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.

tmic-fa20dit-results-1.jpg

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.

tmic-fa20dit-results-3.jpg

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.

Take me to the product listing!

Winter Mode – Rally Armor UR Mud Flaps

It’s not very often that we go out of our way to give a tip of the hat to another manufacturer’s product, but from time to time, there’s a product or service that we feel is deserving of our praise. This week, that product is from Rally Armor and it’s their model-specific urethane mud flap kits. At GrimmSpeed, we pride ourselves not only on engineering top-notch products, but also on creating an experience for the user that is second to none and that’s exactly what Rally Armor has done with these kits.

RA2

Here in Minnesota, it’s no secret that our winter months can be devastating to a car. The roads are frequently covered in snow, slush, ice or some mixture of the three and in all of those cases, there’s plenty of salt. The body shape of most Subarus is such that the front wheels, even traveling straight down the road, anything and everything at the side of the car. This leaves a nasty mess of salt across most of the car, making it look filthy and harder to clean. The best part, thought, is that they also seem to prevent the formation of large ice chunks in and behind your wheel wells, which can cause serious damage if you don’t kick them off before they freeze solid (and make a serious mess on your garage floor).

‘Winter Mode’ for most means a set of snow tires and fresh wiper blades. For most of the GrimmSpeed team, it also means mud flaps. Whether you appreciate the aesthetic or not, they make an excellently functional addition to a car that sees harsh winters, gravel, mud, etc.

RA3

Knowing that I wanted to protect my 2015 WRX as well as I could, I went ahead and ordered the black urethane kit with grey logo. They arrived quickly and were packaged very well. We take a lot of care in our packaging at GrimmSpeed and it’s easy to see that the folks at Rally Armos do the same, complete with a packaged by sticker just inside the box. Each component was nicely protected by plastic, paper or both and printed instructions were included.

RA4

Installation on the floor of the shop took 30min or so. No fancy tools, no lift, no previous experience with this kit. The brackets make perfect sense and install easily and securely. I especially appreciated how there was no modification to factory parts required. The included hardware replaced a couple of the factory clips, so I just put those in the hardware bag, labeled it and tucked it into the bottom of my toolbox. The mud flaps themselves are thick and durable, contoured perfectly for the application and feature slotted mounting holes for adjustment based on preference and precise bracket location.

RA5

In closing, I should probably note that we don’t sell Rally Armor products, nor do we have any sort of vested interest in their success. We’re simply passing along what we think is a functional and inexpensive product that meets a certain need perfectly. I’m very much a DIY person myself, and 6yrs ago, I may have attempted to hack together my own kit with cutting boards or some other nonsense, but for how quick and easy these were to install and the quality of the components, this kit is an absolute no-brainer!

RA1

If you’d like to see us review other products in a similar fashion, let us know! Cheers!

The Gift of GrimmSpeed – 2015 GrimmSpeed Gift Guide

Finding a holiday gift for the car guy or girl in your life is sometimes easier said than done. If they’re anything like us, then their automotive wish list is endless and ever-changing. Here at GrimmSpeed we hope to make things a bit easier by walking you through any product-related questions you might have, with some expert advice along the way. Give The Gift of GrimmSpeed this season and don’t hesitate to call or email us so we can help you make sure your favorite Subaru enthusiast gets exactly what they want this holiday season.

Gifts under $50

  • GrimmSpeed Apparel and Swag – A t-shirt, fitted hat, keychain or pair of license plate frames would make an excellent gift or stocking stuffer for the Subaru fan in your life!
  • Exhaust Gaskets – These might not look like fun to you, but to a Subaru owner, high quality exhaust gaskets are essential, especially if they’ll be installing new exhaust components this winter!
  • Bounty Hunter Sponsorship Kit – Challenge him or her to take part in the GrimmSpeed Bounty Program. The kit includes a shirt, sticker pack and registration to compete in fun challenges to win GrimmSpeed store credit!

Gifts $50 – 100

  • License Plate Relocation Kit – This is one of our most popular gifted products! Moves your front license plate to a less prominent location and eliminates the need for holes in your bumper.
  • Alternator Cover – An excellent GrimmSpeed-branded ‘dress up’ item that typically replaces the less attractive factory cover. Available in red, black or stainless steel.
  • Electronic Boost Control Solenoid – This is another very popular gift! Although most enthusiasts already own one, if your Subaru/Mitsubishi/Mazdaspeed nut is planning on getting tuned anytime soon, it’s a must-have!

Gifts $150 – 400

  • Catless Up-Pipe – An excellent way to free up pre-turbo exhaust flow and remove the restrictive factory cat. Also available with an external wastegate option – be sure to get the correct one!
  • Air Intake System – This seems to be at the top of everybody’s list this year. An upgraded intake system reduces restriction and allows for more power to be made during tuning. It also enhances the sound of the vehicle.
  • Air Oil Separator – Another very popular gift, available in red, blue and black. Be sure to check on which fitment is needed!

Gifts $400 and up

  • Downpipe/J-Pipe – This is the starting point for an upgraded exhaust system and is the piece that generates the greatest performance gains. Available with a number of options, you may need a couple of hints on this one!
  • Top Mount Intercooler – For that very special person in your life, a GrimmSpeed Intercooler is the cream of the crop where intercoolers are concerned. Rated to high horsepower figures, it’s an excellent fit for nearly all applications.
  • GrimmSpeed Power Packages – Available with a wide range of options, GrimmSpeed Power Packages offer a fully engineered system of modifications, designed to enhance the performance of your vehicle to a number of different degrees. A PERFECT starting point for a new enthusiast.

If you have any questions about items that are on the GrimmSpeed Gift Guide or our website, please contact us directly at sales@grimmspeed.com!

Boxerfest 2015 Recap – FedEx Field – Landover, MD

Whenever family, friends or acquaintances ask me what I do for work, I struggle to accurately explain to them just how unique and passionate our community of enthusiasts, manufacturers, shops and retailers is. They’re stunned to learn that there are enough people modifying their Subarus to support even a single person, let alone an entire industry of people developing, manufacturing, selling and installing parts. I’m sure this isn’t a uncommon conversation for people in the industry and even recall answering similarly themed questions when I was just an enthusiast myself from people that don’t ‘get it’.

If you don’t know what ‘get it’ means, you don’t ‘get it’. Keep reading.

IAG Performance TR-42 on the autocross course!

The GrimmSpeed team spent last weekend just outside of Washington DC for the second annual Boxerfest event at FedEx Field in Landover, MD. Boxerfest is one of four national events, organized by our friends at SubieEvents, that caters exclusively to the Subaru community. Manufacturers and vendors from across the country travel to take part in the festivities, meet their customers, display products and enjoy the sights and sounds that thousands of Subaru enthusiasts provide. Yes, thousands. In just it’s second year, Boxerfest 2015 attracted 2700 attendees, dwarfed only by Wicked Big Meet (held in Stafford Springs, CT), which drew nearly 5000 people in 2014. Other events include Big Northwest Meet in Portland, OR and for it’s first year ever in 2015, Rocky Mountain Subaru Festival in Denver, CO.

boxerfest 2015
GrimmSpeed donated $1000 in Gift Cards to the raffle!

Attending one of these events, or even just consuming the MASSIVE amount of media created by them, helps shed some light on just how big this ‘thing’ is. Jaws drop when I share photos of 3000 Subarus parked in the lot or of the vendor area packed wall to wall with people carrying boxes/bags/shirts/hats/etc. They begin to understand that our community is more than just a popular movie franchise from 15yrs ago.

subaru legacy gt airbags
Chuck’s Legacy GT sporting the newest GrimmSpeed TMIC.

The GrimmSpeed team flew into Reagan National Airport on Thursday night and spent the day on Friday checking out the area, visiting IAG Performance in Westminster, MD and helping pack thousands of goodie bags for Boxerfest attendees. The next morning, we were up early and and by 7am, we were at FedEx Field setting up our tent and assembling our display. At 9am when the gates opened, there was already a line of Subarus a mile long ready to rock and roll. For each event, we select a few local guys to join us at our booth and show off their cars. It’s always fun getting to know a couple of local enthusiasts a little bit better. They get top-notch parking and we always have new cars sporting our full product line to show off!

boxerfest 2015
Howie’s super clean GR STI brought a lot of attention to the GrimmSpeed booth.

We had a number of other favorites parked inside and outside of the vendor area as well. We’re car guys to core here and have no difficulty appreciating anything from a great stance on beautiful wheels to an all-out track build like the white STI gracing the IAG booth with it’s presence.

Another favorite of ours is Khanh’s 2015 STI with, literally, every single part that GrimmSpeed makes for his car. 

Enough words – I think you get the idea here. The bottom line is that the Subaru community is growing quickly and that these events are a great way to connect with fellow enthusiasts, see some cool stuff and even learn a thing or two. Nothing can describe our little piece of the automotive industry quite like a gathering this size.

Twin-turbo Subaru BRZ. Very slick setup.
Extremely well-sorted rotated EFR setup.
Super clean engine bay with a GrimmSpeed Boost Control Solenoid keeping that Precision turbo under control.
Subarus and Subaru fans as far as the eye can see. Friends, children, moms, dads, grandparents and even puppies!
subaru svx
Definitely the wildest Subaru SVX we’ve ever seen!
Of course, the event was serviced by a handful of local food trucks!

Thanks for reading! We’ll be recapping each of this years events, so keep an eye out for more! For more photos, visit the GrimmSpeed album on Facebook or visit the Boxerfest page for a number of the day’s albums.

GrimmSpeed Sponsors Dai Yoshihara’s 2015 Formula Drift BRZ

It is with an unhealthy amount of excitement that we announce GrimmSpeed’s official sponsorship of Formula Drift veteran, Dai Yoshihara’s BRZ for all seven rounds of the 2015 season. Dai’s Falken Tire x Turn 14 Distribution Subaru BRZ is sporting a new livery for the season that maintains the classic Falken Tires scallop design but integrates the corporate colors of this year’s co-title sponsor, Turn14 Distribution. When those Falkens aren’t creating a massive amount of tire smoke, you’ll find the GrimmSpeed logo anchoring the rear of the car. That may not be too often and were OK with that; we love us some tire smoke.

dai yoshihara grimmspeed

GrimmSpeed has always been a huge supporter of grassroots motorsports and up-and-coming drivers, having sponsored some of the nations fastest time attack and rally drivers ‘back in the day’. Many times, as those drivers find larger success, they also find larger sponsors. We take pride in supporting the smaller guys and are happy to ‘set them free’ as they advance, but we’re also very excited to be a part of a small group of sponsors that are supporting one of the biggest names, Dai Yoshihara, in Formula Drift this year.

Throughout the season, you can expect to see GrimmSpeed covering Dai’s season with race recaps, technical discussion and other assorted shenanigans. Let us know what else you’d like to see!

2015 Formula Drift Competition Schedule:

Streets of Long Beach (Long Beach, Calif.): April 10 – 11
Road to the Championship (Braselton, GA): May 8-9
Orlando (Orlando, FL): June 5-6
The Guantlet (Wall Township, NJ): June 26-27
Throwdown (Monroe, WA): July 24-25
Showdown (Fortworth, TX): August 21-22
Final Fight (Irwindale, Calif.): October 9-10

sponsors

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

Pattern Shop Newsletter 1_630

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!

Restriction in the Stock BRZ/FR-S Intake – Results

Procedure:

We wanted this testing to be performed on the road to obtain real world data, as opposed to on a dyno. This method would allow the air dam to obtain actual flow to be received from moving at realistic speeds on the street. The conditions were less than ideal for tire grip (28 degrees F), so tests with tire spin were immediately thrown out and retested. However, since we’re measuring differential pressure the high density of the air due to the low temperatures has no effect on the overall pressure reading.

The test was performed the same each time, on the same stretch of road. The road was uphill, which is beneficial to increase the time of each pull in order to have a better chance of obtaining accurate sample data to combat the low sample rate of the manometer’s datalogging capabilities. We started off in first gear, rolling into the pedal to wide open throttle to avoid wheel spin, shifting at 7300rpm into second gear, straight into wide open throttle, shifting again at 7300rpm, and immediately into wide open throttle through all of third gear. Each run took approximately 14 seconds to complete. We performed this test 3 times for each configuration, measuring pressure drop from:

  1. Snorkel inlet to airbox inlet
  2. Front of airbox to rear of airbox (filter)
  3. Rear of airbox to entry of intake elbow (MAF housing)
  4. Entry of intake elbow to throttle body
  5. Snorkel inlet to throttle body

These runs were performed back to back on the same day, stopping each time briefly (less than 5 minutes) to save the datalog file to the computer, and/or to change pressure test locations on the intake tract.

Results:

grimmspeed stock airbox testing

This graph shows what happens across first through third gear, which is clearly shown by the fact that all five components have three clear humps, each with longer durations. These occur during wide open throttle, and the dips show the pressure approaching 0 between shifts. This graph also shows why having such a low sample rate makes for poor data, but we’ve made up for it by increasing the amount of trials. The fact that the graph maxes out for the overall system at about 9.5in of H2O in all three gears shows that that value is most likely correct for the overall system. Same goes for each of the individual components of the system; in each gear they seem to have the same maximum value. The graph also shows that restriction increases as RPMs increase, because as RPMs increase so does the required flow rate. The short duration of first gear shows the weakness of the sample rate, as the peak numbers of the individual components do not exactly match the peak numbers of each component in second and third gear. For this reason, the graph is most accurate for the third gear section (approximately 9 through 14 seconds), and shows a nice curve instead of a quick peak. However, for illustration purposes, showing all three gears shows that the pressure drop is RPM dependent and not speed dependent as would be initially expected. One would expect more air in the front air dam from the increase in speed to change the results in each gear, but clearly it does not.

This graph also does a good job of “double checking our data.” Remember that the orange line (Snorkel to Throttle Body) is the overall restriction of the system, and that it is the sum of the individual components. The graph of this curve is real world data, and is not simply the overall curves added together in Excel. However, if one were to measure the peaks of each gear for each individual component, and add them up, they would find that they total up to about 9.5in of H2O, which is what is shown to be the peaks of the overall system.

The effect the snorkel had on the system was very interesting. The snorkel showed a consistent pressure gain of about 3in H2O. The fact that the inlet is smaller than the outlet lends that the decrease in velocity of the air as it passes through should increase the pressure. However, the fact that this number is nearly high enough to cancel out any one other component’s restriction shows that in stock for the intake is very well designed. Each other component seems to have a restriction of about 4in H2O (air filter, MAF housing, intake elbow).

Conclusion:

This answers a lot about the perceived weakness and the performance of the stock intake. It also goes to show that since the pressure drop doesn’t seem to be dependent on vehicle speed that all of this testing could have been performed stationary while strapped to a dyno. Removing the snorkel should yield no performance gain, but leaving it in could be compared to removing the air filter, or the MAF housing, or having a lossless intake elbow. However, all of these perceived restrictions really are not that bad. Each component having a restriction of 4in of H2O is really only equivalent to about 0.144psi, with the total intake’s restriction being equivalent to about 0.342psi. If I were to perform some completely fake equivalency math, and say that this car makes about 165whp in stock form, and at one atmosphere (14.7psi), a restriction of this size would be equivalent to about 3.84whp. So we would expect to see a gain of only about 3.84whp if we were to create a completely lossless intake system that acted at the exact same air to fuel ratio. However, luckily that math is completely fake, and just for illustrative purposes as there have proven to be larger gains than that achieved without creating a theoretical “lossless intake.” This is true because there are so many more contributing factors than just reducing pressure drop on an intake that is already well designed.

Chase – Engineering

Restriction in the Stock BRZ/FR-S Intake – Equipment

Equipment:

Now that we’ve identified potential restriction, we’ll want to use what we know about differential pressure to determine just what effects these potentially detrimental features actually have on the intake system.

grimmspeed cold air intake testing brz fr-s
This is the differential pressure data logger that was used in this testing.

Anyone could perform the testing for differential pressure as it is relatively easy to do. Since we’ve already located what we believe to be potential points of restriction we know exactly where we should tap into the intake system to gather pressure data. One could accomplish this extremely cheaply by making their own manometers out of water and tube, and it has been done before. However, we did not want to rig up two of these (as they are usually large and hard to read) and spill them all over the place while doing first through third gear pulls. Instead we acquired a digital differential pressure manometer, specifically an “Extech HD750.” This was chosen for it’s low range (5psi) which lends to it’s accuracy, as well as the fact that it can datalog. Being able to datalog was ideal because we can show a chart of what is happening as we row through the gears, which is infinitely more interesting than if we were just to post peak numbers. This will also show if the pressure drop effects are due to speed of the vehicle, or if they are rpm dependent. Unfortunately, the sample rate is only 1 sample per second, which means that a longer pull is necessary to get a better data set, but this can be alleviated by performing more pulls. The units used for measurement during testing are in “inches of water.” 1 in H2O is equal to 0.036psi, and 27.67 in H2O is equal to 1psi. This is a relatively small unit of measure, so it is useful for showing small differences in pressure.

The manometer has two inputs for pressure, and will display the difference between the two pressure inputs. With how we hooked up the pressure signals a positive number indicates a pressure drop, and a negative number indicates a pressure gain. The manometer was to be placed in the cabin, so substantial lengths of hose were needed. Since we’re testing for pressure, the length of the hose was negligible. However, two 10ft lengths of .125in norprene hose were used, and were rated not to collapse under the expected vacuum.

Grimmspeed ft86 intake testing stock airbox
Location of each fitting added to the stock intake system for pressure sensing.

The stock intake was tapped in various places, and fittings were added that would connect to the hose for the manometer. A fitting was placed at the inlet of the snorkel, at the top of the front of the airbox before the filter, at the top of the airbox after the filter and before the MAF housing, at the inlet of the rubber elbow after the MAF housing and before the bend, and finally right before the throttle body. Each fitting was sealed to prevent leaks, and caps were added to all fittings.

See Part 3: Testing Procedure to Continue

Restriction in the Stock BRZ/FR-S Intake – Introduction

grimmspeed intake testing brz frs
This photo shows placement of one of the fittings for pressure sensing.

When we began thinking about designing an intake for the twins, we first wanted to evaluate the claim that “the stock intake is good enough.” Its general knowledge that in the last ten years or so, that factory OEM intakes have become very good in design, and are often difficult to improve upon. There are several ways to evaluate this claim, and we wanted to start out with looking at the design of the entire intake as both an overall system, as well as the sum of all of it’s parts.

Inspection:

A visual inspection doesn’t tell an absolute truth about the system, but it does give you a place to start evaluating. The first source of restriction you’d look for is sharp or abrupt entry points. Air entering a pipe without a flared entry (think velocity stack, or a funnel shape) produces a restriction, compared to one that does have a flared entrance or transition. Just the same, when air has to traverse a larger and larger angle bend, there is an increase in restriction. The same can be said for when air has to pass over surfaces that are not smooth, etc. All of these situations add restriction, which can be measured as a drop in pressure. The ideal case to move air from point A to point B would be a perfectly smooth, straight length of pipe, and even that will have a pressure drop as the length of the pipe increases.

So from a visual standpoint, lets break apart the sections of the intake: There is a snorkel, front of airbox, air filter, rear of airbox, MAF housing, intake elbow, and throttle body. The entire system can be looked at as being the area before the snorkel (behind the bumper cover) to just passed the intake elbow (right at the throttle body). Measuring the difference in pressure between these two points will give you the overall restriction of the system. But in order to identify where the weaknesses in the system are, one would be more interested to measure the difference in pressure between components in the system. For example, to measure the restriction the air filter has on the system, you would measure the pressure before and after the filter. And if you add up the pressure differences between all parts of the system, it should equal the overall restriction.

Back to the visual inspection of the system, what do we see as a potential problem area, and why do we want to choose these locations to test? The first part of the system that air sees as it enters is the snorkel. The inlet of the snorkel looks good; there is a well formed velocity stack that has minimal extra material from being molded. It’s a slight oval shape, roughly 2.25in x2.5in. About 10 inches down the air’s path, the snorkel starts to make an approximate 90 degree bend to it’s exit. The bend is very smooth, and all the while the shape is transitioning to a flatter oval, while at the same time increasing in overall cross sectional area. At the point where the snorkel transitions into the air box, it is roughly 2in x 5.7in. The snorkel contains two resonators along the first section, in two different sizes, each containing a small drain hole at their lowest point. The snorkel is sealed to the air box with a strip of foam that interfaces the outlet of the snorkel to the inlet of the front airbox.

The front face of the airbox is angled at the bottom, and contains a circular emboss. Both features are in place to maximize area before the filter, while still clearing the radiator and fan. There is also a large resonator to the left of the entrance. The front airbox has a hole at it’s lowest point just right of the entrance, as does the large resonator, both for drainage purposes. The inside of the front of the airbox is very smooth across all surfaces. The only noteworthy point from a flow standpoint is at the entrance. The half of the entrance below the snorkel has a smooth radius flowing towards the filter. However, the half above the entrance is abrupt, and looks different than you would expect from viewing it from outside the box. Outside the box, just above the exit of the snorkel there is a hump which looks to exist as an area to smooth airflow going towards the filter, but just the opposite appears to be true as there is a void here. One can only assume this is for strength, or some phenomenon that is hard to explain.

The air then flows through the filter, which is not your typical paper filter, and has only 14 large ribs. I am unsure of the media of the filter, but it is similar to a fabric like cotton. The ribs on the front side are longer than those on the back to increase filter surface area.

After the filter is the rear of the airbox, which contains mostly smooth transitions, with a taper at the opposite side to the exit that should promote flow towards the MAF housing. The only noticeable source of restriction in this piece are several protruding ribs that run lengthwise in the rear of the airbox, however small. The exit of the airbox is technically the mass air flow, or MAF, housing. The entrance to the MAF housing appears to have been optimized, as it is one of the most important parts of the entire engine. The rear face of the airbox has a section “dug out” to smooth the transition into the MAF, and the opposite side of that feature has a molded plastic velocity stack. Immediately at the entrance is a plastic matrix that is commonly referred to as an “air straightener.” This is specifically put in place to help the MAF provide the most accurate reading as possible by modifying the flow of air before it. The thickness of the pieces of this matrix is 2mm, and the diameter of the entrance here is roughly 68.5mm. The entire MAF housing is only about 70mms long, and places the MAF sensor about 25mm, or about 1in after the air straightener. The inner diameter at the MAF sensor is 70mm, and the diameter at the outlet of the MAF housing is about 72mm. So there is a taper through the entire section, albeit minimal.

At the exit of the MAF housing is the entrance of the intake elbow. The entrance to the elbow is just under 3in in diameter, and has an immediate 90 degree bend. This bend is very tight, and has a centerline radius significantly under 3in. This most likely means that the diameter of the cross section does not stay a constant 3in as the bend progresses. There are ribs on the outside of the part for strength, but they do not exist on the internal surface of the elbow. There is a tube exiting the elbow for the sound tube, just opposite of the intake elbow’s entrance, and a resonator toward the bottom of the engine bay, both located directly on the bend. Immediately after the bend is a roughly 2.25in long flex section. This section contains 5 smooth ridges that exist on the inside of the tube, and extend outwards of the tube less than .125in. After this flex section is a 5in long straight section, smooth on the inside, with ridges on the outside. This terminates at the entrance of the throttle body.

Based on this visual assessment there isn’t much to expect in the way of restriction. From the entrance of the system to the exit, we expect to see a restriction from: 90 degree bend of the snorkel, air filter, decreased size (in comparison to the air box volume) of the MAF housing, the tight 90 degree bend on the entrance of the intake elbow, and the flex section located right after the previous bend.

See Part 2: The Equipment to Continue

GrimmSpeed Sponsors The 48hrs of Tristate Drive

grimmspeed 48hrs of tristate

GrimmSpeed is excited to announce that once again, we’re sponsoring The 48hrs of Tristate Drive in New York and New Jersey. A great deal of information, routes and registration are all available at the official website (see below). The charity this year is Alex’s Lemonade Stand, which is dedicated to fighting childhood cancer. There will be a raffle held at the Subar of America Headquarters in Cherry Hill, NJ on Friday and the more money you raise for the charity, the more tickets you get for the raffle! See details below.

  • Date: January 17-19, 2014
  • Registration & Info: http://48hrs.info
  • Cost: Drive Donation to Charity is $100, Passenger is $75

Please visit the website and contact Mike and the rest of the 48hrs committee with questions or to get involved!