2015 Subaru STI SF Airbox & SF Intake/Airbox Combo now available!!

The 2015 Subaru STI SF Airbox and Intake/Airbox Combo are now available from COBB Tuning!

2015 STI SF Airbox

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The SF Air Box adds the benefits of a cold air intake to the outstanding performance of the SF Intake. The factory inlet directs cold air from the front grill to the SF Airbox, which encloses the SF Intake. Hot engine bay air that robs horsepower is prevented from entering the intake system to provide consistent intake performance. This unique design also separates rainwater from the intake air, eliminating the water ingestion issues that plague in-fender cold air intakes. This intake airbox is constructed of 16 gauge aluminum, consisting of a one piece surround, directional lid, stainless steel hardware and all the necessary components for a seamless install with OEM quality fit and finish.

Additional Info: http://www.cobbtuning.com/Subaru-SF-Airbox-2015-STI-p/715150.htm

 

2015 STI SF Intake & SF Airbox Combo

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This intake and integrated airbox looks great and has the combined benefits of a short ram intake and a cold air intake without any of the negatives.

This system utilizes several unique features in an effort to maintain optimal flow for performance while minimizing turbulence that can cause engine management problems. From a custom conical cloth air-filter element, we use a CFD-designed velocity stack leading to an unique air flow straightener grid. This straightener grid is specifically designed to smooth the incoming air flow as it passes the Mass Air Flow sensor for precise readings. This eliminates the “dead spots” experienced by other aftermarket intakes due to turbulence. No other aftermarket Subaru intake system utilizes these critical design elements.

In order to provide a system that looks as good on the outside as the technical advancements happening on the inside, we utilize a one piece design constructed from a high temperature plastic composite. Not only does this save weight compared to the previous metal design, the plastic composite material offers much better heat rejection properties that help keep intake air temperatures cooler. In contrast, intake systems constructed using metal castings or piping can actually retain underhood heat and in turn heat the incoming air.

The SF Air Box adds the benefits of a cold air intake to the outstanding performance of the SF Intake. The factory inlet directs cold air from the front grill to the SF Air, which encloses the SF intake. Hot engine bay air that robs horsepower is prevented from entering the intake system. This unique design also separates rainwater from the intake air, eliminating the water ingestion issues that plague in-fender cold air intakes.

Calibrations – All aftermarket intakes for 08+ Subarus require tuning in order to ensure the MAF sensor reads properly and the engine operates within safe parameters. COBB Tuning has you covered with Off-The-Shelf Maps for the Accessport, making it as easy as install, flash and go! Head over to the Subaru Accessport Map Database to view the full selection of SF Intake Maps for your vehicle.

Additional Info: http://www.cobbtuning.com/Subaru-SF-Intake-SF-Airbox-2015-STI-p/715315.htm

As always, supporting Off The Shelf Maps can be found at COBBTuning.com.

Bucky Lasek’s “Subrina” STI Build

Bucky Lasek has been a customer of COBB Tuning for a number of years now.  A true gearhead at heart, he loves being behind the wheel and enjoys being able to blow off a bit of steam when necessary.  Being a driver for Subaru Rally Team USA, Subaru is obviously in his blood.  He recently paid our COBB Tuning SoCal shop a visit to bump up the power output of his 2012 STI.

Bucky’s goal with his 2012 STI was to show what the car is capable of with the budget of an average enthusiast in mind.  Simple is the name of the game here, every bolt-on part has a purpose.  The car is equipped with a coilover suspension kit, upgraded swaybars, and basic bolt-on performance pieces to increase airflow through the engine.  This is a car Bucky can take his kids to school in, enjoy a bit of spirited driving in the canyons outside of LA, or beat on at the road course.  He originally came in a few years ago to have the car custom tuned on the stock turbo utilizing the COBB Accessport.  The car made 321 hp and 364 ft/lb on a 50/50 blend of ACN91 and 100 octane fuel with an upgraded exhaust manifold, turboback exhaust, fuel pump, and intake.

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Recently, Bucky approached us looking to step up the power of his STI.  The car already had great low-end torque, he was simply looking to add more mid and high-end power to back up that torque.  After a consultation with the crew at COBB Tuning SoCal, a short list of modifications was established to reach Bucky’s power goal.

All of that would be tied together with custom tuning on three fuel types – 91 octane, 91/100 octane blend, and E85.  With the convenience of the Accessport, Bucky is able to switch between these maps in no time at all depending on the fuel in the tank.

When all said and done, Jon Hebbeln of COBB Tuning SoCal was able to squeeze out 431 hp and 445 ft/lb with the new setup on E85 fuel.  For the every day driving on ACN91 fuel, the car is making 362 hp and 378 ft/lb and the 50/50 blend of 91/100 octane is putting out 385 hp and 406 ft/lb.  As you can see, with the addition of just a few parts, the car has really waken up.  The use of E85 allows a tuner to be much more aggressive with timing and boost.

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2015 STI Development : Staged Power Package Evaluation

2015 Subaru STIAs you may know, one of our public commitments following the release of the new 2015 model year VA-series chassis code Subarus (2015+ WRX and STI) was to thoroughly explore each platform and quantify our findings whenever possible.  Because the 2015 STI retained a very similar mechanical configuration to the 2008-2014 STI (GR-series chassis code), many in the community have anticipated that hardware and tuning options would be identical to the current offerings.  The idea behind our testing was to discard any existing assumptions about how the 2015 STI may compare to its older brothers and make sure that we are providing hardware and tuning solutions that exceed expectations.

Two of the prevalent issues with the GR series WRX and STI have been a “Boost Creep” problem and a fuel system that is at or beyond capacity on cars that are equipped with a turboback exhaust, especially when combined with an upgraded free-flowing intake.  This topic was previously discussed here: Subaru Tuning : A Quick Look into Boost Creep.

The key item of significance here: Airflow increases must be met by increases in fuel flow – AFR is a ratio air against fuel, by definition, and thus they must increase proportionally with each other.  We’ve previously explored how adding an intake increases airflow on the 2015 STI in a previous article, available here: 2015 Subaru STI Development Update – COBB SF Intake Testing.

COBB Tuning's 2015 STI undergoing dyno testing a COBB Tuning Surgeline in Portland, OR
COBB Tuning’s 2015 STI undergoing dyno testing a COBB Tuning Surgeline in Portland, OR

Goal:  Analyze fuel system performance when attempting to tune for a COBB Turboback Exhaust and COBB SF Intake System on a 2015 STI.  Will the factory fuel system be adequate to support this setup?

Vehicle:  COBB Tuning R&D 2015 STI (#2).  ~900 miles on odometer.  92 octane pump gas.

Method:  In order to gather numerical data for analysis, we collected datalogs from the car under wide open throttle (WOT) dyno runs, in the following tune/hardware configurations:

  • Stock (S#); Stock
  • COBB v340 Stage1 93 OTS (S#); Stock
  • COBB v340 Stage2 93 OTS (S#); COBB Turboback Exhaust
  • COBB v340 Stage2+SF 93 OTS (Experimental) (S#); COBB Turboback Exhaust + COBB SF Intake System

Conditions:  45-48 degrees F, Sea Level elevation.  COBB Tuning Surgeline, Portland, OR.

Background:  In general, while performing aftermarket tuning, a fuel injector is considered to be at their flow limits once reaching ~95% Injector Duty Cycle (IDC).  Beyond this, the amount of “off” or non-driven time for the injectors between injection events is inadequate for allowing the electrical coil within the injectors to fully discharge.  With this, the beginning of the next injection event comes earlier than anticipated, as the injector is already partially charged when the ECU begins driving it for the next injection cycle, and the net result is a flow non-linearity (usually demonstrated as a brief rich dip in air-fuel ratio).  After passing roughly 105% IDC, even with this rich-leaning non-linearity, the total window for injection in terms of time is now simply too short, and an inadequate amount of fuel is delivered to maintained the desired air-fuel ratio, so air-fuel ratios begin to go lean of targets.

What does this mean?  Past ~95% IDC, we mechanically lose control over fueling and air-fuel ratio will not be on-target.  Dangerous lean conditions will result past ~105% IDC.

Things to keep in mind:  Air density is a critical factor.  We intentionally tested in Portland winter months, where temperatures are cool and atmospheric pressures are high.  At elevation and high ambient temps, the concerns mentioned above become reduced as air mass is reduced.  Keep in mind, however, that it was still in the mid 40’s during this testing.   Injector Duty Cycles could easily be 5-15% higher if the testing were completed in a much colder area around the United States, such as New England, which has seen a long period well below frozen this winter.

Results:  OK, time for the relevant stuff.  This chart shows the logged Injector Duty Cycle during a full-throttle dyno run for each of the aforementioned configurations.  We’ve added a red line showing the 95% threshold we would ideally like to stay below.

Graph of Injector Duty Cycle (Y-axis) against Engine Speed (X-axis) for each configuration
Graph of Injector Duty Cycle (Y-axis) against Engine Speed (X-axis) for each configuration

As we can see, the issue is already borderline on the completely stock vehicle.  Subaru targets an extremely rich air-fuel ratio and the 2015 STI has been observed to be the most powerful STI to date; one has to wonder why they have not upgraded the fuel system’s capacity to match this.

With tuning (Stage1), we see that peak values are similar to stock.  We are targeting a leaner AFR but using more boost/airflow to make more power, so overall total injector usage remains similar.

At Stage2, we’re really getting up there.  The fully upgraded post-turbo exhaust hardware facilitates more airflow and we use even more injector as a result.  No NASA scientists needed on this one!  However, while Injector Duty Cycle does definitively now exceed 95% for a good portion of the run, it stays around 100% peak.  We have lost control of fueling, but we probably are not going to induce lean conditions yet, meaning the engine should not be at any significant new risk.

Stage2+SF: Uh-oh!  Now that the intake side has been freed up, we’re using a LOT more injector.  With Injector Duty Cycles peaking around 107%, we can no longer be sure that there is enough fuel available to keep a ball-park safe air-fuel ratio, let alone precise control over it.

As mentioned earlier, this would only get worse as ambient temperatures go further downwards.  While mid-40’s is definitely cold for all of the Arizonians reading along, Michigan residents are likely nodding along in full agreement.  Much of the U.S. sees sustained temperatures well below 40 F during their colder periods of the year.

Summary:  So, where does this leave us?  In short, it means that we (COBB Tuning Subaru Experts) are not comfortable offering “Stage2+SF” as a released stage package for the 2015 STI.  We know this is likely to disappoint some and confuse others, especially since the package is still offered for the GR vehicles.   However, not all is lost.  Thanks to our partnership with Injector Dynamics, we are well-positioned to now offer OTS packages that include fueling system upgrades, which have typically been “custom tune only” territory for Subarus.  Be on the lookout for an upcoming COMPLETE Stage3 package for 2015 STI that includes fuel system solutions in addition to full turboback and intake hardware!

Accessport Updates: January 2015

In our quest for World Domination, we’ve pushed out two large updates for our Accessport product line.  The extremely versatile COBB Accesport now supports the 2015 Subaru WRX CVT and Porsche 996 Turbo/X50/GT2!

2015 WRX

Rounding out USDM Subaru DIT vehicle support, 2015 WRX CVT support is now LIVE for any SUB-004 Accessport!  All new orders shipped from cobbtuning.com will be ready to go out of the box, previously sold Accessports may require a firmware update using Accessport Manager.  All Subaru Accessports now feature our Auto On/Off feature!  This allows the Accessport to power on/off automatically with the vehicle!

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Further expanding vehicle support in the Porsche market, we are excited to announce the availability of the POR-004 Accessport, supporting the Porsche 996 Turbo/X50/GT2!!  Initially, these Accessports are available only through COBB Authorized Dealers and Protuners.

Contact your preferred dealer now to place your order!!

COBB R&D Update : January 2015

We’ve been hard at work on some new products and features due out in early 2015!

Here’s a quick peak at some of the exciting upcoming releases from the Subaru and Ford Expert Groups!!

2015 WRX Tuning Results : 344 WTQ / 313 WHP

2015 WRX_George_18_blog

We have enjoyed seeing all of the 2015 WRX custom tune results being posted around the ‘net and decided to jump in with our own after a bit of playing around with our car on the Austin R&D dyno today. While this combo of parts isn’t likely to be an pre-configured OTS “StageX” package that is available from us, we try to do as much hard parts testing as we can to make sure we have a good understanding of the cars. It’s important for us to have knowledge over how the car will react to common aftermarket upgrades. No records or anything crazy but this thing is definitely one quick WRX now!

We bolted up all of the airflow mods we have on-hand for the car and decided to see what she could do. A bit more time to continue refining the tune would have likely yielded even larger results, but I quickly “chickened out” after realizing how close we were to 350 wtq. :eek:  It is likely that the connecting rods will prove to be the long-term weak spot for modified FA20DIT cars, so we decided to call it an afternoon with our engine still intact for now :cool:

Engine/Power Modifications on our WRX consist of the following: COBB Tuning Accessport V3, COBB Tuning Turboback Exhaust (Catted), COBB Tuning SF Intake/Airbox (Prototype), TurnInConcepts TGV Delete Housings, Upgraded Aftermarket TMIC.

2015 WRX Dyno Chart

Results vs stock vehicle: +77 wtq (28.8%) , +62 whp (24.6%) 

At this point this car is now making a tad more torque and horsepower than a Stage2+Intake 2015 STI on the very same dyno — very impressive for a 2.0L with diminutive factory turbo. We are slowly beginning to really like these cars now as the uncorking process continues :)

Long term, this testing helped us identify some other areas of the factory ECU where we should focus our future reverse engineering (table/logic discovery) in order to provide the precise control and ease of tunability that the COBB Protuner network demands, even as the power numbers get crazier and crazier as new mods become available over time. We can’t wait to keep pushing this platform and seeing what kind of amazing results you guys achieve over time!

Thank you for your support during the DIT craze!

Cheers

The COBB Subaru Expert Group

2015 WRX Rev Hang

For 2015, Subaru introduced a completely overhauled WRX!  There are some awesome new changes, like direct injection,  and other changes many aren’t too thrilled about.  Subaru’s new “Rev Hang” logic seems to top the list of complaints.  Luckily though, COBB is hard at work coming up with a solution!

What is Rev Hang?

Typically, when you are in gear and revving high into the RPM range, pressing in the clutch would result in the RPMs quickly falling.  With Rev Hang, the RPM stays constant for a bit and slowly falls.

This isn’t necessarily a bad thing.  However, many car enthusiasts are purists and feel the only inputs the car should be considering, especially when it comes to throttle, come only from the driver.  We tend to agree!

Here’s a quick video of the Rev Hang “Fix” in action:

 

This does look subtle on video but if you own or have driven a 2015 WRX, you know how big a difference this will make!  Check out the latest v111 maps to try out the fix: https://cobb.app.box.com/2015-wrx-v111.  Stay tuned to our Website, Facebook Page, Twitter, Instagram, and Blog for the latest!

COBB at Subiefest 2014!

We’ll be heading out to Subiefest next weekend at Auto Club Speedway in Fontana, CA!

Make sure to come by the COBB booth to check out new products and enter in for your chance to win some awesome prizes!

COBB Socal will also be at Subiefest selling all of your favorite COBB parts!!

Subiefest 2014 Flyer 5 Version 3

2015 Subaru STI Development Update – COBB SF Intake Testing

So, you’ve probably seen some pretty cool early results from hardware swaps on the 2015 STI platform.  But, have you seen any actual data besides some basic dyno charts with really high smoothing?  Probably not. :) Lucky for you, we’re here to provide actual quantified data behind the madness.

Many people were initially disappointed that our first release only included Stage1 maps.  This was because we prefer to *thoroughly* test parts to find out what each modification will do so that we can be sure our Staged Package offerings have a definitive gain for your investment.  For example, here is a NASIOC thread showing some of the testing we did to compare power output when a downpipe is added to a 2015 STI: http://forums.nasioc.com/forums/showthread.php?t=2639122

For intakes, we decided that looking at only power wasn’t good enough.  An age-old claim in Subaru world is that the factory airbox is not restrictive with the stock turbo, and we wanted to see it for ourselves.  We put this to the test by measuring turbo inlet vacuum generated on the stock airbox and with a COBB Tuning SF Intake system fitted to the car.  Garrett refers to vacuum in the turbo inlet as “depression”:  “Any restriction (caused by the air filter or restrictive ducting) will result in a “depression,” or pressure loss, upstream of the compressor that needs to be accounted for when determining pressure ratio.” (http://www.turbobygarrett.com/turbobygarrett/pressure_ratio)

By comparing the depression created by the factory intake against an upgraded intake, we can actually “see” if we have removed a restriction or not.  If the depression is the same, well, all we’ve done is added a noise-maker to the car :)

To complete this test, we first gathered boost and depression data on the stock airbox using a stock-hardware 2015 STI (tuning only), first on wastegate boost pressures only, then at ~17.5psi peak via our Stage1 93 OTS map in “S#” mode.  Next, we gathered the same data on the COBB SF Intake, with no calibration changes other than for the different MAF curve required.

What did we find?  Results!  The stock airbox creates depression levels of a bit over 1psi on wastegate boost at redline, and well over 2psi on the Stage1 boost levels!  What does this mean?  Here in Austin, where the elevation is ~800 ft, the barometer was ~14.21psi for the testing day.  With the stock airbox at redline, the turbo was only being fed with approximately 12psi of pressure due to the depression.  For comparison, this would be the same as running the car at 5500 ft of elevation if there were no depression!

Here is the boost and depression (intake pressure) data for wastegate and for 17.5psi, shown in gauge pressure relative to ambient atmosphere:

Boost and Intake Pressure – Wastegate Spring Only

 

Boost and Intake Pressure – 17.5psi Setting

As you can see, thanks to the reduction in depression with the upgraded intake, boost is a bit higher on the wastegate.  At 17.5psi, we can see that spool has improved and high RPM boost is held out better on the same WGDC settings.  In each case, the depression created by the COBB SF Intake system is roughly half of the factory airbox.  What does this mean?  Simply put, we’ve reduced restriction in the turbo’s inlet path, as shown by the reduction in depression.

I also decided to take this data one step further, which is to calculate the turbocharger’s effective pressure ratio for each case.  One caveat is that we’re looking at post-IC pressures, not pre-IC, but because the intercooler has not changed at all between tests, it shouldn’t skew the results too greatly.

Here is the pressure ratio for each scenario (again, baro in Austin was ~14.21psi on testing day), calculated using Garrett’s methodology here: http://www.turbobygarrett.com/turbobygarrett/pressure_ratio

Pressure Ratio Comparison – Wastegate Spring Only

 

Pressure Ratio Comparison – 17.5psi

On wastegate boost pressures, we can see that there isn’t too drastic of a difference — perhaps a tenth of a point at very most.  However, at 17.5psi, we can see the COBB SF Intake really start to separate itself: pressure ratio is decreased by about two full tenths across the board after spool.  What does this mean?  The turbocharger compressor is now operating more efficiently, at least in terms of the demanded pressure output (boost) again the amount of pressure available at the input.

So, at the end of the day, here’s what power looks like between the two.  COBB SF Intake are the solid lines, stock airbox are the dashed lines:

Stage 1 vs Stage 1+SF Intake Dyno Comparison

Long story short?  On the 2015 STI, even in otherwise-stock configuration, the COBB SF Intake system (and others that have the same or better airflow capabilities) help the turbo breathe easier and in turn, make the same boost more efficiently or more boost at the same efficiency when compared to the stock airbox.

Thanks for reading along! Hopefully you found this data interesting and helpful. We plan to keep providing results like this as we dig in further on the 2015 STI and WRX, so stay tuned :)

Cheers,

The COBB Subaru Expert Group

Suspension – Yes, you should probably upgrade that too!

We can all sometimes get a little caught up in making power…and that’s great!  But what good is all of that power if you cant put it to the ground?

Check out our latest video for a little insight into what suspension modifications you can make to improve Contact, Comfort, and Control of your car.

Then, head on over to our website to check out what suspension parts we offer for your specific vehicle!

www.cobbtuning.com/suspension

www.cobbtuning.com/suspension