Category Archives: Subaru

2015+ Subaru WRX Top Mount Intercooler: Performance Testing

Dyno testing and long-term road testing are where all of this theory meets reality when it comes to the Subaru WRX Top Mount Intercooler. Knowing that the same application of these design techniques resulted in intercoolers that work extremely well for the 04-17 STI and 02-14 WRX, we were confident in our chosen configuration. Our goal was to once again, produce an intercooler that offered excellent cooling capacity without a massive pressure drop. We tested the OEM TMIC, GrimmSpeed TMIC and a leading competitor TMIC in a back to back to back comparison that consisted of driving while everything reached a steady state operating temperature and then three consecutive pulls to redline. The car used in this testing is a GrimmSpeed Stage 2 car on 93oct and was equipped with the same charge pipe for all pulls. Ambient temperatures were around 65F all day. The GrimmSpeed TMIC tested was not thermal dispersant coated.

The chart below shows TMIC efficiency test results. Efficiency is calculated based on the measured inlet and outlet temperatures of the intercooler compared to ambient. If the outlet were to exactly equal to ambient temperature, then efficiency would equal 100%. This isn’t possible, so we strive to get as close as possible. As you can see, the GrimmSpeed and competitor intercoolers outperform the OEM intercooler handily.

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The chart below is much less important, but shows the raw temperature data, to give you an idea of how much better performing the GrimmSpeed is compared the OEM TMIC.

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The chart below shows the pressure differential between the inlet and outlet of each intercooler. The higher the pressure drop, the more restriction the TMIC causes. This restriction forces the turbo to work harder to build the same amount of boost (which increases heat and is counter-productive), so we want to get keep it as low as possible without sacrificing cooling. You see the the OEM intercooler has the lowest pressure drop, followed by the GrimmSpeed and then the competitor.

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One interesting thing that we found is that during the second and third pull, when the car is transitioning from heavy vacuum to full boost, the GrimmSpeed and OEM intercoolers both spooled measurably faster than the competitor TMIC. The GrimmSpeed subaru wrx top mount intercooler has a larger overall volume, so that isn’t the cause. We’re going to continue experimenting to determine the exact reason for this, but it’s likely to be a result of the higher pressure drop and the way that air flows through the intercooler.

The bottom line is that both the GrimmSpeed and competitor unit offer a very nice upgrade from the OEM TMIC as far as efficiency goes. However the GrimmSpeed unit provides a lower pressure drop, and a substantially easier installation. If you have any questions regarding performance or our testing, please don’t hesitate to be in touch with us via phone or email.

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Introduction: 2015 Subaru WRX 3-Port Boost Control Solenoid

If you’ve been in the Subaru game for long, you’re probably well aware that a 3-port Boost Control Solenoid (BCS) is considered my most to be a ‘must have’ improvement before having your car tuned. GrimmSpeed has become the trusted brand in the BCS market, with tens of thousands of solenoids in operation today across the globe.

The 2015 WRX offers a unique change of pace, as the factory 2-port solenoid is mounted directly to the plastic turbo inlet and interfaces with an o-ringed feature, rather than a vacuum hose. With expertise in designing machined parts and a tried and true boost control solenoid, we were excited to dig in and create a solution with an already proven pedigree of high performance and quality.

GrimmSpeed 2015 WRX BCS

GrimmSpeed 3-port BCS 2015 WRX

GrimmSpeed 2015 WRX Solenoid

Enter the GrimmSpeed 2015 Subaru WRX 3-Port Boost Control Solenoid, the first and only of it’s kind.

We began by recreating the factory turbo inlet and solenoid in CAD to ensure a perfectly fitting system. From there, we designed a beautifully fitting machined adapter that would recreate the o-ring sealing feature that the factory solenoid uses. This bracket features 1/8 NPT threads so that both barbed fittings (included) and AN fittings can be used interchangeably, for use with the GrimmSpeed BCS, Manual Boost Controller, or other boost control solutions.

A small mounting bracket secures the solenoid to the machined adapter, to create a compact system, while still allowing those interested in running other boost control solutions the flexibility to do so. Mounting the solenoid directly in place of the stock solenoid allows for vacuum hoses of similar length and a shorter wiring harness. We contemplated the option to make a fully integrated solenoid, but decided that creating an adapter and mounting solution allowed people to use a solenoid that’s already been heavily tested and that tuners are familiar with. One possible change between now and production is to integrate the BCS mounting feature into the adapter. Cost and complexity will determine if that’s feasible shortly.

GrimmSpeed 2015 WRX BCS

2015 Subaru WRX Boost Control Solenoid

2015 wrx boost controller

Lastly, we worked to identify the exact electrical connector used on the stock solenoid so that the GrimmSpeed solution would be a true plug and play (differs slightly from the connector pictured). After that, we went ahead and built prototype and pre-production units.

2015 wrx boost control solenoid

As a brief overview of the advantages of a 3-port boost control system vs. the factory 2-port system, the 3-port systems works by interrupting the boost signal traveling from the turbo to the wastegate. That boost is redirected back into the turbo inlet (post-MAF sensor) and re-ingested by the turbo. The factory configuration simply ‘bleeds’ the signal from between the turbo and wastegate which creates a system that is a bit less complex, but reacts more slowly and with less precision.

We’re currently finalizing the detailed design and moving into production. As soon as we have an estimated release date (expected 2-3wks), we’ll begin accepting pre-orders at a discounted group buy price. We’ll start a different thread for that when the times comes, so for now, let’s keep this discussion technical.

The next step is to get a small initial batch of solenoids into the hands of your favorite local tuners. If you’re a tuner yourself or you’d like to nominate a tuner for receipt of a prototype unit, please comment below and we’ll add you to the list. From this list, we’ll select testers based on experience and geographic location.

Top Mount Intercooler Test Results – Part 1: OEM vs. GrimmSpeed

The moment many of you have been waiting for – top mount intercooler test results! In testing and developing a heat exchanger, there are countless bits of data to collect and analyze in order to facilitate the decision making process, but when it comes to evaluating the final product, performance can be quantified with relative simplicity. Everything boils down to temperature and restriction. The intercoolers primary duty is to lower and control the temperature of the hot charge air leaving the turbo and running through the intercooler. This is the first test that we performed on both the stock unit and the GrimmSpeed unit.We setup this test to simulate a real world scenario that’s typically demanding of an intercooler. The test vehicle is a 2012 WRX with a GrimmSpeed downpipe, boost control solenoid, prototype intake and tuning. On a closed course, we accelerated in 3rd gear from 3000rpm to redline repeatedly, with 5-8sec between runs. Temperature was logged via k-type thermocouples between the turbo and the intercooler and between the intercooler and the throttle body on both units. Ambient temperature here in Minnesota for both tests was between 20 and 22 degrees F.The results above speak for themselves, but here’s a breakdown. The phase differences between the runs are a result of how quickly we could safely get the car back down to speed for another run, but the important thing to notice is the magnitude of the temperature fluctuations. Predictably, both intercoolers were seeing similar Pre-IC temperatures on each run (180-190F peak), but while the GrimmSpeed TMIC kept Post-IC temperatures between 30-40F the entire time, the OEM TMIC fluctuated between 35-75F. This is the kind of consistent cooling that you should expect from a high quality TMIC and is a function of the geometry and design of the bar and plate core. Our high density core has a massive heat transfer surface area but maintains a large enough cross-sectional flow area that there’s no added restriction.

What’s Next – Pressure Drop, Aftermarket TMICs and Warm Weather Testing

The second part of our final testing will be to measure the pressure drop across each intercooler to demonstrate that the increased cooling performance comes with no sacrifice in flow rates. We’ll also run the same tests with a couple of other aftermarket TMICs. You can expect to see these results in the coming week. Lastly, in the spring, we’ll complete all of this testing again in warmer weather to show that the same effectiveness can be expected, regardless of ambient temperature. We’ll also try to find it’s limits with our 600whp STI.

Casting Intercooler End Tanks – A Day at the Pattern Shop!

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The photo above shows the machining of the TMIC outlet end tank master. The Bottom received a finishing pass and then the part was flipped so that the top could be roughed out. When all is done, this will be a flawless part. Now that the master parts for both end tanks have been completed, we’ll make a cast iron match plate from each of them. You probably noticed that it looks a lot like they’re being machined from wood and that’s because they are! These master parts will only be used a single time – to cast the real molds from, so a heavier duty material only costs more and takes longer, with no added value.

Interesting Note: The master that you see here is not dimensionally identical to our final part – it’s actually larger. Based on the foundry’s preferences, standard shrink allowances and the geometry of the model, the pattern makers job is to determine how much the cast aluminum part will shrink/contract during solidification. An easy way to cut cost, especially if you’re casting overseas, is to skip this step. Ever had an application-specific intercooler that didn’t fit quite right? There’s a decent chance that uncontrolled shrinkage was at least partially to blame.

For those unfamiliar with high end casting processes, creating the tooling and molds is the giant hurdle standing between your design in CAD and real parts. With properly designed and manufactured tooling, casting and machining the parts is relatively straight forward. One of the many benefits of casting right here in Minnesota is that we’re able to sit down with everybody involved and work through potential issues to mitigate the risk of trouble during production almost entirely. That means lower production cost for us and lower pricing for you!

GrimmSpeed Downpipe – Frequently Asked Questions

grimmspeed wrx downpipe

There’s are certain questions that we typically get from customers, regardless of the product being discussed. Instead of making you call or email for an answer, we thought we’d address a few of the heavy hitters right here so that the information is available to you 24/7.

Question: I’m planning on going Stage 2 with my car, do I really need an aftermarket downpipe to run higher boost and make more power?

Answer: Yes! The purpose of an aftermarket subaru downpipe is to remove restriction from your exhaust system. In the stock downpipe, that restriction comes in a three different forms. The first and most important is that the factory downpipe contains highly restrictive catalytic converters. Aftermarket downpipes generally either remove the catalytic converter all together or replace it with a much higher flowing unit. GrimmSpeed offers options for both. The second restriction is a result of the design of the turbine outlet flange. The OEM flange is a flat plate, obstructing exhaust flow from the IWG and forcing it to merge with exhaust from the turbine immediately. As soon as you’ve seen one, you’ll know what I mean. The third is in diameter. Stock downpipes use a smaller diameter tubing than most aftermarket downpipes. If the purpose is to remove restriction, the reason for larger tubing is clear. Even a small increase in internal diameter has a large impact on the total flow area of the tube.

grimmspeed subaru downpipe engineering

Question: Ok, so I know I need an aftermarket downpipe. There are a bunch of different styles. Do I want bellmouth or divorced?

Answer: This is where things get a little bit tricky, because you’ll get different answers depending on a person’s personal opinion regarding the proper design of a subaru downpipe. It’s important that you understand the pros and cons of each and make an educated decision for yourself. To be clear, both will do what you want, which is to unlock some serious power potential, but there are differences that can facilitate more efficient tuning and better boost control that are equally important. The reason that we’ve gone with the divorced design, despite the increased cost and complexity, is that we believe that it’s the best, plain and simple.

Imagine that your downpipe is a freeway, your turbo is a tunnel and your internal wastegate is traffic trying to enter the freeway. On a typical freeway, a car would use an on-ramp to get up to a proper speed and direction before merging with traffic in a controlled manner. That is exactly what a divorced subaru downpipe, like the GrimmSpeed unit, facilitates. Our divorced tube is the perfect length for the exhaust gases from your IWG to merge with the rest of your exhaust with minimal turbulence. Any shorter, and the exhaust from your turbine is still recovering from leaving the turbo, expanding into a larger tube and making a turn down towards the ground. Any longer and you’re simply adding unnecessary cost, material, weight and complexity to the assembly. Now, imagine that the traffic entering the freeway simply enters from a stop sign. We’ve all had to make that nasty right-hand turn during rush hour, don’t make your exhaust do the same. Good, predictable exhaust flow for your internal wastegate will ensure that you are also able to create good, predictable boost control.

grimmspeed sti downpipe faro arm

Question: I have X downpipe right now and i didn’t have any trouble installing it, but I just can’t get rid of my exhaust leaks now.

Answer: This is something that we hear very often. Persistent exhaust leaks of this kind often come from flanges that are severely warped or from parts that don’t fit properly. Creating exhaust components that fit perfectly is more complex than most people (and other manufacturers, it seems) realize. Designing a part that installs easily is one thing. Engineering a part that installs easily, has appropriate clearances from other components and has nice, relatively flat flanges that are are at exactly the right angle to create a perfect seal is a bit more difficult.

Here’s where GrimmSpeed’s engineering process emerges miles ahead. Other manufacturers create their welding fixtures from an OEM downpipe to match it exactly. Sounds great, right? Wrong. We’ve been engineering top of the line exhaust components for a while now and we’re going to let you in on a little secret – Subaru isn’t perfect. In the design of this downpipe, we used our FARO Arm to 3D scan a handful of OEM downpipes and saw that from pipe to pipe, there was a significant amount of variation. We bring all of this data in CAD, overlay the scans, and then find the average of each flange location. We then design our pipe and build our fixtures to that average, instead of a single downpipe. This ensures that our tolerance range is at least as tight as the OEM, with no GrimmSpeed downpipe ever fitting worse than an OEM part. On top of that, we also use our FARO Arm to 3D scan the areas of each test vehicle affected by the downpipe. This ensures that we have proper clearances for the firewall, O2 sensors, transmission bracket, subframe and so on.

Question: So what sets the GrimmSpeed Subaru Downpipe apart from other downpipes that get decent reviews but are a little bit less expensive?

Answer: This is where you’ll have to use the information that we’ve shared to make an educated decision for yourself! If you’ve made it this far, you already understand the care that we take in our design and manufacturing processes. Now, we’ll overlook fitment and design and consider just build quality. All of our materials are top-quality, Made in the USA stuff. Aside from the obvious benefits of supporting local and domestic business, this means that we know exactly what we’re using to build these downpipes. All “Stainless Steel” downpipes are not created equal. Our 3″, 16ga tubing is beefy and our 1/2″ 304 stainless flanges are the thickest and flattest around. Thick flanges help us avoid warping during the welding process and ensure a fantastic seal to your turbo.

We periodically check our fixtures for accuracy using our 3D scanning equipment, to ensure that over time, it hasn’t pushed or pulled from the heat cycling. Each downpipe is welded by hand just feet (literally) from where they were designed and developed. Robotic welding looks great, but in an application like this, nothing can replace the skilled hand of a true craftsman. This type of welding requires that changes be made on the fly to ensure not only a cosmetically excellent weld, but more importantly, a structurally flawless one.

grimmspeed exhaust welding tig

The bottom line is that we’re all Subaru enthusiasts here. We get it. We’ve all had the ‘budget’ downpipes at some point and while some of us have had fine experiences with them, others of us have not. We take pride in developing and manufacturing products that we know won’t let you down in 5 days, 5 months or 5 years from now. A GrimmSpeed downpipe will outlast your car and we stand behind each one that leaves the shop 100%.

Need help with which GrimmSpeed Subaru Downpipe will work best for you? Check out the links below for more information on each fitment.

http://www.grimmspeed.com/downpipe-02-07-wrx-sti-fxt/

http://www.grimmspeed.com/downpipe-catted-02-07-wrx-sti-fxt/

http://www.grimmspeed.com/downpipe-08-wrx-sti-fxt-lgt/

http://www.grimmspeed.com/downpipe-catted-08-wrx-sti-fxt-lgt/

Product Release – GrimmSpeed Alternator Cover

We’ve done it again! We know that there are a lot of options out there for Subaru alternator covers, so when we decided that it would be fun to put the GrimmSpeed spin on it, we knew that we needed to come up with something that had all the characteristics of a great GrimmSpeed products (quality, craftsmanship, fitment, style) but that also had a unique look. For this, we looked to the Subaru engine bay for inspiration.

grimmspeed alternator cover

Drawing from the asymmetrical features in the engine bay, the horizontal lines on the Top Mount Intercooler and the design of the GrimmSpeed Tool Tray Radiator Shroud, we created something pretty neat. It all started with the use of our FARO Arm, to 3D scan the OEM alternator covers as well as the factory engine bays.

grimmspeed alternator cover engineering faro armWhat we ended up with was a unique shape that provided protection from the accessory belts as well as added a bit of style to what is typically an ugly, cluttered are of the engine bay. Machined and anodized mounting hardware provide a clean, safe and secure method of keeping the cover in place and brushed stainless steel, red, black and silver powdercoated finishes provide options for just about everyone, whether you want sleek and subtle or a splash of color.

grimmspeed alternator coverAs always, feel free to contact us with any questions or to order your own!

– Matt