'05 OBXT Power/Reliability Mods, Suggestions, Cautions, etc. - Subaru Outback - Subaru Outback Forums

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Old 07-16-2011, 02:30 AM   #1 (permalink)
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Default '05 OBXT Power/Reliability Mods, Suggestions, Cautions, etc.

Hello! I have a 2005 Outback XT 5EAT (daily driver). I know little about cars right now, but I can learn relatively quickly. I apologize for the length of this post, but if you have the patience, I want to learn from you. Right now I have all stock hardware as far as the power-train goes, but I have a Legacy GT tune. It is a generic tune.

I like to drive my car the, uh, "fun way" sometimes. I don't launch my car ever, but I accelerate quickly, turn hard, and shift at high RPM. I understand that this will, of course, decrease the reliability and longevity of the vehicle/tires/etc, but I am willing to thoroughly maintain my car and repair what I need to when I need to. What I want to do is increase my power a bit, but I also want to increase reliability as much as possible. Please advise me accordingly.

Here's what I'm thinking regarding mods I want to do over the next few/several years, as budget/time allows, and probably in this order:
1. Lightweight Crank Pulley
2. Up-Pipe (both for increased exhaust flow and to avoid cat. failure and subsequently turbo failure)
3. Strut Braces and Rear Anti-Sway Bar
4. Struts and Rear Coils
5. Turbo-Back Exhaust (high-flow cats, not catless)
6. Maybe a better tune

Consider mods that I have not listed. What mods should I NOT do? What mods should I do? What mods should I do first? What mods will be necessary to handle extra power while remaining reliable? I know if I want "real" power that I need a different intercooler and other stuff, so I guess my power/boost objective is just before the limit of the stock intercooler. I'm sure that will change a couple of years from now, but that's where I'm at right now.

Perhaps more importantly than power is suspension, since I will not be drag-racing this vehicle. What are the best suspension mods that will make this vehicle quite fun, but still not useless on trails or when hitting Minnesota's road's potholes. Also, I love my 8.7 inches of ground clearance. What suggestions do you have?

Also, I once read something Seabass posted somewhere about the XT shifting slowly with the automatic, and how that can start burning clutches with power increases.
1. How tricky is a clutch to replace on an auto? Can I do this with only jack-stands and no engine lift?
2. Would I need to replace the stock clutch with something stronger/better, or do I not replace it until I've burned through it?
3. How do I know when I've burned through a clutch? I assume I want to replace that before it's "gone" to prevent transmission damage.
4. Can I make the car shift faster to avoid this issue? Is that an ECU parameter I can change, or is that something strictly mechanical?
5. I like driving in the manual/sport-shift mode. Does this make it shift more quickly?

I am a n00b, so your patience is appreciated and your constructive criticism is welcome here. By-the-way, I'm not completely incompetent, as I have replaced an axle, an oil cooler gasket, and done some other stuff, but I significantly lack tools, experience, and engine knowledge.

Thanks in advance for your help!
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Old 07-16-2011, 10:32 AM   #2 (permalink)
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When they were both still stock, our cars behaved much the same (accounting for weight, transmission, and suspension differences), so I'm not clear on what a"Legacy GT tune" is. But, for power, the place to start with these cars is Cobb Tuning's AccessPort.

The next step is (for '05s) the up/down pipes, which will allow the AccessPort to provide an additional significant power boost. While that's being done, the pulley is easy to do, although I can't say it's contributed much to my setup.

At that point you can let things settle in to see if you're satisfied with the power train while you tweak the suspension. Start with sways. HPH
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Old 07-16-2011, 12:34 PM   #3 (permalink)
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What are you using for the tune? I assume it's an opensource stage 1 tune. Tunes are interchangeable between the lgt and obxt as long as theyre the same year and ecu code.

The only things I see that aren't necessary are the crank pully and the strut braces. You could either do an up/down pipe and keep the stock exhaust or go with a turbo back.

There are coilovers that fit the obxt and will keep the ride height. They are a bit expensive and usually require rebuilds annually or every other year. Other than that, there's the jdm bilstein kit which is at least a couple thousand, or kyb struts (03-04 up front and 00-04 in back) coupled with rallitek rear overload springs. If you decide to lose the ride height, there are a lot of options. There are people who love trails with legacy ride height.

You'd need a tune if you replace the downpipe. There are a lot of options for that.

The stock intercooler's limitation is around 17.5psi. There is a ghetto mod that will keep the tanks from separating and allow it to handle anything the stock turbo can throw at it. Look for bulletproof tmic mod on legacygt.com.

As for the 5eat clutches, there are a lot of them and it is not your typical diy job. It requires extensive knowledge and patience to replace them. You are pretty safe if you are on stock parts. They will typically last a very long time unless they are abused. They can hold way more than the engine can throw at them, it's just the slow shifts that eat them up with more power...especially stage 2 power with tons of low end torque.

There is a valve body modification that ClimberD has come up with on legacyGT.com. It ups the line pressure in the trans and speeds up those slow shifts. It's around $500, but is by far the best option for allowing huge power from our cars. The manual mode does shift quicker, but it's still not fast enough for more power. There is nothing that can be done with the ecu to change this. There is a table that effects line pressure in the ecu, but the affect is minimal and gets learned away pretty fast.

If you're looking for reliability, then there's also a new turbo oil line replacement with a serviceable filter that replaces the banjo bolt with something much better.

The valve body mod also opens the door for bigger turbos. There are a lot of options for that as well from BNRsupercars.com
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Old 07-16-2011, 06:17 PM   #4 (permalink)
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For the tune I used a ~$35 VAG-COM cable from Amazon with ROMRaider and ECUFlash (or whatever the software from Tactrix is). When I say it is a Legacy GT tune, I mean that I manually typed in values in the ROMRaider tables using values from a spreadsheet intended for use in a LGT. It was a spreadsheet from the ROMRaider forums. It was for the same MY vehicle ('05 Legacy chassis). I seem to recall the highest boost value I entered was around 15.x PSI under full load.

I was under the impression that the light-weight crank pulley "makes acceleration more responsive" or something to that effect.

I was planning on doing the KYB struts with the Rallitek Overload Springs for suspension.

Regarding ride height, I basically want to be able to clear curbs for when parking or for over-esrtimating my turn radius.

I will almost certainly keep the stock turbo, at least as long as this is my daily driver. It was brand new (OEM) and dealer-installed after the original failed at the dealer while I was test-driving it. (The engine itself is fine. I am religious about full-synthetic oil changes and Subaru oil filters)

Thank you for your input Dr. Cloud and Seabass! Forum members, keep the advice coming, if you wish. :-)
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Old 07-17-2011, 12:18 PM   #5 (permalink)
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Quote:
Originally Posted by silen7guardian View Post
I was under the impression that the light-weight crank pulley "makes acceleration more responsive" or something to that effect.
A lightweight crank pulley will help a little, but if you have the potential for massive increases of power through tuning and exhaust upgrades, it simply isn't worth the bother for a few bhp.

The easiest way to gain "faster acceleration" is by getting more torque out of the engine, not by reducing the pulley weight by a few pounds...

With the normally aspirated engines, OTH, reducing rotational weight is a decent upgrade simply because you can't get massive gains without forced induction, so you have to accept any little gains that you can get.

The cash/ benefit ratio is much higher with a forced induction engine. You can spend a couple of thousand bucks and get some really serious power, whereas that same expense doesn't really get you that much extra power with a NA engine.

Forget the crank pulley for now. I suggest a Stage 2 Cobb upgrade and you should be pretty happy.



CobbTuning.com - 05-06 AccessPORT

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Old 07-17-2011, 05:42 PM   #6 (permalink)
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^^ Exactly. With a RomRaider Stage I now, new up/downpipes would allow going to a Stage II map (again with the RomRaider approach), with significant power/torque increases. I used that route (only with the AccessPort), and each time was quite gratified. And, for me, Stage II has been plenty. HPH
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Old 07-17-2011, 08:10 PM   #7 (permalink)
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Just understand that stage2 is very abusive to the 5eat. If you look at that huge torque peak, it happens as the trans is shifting to the next gear and it happens when the torque converter is trying to lock up. If you want longevity, do the valve body mod before you go to stage 2, or keep the tune conservative by limiting boost to around stage 1 levels. Or just keep off of the pedal while shifting.

If you went with an up/down pipe and stage 2 tune but reduced boost levels to around 15 or 16psi, you would get much faster spool and hopefully not damage anything.
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Old 07-17-2011, 10:17 PM   #8 (permalink)
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Great info! Thank you!

For reference purposes, here is a link to the valve body mod by ClimberD. It looks like one removes his or her valve body and ships it to ClimberD to be modded.

http://legacygt.com/forums/showthrea...rd-160101.html
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Old 07-17-2011, 11:26 PM   #9 (permalink)
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That's how it's done. He also has a no down time option where he'll ship you a modified valve body and you can remove yours and install his at the same time. You then send in the core. The price ends up the same after the core refund.
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Old 07-17-2011, 11:56 PM   #10 (permalink)
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Quote:
Originally Posted by Seabass View Post
He also has a no down time option where he'll ship you a modified valve body and you can remove yours and install his at the same time.
I'll probably have to do it this way, since the OBXT is my daily driver. Thanks!
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