Turning up the stock turbo / top mount inter-cooler

[Treyw147]

My next mod that im thinking about doing is a upgrading turbos and top mount inter-cooler. But after doing some quick research I noticed that there is a way to essentially turn up the stock turbo. Could you explain to me how i can get more boost out of the stock turbo before i buy $1,200 Cobb turbo. I'm currently peaking at 16.54, id like to get 20. And any suggestions about the inter-cooler?

I do have a Cobb accessport and i'm currently running the correct map for the mods i have installed. Can i use the accessport to turn up the turbo or is there more to it then that?

Any help would be muchly appreciated.

 

[War_Panda04]

i would recommend getting pro-tuned buy a reputable tuner as apposed to using the general maps that cobb has for the accessport.

 

[STIMULA8]

What year/ and what motor/ size turbo do you have? Any current mods?



Sent from my iPhone using Tapatalk

 

[Batmobile_Engage]

I have a 2011 sedan Sti limited. I'm currently running: cobb cold air intake with box, cobb turbo back exhaust, and v3 access port with 91 oct boost map ext.

First off, do you live out west where 93 octane isn't readily available?
If 93 octane is readily available, I'd definitely recommend it and start using the 93 octane off the shelf map.

Turning up boost is possible if you were to install a manual boost controller, but doing this without tuning is a surefire way to damage your engine. The best way would be to get a protune on a dyno (though [MENTION=9]HolyCrapItsFast[/MENTION] does do e-tunes). Most tuners use some sort of Open Source tuning, but you can go on Cobb's website and see if there is a tuner nearby you that uses Cobb Accessport compatible tuning software. http://www.cobbtuning.com/dealers You can still run an Open Source tune, but it will only be saved on the ECU. With an AP compatible tune, you can save it on your Accessport and so forth. To get the most out of your protune, you should install an upgraded fuel pump and probably injectors as well (though you might get away with putting that off until later). NGK Iridium one-step colder (part #: NGK LFR7AIX) plugs is a good idea.

If you want your turbo to last, 20 psi might be a little too much. I'd shoot for 18-19 instead. If you want more boost that that, you'll have to consider a turbo upgrade.
At that point, things can get more complicated.

As far as an intercooler goes...do yourself a favor and refrain from buying a front mount unless you upgrade the turbo. Even then, the general rule of thumb is, a big top mount can support up to a GT30 turbo. Unless you are installing a turbo around this size or larger, a front mount is going to contribute to lag and reduced throttle response. If you must upgrade the intercooler, try to find the largest top mount possible that can be installed without modifying anything under the hood (such as upper coolant reservoir). This will give you the best combination of charge cooling and throttle response, while allowing you a bit of room to grow.

I've gotta get back to work now, but let me know if you have any other questions.

 

[HolyCrapItsFast]

Look into a stage 2 setup. Definitely need to replace the fuel pump on anything before 2008 with at least a Walbro 255.

Since you have the AccessPort already, then that is what you should tune with, You can do it yourself by downloading AccessTuner Race for your vehicle. It is free from Cobb and it gives you access to every conceivable parameter the ECU has including all of your boost tables. I will say this... if you don't know what you are doing with tuning then let someone else do it. Just turning up the boost is the worst thing you can do if you don't also take fuel and timing into consideration. Cobb does have Stage 2 off the shelf maps that you can use for either 91 octane or 93 octane respectively and though they are better than the stock tune, I would still have at least an e-tune to tweak it specifically to your setup.

I am with @Batmobile_Engage regarding the intercooler. ETS, ProcessWest, Grimmspeed are some examples but they are all expensive. I would try a simple stage 2 setup using the stock top-mount first and see how you like it. Then up grade later. Just changing the top-mount does not require a tune so you can do it when ever you like.

Just for your info a stage 2 setup usually includes the stock air box and intake with a K&N drop in filter, A after market down pipe, a fuel pump and a full 3 inch exhaust system.

I also recommend a wide band AFR gauge especially if you plan on doing any tuning yourself.

 

[Batmobile_Engage]

Also, not to sound pessimistic here, but that Cobb downpipe you have, has a section in the throat that tapers to 2.5". This restricts flow, but isn't that much of a problem until you start shooting for much higher numbers. At some point, provided that you don't live in somewhere like the Democratic People's Republik of Komiefornia, you should at least consider swapping in a true 3" downpipe without a catalytic converter (your Cobb catback should be fine with this setup).

 

[Treyw147]

thanks for the responses guys. I'll start of by saying i live in Colorado, so 93 oct is not readily available. Especially since i get my gas on post. Oh, i am military by the way. I had no idea that the cobb down pipe wasn't a true 3'', thats really good to know. I think i will start off by getting it tuned by one of the shops that was provided in your link. After that, it should give me a good indication of exactly what i should do next. weather upgrade the turbo or keep it stock. Im not sure i want to upgrade the fuel pump just yet on a count that it is one of my dailies. So conserving fuel mileage would be in my best interest for now.

I have considered cutting the cat of awhile ago. Even though Colorado does not have emissions, theirs no telling where i might get stationed next. Also a friend of mine told me that cutting the cat off of the type of car, with the simple mods/maps that i have on it can cause the famous back fire flame out of the tail pipes. Though it is cool looking, I am not a teenager who is looking for props. I'm simply a family man who likes to go fast.

On a further note, which downpipes are true 3'' piping?

 

[HolyCrapItsFast]

Just FYI, A fuel pump has absolutely no effect on gas mileage or fuel consumption and does not require any kind of tuning so you can do it any time your heart desires. It merely delivers the required amount of fuel that your setup demands. The injectors are what meter the fuel so any fuel that is not going through the injectors will simply be returned to the tank. Essentially you could have a Dyson vacuum cleaner for your fuel pump and it won't make a difference to mileage

Since you have 2011 it is not so much an initial concern but the problem with 2007 and earlier STi's is the manufacturer provides a fuel pump that is adequate for stock setups only. Once you make modifications, you can easily run into a situation where not enough fuel is delivered. If you are considering any kind of power mod, the first thing you should be doing is fuel delivery. Realistically, only going through the tuning process can reveal if you actually need a fuel pump or not but it couldn't hurt to have one regardless. Since you have an AccessPort, you can monitor Injector Duty Cycle. This will reveal the fuel delivery status. If your Injector Duty Cycle approaches 95% at any time then you should consider a fuel pump.

Invidia, AVO, Nameless, Grimmspeed, HKS, Tomei are some down pipes worth considering and all are 3". I'm partial to Invidia myself for durability and quality. The flanges are super thick and cast stainless.

George

 

[War_Panda04]

i believe Invidia makes a good 3" downpipe. i currently have their high flow catted one on mine

 

[Batmobile_Engage]

I also like Invidia. I have a Cobb SS 3" catback and an Invidia catless, partially-divorced-wastegate downpipe.

@Treyw147
(A divorced or partially divorced downpipe basically means that there is a metal divider inside the bellmouth section of the downpipe that mates up to the turbo. The divider[1] separates the main turbine exhaust flow from the wastegate port exhaust flow. This reduces exhaust flow turbulence in the throat, which allows the turbo to spool faster and produce more stable boost numbers at WOT/peak boost. Most of these downpipes then reintroduce the wastegate exhaust flow back into the main turbine flow, 18-24" downstream from the turbo where it won't really cause any turbulence issues.[2])

[1]

[2] Shitty example photo, but you get the picture.

I think most agree that flow separation is a good idea. What do you think, George? @HolyCrapItsFast

*****Before I forget, I must mention. IF at all possible, try to choose a downpipe that has an extra exhaust bung already welded in place. That way, if you end up getting a Wideband AFR gauge/meter, you'll already have a bung to screw the extra O2 sensor into.

 

[HolyCrapItsFast]

I think most agree that flow separation is a good idea. What do you think, George? @HolyCrapItsFast

Honestly I have no real opinion. I do feel that a divorced down pipe does nothing for external waste gate setups though :tup: For internal I believe they have merit.

 

[Batmobile_Engage]

Honestly I have no real opinion. I do feel that a divorced down pipe does nothing for external waste gate setups though :tup: For internal I believe they have merit.

Of course. There's no point in a divorced downpipe if your turbo is externally gated. The turbulence in the throat of the downpipe at peak boost only occurs if the wastegate port is part of the hot side turbine housing. Plus, if you're running an external wastegate, dump that shit straight to the atmosphere. :lol:

 

[Grinder34]

thanks for the responses guys. I'll start of by saying i live in Colorado, so 93 oct is not readily available. Especially since i get my gas on post. Oh, i am military by the way.

.....

I have considered cutting the cat of awhile ago. Even though Colorado does not have emissions, theirs no telling where i might get stationed next. Also a friend of mine told me that cutting the cat off of the type of car, with the simple mods/maps that i have on it can cause the famous back fire flame out of the tail pipes. Though it is cool looking, I am not a teenager who is looking for props. I'm simply a family man who likes to go fast.

1) If you're on base, what about E85? Can you get that? E85 can be a game changer.

2) I don't think ANY states still do sniffers for new cars (I could be wrong?). But if you knock out the cat innards, and leave the visible bulge, you'll pass any visual inspection. Then you can almost certainly tune out any post-cat-o2-related codes. But then again, why? You're probably not really gaining much of anything by doing it, so I'd probably leave that cat as-is