap/re-gear.

Has the head gasket been replaced yet? If I recall the 97 2.5L is a problematic one.

The previous owner swore 32 mpg highway on his 40 mile round trip commute to work. And it doesn't seem impossible. I think with the right aero mods and the right driving techniques, I should be able to nail down 35 highway.

Head gaskets have been replaced with the updated MLS gaskets. All of the 2.5l's had issues, just depends on the year what kind of issues (96-97 outbacks had problems with internal leaks due to the composite gasket used, 98-99 have issues with external leaks from the MLS gasket). Its also my understanding that the 98-99 (Phase 2) 2.5 had issues with wrist pins, connecting rods, and other internal failures. however I have the Phase 1 engine, and I believe this engine has either been rebuilt or replaced. I would like to put a Phase 1 4.11 ratio trans in, however that is yet TBD. Motor/trans swap will be a last mod if I decide to do it. The 2.5l wasn't my first choice, but given my limited budget and dire need for a vehicle at the time, this was my only option (since I insisted on sticking with a Subaru and AWD). I looked at buying a 97 Outback SUS that someone swapped an OBD1 1.8l into, but they wanted way too much money for the car. Given mileage, tranny problems, and other issues, they wanted close to $4000 and didnt have the title on hand.

[97LegoBackWagn]

Originally Posted by LeanBurn

Auto transmissions on the highway are no problem for most car built in the past 15 years. Fueleconomy.gov confirms that it is within 1mpg of the manual version. Today's cars are often showing an auto getting better on the highway than a manual. The city mileage is more of an issue but driven conservatively can also net great numbers.

-1.8l H4 engine swap <-(I would save this one for last...$$ and complicated, the car is no spring chicken)
-Higher gear ratio auto trans with auto OD/manual lockup, <--(what about taller tires to test first?)
-exhaust mods (better flow) <--(because at low throttle you need more flow? Most stock systems flow enough for an additional ~40hp, stock is fine)
-minor aero mods, <-----(grill block, front/full belly pan, wheel covers/skirts)
-weight reduction, <-(tough one if you want to retain close to full ability of car)
-lighter wheels, LRR (run flat???) tires, <---(Are the OEM aluminium lighter..try to get to 40psi)
-ScangaugeII or similar (possibly CarChip fleet with wireless download to laptop) <--(I have heard good things about Utragauge as well less$$, worth a search)

Engine/trans swap are definitely a last ditch effort. As for tires/wheels, I already have the stock aluminum wheels on the car. However I would like to go lighter. Possibly switching to 14" with a taller profile (trying to keep the odometer and speedo reading as close to perfect as possible).

Weight reduction shouldn't be an issue. To me, full ability of the car (given what I plan to use it for) is the ability to throw all my necessary stuff in and still be able to have an air mattress to sleep on. I can deal without having a rear seat and can make a fiberglass or mdf shelf to cover the area the seat is in. I could probably even do away with the front passenger seat. I am the only one who is ever in the car at any given time (very rarely do I have passengers). Plus side is, by removing all of the seats except the driver's, I never have to be the one to drive everyone around That should be worth some mpg's right there

For mpg monitoring, I am leaning towards the CarChip Fleet (or at least the Pro). I am a reseller for rallylights.com, and close friend of the owners, so getting one wouldn't be too bad $$$ wise

You nailed my thoughts on the aero mods almost perfectly, but I will save the rest for later

And I should have clarified a bit better on the exhaust. It isn't so much for better flow, more for the fact that I want to replace the cat that is on there, just in case (maintenance). Better safe than sorry, and while the exhaust looks pretty new I have no way of knowing how many miles are really on that cat. Figure it'd be a good time to install a hi flow cat and cut out the resonator, possibly change the muffler for a different (lower) tone.