[only126db]

Hey everyone, I am new to Subaru's and have a couple questions.

Vehicle = 1996 Subaru Legacy Outback 2.5L Automatic

Basically I am wondering what bolt on upgrades are available to increase fuel mileage and gain some low end torque without losing top end power.

I have seen mention of the Borla knockoffs on Ebay, but I only see units made for 1997+ models.

Will the 97+ models also fit mine?

Will they benefit me in the low end and with fuel mileage or are they designed for top end gains?

What about a cat delete, does it help on these vehicle, or hurt?

Any other mods which have proven gains in the area I am looking to get my gains?

This is 100% daily driver commuter vehicle, not a racer and not interested in a loud exhaust either.

If of course a little more volume from the exhaust is inevitable than so be it, but interior drone is unacceptable.

 

[1 Lucky Texan]

best bet is to get the car in top condition (tight suspension, good alignment, properly inflated tires, good brakes with lubed and free calipers, clean, fresh fluids, etc.). Next, make certain you aren't hauling any mass around you can leave at home - even to the extent of removing seats if you literally will never need them.

drive as if there were an egg on top of the gas pedal for better mileage.

the majority of intake and exhaust mods will increase noise - without a measurable gain in performance.

 

[cardoc]

Dito. Use premium fuel though. More power from the burn and less volume.

 

[subiesailor]

Dito. Use premium fuel though. More power from the burn and less volume.

Cardoc - how does higher octane ie more stable fuel - with the same or less energy per volume than regular cheap gas generate more power and less fuel burned in an engine that was designed to run on low octane fuel?

Just curious?

 

[outbackpacker3]

I do know the headers do give better mileage and low end power if you check out Mudrunner's thread on the Battlewagon build he used them and got the power increase. but most wont get the mileage gain because they accelerate hard to hear that signature boxer growl.

 

[cardoc]

I have always compared how my cars run based on differing fuel ratings. MPGs, knocking, power output, engine load comparisons and overall feel of the car. Also keep in mind, I don't miss anything in maintenance needs. If something happens, its taken care of quick. I drive 75-100 miles a day depending on circumstances through the day. Minimum is 52 miles round trip just to and from the shop 6 days a week.

1996 Cavalier 2.2 Saginaw engine with 5MT. 9:1 compression. Hates regular gasoline. This car now has 211,xxx miles. The EPA rating on this car was like 22-25/32-37. On regular 87 octane, that's about what it got, avg 22-25 mpg between fill ups. Sometimes worse. Midgrade, mpg went up a bit, load dropped, the engine reacted better. High octane, 93, the mpg jumped, load dropped again, engine loves it. I get 33 mpg between fill ups with a mix of highway and city driving. When I drive it across the country, SoCal from Tx and back, avg 45 mpg between fill ups cruising on the highway. It also still has the original CAT.

99 Outback 2.5 DOHC automatic. 9.7:1 compression. Would run good on 87, better with 93. This one it was more the way the engine reacted to the fuel than a huge difference in mpg. It averaged 21 between fill ups with 87 and increased to avg 22-23 with 93. Knocking reduced, engine load dropped and it reacted better, mostly on the highway.

01 VDC 3.0 DOHC automatic. 10.7:1 Prior to the SC installation and remapping for boost and then E85, this car got 20 mpg on 87 and 24 on 93. Again, the engine reacted better, load decreased and it was noticeable. Cruising on long drives, the longest from Austin to Padre Island last summer, the mpg increased a couple more points to 26. (side note: We did 3 remaps to the ROM just weeks before the SC install. After Ed's 2nd ROM revision altering the fuel/ignition map, my fuel mileage went from 24 to 27 mpg with improved performance and reaction. Running 93)

Every car I have owned for the last 27 years has performed better on higher octane fuels with exception of a Datsun 210 that didn't care one way or the other.

I don't care what articles say one way or the other and it doesn't matter how the fuel companies blend the fuel or process it. I know what I see as a result when I test it out. If I cared what was posted in articles, I wouldn't have modified the VDC because the articles said it was detrimental and wouldn't work. Professional builders told me it wouldn't work. Programmers told me what I intended was impossible.

So, try it yourself and see. Here is a link on how to do a detailed test in fuel usage comparison: Fuel Octane Selection

Look it over. Go through the exercise if you like, only I would suggest you do a test now with the cooler weather, then again in the summer and average the numbers. Find what your car performs best on and go with that.

Some of my customers have done the same type of evaluation. Some run 89, others 93. In Subarus. Everyone drives differently and that would also determine your outcome.

 

[only126db]

I do know the headers do give better mileage and low end power if you check out Mudrunner's thread on the Battlewagon build he used them and got the power increase. but most wont get the mileage gain because they accelerate hard to hear that signature boxer growl.

That is usually the case with most exhaust or intake upgrades. As the sound level goes up the foot gets heavier.

Dito. Use premium fuel though. More power from the burn and less volume.

I have just bought it, filles it with 89 then read the manual in the glove box and it specifies 91 or better...

Kind of sucks with todays prices....

 

[AWDFTW]

Cardoc - how does higher octane ie more stable fuel - with the same or less energy per volume than regular cheap gas generate more power and less fuel burned in an engine that was designed to run on low octane fuel?

Just curious?

The 96 recommends premium fuel. 97 and on were for regular.

 

[1 Lucky Texan]

That is usually the case with most exhaust or intake upgrades. As the sound level goes up the foot gets heavier.



I have just bought it, filles it with 89 then read the manual in the glove box and it specifies 91 or better...

Kind of sucks with todays prices....

I'm old enough to recall when the price structure was like; reg. $1.00, mid. $1.12, prem. $1.25 and similar. But, instead of a 25% difference, it's more like 9-11% or so around here.

never been cheaper to run premium.


consider running a bottle of Seafoam or Techron through the tank as well as a throttlebody cleaning.

 

[cardoc]

The 96 recommends premium fuel. 97 and on were for regular.

Programming change. The Mapping was changed to run low octane by changing the knock retard, injectors and timing. When the low octane causes knock, the timing is pulled to stop detonation and fuel is added. At the times the timing is pulled and fuel added, power is reduced. Reducing the chances of knock reduces the rates of retard and keeps the power leveled. Higher octanes do this.

I have seen in data the timing being reduced up to -15. Never hearing one ping out of the engine. Changing fuel stopped it.

High octane is higher in cost. But it's been my experience that it is better for engine performance and reduces maintenance over the long term. It's like using synthetic oil. Reduces carbon buildup and reduces engine loads.