Welcome to the North American Subaru Impreza Owners Club Tuesday September 23, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Factory 2.5L Turbo Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 08-12-2013, 11:11 AM   #51
Dmochowski
Scooby Specialist
 
Member#: 306478
Join Date: Jan 2012
Chapter/Region: South East
Location: chattanooga, TN
Vehicle:
2012 WRX limited
305whp/360tq TSM tuned

Default

Quote:
Originally Posted by isotopesope View Post
subscribed and stoked!

after seeing your 02-07 intercooler, i have since been waiting paitently for a 08+ to be developed. i've been quite interested in the PW one, but the price tag ultimately keeps me at bay. their splitter and the ability to adapt it to fit various turbos is most appealing about it, other than the excellent performance that is reported.

the AVO TMIC also has had my attention too. i like that it's not quite as thick as the perrin and their knockoffs, so the MC bolt clearance isn't as much of an issue, or so i have read. i also like that the AVO, perrin and the knockoffs are a similar footprint as the stock one, so an alternate splitter isn't neccessary, thus probably helps keep it more affordable.

so, adaptability to various turbo styles, excellent fit (no rubbing or install quirkiness and success with various BPV's), an excellent splitter fitment whether fitting to the OEM one or a new supplied one, and affordability are my four points.
Unfortunately I think that is what keeps them at their performance level. Anything that is similar shape to the oem one will not perform as well as a PW with splitter.

Seems all oem style squarish I/c's are all rated about 400hp, where are the PW one is at 450. 400 whp is pretty much at a dom 1.5 or 20g level so that isn't that much, having something rated to ~450 gives you a little more headroom.
* Registered users of the site do not see these ads.
Dmochowski is offline   Reply With Quote
Old 08-12-2013, 06:43 PM   #52
point78
Scooby Newbie
 
Member#: 344329
Join Date: Jan 2013
Location: Denver
Vehicle:
2008 Wrx, 6mt

Default

This would make an excellent Christmas present for my '08 wrx, please make it sooner than later!
point78 is offline   Reply With Quote
Old 08-12-2013, 07:57 PM   #53
2012STORMTRP
Scooby Newbie
 
Member#: 313767
Join Date: Mar 2012
Chapter/Region: Tri-State
Location: Pomona, NY - Rockland County
Vehicle:
2012 WRX Limited
Satin White Pearl

Default

Quote:
Originally Posted by cbs160 View Post
a few things i can think of off the top of my head

1) bpv flange that can accomodate all. currently if you have a big top mount like the process west or spearco you are stuck with a stock type bpv like a forge otherwise it'll hit the hood. find a way for us to get a tial or synapse on there...
2) the spearco mounts to the 5 speed trans case. not a huge deal, but what about the number of wrx's driving around with 6 speed swaps?
3) strut tower braces are tough/impossible to fit with a big top mount. can you figure out a way?

thats all i got for now...
Quote:
Originally Posted by kizzer505 View Post
+1 to being able to fit the larger aftermarket bpvs
+1 to strut tower brace clearance

I'd like to see something with a lightweight under the hood duct and splitter
Quote:
Originally Posted by A Fatal Ode View Post
subscribed... excellent company. already have so many of their works.
+1, love the quality and workmanship that goes into your products

Quote:
Originally Posted by rwb88 View Post
It sounds like the more hp-capable this intercooler is the more prone it will be to heat soak. If this is the case then it's dependent on where most people are as far as power levels and what percentage of people use their car as a daily driver (most). I'd say most people are stage 2 but would like some room for future modifications. I would like to see this intercooler in the 400-450 whp range as a nice medium between performance and heat soak. Not that you're trying to imitate process west but I believe their intercooler is in this range and look at all the success it has had.
As an owner of a Stage 2 + 2012 WRX that's currently running a Slew of Grimmspeed Products, Id love to see a Top mount that's a step up from my Process West. I Agree with all of the above points especially the BPV/BOV one.
1) I'm running a Turbosmart Dualport BOV currently set to Resirc and it's so tall that it poked a hole in my scoop Shroud the Flange on the Process West is just too tall.
2) Another issue is the way the PW Top mount is secured. The weld under the core broke and now My Intercooler is just hanging in place. The vibrations from the transmission to that bracket was just too much or perhaps I just had a bad weld.
3) That 90 degree bend on my Process West Intercooler Piping really bother's me. There's got to be a better way to do the plumbing without creating such a restrictive Bend in the piping.
4) as started before 400-500 whp rating would be nice or 400-450, it's nice to be able to support the power mods without modding or cutting your front bumper. Plus it adds a small sleeper effect, having a frontmount gives away performance mods. whereas a Topmount is a bit more stealthy

I'm looking forward to seeing what you guys come up with and let me know if you want my Process West as a test mule or competitor comparison Id be down to be your East Coast NY Test Mule I rep you guys all day everyday, see below

2012STORMTRP is offline   Reply With Quote
Old 08-12-2013, 11:36 PM   #54
point78
Scooby Newbie
 
Member#: 344329
Join Date: Jan 2013
Location: Denver
Vehicle:
2008 Wrx, 6mt

Default

I have a '08 wrx, but it has a 6mt, and sti style turbo, forge BPV, So those are a must...(would like 400-450hp size)

Last edited by point78; 08-13-2013 at 12:17 PM.
point78 is offline   Reply With Quote
Old 08-13-2013, 12:14 PM   #55
GrimmSpeed
NASIOC Vendor
 
Member#: 136396
Join Date: Jan 2007
Chapter/Region: MWSOC
Location: Minneapolis, MN
Vehicle:
2013 BRZ
SWP

Default

Quote:
Originally Posted by isotopesope View Post
subscribed and stoked!

after seeing your 02-07 intercooler, i have since been waiting paitently for a 08+ to be developed. i've been quite interested in the PW one, but the price tag ultimately keeps me at bay. their splitter and the ability to adapt it to fit various turbos is most appealing about it, other than the excellent performance that is reported.

the AVO TMIC also has had my attention too. i like that it's not quite as thick as the perrin and their knockoffs, so the MC bolt clearance isn't as much of an issue, or so i have read. i also like that the AVO, perrin and the knockoffs are a similar footprint as the stock one, so an alternate splitter isn't neccessary, thus probably helps keep it more affordable.

so, adaptability to various turbo styles, excellent fit (no rubbing or install quirkiness and success with various BPV's), an excellent splitter fitment whether fitting to the OEM one or a new supplied one, and affordability are my four points.
Great input, thank you! We have both an AVO and a PW unit in house to baseline against and compare fitments, so you'll be able to get a good idea of how our designs stack up!
Quote:
Originally Posted by Dmochowski View Post
Unfortunately I think that is what keeps them at their performance level. Anything that is similar shape to the oem one will not perform as well as a PW with splitter.

Seems all oem style squarish I/c's are all rated about 400hp, where are the PW one is at 450. 400 whp is pretty much at a dom 1.5 or 20g level so that isn't that much, having something rated to ~450 gives you a little more headroom.
Agreed! I'm hoping to post some calculations for theoretical sizing that have worked very well for our 02-07 TMICs later today or tomorrow and we can work together to understand the details. What's interesting is that PW uses a larger volume core, but its flow area doesn't seem to increase, which I believe to be a downfall to their design. That said, we'll do our own testing and work out the details to see where we fall with core sizing! Should be fun!
Quote:
Originally Posted by point78 View Post
This would make an excellent Christmas present for my '08 wrx, please make it sooner than later!
Might have to be a late Christmas present, but we'll do our best! Earmark a few of those 2013 tax return dollars!
Quote:
Originally Posted by 2012STORMTRP View Post
+1, love the quality and workmanship that goes into your products

As an owner of a Stage 2 + 2012 WRX that's currently running a Slew of Grimmspeed Products, Id love to see a Top mount that's a step up from my Process West. I Agree with all of the above points especially the BPV/BOV one.
1) I'm running a Turbosmart Dualport BOV currently set to Resirc and it's so tall that it poked a hole in my scoop Shroud the Flange on the Process West is just too tall.
2) Another issue is the way the PW Top mount is secured. The weld under the core broke and now My Intercooler is just hanging in place. The vibrations from the transmission to that bracket was just too much or perhaps I just had a bad weld.
3) That 90 degree bend on my Process West Intercooler Piping really bother's me. There's got to be a better way to do the plumbing without creating such a restrictive Bend in the piping.
4) as started before 400-500 whp rating would be nice or 400-450, it's nice to be able to support the power mods without modding or cutting your front bumper. Plus it adds a small sleeper effect, having a frontmount gives away performance mods. whereas a Topmount is a bit more stealthy

I'm looking forward to seeing what you guys come up with and let me know if you want my Process West as a test mule or competitor comparison Id be down to be your East Coast NY Test Mule I rep you guys all day everyday, see below
First of all, thank you for the support! Second, thanks for the great, well-organized input! I'm keeping track of all of this feedback and you can bet that your input will affect the actual design of this product. Pretty cool, right!? If I need a tester out east, I know who to call!
Quote:
Originally Posted by point78 View Post
I have a '08 wrx, but it has a 6mt, and sti style turbo, forge BOV, So those are a must...(would like 400-450hp size)
Perfect, thanks!

Keep an eye out for more info on sizing and core specifications later today or tomorrow!

Matt Beenen
Engineering
GrimmSpeed is offline   Reply With Quote
Old 08-13-2013, 01:59 PM   #56
GrimmSpeed
NASIOC Vendor
 
Member#: 136396
Join Date: Jan 2007
Chapter/Region: MWSOC
Location: Minneapolis, MN
Vehicle:
2013 BRZ
SWP

Default

Quote:
Originally Posted by 2012STORMTRP View Post
2) Another issue is the way the PW Top mount is secured. The weld under the core broke and now My Intercooler is just hanging in place. The vibrations from the transmission to that bracket was just too much or perhaps I just had a bad weld.
P.S. If you have a picture of this, I'd be interested in seeing it!

Matt Beenen
Engineering
GrimmSpeed is offline   Reply With Quote
Old 08-13-2013, 02:40 PM   #57
1wrxtra
Scooby Specialist
 
Member#: 316364
Join Date: Apr 2012
Chapter/Region: International
Vehicle:
2012 WRX

Default

Quote:
Originally Posted by 2012STORMTRP View Post
+1, love the quality and workmanship that goes into your products

1) I'm running a Turbosmart Dualport BOV currently set to Resirc and it's so tall that it poked a hole in my scoop Shroud the Flange on the Process West is just too tall.
2) Another issue is the way the PW Top mount is secured. The weld under the core broke and now My Intercooler is just hanging in place. The vibrations from the transmission to that bracket was just too much or perhaps I just had a bad weld.
3) That 90 degree bend on my Process West Intercooler Piping really bother's me. There's got to be a better way to do the plumbing without creating such a restrictive Bend in the piping.
4) as started before 400-500 whp rating would be nice or 400-450, it's nice to be able to support the power mods without modding or cutting your front bumper. Plus it adds a small sleeper effect, having a frontmount gives away performance mods. whereas a Topmount is a bit more stealthy
I agree with the above. I also run the PW TMIC, and I've seen the same issue with #1 - the flange being too high up. I have the Synapse Diverter Valve (which is awesome) which fit perfectly on the stock TMIC. However, the PW pushes that flange pretty far over to the driver's side, which requires you to really stretch the recirc hose. Mine was stretched so far that the hose was fatiguing right before the clamp on the BPV. I had to resort to "modifying" (mutilating) my recirc hose in order to get it to fit. It looks ghetto as hell but is still completely functional

Point #2 - Mine hasn't broken, but I agree that there has to be a more efficient design for this bracket. Not that this is a huge issue, but getting that passenger side bolt to thread into the IC through the bracket is a PITA.

Point #3 - The size of the IC is why this hose is designed the way it is. You could have an adapter that installs on top of the turbo that makes a 90* bend into a very short hose that goes right into the IC, but then the IC would STILL be shorter than the PW.

I don't really have anything on point 4 - personally, if I was looking for a 500WHP setup I'd just go front or v-mount with a rotated intake manifold.

I have some insights on the PW TMIC if you're interested Matt, here's the link to the thread:
http://forums.nasioc.com/forums/show....php?t=2223548

IMO, the posts of interest are #'s 14-32.
1wrxtra is offline   Reply With Quote
Old 08-13-2013, 08:09 PM   #58
2012STORMTRP
Scooby Newbie
 
Member#: 313767
Join Date: Mar 2012
Chapter/Region: Tri-State
Location: Pomona, NY - Rockland County
Vehicle:
2012 WRX Limited
Satin White Pearl

Default

Quote:
Originally Posted by GrimmSpeed View Post
P.S. If you have a picture of this, I'd be interested in seeing it!

Matt Beenen
Engineering
There's 1 other issue I forgot to mention was the lack of T-Bolt Clamps. I also had an issue like 1wrxtra mentioned, with my passenger and driver side piping getting blown off due to the use of those lame worm drive units. Running T-bolt Clamps is a must! Id rather get the correct hardware upfront then having to go back in and redo it right a second time. I've only owned the car since May of 2012 and installed that IC about 1 year ago... needless to say I was surprised to learn that the Weld broke

Pictures as Requested

Here's the break under the PW IC





The Bracket



Here's the hole in my Scoop... Note I actually had to cut out a hole in the shroud so that the Turbosmart Dual Port would fit. When the hood is closed it doesn't rub however under load it'll rub. My PW sits a little lopsided since the weld broke, because of the lack of support on the Passenger side.



2012STORMTRP is offline   Reply With Quote
Old 08-13-2013, 08:21 PM   #59
1wrxtra
Scooby Specialist
 
Member#: 316364
Join Date: Apr 2012
Chapter/Region: International
Vehicle:
2012 WRX

Default

That sucks man. Have you contacted PW? They will likely give you another bracket at no charge when you show them the pics. They have great customer service.
1wrxtra is offline   Reply With Quote
Old 08-13-2013, 08:27 PM   #60
2012STORMTRP
Scooby Newbie
 
Member#: 313767
Join Date: Mar 2012
Chapter/Region: Tri-State
Location: Pomona, NY - Rockland County
Vehicle:
2012 WRX Limited
Satin White Pearl

Default

I haven't tried yet, the core needs to be repaired. I can't seem to find the piece that broke off I need it to bolt the bracket up. It's not like I got an Ebay unit I bought this straight from Rally Sport Direct and still have the receipt.
2012STORMTRP is offline   Reply With Quote
Old 08-13-2013, 08:43 PM   #61
1wrxtra
Scooby Specialist
 
Member#: 316364
Join Date: Apr 2012
Chapter/Region: International
Vehicle:
2012 WRX

Default

Quote:
Originally Posted by 2012STORMTRP View Post
I haven't tried yet, the core needs to be repaired. I can't seem to find the piece that broke off I need it to bolt the bracket up. It's not like I got an Ebay unit I bought this straight from Rally Sport Direct and still have the receipt.
Contact PW. With my dealings with Kevin I wouldn't be surprised if he just shipped you an all-new core and bracket.
1wrxtra is offline   Reply With Quote
Old 08-13-2013, 10:47 PM   #62
INVN01
Scooby Newbie
 
Member#: 290371
Join Date: Aug 2011
Chapter/Region: MWSOC
Location: Michigan
Vehicle:
06 OBXT
black on black on black

Default

Seeing how I sold my wrx wagon and am now buying an Outback XT, I am putting my name on the list now. Hell, I am ready to put a deposit down now for one of these! Grimmspeed, I think it's time to get building! LOL!
INVN01 is offline   Reply With Quote
Old 08-15-2013, 05:55 PM   #63
GrimmSpeed
NASIOC Vendor
 
Member#: 136396
Join Date: Jan 2007
Chapter/Region: MWSOC
Location: Minneapolis, MN
Vehicle:
2013 BRZ
SWP

Default

Quote:
Originally Posted by 1wrxtra View Post
I agree with the above. I also run the PW TMIC, and I've seen the same issue with #1 - the flange being too high up. I have the Synapse Diverter Valve (which is awesome) which fit perfectly on the stock TMIC. However, the PW pushes that flange pretty far over to the driver's side, which requires you to really stretch the recirc hose. Mine was stretched so far that the hose was fatiguing right before the clamp on the BPV. I had to resort to "modifying" (mutilating) my recirc hose in order to get it to fit. It looks ghetto as hell but is still completely functional

Point #2 - Mine hasn't broken, but I agree that there has to be a more efficient design for this bracket. Not that this is a huge issue, but getting that passenger side bolt to thread into the IC through the bracket is a PITA.

Point #3 - The size of the IC is why this hose is designed the way it is. You could have an adapter that installs on top of the turbo that makes a 90* bend into a very short hose that goes right into the IC, but then the IC would STILL be shorter than the PW.

I don't really have anything on point 4 - personally, if I was looking for a 500WHP setup I'd just go front or v-mount with a rotated intake manifold.

I have some insights on the PW TMIC if you're interested Matt, here's the link to the thread:
http://forums.nasioc.com/forums/show....php?t=2223548

IMO, the posts of interest are #'s 14-32.
Awesome info and a great write-up! Thanks!
Quote:
Originally Posted by 2012STORMTRP View Post
There's 1 other issue I forgot to mention was the lack of T-Bolt Clamps. I also had an issue like 1wrxtra mentioned, with my passenger and driver side piping getting blown off due to the use of those lame worm drive units. Running T-bolt Clamps is a must! Id rather get the correct hardware upfront then having to go back in and redo it right a second time. I've only owned the car since May of 2012 and installed that IC about 1 year ago... needless to say I was surprised to learn that the Weld broke
Awesome, thank you!
Quote:
Originally Posted by 1wrxtra View Post
That sucks man. Have you contacted PW? They will likely give you another bracket at no charge when you show them the pics. They have great customer service.
Quote:
Originally Posted by 2012STORMTRP View Post
I haven't tried yet, the core needs to be repaired. I can't seem to find the piece that broke off I need it to bolt the bracket up. It's not like I got an Ebay unit I bought this straight from Rally Sport Direct and still have the receipt.
Quote:
Originally Posted by 1wrxtra View Post
Contact PW. With my dealings with Kevin I wouldn't be surprised if he just shipped you an all-new core and bracket.
Whether its GrimmSpeed or another manufacturer, I always encourage folks like yourself to give the company a chance to handle the situation swiftly and in a professional manner! We all make mistakes and we all have warranty issues from time to time!
Quote:
Originally Posted by INVN01 View Post
Seeing how I sold my wrx wagon and am now buying an Outback XT, I am putting my name on the list now. Hell, I am ready to put a deposit down now for one of these! Grimmspeed, I think it's time to get building! LOL!


Matt Beenen
Engineering
GrimmSpeed is offline   Reply With Quote
Old 08-15-2013, 06:03 PM   #64
GrimmSpeed
NASIOC Vendor
 
Member#: 136396
Join Date: Jan 2007
Chapter/Region: MWSOC
Location: Minneapolis, MN
Vehicle:
2013 BRZ
SWP

Default

Intercooler Sizing

As air is compressed by your turbo, it heats up, not because of the heat of the turbocharger, but because as the air is pressurized, the air molecules are forced closer together and that results in an increase in energy. This energy manifests itself as heat. The function of an intercooler is to remove that heat from the intake charge. Removing heat from the charge air means that your intake charge becomes denser, making more power and reducing detonation. The proper sizing of an intercooler core is a careful balance of airflow and cooling capacity. When it comes to comparing an intercooler’s capacity to perform efficiently, it’s important to talk about both of these factors together. Simply quoting a volume or maximum flow rate does also no good.

A well rounded design is one that removes heat efficiently without creating a pressure drop that negates the gains from doing so. The main factors that come into play here are heat transfer area, internal flow area and internal volume. Heat transfer area is the total area of all of the fin packs and plates in the core. Internal flow area is pretty straight forward. This is the total area that charge air can flow, internally, through the core. Lastly, internal volume is simply the flow area multiplied by the channel length. Larger internal core volumes contribute to turbo lag and a loss in throttle response, as the entire volume must be pressurized before that amount of pressure will exist in the intake manifold.

Now, we’ll take a step back and calculate, roughly, a few of the variables that exist in our specific application, in order to determine requirements for maximum flow rate and cooling capacity. My goal here is to create a table that shows CFM requirements at a given RPM and boost level. To do so, I’ve made a few assumptions about volumetric efficiency, ambient temperature and adiabatic efficiency. These calculations will at least give us the framework to move forward confidently. Below are some applicable equations.



As you can see, we use an air density ratio to accommodate for the fact that only in an ideal system do the pressure ratio and density ratio rise together. This is where a carefully designed intercooler (and a properly sized turbo setup) will help. The closer we can get the two ratios, the higher our efficiency. Back to numbers. Below is an example, using out calculations, for a 2.5L Subaru producing 27psi at 8000rpm, assuming volumetric efficiency of 80%, ambient temp of 80F and 90% compressor efficiency.

Boost Pressure = 27psi
Pressure Ratio = 2.84
Ideal Turbo Outlet Temp Rise = 185.34
Actual Outlet Temp = 285.93
Air Density Ratio = 1.85
Airflow Rate = 518.62CFM

So now we have a flow rate. We’ll add a little headroom and round to 550CFM for simplicity. Now, there isn’t any particular equation that will tell us exactly what size core we need based on a CFM requirement, but there’s a good amount of historical data and it’s been compiled into a single chart by Corky Bell in his book, “Maximum Boost”. This chart takes both cooling capacity and pressure drop (among other things) into account. Again, remember that all of this is to determine a starting point and some sizing framework. The actual size that we decide to use will be greatly influenced by the space claim available in the engine bay.



What you can see is that an internal flow area, according to Corky Bell, should have a minimum flow area of around 22sq in. with closer to 28sq in. for an intercooler of typical density. Without our rounding these figures change to about 21sq in. and 26sq in., respectively. For reference our 02-07 TMIC is pretty dense and has 30sq in. of internal flow area. This has supported over 600whp, so our math is right on track.
Here is where things get tricky. Below, I’ve taken measurements of the stock TMIC along with a few of the current aftermarket options.

OEM TMIC
Core Thickness = 2.25in
Channel Width = .20in
Channel Length = 10.75in
Number of Channels = 16
Internal Flow Area = 7.20in^2
Total Internal Volume = 115.20in^3

PW TMIC
Core Thickness = 3.52in
Bar Thickness = .25in
Channel Width = .27in
Channel Length = 15.50in
Number of Channels = 10
Internal Flow Area = 8.15in^2
Total Internal Volume = 126.39in^3

It’s worth noting that if we go back through our math and use values typical of a stock 2.5L, turbo Subaru, we find a maximum air flow rate of around 240CFM. According to the chart above, this flow rate, with low density fins (stock intercooler) demands a flow area of about 10sq in. This doesn’t tell us much except that the factory intercooler is sized about right for the job. It’s unlikely that they sized it for maximum performance at redline, so it’s understandable that they actually fall a bit short in flow area. If we can get these flow areas closer to ideal values, we can reduce the amount of work that the turbo needs to do to provide the same amount of boost to the intake manifold. This will not only allow the turbo to work more efficiently, but will also reduce compressor outlet temps.

So, we’re at a point where we need to consider a number of different fitments that might allow for a large overall core volume, but also for a flow area that will adequately and efficiently support a wide range of power levels. Feel free to poke holes in what I’ve got typed here and let me know if you see errors or areas where clarification may be of use! Trying to keep this technical but relatively basic!

Matt Beenen
Engineering

Last edited by GrimmSpeed; 01-28-2014 at 06:19 PM.
GrimmSpeed is offline   Reply With Quote
Old 08-16-2013, 08:04 AM   #65
TS7XREX
Scooby Newbie
 
Member#: 287450
Join Date: Jul 2011
Chapter/Region: SWIC
Location: Gallup NM
Vehicle:
2011 Impreza WRX
Satin White Pearl

Default

Quote:
Originally Posted by GrimmSpeed View Post
Intercooler Sizing

As air is compressed by your turbo, it heats up, not because of the heat of the turbocharger, but because as the air is pressurized, the air molecules are forced closer together and that results in an increase in energy. This energy manifests itself as heat. The function of an intercooler is to remove that heat from the intake charge. Removing heat from the charge air means that your intake charge becomes denser, making more power and reducing detonation. The proper sizing of an intercooler core is a careful balance of airflow and cooling capacity. When it comes to comparing an intercooler’s capacity to perform efficiently, it’s important to talk about both of these factors together. Simply quoting a volume or maximum flow rate does also no good.

A well rounded design is one that removes heat efficiently without creating a pressure drop that negates the gains from doing so. The main factors that come into play here are heat transfer area, internal flow area and internal volume. Heat transfer area is the total area of all of the fin packs and plates in the core. Internal flow area is pretty straight forward. This is the total area that charge air can flow, internally, through the core. Lastly, internal volume is simply the flow area multiplied by the channel length. Larger internal core volumes contribute to turbo lag and a loss in throttle response, as the entire volume must be pressurized before that amount of pressure will exist in the intake manifold.

Now, we’ll take a step back and calculate, roughly, a few of the variables that exist in our specific application, in order to determine requirements for maximum flow rate and cooling capacity. My goal here is to create a table that shows CFM requirements at a given RPM and boost level. To do so, I’ve made a few assumptions about volumetric efficiency, ambient temperature and adiabatic efficiency. These calculations will at least give us the framework to move forward confidently. Below are some applicable equations.

As you can see, we use an air density ratio to accommodate for the fact that only in an ideal system do the pressure ratio and density ratio rise together. This is where a carefully designed intercooler (and a properly sized turbo setup) will help. The closer we can get the two ratios, the higher our efficiency. Back to numbers. Below is an example, using out calculations, for a 2.5L Subaru producing 27psi at 8000rpm, assuming volumetric efficiency of 80%, ambient temp of 80F and 90% compressor efficiency.

Boost Pressure = 27psi
Pressure Ratio = 2.84
Ideal Turbo Outlet Temp Rise = 185.34
Actual Outlet Temp = 285.93
Air Density Ratio = 1.85
Airflow Rate = 518.62CFM

So now we have a flow rate. We’ll add a little headroom and round to 550CFM for simplicity. Now, there isn’t any particular equation that will tell us exactly what size core we need based on a CFM requirement, but there’s a good amount of historical data and it’s been compiled into a single chart by Corky Bell in his book, “Maximum Boost”. This chart takes both cooling capacity and pressure drop (among other things) into account. Again, remember that all of this is to determine a starting point and some sizing framework. The actual size that we decide to use will be greatly influenced by the space claim available in the engine bay.

What you can see is that an internal flow area, according to Corky Bell, should have a minimum flow area of around 22sq in. with closer to 28sq in. for an intercooler of typical density. Without our rounding these figures change to about 21sq in. and 26sq in., respectively. For reference our 02-07 TMIC is pretty dense and has 30sq in. of internal flow area. This has supported over 600whp, so our math is right on track.
Here is where things get tricky. Below, I’ve taken measurements of the stock TMIC along with a few of the current aftermarket options.

OEM TMIC
Core Thickness = 2.25in
Channel Width = .20in
Channel Length = 10.75in
Number of Channels = 16
Internal Flow Area = 7.20in^2
Total Internal Volume = 115.20in^3

PW TMIC
Core Thickness = 3.52in
Bar Thickness = .25in
Channel Width = .27in
Channel Length = 15.50in
Number of Channels = 10
Internal Flow Area = 8.15in^2
Total Internal Volume = 126.39in^3

It’s worth noting that if we go back through our math and use values typical of a stock 2.5L, turbo Subaru, we find a maximum air flow rate of around 240CFM. According to the chart above, this flow rate, with low density fins (stock intercooler) demands a flow area of about 10sq in. This doesn’t tell us much except that the factory intercooler is sized about right for the job. It’s unlikely that they sized it for maximum performance at redline, so it’s understandable that they actually fall a bit short in flow area. If we can get these flow areas closer to ideal values, we can reduce the amount of work that the turbo needs to do to provide the same amount of boost to the intake manifold. This will not only allow the turbo to work more efficiently, but will also reduce compressor outlet temps.

So, we’re at a point where we need to consider a number of different fitments that might allow for a large overall core volume, but also for a flow area that will adequately and efficiently support a wide range of power levels. Feel free to poke holes in what I’ve got typed here and let me know if you see errors or areas where clarification may be of use! Trying to keep this technical but relatively basic!

Matt Beenen
Engineering
You're a BAMF....
TS7XREX is offline   Reply With Quote
Old 08-16-2013, 09:23 AM   #66
gutie04
Scooby Newbie
 
Member#: 219717
Join Date: Aug 2009
Chapter/Region: South East
Location: Milton, Florida
Vehicle:
05 FXT Dom2.5R
4EAT FTW!!!!

Default

This message has been approved by a Nuclear Engineer.

I always struggle to explain that stuff to people and how Huge ICs aren't always better.
gutie04 is offline   Reply With Quote
Old 08-16-2013, 10:42 AM   #67
isotopesope
Scooby Specialist
 
Member#: 265783
Join Date: Dec 2010
Chapter/Region: RMIC
Location: colorado springs
Vehicle:
2008 wrx

Default

how does the AVO TMIC compare to stock and the PW?
isotopesope is online now   Reply With Quote
Old 08-16-2013, 11:53 AM   #68
GrimmSpeed
NASIOC Vendor
 
Member#: 136396
Join Date: Jan 2007
Chapter/Region: MWSOC
Location: Minneapolis, MN
Vehicle:
2013 BRZ
SWP

Default

Quote:
Originally Posted by isotopesope View Post
how does the AVO TMIC compare to stock and the PW?
I've actually got one on our 2012 WRX right now. I'll pull it next week for measurements. If I had to guess, though, I'd say that the flow area is larger and that internal volume is similar. The difference, though, is that it's overall heat transfer area is likely smaller, as the overall volume of the core is also smaller. Just speculation though. I'll have better info next week.

Matt Beenen
Engineering
GrimmSpeed is offline   Reply With Quote
Old 08-16-2013, 12:04 PM   #69
Turbo27
Scooby Newbie
 
Member#: 270182
Join Date: Jan 2011
Chapter/Region: MWSOC
Location: Louisville, Ky
Vehicle:
2003 WRX
OBP

Default

Turbo27 is offline   Reply With Quote
Old 08-16-2013, 02:12 PM   #70
Unabomber
Big Ron
Moderator
 
Member#: 18062
Join Date: Apr 2002
Chapter/Region: MAIC
Location: I can save you a ton of cash
Vehicle:
on car parts so PM
me b4 j00 buy

Default

You might be doing yourself a favor if you reach out to Corky Bell and talk to him about your ideas. The phone call will last 3 hours and you'll talk about everything from intercoolers to grape leaves, but if you want to talk to the Lord Arisen himself about thermodynamics and intercoolers, it is a must. If you need help getting together, I can probably arrange it.
Unabomber is offline   Reply With Quote
Old 08-16-2013, 04:45 PM   #71
Nimbus09
Scooby Specialist
 
Member#: 212399
Join Date: May 2009
Chapter/Region: NWIC
Location: portland, or
Vehicle:
09 wrx 301hp/328tq
'00 miata blue

Default

dont forget to keep the flow laminar(resist temptation to have a large number of passages for the better cooling it would appear to provide)

Nimbus09 is offline   Reply With Quote
Old 08-17-2013, 09:42 PM   #72
ImprezaRose
Scooby Newbie
 
Member#: 111475
Join Date: Apr 2006
Chapter/Region: NESIC
Location: Griswold, CT
Vehicle:
2005 Legacy GT LTD
Brilliant Silver Metallic

Default

Quote:
Originally Posted by GrimmSpeed View Post
1.) Shout-out the strut tower brace that you have. I'd like to get a few in house and test fitment so that I can do my best to fit them with our tmic!
2.) Are features for holding the LGT/OBXT engine cover important to you guys? I suppose I should ask the same question on the lgt forums.
1. The strut brace I have is an ebay knock off that my husband says is similar to a GT spec.

2. My LGT no longer has the engine cover due to my FMS intercooler. So in that regard im not worried about size. Not hitting the strut brace would be nice though lol.
ImprezaRose is offline   Reply With Quote
Old 08-17-2013, 10:16 PM   #73
urfsin
Scooby Specialist
 
Member#: 128975
Join Date: Oct 2006
Chapter/Region: SCIC
Location: Santa Barbara
Vehicle:
2005 Outback XT
Golden Thunder

Default

Thanks to Grimmspeed for taking this on and I look forward to your finished product. You guys are putting some good thought and effort into this project.

What I would like to see are some actual numbers in terms of air intake temps post turbo, but before the intercooler, then after the intercooler, pre throttle body. Maybe I have not searched hard enough, but I have NEVER seen these numbers published on any aftermarket intercooler. I think these numbers will show where the rubber meet's the road so to speak.

Is this something that is hard to do? Why is this not talked about more? Please enlighten me.

For some background on my interest in this, I did my own little DIY TMIC project back in 2010 before the Process West intercooler was out. Here is a link to that thread just in case you want to use it for inspiration!

http://legacygt.com/forums/showthrea...er-128914.html

Last edited by urfsin; 08-17-2013 at 10:41 PM.
urfsin is online now   Reply With Quote
Old 08-18-2013, 12:47 AM   #74
gutie04
Scooby Newbie
 
Member#: 219717
Join Date: Aug 2009
Chapter/Region: South East
Location: Milton, Florida
Vehicle:
05 FXT Dom2.5R
4EAT FTW!!!!

Default

There are too many variables for that method to provide a solid comparison. That test would have to be done in controlled environment with a solid temperature, humidity, winds, etc. It's like you would have to have a wind tunnel with an AWD dyno in it for accurate results.
gutie04 is offline   Reply With Quote
Old 08-18-2013, 03:17 AM   #75
urfsin
Scooby Specialist
 
Member#: 128975
Join Date: Oct 2006
Chapter/Region: SCIC
Location: Santa Barbara
Vehicle:
2005 Outback XT
Golden Thunder

Default

OK I see what you are saying, but there are lot's of dyno's out there that have controlled environments, or at least semi controlled. Even if you can't control all the factors like temp, humidity and wind 100%, you can get pretty darn close. Let's say you have a dyno in an open air shop and do one run (or multiple runs) with intercooler "A" to get data, then swap to intercooler "B" to get new data. Unless you have complete monkeys working at the shop you can get that swap done in 20 minutes. Things like temp and humidity and won't change that much if at all. As for the "wind" factor, there are all sorts of set ups with fans that can keep a constant flow over the intercooler from subject "A" to "B".

Besides, let me play devils advocate here for a second....people compare dyno results from across the country on this forum everyday. Are all of these run's done under the same conditions? Of course not, but the comparisons are still done. I just don't see why this can't happen for intercooler testing.
urfsin is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 06:14 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.