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Issues during my tuning session
As some of you know, my latest tuning session was this past weekend. Before you get excited, I have no official new numbers yet. Mods this time around (new ones listed in [COLOR="magenta"]this[/COLOR] obnoxious color) included the following:
[COLOR="magenta"]ACL race main/rod bearings[/COLOR]
[COLOR="magenta"]ARP head studs[/COLOR]
Cobb AP V2
Cobb catted dp
[COLOR="magenta"]GrimmSpeed 3 mm phenolic spacer[/COLOR]
GrimmSpeed 3 port ebcs
[COLOR="magenta"]GrimmSpeed air oil separator[/COLOR]
GrimmSpeed ported/polished stock headers w/ high flow crosspipe
[COLOR="magenta"]GrimmSpeed turbo heat shield (replaced Cobb turbo heat shield)[/COLOR]
HKS Hi-Power Carbon-Ti cat back
IAG Big MAF intake
[COLOR="magenta"]IAG TGV deletes w/ air pump block off plates[/COLOR]
Injector Dynamics 1000 cc injectors
[COLOR="Magenta"]Invidia up pipe[/COLOR]
[COLOR="magenta"]Kelford 264 cams[/COLOR]
[COLOR="magenta"]Killer B ultimate oil pickup[/COLOR]
[COLOR="magenta"]Manley 99.75 mm pistons[/COLOR]
[COLOR="magenta"]Manley H-beam rods[/COLOR]
NGK one step colder Iridium plugs
Perrin crank pulley
Perrin turbo inlet
[COLOR="magenta"]STi 11 mm oil pump[/COLOR]
Walbro 255 fuel pump
The first problem that arose was that my car was producing an abnormally high volume of air out of the exhaust tip - enough to blow over the O2 sensor that was mounted on a jack stand and braced with a sand bag. Easy fix - the O2 sensor was clamped on to the exhaust tip, no big deal - just pretty cool :cool:
The next problem that arose was that my car was making the same power (low 300's) at 16 psi as it was up into the low 20's (turning up the boost didn't produce more power like it should). After some discusson and pondering, the issue was narrowed down to several potential sources. The first, being a leaky stock BPV. The solution: get a rather large socket and a BIG fing hammer and crush the BPV slightly to increase the pressure needed to open the valve inside. Ultimately, this didn't solve the problem.
The next thing we tried was swapping my Cobb catted downpipe to a catless model. The thinking here was that the catalytic converter might possibly be clogged. The catless dp caused the car to breathe so much easier that it was boost creeping like crazy! It would build boost when it wasn't supposed to and spike pretty high when it was supposed to. This was happening because the engine was forcing so much air through the turbo that the internal wastegate, even when fully open, was not allowing the air to travel through fast enough so it was backing up before it could get out.
At this point, it was decided that the Cobb catted downpipe would be put back on and I would have a temporary map that is rev-limited to 5,700 rpm and boost-limited to 16 psi. Fortunately for me, there is another tuning session scheduled for the weekend after next and I was able to schedule a timeslot for the following mods to be installed before then:
GT Spec unequal length header (to replace GS PnPnC w/ high flow crosspipe)
IAG up pipe w/ external wastegate (to replace Invidia catless up pipe)
Invidia catless bellmouth dp (to replace Cobb catted dp)
Prosport turbo blanket (to replace GrimmSpeed turbo heat shield)
TiAL 38 mm external wastegate
Since the headers have to be removed to get to the up/ewg and they're another potential restriction (although not likely), I might as well upgrade them to be safe. I decided upon the unequal length headers because (1) I want to keep the Subaru stumble because I still love the way it sounds and (2) even though the unequal length headers provide less horsepower than equal length, they provide more torque which is what you really feel when you drive. I don't have a monster turbo and I'm not looking to make huge numbers, so I'd rather feel a bit more on the street than be able to brag about having slightly higher horsepower numbers which don't mean a thing.
I'm going to dump the ewg directly to atmosphere under the car instead of plumbing it back into my exhaust because (1) plumbing it back into the exhaust piping causes a horsepower loss because it would disrupt the exhaust flow and (2) it would cost more. I know I said I wasn't worried about sacrificing horsepower in the previous paragraph, but I lied :p
I wanted to install a turbo blanket from the moment I upgraded to the 20G, but I found out that I was unable to use it with the internal wastegate because it would interfere with the wastegate actuator arm. Since that won't be an issue any more, I'll finally be able to use a blanket. It will be nice to efficiently block some heat directly at the source - especially because I still have a tmic. I thought about header/up/dp wrap, but there are too many issues associated with it and although I enjoy keeping up with maintenance, I wouldn't want to have to re-do it on a regular basis since it's a wear item. I'll save that for the serious racers and die-hard temperature freaks.
The 38 mm wastegate should be plenty for my application. The 44 mm model might sound a little deeper, but it also costs more and I don't want to spend too much more on this car if I can help it.
I'm contemplating getting a Cobb bpv and fully recirculating it, but that can be done after the tune. I'd just hate to get on the rollers again and find out that after this round of work, my stock bpv is indeed leaking. Thoughts on that? :: cough, cough Joshua ::
P.S. I'll probably be selling the Invidia catless up pipe and GrimmSpeed ported/polished/ceramic coated stock headers w/ GrimmSpeed high-flow crosspipe. If anybody is interested, the up pipe will fit an 02-07 WRX/STi and the headers will fit an 06-07 WRX/STi (sorry 02-05 folks, the design is a little bit different so it won't fit yours). The cat in the Cobb downpipe is partially blocked, so if you want to buy that, you could cut the cat out and weld in a straight piece of 3" pipe and a new flange and it'll be good to go :sneaky:
2.5L exhaust manifold will fit on a 2.0L, just not vice versa. At least from what I remember.
Ah, you might be right. I just know for sure it doesn't work the other way around. The bend in the crosspipe is what makes it different, but the cast end pieces should be the same.
My apologies for the long-winded post, just had a lot to share.
If I wasn't looking into a twin scroll set up, I would be all over your current exhaust set up!
Damn John and hear I thought you'd have a nice tune session. You get to have the obnoxious angry honey badger under the hood and catless DP. I replumbed my EWG and still have the CAT'd DP (though I'm not sure if my high zinc oil is killing th effectiveness of the CAT or not). I hope it gets reticified this time.
Guess I've been offline longer than I realized. Glad your build is done ! You've done break in already ?
Yeah, thanks, me too. I'm fairly confident that this round of mods should iron out all the kinks. From what I hear, the rule of thumb is ~10 hp per 1 psi increase, so going from ~16 psi to ~21 psi, I should probably be somewhere in the mid to upper 300's which is awesome!
And yep Cullen, I already have four oil changes and several thousand miles under my belt with the new motor. Up until the tune, I was engine-breaking as much as possible and constantly varying the load and rpms. I'm sure I annoyed a bunch of other drivers by not driving at a constant speed/rpm for more than a minute at a time.
LOL, but I swear my engine doesn't burn oil at all and I did pretty much what you did John. Including some different levels of boost pulls on the highway.
Was I dimed out just for input on the Cobb BPV? If so, I love it, have never had an issue with it, solid sharp looking piece under the hood. If you got the money and get it before your next tune John I would get it.If you dont and it does leak, should be able to just throw it on after the tune and be golden, but we arent always that lucky. Not trying to scare you, but thats my thoughts on it. I really hope that you break 350AWHP tho, you have more/better parts (to include engine and a similar tranny setup). I was limited by my transmission when I tuned mine years ago, and still hit 350 on 92OCT with my setup. Just think when I had my car done, you were looking forward to having a similar setup, well sir you have surpassed me now, lol. Good luck with everything.
Nice... I decided to get a Cobb XLE bpv after all. The abovementioned parts were all installed today and everything went smoothly. Now I'm anxiously awaiting my tune this weekend.
<iframe width="560" height="315" src="http://www.youtube.com/embed/DUoVzfszCDs" frameborder="0" allowfullscreen></iframe>
^ AhahahHAH thanks, that's just what I needed!
LOL. I thought it was appropiate.
I'm planning to change my oil again today after work... final tune is tomorrow morning. I hope I get some sleep tonight!
Final numbers are 365 whp/340 wtq. Mods are listed earlier in this thread and I'm feeling a bit lazy so I won't repost them. Boost is 21 psi tapering to 19 psi. The tune is fairly conservative because I want the car to last a while, but the external wastegate can be absolutely obnoxious and I love it more than a g@y man in a d!ck tornado! :D
Unfortunately, a generous portion of my undertray melted from the heat emitted by the GT Spec unequal length headers as did the harness clip for my passenger side radiator fan and much of the plastic support structure for it. Gonna have to do something about that I guess... time to bust out the old dremel tool and some zip ties :rolleyes:
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