DadMod Posted November 2, 2018 Share Posted November 2, 2018 Has anyone tried to make any modifications to increase the air flow through the stock TMIC on the 5th Gen LGTs? I'm talking specifically about the cooling air and not the air to the engine. The stock plastic engine cover obviously serves a purpose, but the hood scoop opening isn't all that big. Inside of the scoop has a metal plate that doesn't seem to be placed that well, and it doesn't extend across the entire width of the scoop. Just one idea, I'm open to anything related to air flow: Does it make sense to try to bend this metal plate to a better angle and then add something to both sides to extend it all the way across? Completely random side question: Do dynos typically underestimate horsepower because air is not flowing through the intercooler, or do they usually ice them beforehand? Link to comment Share on other sites More sharing options...
Sarang Posted November 2, 2018 Share Posted November 2, 2018 Good timing: I have the plastic painted outside piece of my scoop off right now so that it can be repainted and I was thinking about this type of thing. It looks like the painted piece directs air back in to the inner metal plate, but the actual opening in the hood is significantly bigger and there's more room if you wanted to get adventurous with the tin snips. If someone made a replacement outer painted piece and inner metal plate, I bet you could double the cross section of the opening. I'm not so sure that bending that would make a difference. I would suggest taking it apart and seeing how it all fits together; it;s just a few clips, screws, and nuts. Do you still have the OEM TMIC? My understanding is that a bigger intercooler helps partly from heat rejection, but also significantly just as a larger heat sink that takes longer to heat up. Side question: My dyno tuner did not, but the final thing he did was a couple of street pulls, with me driving and him on his laptop in the passenger seat. My etune was (of course) all street pulls. I have seen pictures of other tuners with fans forcing air in the intercooler. Link to comment Share on other sites More sharing options...
Scubaboo Posted November 2, 2018 Share Posted November 2, 2018 OP, I've been pondering at this myself and scouring the web for info on this. It has been kindly documented by tuner Fahr_side that the scoop opening is a limiting factor. The scoop opening follows the line of the hood so there is no way to replace just the opening to make it bigger. There are scoops that go over the existing one that have correspondingly bigger openings (but only slightly) made by Corazon and a few others. They havent helped much in actual testing according to Fahr_side. I wouldnt futz with that metal plate. In my unedcated eye and opinion it is there to divert a portion of the flow to the bottom half of the cooler, to sort of equalize the area the air hits. I imagine without it the air flows into the scoop, then hits the rear of the scoop, then funneled down, mostly cooling the top half of the cooler. If the bottom plate is too effective, it may adversely affect flow to the top of the cooler. That is, unless there is some way to test the flow to optimize the plate angle and coverage. I assume Subaru would have done that and wouldnt alter it without data. But given how they futzed up the scoop my mind is open on the plate, if someone can show a better design for it. Link to comment Share on other sites More sharing options...
Scubaboo Posted November 2, 2018 Share Posted November 2, 2018 Good timing: I have the plastic painted outside piece of my scoop off right now so that it can be repainted and I was thinking about this type of thing. It looks like the painted piece directs air back in to the inner metal plate, but the actual opening in the hood is significantly bigger and there's more room if you wanted to get adventurous with the tin snips. If someone made a replacement outer painted piece and inner metal plate, I bet you could double the cross section of the opening. I'm not so sure that bending that would make a difference. I would suggest taking it apart and seeing how it all fits together; it;s just a few clips, screws, and nuts. Do you still have the OEM TMIC? My understanding is that a bigger intercooler helps partly from heat rejection, but also significantly just as a larger heat sink that takes longer to heat up. Side question: My dyno tuner did not, but the final thing he did was a couple of street pulls, with me driving and him on his laptop in the passenger seat. My etune was (of course) all street pulls. I have seen pictures of other tuners with fans forcing air in the intercooler. From what I came across online, I think it may have to do with how ducts work. I saw reference to how the opening and outlet were related/proprtional in size to the other. I hope someone smarter than me sees what OP and Sarang see and gets a lightbulb moment, and finds a flow improvement that is backed up by logs or the dyno. On the TMIC as heat sink, as I understand Fahr_side the TMIC should increase performance from efficiency BUT because of our air flow problems it helps more by being a bigger heat sink instead. On the Forester forums it was mentioned in the SG9 VF48 threads that bigger scoops didnt help on the dyno but were noticeable on the street. No data was given though, just passing it along. Link to comment Share on other sites More sharing options...
islandborn Posted November 2, 2018 Share Posted November 2, 2018 You could always get a smaller TM.... Link to comment Share on other sites More sharing options...
FLlegacy Posted November 2, 2018 Share Posted November 2, 2018 If you really want to improve that airflow over the tmic, the better bet would be to retrofit the ducting on the hoodless turbo Subarus. Then you are feeding air from the point of highest pressure, the scoop looks cool but when you look at the profile and how the air flows over the car, the flow into the hood scoop is an afterthought compared to what hits the frontal area of the car. Link to comment Share on other sites More sharing options...
Perscitus Posted November 2, 2018 Share Posted November 2, 2018 You could always get a smaller TM.... LOL, you mean an engine oil or transmission fluid cooler AFTER you've eliminated the TMIC and replaced it with a FMIC. Then there are also the gizmo-gadget flavors such as the Verticooler or a water-to-air TMIC setup. But buying most of these things is just throwing money away with a DD. Nowadays, especially if not dealing with DI and HPFP limitations, its far better just to get a flex-tune to the sound of say E30 or E40 and keep the motor and support assemblies bone stock. Plenty of oomph from good'ol ICE when you want/need it and back to stock when you don't. Money saved can go into suspension, brakes, comfort, interior cosmetic mods or better yet - anything but cars. Link to comment Share on other sites More sharing options...
Scubaboo Posted November 2, 2018 Share Posted November 2, 2018 You could always get a smaller TM.... Link to comment Share on other sites More sharing options...
Sarang Posted November 2, 2018 Share Posted November 2, 2018 FWIW here's a pic of my scoop without the painted piece: https://imgur.com/a/KdNcXdO You can see there's some potential room for expansion. IT would be cool if someone fabbed up a more aggressive scoop that replaced the painted piece and funneled more air down through, but I wouldn't want to pay for it. Link to comment Share on other sites More sharing options...
islandborn Posted November 2, 2018 Share Posted November 2, 2018 FWIW here's a pic of my scoop without the painted piece: https://imgur.com/a/KdNcXdO You can see there's some potential room for expansion. IT would be cool if someone fabbed up a more aggressive scoop that replaced the painted piece and funneled more air down through, but I wouldn't want to pay for it. Thats what you do to attach the corazon fit piece. I would imagine that the large opening should push more air into the bay.... just acts like a bigger mouth - like on a funnel... but I'm no air engineer. of course sitting on a dyno would not really benefit unless you can duplicate 70mph winds with a fan. I have no understanding why I can sit my photo right... Link to comment Share on other sites More sharing options...
Scubaboo Posted November 2, 2018 Share Posted November 2, 2018 ... I have no understanding why I can sit my photo right... Since you have a front mount the wind pushes so much harder on the scoop, causing the pic to fall on its side. Front mount would have been great but its too much work for me. Link to comment Share on other sites More sharing options...
moral hazard Posted November 3, 2018 Share Posted November 3, 2018 I'd like to see more engine bay shots of the front mount. Link to comment Share on other sites More sharing options...
dgoodhue Posted November 4, 2018 Share Posted November 4, 2018 A bigger opening with same restriction at the base doesn't necessarily mean better air flow. The bigger opening may create more turbulence and less air flow. An example in intake porting of port mismatches, in general a bell mouth (rounding of the edge) has better airflow than a funnel shape(ie gradual transition) even though it may seem like it would intuitively flow more air. Link to comment Share on other sites More sharing options...
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