Welcome to the North American Subaru Impreza Owners Club Tuesday July 7, 2020
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC General > Newbies & FAQs

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.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 06-08-2020, 03:04 PM   #1
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default Hood Vents - 2016 STI, looking to help airflow

Long-short; looking to get some air out of the engine bay. There's quite a bit done to the car in terms of temp maintenance and i wouldn't say the car is over heating by any means, but it can get up there 220-230 coolant before i start my cool down lap.

I know moving to a FMIC would make things a whole lot easier in terms of airflowing into the nose, then out the vents over the car, but i'd like to keep the car with a TMIC as i'm only going to be pushing 350-375whp for now.

Question - best place for high pressure zones on the hood? Do vents disrupt the efficiency of the hood scoop to function correctly, even when placed in a high pressure zone?

Last thing i want to do is to slap vents on there like a moron and completely destroy what little airflow the scoop gets, along with the rad.

May not even do the vents depending on what i find researching, but wanted to see if anyone has, with a tmic, received good results (Obviously i don't expect 10F drops from these).

* Registered users of the site do not see these ads.
rymaggi is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 06-08-2020, 03:26 PM   #2
Samurai Jack
Scooby Guru
 
Member#: 21145
Join Date: Jul 2002
Chapter/Region: NESIC
Location: Not in my own time
Vehicle:
2002 Enemy of Aku

Default

A FMIC will only cause more issues w/cooling. You will now have an AC condenser as well as an FMIC the air has to get through before it reaches the radiator.

Can tell you I previously had a Trans AM, which had side vents along the side top of the front fenders in front of the doors. Could feel the air passing out from under the hood just standing next to the vents and only slightly revving the engine. Helped keep trapped air from under the hood.

You could install vents at the base of the windshield where air gets trapped.

WRC installed vents at the leading edge of the hood BUT they were directing hot air from directly behind the radiator right to those vents.
Samurai Jack is online now   Reply With Quote
Old 06-08-2020, 03:51 PM   #3
Jack
Add Lightness
Moderator
 
Member#: 13699
Join Date: Dec 2001
Chapter/Region: NESIC
Location: Hopkinton, MA
Vehicle:
not my president
(From General)

Default

Be careful with placement. You won't want the hot air leaving the underhood area going into the scoop, right? So don't go across the entire front of the hood. Look at GC8 vents. They are functional even in a USDM 2.5RS with the simple removal of 4 nuts on the underside of each vent. Their placement near the front of the hood is correct as its a negative pressure area. There's a picture somewhere on NASIOC that's probably 20 years old of a GC8 where the vents and scoop of a 2.5RS were unblocked. The car was covered in ice, then driven. The picture then showed that indeed, heated air melted the ice behind the vents and the scoop had no such indication as it's in a high pressure area, forcing air underhood (remember that this is an N/A car, so no intercooler there). The rear of the hood or cowl are not places to exhaust air and would only increase underhood pressure since the windshield creates the highest pressure area on the entire car.

Behind the wheel wells is another area (reference the Bandit Trans Am) where there's a low pressure area that could serve as an exit vent area.
Jack is offline   Reply With Quote
Old 06-08-2020, 04:04 PM   #4
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Definitely staying out of the middle of the hood and anywhere in front of the the TMIC.

I have the sides (inside the engine bay) open, instead of those push pinned on carpet style covers. With the fender liners cut because of the wheel/tire setup, i figured it would help pull out air. I know guys have drilled holes into those fender grills, right in front of the doors on both sides, that might help direct air as well.

I'm having trouble thinking of where you're suggesting to look into the vents. I had imagined putting them right in the corners towards the windshield, but it sounds like with the RS, and if my memory serves me right, those vents (I think they're more like 2 parallel openings (4 total), long ovals, are more in the front of the hood almost near the headlights.

Last edited by rymaggi; 06-08-2020 at 04:16 PM.
rymaggi is offline   Reply With Quote
Old 06-08-2020, 04:19 PM   #5
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

I know this is a rendered picture, but it serves the purpose of where i was thinking.

rymaggi is offline   Reply With Quote
Old 06-08-2020, 04:27 PM   #6
Samurai Jack
Scooby Guru
 
Member#: 21145
Join Date: Jul 2002
Chapter/Region: NESIC
Location: Not in my own time
Vehicle:
2002 Enemy of Aku

Default

So, you take those vents and stick them on the fenders near the A-pillars.
Samurai Jack is online now   Reply With Quote
Old 06-08-2020, 04:29 PM   #7
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Quote:
Originally Posted by Samurai Jack View Post
So, you take those vents and stick them on the fenders near the A-pillars.
Interesting, haven't thought of that.
rymaggi is offline   Reply With Quote
Old 06-08-2020, 04:52 PM   #8
Samurai Jack
Scooby Guru
 
Member#: 21145
Join Date: Jul 2002
Chapter/Region: NESIC
Location: Not in my own time
Vehicle:
2002 Enemy of Aku

Default

Take a look at the 76 Pontiac Trans Am, or the 77 Bandit model that Jack mentioned. That's where their functional vents were placed.
Samurai Jack is online now   Reply With Quote
Old 06-08-2020, 08:02 PM   #9
Jack
Add Lightness
Moderator
 
Member#: 13699
Join Date: Dec 2001
Chapter/Region: NESIC
Location: Hopkinton, MA
Vehicle:
not my president
(From General)

Default



Those are INLETS.



Those are OUTLETS.

Keep them near the front.
Jack is offline   Reply With Quote
Old 06-08-2020, 08:14 PM   #10
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

How do you tell them a part?



I'm taking a guess here, these would be outlets, and i'd want them next to the scoop?
rymaggi is offline   Reply With Quote
Old 06-09-2020, 12:33 PM   #11
R1Armadillo
Scooby Newbie
 
Member#: 481444
Join Date: Jan 2018
Chapter/Region: MAIC
Location: Baltimore, MD
Vehicle:
2018 STI Limited
WRB

Default

Something else to look at - check out Smeedia on the utubes. He just did this to his STi and measured before and after temps. Not a huge difference, but he was pretty happy with how it turned out.

The ones he installed look like the ones posted above.
R1Armadillo is offline   Reply With Quote
Old 06-09-2020, 02:30 PM   #12
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Quote:
Originally Posted by R1Armadillo View Post
Something else to look at - check out Smeedia on the utubes. He just did this to his STi and measured before and after temps. Not a huge difference, but he was pretty happy with how it turned out.

The ones he installed look like the ones posted above.
I'll take a look definitely, but if i remember correctly, he has a FMIC. Pretty sure that is a huge factor in setting up airflow.
rymaggi is offline   Reply With Quote
Old 06-25-2020, 03:47 PM   #13
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Hi All, wanted to double back here. I picked up a set of the varus hood louvers and i'm also about to pick up some slim fender louvers as well.

What i'm curious to find out, as i've heard conflicting opinions, is how to properly run the fender louvers.

As you may know, with the 2015's on the left and right side of the engine bay are carpet trim pieces that cover up the gap/opening between the fenders/wheel wells and the engine bay.

What i've been told is this

1. You need to keep those there, but remove the fender liners.

2. You remove the inside trim in the engine bay, and can cut out the fender liners.

With opinion 1, i was told that if i removed the trim it would create turbulence in the engine bay. When looking at the GTA cars like Sally McNulty's VA, she has the trim pieces removed. I also, don't see how there would be turbulence as the air would be getting pulled towards the low pressure zone created by the hoot louvers and fender louvers.

Interested to hear any other input on the matter.
rymaggi is offline   Reply With Quote
Old 06-25-2020, 05:13 PM   #14
Jack
Add Lightness
Moderator
 
Member#: 13699
Join Date: Dec 2001
Chapter/Region: NESIC
Location: Hopkinton, MA
Vehicle:
not my president
(From General)

Default

Quote:
Originally Posted by rymaggi View Post
How do you tell them a part?
It's WHERE they are on the hood.....not what they look like. From just behind the front of the hood to where that GC8 shows is a low pressure area, so air comes out of the engine compartment. From about the front of the scoop all the way to the windshield is a higher pressure area and will force air into the engine compartment.

Back in the olden days when the GC8 was current, there were air intake solutions that hooked into the wiper motor area. Since that's at the base of the windshield, it's one of the highest pressure areas when the car is moving, so air is forced down the throat of the intake. (forced air intake). Or cowl induction.

On the opposite world end, all the Civics with spacers on the hood hinge, holding the back of the hood up an inch, supposedly to reduce under hood pressure actually works the opposite. Now, because there's a space all the way down the hood, near the middle and front, some air may escape.
Jack is offline   Reply With Quote
Old 06-25-2020, 09:03 PM   #15
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Quote:
Originally Posted by Jack View Post
It's WHERE they are on the hood.....not what they look like. From just behind the front of the hood to where that GC8 shows is a low pressure area, so air comes out of the engine compartment. From about the front of the scoop all the way to the windshield is a higher pressure area and will force air into the engine compartment.

Back in the olden days when the GC8 was current, there were air intake solutions that hooked into the wiper motor area. Since that's at the base of the windshield, it's one of the highest pressure areas when the car is moving, so air is forced down the throat of the intake. (forced air intake). Or cowl induction.

On the opposite world end, all the Civics with spacers on the hood hinge, holding the back of the hood up an inch, supposedly to reduce under hood pressure actually works the opposite. Now, because there's a space all the way down the hood, near the middle and front, some air may escape.
That's good to hear, the verus louvers install just a touch in front of the hood scoop, on the sides
rymaggi is offline   Reply With Quote
Old 06-25-2020, 09:06 PM   #16
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

rymaggi is offline   Reply With Quote
Old 06-30-2020, 01:09 AM   #17
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Quick update and any input welcome.

Will be picking up the following and i'm hoping all of these help the same common goal; keep coolant/engine temps down.
  • Verus Hood Louvers (Have)
  • Fender Louvers (Purchasing)
  • Verus Hood Scoop Block off Plate
  • ETSFMIC (Purchasing) - Replacing the VF48 for a COBB 20g (Little upgrade, nothing serious)
  • Swapping out Subaru Coolant for Water & Water Wetter (Not sure on mixture, advice?)

I will be removing the carpet trim pieces on the sides of the engine bay which seal off the fenders from the engine bay. My goal is to allow heat to escape out the fenders.

One item i'm not sure on - Do i need to remove the fender liners completely to allow the fender louvers to function properly? I've heard yes. Could i cut them at the 12 o'clock area and keep the front and backs on, essentially cutting out 9 o'clock to 2 o'clock?


I've seen people cut customer louver/ducting out of their splash guards, efficient or counter productive?

I do hope and plan to create some sort of dam on the sides at least from the bumper, sealing or at least directing air through both cores.

Open to suggestions or other thoughts. I'm really wanting to focus on air entering the bumper, and being able to flow freely through the exchanges, then out the louvers vs having a TMIC and having a ton of turbulence under the hood, hindering airflow into the bumper
rymaggi is offline   Reply With Quote
Old 06-30-2020, 06:23 PM   #18
phxsubaru
Scooby Newbie
 
Member#: 441528
Join Date: Feb 2016
Location: Phoenix, AZ
Vehicle:
2015 STI

Default




I put the carpet liners back in after adding the fender vents. And I have not removed the full fender liner, only added a large opening in the area of the fender vent. I am currently on a stock tmic with a BPT 1.5xtr making 430hp 420tq on e85. I have not been on track since adding fender vents and larger turbo. In Arizona it is the off season. Driving around in 110f weather couple of days ago with water temps around 205.

Hood venting and proper radiator ducting are crucial if you are pushing the va chasis Hard on track.
My current radiator ducting



My Oil cooler is ducted through the fog light


Link to tuft testing the hood vents
https://youtu.be/rvrs2o4CbpU

Last edited by phxsubaru; 06-30-2020 at 06:33 PM.
phxsubaru is offline   Reply With Quote
Old 07-01-2020, 10:47 PM   #19
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

phxsubaru - Damn, i tip my hat to you man, that ducting is on point and is exactly what i want to do with mine.

I just got home from installing a COBB 20g on mine, with the stock tmic as well. We ran out of pump (DW65) and i just now ordered an AEM340. ETS FMIC is going to take 3-6w to get here. You don't still happen to have templates the the rad ducts or oil cooler by chance?

We switch out the Subaru coolant for water & water wetter and it wouldn't even get up to temp to turn the fans on (It was 96-98 degrees out today), so i'm hoping that helps with the cooling as well.

I'd likely have issues ducting the rad once the FMIC is on, but i think we're going to at least try something like you've done at some point. I have a Laguna Seca day coming up on the 26th, so it'll be interesting to see how the water/water wetter does vs the 100% coolant.
rymaggi is offline   Reply With Quote
Old 07-01-2020, 10:50 PM   #20
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

When i get the FMIC, i'm going to see how everything does on the track together temp wise, before i relocate it. I know i'll likely have to due to temps, but i want to see first.

I was thinking about doing the mocal duct, which goes on their 13 row cooler which by looking at the dimensions is exactly the same size as the Perrin (Someone correct me if i'm an idiot).



I would have to just run a tube to the fog light.

Only issue is i would have to drill a second hole if i wanted to eventually run brake ducting.



P2P Racing also makes a custom oil cooler which is massive. This would be last resort and only if i find myself having oil temp issues (Which at this point i haven't). Only time i've seen over 240 oil (242 degrees), was on my 5th session which was 35 mins long at the very end. Even then i think my water temp only reached 232 and oil was 242. Throughout the day, my oil temps were 210-220.
rymaggi is offline   Reply With Quote
Old 07-02-2020, 04:36 PM   #21
phxsubaru
Scooby Newbie
 
Member#: 441528
Join Date: Feb 2016
Location: Phoenix, AZ
Vehicle:
2015 STI

Default

Quote:
Originally Posted by rymaggi View Post
When i get the FMIC, i'm going to see how everything does on the track together temp wise, before i relocate it. I know i'll likely have to due to temps, but i want to see first.

I was thinking about doing the mocal duct, which goes on their 13 row cooler which by looking at the dimensions is exactly the same size as the Perrin (Someone correct me if i'm an idiot).



I would have to just run a tube to the fog light.

Only issue is i would have to drill a second hole if i wanted to eventually run brake ducting.



P2P Racing also makes a custom oil cooler which is massive. This would be last resort and only if i find myself having oil temp issues (Which at this point i haven't). Only time i've seen over 240 oil (242 degrees), was on my 5th session which was 35 mins long at the very end. Even then i think my water temp only reached 232 and oil was 242. Throughout the day, my oil temps were 210-220.
I would just buy one of the mocal duct or similar once you move the oil cooler. I used to think I needed a larger oil cooler but once ducted it worked great. I was going to buy a similar duct if my custom version didn't work.

I feel having the oil cooler mounted in front of the radiator is not helpful on track. I have had oil temps approaching 260+ on track. The air coming off the oil cooler and then going through the radiator is not helping alot. Once I moved the oil cooler to where the "stock sti intake milk jug" is located cooling improved.

That is also why I have stuck with a top mount intercooler (currently stock with boost referenced exterior water spray). I worry about another hot item in front of the radiator. Every summer in arizona Facebook groups there are posts about increased water temps with a front mounted intercooler. I feel the increased temps can be fixed with proper ducting. With a front mount I would get a hood with no scoop and properly vent the radiator through the hood.
phxsubaru is offline   Reply With Quote
Old 07-02-2020, 05:53 PM   #22
rymaggi
Scooby Specialist
 
Member#: 253442
Join Date: Jul 2010
Chapter/Region: BAIC
Location: Sacramento, Ca
Default

Quote:
Originally Posted by phxsubaru View Post
I would just buy one of the mocal duct or similar once you move the oil cooler. I used to think I needed a larger oil cooler but once ducted it worked great. I was going to buy a similar duct if my custom version didn't work.

I feel having the oil cooler mounted in front of the radiator is not helpful on track. I have had oil temps approaching 260+ on track. The air coming off the oil cooler and then going through the radiator is not helping alot. Once I moved the oil cooler to where the "stock sti intake milk jug" is located cooling improved.

That is also why I have stuck with a top mount intercooler (currently stock with boost referenced exterior water spray). I worry about another hot item in front of the radiator. Every summer in arizona Facebook groups there are posts about increased water temps with a front mounted intercooler. I feel the increased temps can be fixed with proper ducting. With a front mount I would get a hood with no scoop and properly vent the radiator through the hood.
Yea, plus Arizona gets super freaking hot. I have the verus block off plate, which is supposed to actually do wonders, so hopefully with the ducting (Might had to make modifications since i'll be running a FMIC) and the cooler placed somewhere else, we can finally push through an entire afternoon session without doing a cool down lap.

I've also purchased a ton of different sized adhesive foam so i can seal the OEM fan shroud to the radiator, then from there fill the outer edge of the csf radiator to the bumper beam and supports.

Ideally, i want to make a little damn on the front lower portion of the bumper and run it to the front lower portion of the FMIC, then do it on the bottom L and R corners.

Another issue i'll have is that i'm running an AEM CAI which goes down right behind the passenger fog housing, so i'd have to put the cooler on the driver's side and remove the wiper reservoir which i planned on doing anyway.
rymaggi is offline   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 12:15 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.