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Discussion Starter #1
Hey guys, I have an '09 Outback with the 2.5 and a manual trans. It is about as base as it gets. It is stock with 170 horses and I'd like to know if there is a relatively inexpensive way to get a little more out of her. I would also like to be able to stick with regular gas. I'm not trying to get STi performance out of her but a 10-15 horse bump would be nice. I have heard that putting a higher volume air filter in and replacing the exhaust could possibly do what I want but I have been reading that some of you are not having a good experience with the high flow air filters. I also realize that the on board chip may need a little adjustment to see any benefit from the new filter and exhaust? Have any of you tried this? What else have you done to get a little boost out of your Outback? Thanks.
 

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You can get minor gains out of intake & exhaust upgrades. There are significant downsides as well.

The intake & exhaust plumbing on a stock 2.5 is pretty well optimized for low and mid-range power. Aftermarket pipes out there will get you more on the high end, if you desire it. The catch: do you really want to wait until the tach reads 4000 RPM before you notice the difference? Are you really going to stay a gear lower all day in order to enjoy that extra HP?

Here's a free experiment you can try. You can simulate the sort of HP gain you are talking about by temporarily removing weight from your car.

For one afternoon, empty out your car. I mean remove everything that doesn't require heavy tools to get out. Any "stuff" you have in the console or glovebox, or in the cargo area. Remove the jack, tools, spare tire, tire well lid, owners' manual, cargo cover, roof rack bars, headrests, floor mats... you get the idea. Run yourself out of windshield washer fluid and keep the gas tank mostly empty. Make sure the A/C is off & windows are up during the test drive.

You'll definitely notice a difference. Pay particular attention to the way it feels in 2nd-4th gear when you have the tach above 4000, you'll get a pretty good idea of how it will feel with hi-flow pipes plus all your stuff.

It doesn't cost anything to do the above, and it involves less actual work than changing out pipes.

It's not a pure test- removing weight is really not the same as having extra HP. Also, removing weight will make the car feel faster at all engine RPMs- not just the high end where pipes can help you. So if anything, the "weightless test drive" will feel better than a new set of pipes.

After trying it out, ask yourself if it is going to be worth the cost & increased noise.

Regarding tuning the computer- there are two basic methods. One is to buy a gadget that supplies false sensor readings to the ECU, to trick it into delivering a bit more power. These are a bit dangerous in the sense that the computer has less ability to protect the engine from damaging conditions, because it doesn't really know what is going on. I'm not a fan.

The second is to pay a pro tuner to tweak it. This is significantly more expensive, though the results are likely to be better. The problem is that a pro tuner is going to charge you the same money for your 10hp gain as he might charge an STI owner for a 40hp gain, because he has to do the same amount of work. That's assuming you can find one willing to take it on- some just don't want to touch a car that doesn't have beefed up parts like the STI.

I'll leave you with this- I needed to replace the wheels on my '98 2.5 due to cracks- previous owner was big on parking by feel. The replacement set of wheels & tires I wound up with turned out to be significantly lighter than the stock set, and the difference was very noticeable. Dropping weight from the drivetrain counts much more than just losing some dead weight. I hadn't planned on it, but I was delighted by the results. When I wanted more, I went through the above and decided that the answer was to trade up to a model that had more power to begin with and more potential for future upgrades.

Hope this helps!
 

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Discussion Starter #3
Well... that was a lot more than I was expecting, but very helpful. Honestly, it is the low end where I am most disappointed with my car. It kills me when I want to either pass/overtake and the power just isn't there. Most of my cars have been little light sedans like the Jetta GLI with 200Hp and zippy. Unfortunately, it isn't budget friendly for me to trade for something more powerful, so I was hoping there was something I could do myself as I am not afraid to grab my tools and do some work. I need the utility that my Outback provides, but I would really like a bit more zip out of it. I guess I'll just have to think about it some more.
 

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Think about a lighter wheel & tire combo- that change is noticeable right off the line as well as passing on the highway. Generally speaking, a larger wheel with a lower profile tire will be lighter than a smaller wheel with a higher profile tire, and preserves the overall diameter so that your gear ratios, MPG & speedometer readings all stay true to factory.

It doesn't have to be crazy expensive, you can install it yourself, and you have the potential for a style upgrade as well.
 

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Discussion Starter #5
Nice. I kinda gave up on the whole "style" thing went I went wagon ;) Not that I don't like the looks of my Outback mind you. But I wouldn't call it sexy. I'll shop around. Thanks.
 

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an '09 Outback with the 2.5 and a manual trans...

....I'd like to know if there is a relatively inexpensive way
to get a little more out of her.
Downshift.

 

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Never seen an Outback with a nitrous kit...There's a whole lot of room in the back for bunch of bottles too. Just kidding, and Rasterman's reply was about the most complete post i've ever seen.
 

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Lemme guess: didn't pass physics?
not a physics thing a numbers thing, if you dont like the amount of peak horsepower you have, downshifting just puts you closer to that peak, still no more actual power.
 

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not a physics thing a numbers thing, if you dont like the amount of peak horsepower you have, downshifting just puts you closer to that peak, still no more actual power.
Actually by down shifting and raising the RPM the engine does actually generate more power within the max power range the engine is capable of course.

If your running around town most people never EVER are using 100% of the power any of their cars are capable of generating. Hence if you need more power you down shift.
 

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but if he was not happy with the over all power of the vehicle downshifting does not change the power band.
 

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if you dont like the amount of peak horsepower you have, downshifting
just puts you closer to that peak, still no more actual power.
Just plain wrong.

- What does "closer to that peak" mean if it doesn't mean more power?

- If gear selection doesn't affect (??"actual"??) power, please explain why
"actual acceleration" majorly sucks at 10 mph in top gear


 

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Guardian is actually correct. By downshifting he's not going to get more power since he's limited by the maximum capability of the engine. Of course we're arguing semantics here.

It's all about gearing. If you're on a bicycle your gearing affects how fast you go relative to how much effort you're putting in. Your power doesn't change when you select a different gear ratio but your velocity does.

Back on topic. Using the flappy paddles to in effect hold a gear and downshifting will gain you a little more speed but it's probably not what the OP is looking for in terms of wringing out his engine.

Intake and exhaust can give you a little extra performance as will lighter wheels. Those are relatively inexpensive upgrades. Tunes aren't great for NA engines as they're already running near the top of their capabilities. Exceeding those capabilities can have disastrous results.

My suggestion is a simple driving adjustment. Passing is more difficult from directly behind a slow moving vehicle. You can do wondrous things as long as your rubber band is tight. Look ahead and get on the throttle when you expect to need to pass. Keeping Ten car lengths between you and the car you want to overtake should be enough for you to get by quickly and safely.

Downshifting wouldn't hurt either. ;)
 

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Just plain wrong.

- What does "closer to that peak" mean if it doesn't mean more power?

- If gear selection doesn't affect (??"actual"??) power, please explain why
"actual acceleration" majorly sucks at 10 mph in top gear

Yeah, just keep it in a lower gear.
 

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Guardian is actually correct. By downshifting he's not going to get more
power since he's limited by the maximum capability of the engine.
Twaddle! The "maximum capability of the engine" (a.k.a. max power)
is available only at one particular rpm (5600 rpm for Gen4 2.5i OBs).

If you're not at 5600 rpm AND wide-open-throttle, you're not making
use of the engine's "maximum capability."

Of course we're arguing semantics here.
No, not semantics. Simple high school physics.

It's all about gearing. If you're on a bicycle your gearing affects
how fast you go relative to how much effort you're putting in.
Your power doesn't change when you select a different gear ratio
but your velocity does.
Dead wrong. Again.

The "effort you're putting in" corresponds (roughly) to torque.
Accelerating from dead stop in top gear is a guaranteed FAIL
even if you're using "maximum effort." Why? Because high
"effort" without rpm doesn't generate squat for POWER. My
homie Isaac sez so.

power = torque x rpm

He also sez that acceleration depends only on mass and power,
NOT torque. 10,000 lb-ft @ 1 rpm = 1 lb-ft @ 10,000 rpm.

"Stand firm in your refusal to remain conscious during algebra.
In real life, I assure you, there is no such thing as algebra."

-- Fran Lebowitz
.
 

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Horsepower = Torque x RPM ÷ 5252, but who's counting?

To be a bit more constructive here, the OP wants more 'umph' at the same RPM, so basically they're seeking to move the power band lower. This means they want more torque. Suggestions for how to achieve that would be the best we can do here. The correct headers with a slightly more free flowing exhaust might help most.

Tachophobia is the fear of speed, not engine RPM. I don't think the OP or any of us here are suffering from that.
 

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Horsepower = Torque x RPM ÷ 5252, but who's counting?

To be a bit more constructive here, the OP wants more 'umph' at the same RPM, so basically they're seeking to move the power band lower. This means they want more torque. Suggestions for how to achieve that would be the best we can do here. The correct headers with a slightly more free flowing exhaust might help most.

Tachophobia is the fear of speed, not engine RPM. I don't think the OP or any of us here are suffering from that.
Traditionally, low-rpm improvements come from the intake side. Subaru did that themselves in other engines & later models. The AVCS system leaves half of the intake valves closed at low RPM to raise intake velocity and boost torque. Other manufacturers use variable volume intake manifolds or related devices for this effect.

I've seen some intake mods for subarus, but all of them seem to be optimized for high RPM power instead of low end torque.
 
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