Boosting Weather Is Back

Fall is officially just a few days away from the time of this article, and you know what that means…

 

 

That’s right. It’s time to dust off those Han Solo boots, get them girly curls, and punkin spice the sh** out of your existence until Halloween hits midnight, and then it’s Christmas. More importantly, it’s boost season. For those with turbocharged vehicles such as the Subaru WRX, STI, or even the A90 Supra what does this mean? This means that the colder weather obviously creates cooler intake charge temperatures make from the intercooler and into your intake manifold. Almost like giving your engine a 2-shot of NOS. Whether you believe in climate change or not, you cannot deny the fact that we have been hitting record high summers for many parts across the globe, and this has created heat-soaking issues that are especially prevalent for Subarus as the top mount intercooler is prone to heat soaking because it sits above the turbocharger that creates the hottest temperatures in the engine bay.

The first cool day in September, you may notice that under boost, your vehicle may have a little more ‘pep in the step’. As mentioned earlier, that is because through your factory, or aftermarket cold air intake, the turbocharger is inhaling cooler temps to compress into the intercooler which will further chill those temperatures, just before pushing that air through the intake manifold. This is why larger front mount intercooler cores are required for vehicles that make substantial amounts of horsepower because otherwise in the height of summertime, triple-digit days put a limit on all your modifications. Yes, all your modifications combined with all of the supporting mods and a good tune will make more power no matter what, but during those triple-digit days, the power will hit a ceiling as the intercooler can only lower those charge temps to a certain degree, and you are not hitting max efficiency. Because of these reasons, this is why there is so much emphasis involved with cooling in the aftermarket performance spectrum as a whole.

Whether if you are turbocharged or naturally aspirated, Cold air intakes do just that, try to draw-in cooler air for the intake manifold. Now although those engine bay temps will be very hot, manufacturers of cold air intakes do the best they can from a design standpoint to bring those breathing temps as close to an ambient temperature as possible by providing heat shields, filter boxes, or designing the intake pipe closer to an opening where the filter itself is exposed to cooler air. Regardless, an aftermarket intake will always make the turbocharger spool faster because it can breathe in a larger volume of air when compared to a highly restrictive paper element panel filter that is supplied with OEM intake boxes.

That being said, for those of you looking to make more power in general no matter what you drive, a performance intake system will always be a staple in the “basic performance upgrades” starter pack. Just look at these few examples objectively and look at the design, it all makes sense.

COBB Tuning SF Intake System 2015-2021 WRX

 

GrimmSpeed Cold Air Intake 2002-2007 WRX/STI

 

 

 

HKS Cold Air Full Intake Kit 2020-2024 A90 Supra

 

 

INTERCOOLER

You can see how the OEM top mount intercooler sits on top of the motor, but more importantly during punkin spice season, it’s the cooler temps entering the hood scoop that make the big difference.

 

Now the reason why the term heat soak and Subaru WRX go hand and hand is because as mentioned earlier, the factory top mount intercooler rests on top of the engine. Now “hot side” pipe connects to the turbocharger which is underneath the intercooler while the other port of the intercooler connects directly to the throttle body. It’s actually a great design as the route of travel is very minimal, and the result is a faster turbo response. But because by design, the OEM intercooler is so small, and because the exhaust housing of the turbocharger is just about directly beneath the intercooler, the heat consumes the intercooler.

The fix is to either get a thicker top mount intercooler core, in which there have been great advancements in design by the likes of GrimmSpeed, Process West, PERRIN, COBB, etc. You can get a larger intercooler core that will fit in the stock location, and many aftermarket examples will include their own shrouds to direct the air to hit the direct top surface of the intercooler. Since most WRX and STI models on the road will remain under 400 HP, a thicker top mount should suffice against heat soak and the installation will be much easier. However, you also have the front mount intercooler option which will provide you with maximum cooling efficiency, and front mount intercooler setups will support higher horsepower levels for those of you with a built forged block and a larger turbocharger setup.

Let’s look at both options, and here are some great examples that are offered on our website:

 

 

 

GrimmSpeed Top Mount Intercooler Kit w/Splitter 2015-2018 WRX

 

PERRIN Top Mount Intercooler 2015-2021 WRX

 

COBB Tuning Front Mount Intercooler Kit 2002-2007 WRX/STI

 

 

 

 

WITH COLDER TEMPS AND MORE POWER, MAKE SURE YOUR ENGINE IS MAINTAINED

Now the majority of modded Subarus will have a COBB Accessport or perhaps a flash tune to smooth out the RPM band for those of you with a cold air intake, catted downpipe, and a cat-back exhaust. In fact, you must have a tune to run these basic mods because these mods are going to add more horsepower. Without a tune as mentioned in many blogs about upgrades, your engine won’t boost right and will buckle up top at the RPM range. This is because your boost trims are going beyond your ECUs OEM settings, and the fuel delivery is also maxed out.

With colder weather, the mods you should be on top of is the fuel system because with that extra 10ish horsepower depending on where you live, your fuel pump will be at its threshold especially if you have an OEM fuel pump. With basic mods, such as an intake and cat-back, it is smart to at the very least, have an upgraded fuel pump. If you have a catted downpipe that can produce more power with a proper tune, you will need a slightly larger injector to avoid a lean condition.

But with cooler weather with variables such as the altitude depending on where you live, you can hit fuel cut. Fuel cut is where under load, your Subaru’s engine doesn’t have enough fuel to combust at the top of the RPM range, and your engine will severely misfire.  And while driving, it physically feels like the car is hitting something. If you are hitting fuel cut, stay off the boost immediately until you have upgraded your fuel pump because you are creating a lean condition. A lean condition means that you don’t have enough fuel in the cylinder to keep your pistons at a proper temp during combustion, and this is where you melt a hole on the top of the piston. Running lean means that you are not getting enough fuel in the cylinder during load, and the cylinder will get too hot. Running rich means that you are getting too much fuel in the cylinder, and your spark plugs cannot burn the fuel fast enough. The risk with running rich is that too much fuel can get into the cylinders, and the fuel can leak passed the piston rings and into your oil which can cause contamination.

Technicalities aside, because cooler weather increases boost by a few psi which increases the horsepower, make sure that your fuel pump is at least upgraded. Here are a few options:

 

DeatschWerks DW65C Series Fuel Pump w/Install Kit 2008-2014 WRX / 2008-2021 STI

 

DeatschWerks DW300 Series Fuel Pump w/Install Kit 2002-2007 Subaru WRX/STI

 

 

 

AEM Electronics 340 LPH E85 Hi Flow In-Tank Fuel Pump (Universal)

 

 

MAKE SURE YOUR PREVENTATIVE MAINTENANCE IS UP TO DATE

From the beginning of September, to just about New Year’s Eve, it feels like this giant proverbial slide. September is at the top where were start dusting off our sweaters, then before you know it depending on where you live, we are scraping ice off the windshields wondering what happened to last month when we had the AC on? Point being, because it’s still September at the time of this article, now is the time to make sure that anything that needs attention to your Subaru needs to be done now. Especially if you are mechanically inclined enough to do all of your maintenance, and maybe you don’t have a garage. Nothing sucks more than trying to replace brake pads when you can’t feel your fingers, and you’re sitting on a cold driveway with ice on it. The maintenance tasks that need to be addressed should be done now, while the weather is still relatively good for the next month. Because if you live in an area that experiences harsh winters, and you don’t have a garage, you are not doing anything between mid-November until the beginning of March. For now, let’s look at some basic items.

 

OIL CHANGE KITS

Having good oil is imperative to your engine’s survival. In the summer you need those fully synthetic formulas to protect your internals during extreme heat, but when the temps get cooler, you especially need to make sure that your oil change intervals are always on time. Because the cooler it gets, the thicker your oil will be upon startup. It takes a minute for your oil temps to get up to optimal protection levels, and because of this reason, this is why you should never rev your engine on cold oil.  Also, you should especially not boost your engine when it has not had the chance to get up to operating temps. The reason you need to make sure your oil is always in good standing is because the dirtier it gets, the thicker it gets. And it will take longer for your engine to warm up and be protected.

 

Oil Change Kit w/Motul 0W20, OEM Filter, and Washer 2022-2024 WRX

 

Oil Change Kit w/Motul 5W30, OEM Filter, and Washer 2002-2014 WRX / 2004-2021 STI

 

 

CHECK YOUR WINDSHIELD WIPERS

Now that summer has ended, think about those peak temp days in July where you didn’t see much precipitation, and the rubber wiper blades just sizzled like bacon on the windshield. Because that’s kind of what it does minus the actual frying part. The rubber will wave, and you will have the most annoying streaks on your windshield when it rains. And just so you know, it only gets worse with the snow and salt. Figure out what windshield size you need and get them replaced.

 

PIAA Super Silicone Wiper Blade 24in

 

PIAA Si-Tech Silicone Flat Wiper Blade 26in

 

 

ACCESSORY BELTS

That squeaky belt is the result of most of the times a loose belt, but for many of the times, the belt is so old and dry that it slips on the pulley until the friction causes enough heat for the belt to grab. But it would certainly suck if you’ve got a long commute home, and you lost a belt that powers your steering or alternator. Make sure you check out the overall welfare of your accessory belt to make sure that there are no cracks, or missing sections of groove. And you damned better not be over the service mileage on your timing belt, otherwise if that snaps your motor needs to come out.

 

Gates Micro V-Belt 2002-2021 WRX/STI

 

TAKE THE TIME TO INSPECT YOUR COOLANT HOSES

When we get to those chilly temps entering December, cold temperatures cause coolant lines to leak especially if they are old. Because coolant hoses experience endless heat cycles as the car runs, the rubber will get harder. As the rubber gets harder it can crack. During the summer when we have extreme temps, the rubber expands under pressure. Colder temps will harden the rubber. The best remedy is to upgrade to nicer multi-layer silicone example which will last for the lonest time.

 

Torque Solution Silicone Radiator Hose Kit 2002-2007 WRX/STI

 

GrimmSpeed Radiator Hose Kit 2008-2014 WRX/STI

 

Now listen. This article is about how punkin spice weather and how cooler temps will increase boost and the power to a degree. But then we talk about how you should take advantage of our last relatively warm days of the year, and make sure that you’re prepared for colder temps. We will circle back to this issue in a few months when we take a deeper dive into winter tires, and how you really need to make sure you’re prepared for the winter. For now, stay safe, and stay maintained.