TSiWRX Posted December 2, 2008 Share Posted December 2, 2008 Subscribed as well.... SSpeed, this is most interesting. I don't believe that anyone here (on LGT.com) has actually logged charge temperature. This is indeed new data. Yes, I've seen the thread with the video SeeeeeYa. Everyone here knows how highly I regard praedet's words, on everything aero-related - and definitely, I also implicitly trust Trabbic, and his video left nothing to the imagination. I just can't reconcile (OK, keep in mind that I took "physics for poets" in my undergrad days! ) the actual, real-world numbers that SSpeed sees, with the observations and calculations made in the other thread..... ??? So, other questions for SSpeed - - Do you have an aftermarket radiator "deflector?" - Any modifications to the grill or bumper skin? - Any modifications to the front undertray/splash-guard? Question for ALL - - Does the fact that SSpeed uses an aftermarket TMIC throw a curveball into this equation? <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
vet Posted December 2, 2008 Share Posted December 2, 2008 SSpeed, Any chance you can swap back to the oem tmic and check temps under similar conditions? Link to comment Share on other sites More sharing options...
TSiWRX Posted December 2, 2008 Share Posted December 2, 2008 ^ The charge temp. probe, location/installation, would be something that he'd have to re-do. <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
praedet Posted December 2, 2008 Share Posted December 2, 2008 One thought... The faster you go, the more the gearbox will heat up, period. Your temp probe is on the bottom of the tmic, right above the gearbox, and I also can't see how far into the TMIC it is sticking to make sure it is not effected too much by wall temperatures. The tailgate issue is completely separate as they will have a low-pressure region behind them that tapers and swirls as it goes back. If the region of relatively low-pressure air enters the engine bay through the grill and lower opening, it WILL pull in the higher pressure air through the scoop even more than normal... I actually think the stock TMIC would fare better on this test. It could be that both AVO and Perrin restrict flow (since they are deeper) so much that they drive up the pressure and cause an adverse pressure gradient, especially as you speed up. This would meant that the air would enter the hood scoop, but it would flow over the top of the IC instead of through it since it would not want to flow low to high... So, the Perrin and AVO allow more flow at higher psi, but sacrifice cooling ability. (use WI Link to comment Share on other sites More sharing options...
SSpeed Posted December 4, 2008 Author Share Posted December 4, 2008 One thought... The faster you go, the more the gearbox will heat up, period. Your temp probe is on the bottom of the tmic, right above the gearbox, and I also can't see how far into the TMIC it is sticking to make sure it is not effected too much by wall temperatures. I had some of the same thoughts, although I was leaning towards more hot air will come through the radiator and be forced back there. Over Christmas I'm going to insulate the part of the sensor (wiring and end piece) that is outside of the intercooler so that exterior heatsoak is ruled out... I actually think the stock TMIC would fare better on this test. It could be that both AVO and Perrin restrict flow (since they are deeper) so much that they drive up the pressure and cause an adverse pressure gradient, especially as you speed up. This would meant that the air would enter the hood scoop, but it would flow over the top of the IC instead of through it since it would not want to flow low to high... I was thinking about this as well... the AVO IC is thick, very thick, the front (top) part of the IC is very cool even when the temp probe is reading warmer, whereas the back side feels warmer from radiant heat... I also wonder if air is hitting the top, cooling that, but not making it through the thick core of fins... Subscribed as well.... So, other questions for SSpeed - - Do you have an aftermarket radiator "deflector?" - Any modifications to the grill or bumper skin? - Any modifications to the front undertray/splash-guard? Question for ALL - - Does the fact that SSpeed uses an aftermarket TMIC throw a curveball into this equation? No aftermarket radiator deflector.... No modifications to the grill or bumper skin No modifications to the undertray/splash-guard. The aftermarket IC might throw a curveball in to this from it's thickness... I'd love to see stock IC temp numbers, I can't wrap my arms around how the stock IC works very well as a heatsink removing heat from the air when it's mostly plastic, plastic isn't a good absorber of heat, but there had to be a good reason for making it plastic beyond cost... Here's another interesting point, leave the car set on a 30 deg day with the engine hot for an hour or so, and the air temp numbers inside the IC will be well over 120deg when you start the car up... that one makes a little more sense with the IC sitting right on top of the engine... Link to comment Share on other sites More sharing options...
SeeeeeYa Posted December 5, 2008 Share Posted December 5, 2008 As a result of this thread, and similar ones where I have commented on the engine cover, I have a correction to make. Up until late last week I thought I had cut and configured my engine top cover to provide for 100% of the TMIC core to get cooling air from the scoop. I was wrong. In fact, I was wrong almost two rows of fins and one air channel.... a significant omission in terms of cooling capacity. In the beginning I found adjusting the top cover to the Perrin TMIC both easy, and yet later difficult. It was easy because side to side it fit very well. Cutting back the bottom (side nearest the front) took care of that area. It was a little later that I saw the top (windshield side) covered up the last row of fins, so I trimmed it there and it wasn't so easy to both uncover the fins and at the same time ensure a seal. But last week, almost three years later, I used a bright light through the scoop opening and saw I'd made a mistake in judgeing things, saw that the rear of the scoop sealing plastic sat directly onto the TMIC EXCLUDING the last air channel and the two rows of cooling fins on either side of it. While the Perrin TMIC has always fulfilled my IC needs, mostly because I use WI, back to back runs at WOT under the most demanding temperature conditions showed that the TMIC would eventually heatsoak. Today I feel that the extra significant cooling area I uncovered will make its effectiveness even better. Certainly, touching the TMIC now shows a consistent temperature across the entire TMIC surface where before that wasn't entirely true. To "fix" the problem and ensure cold scoop-fed air to the entire TMIC while ensuring a good seal I added a sealing surface to the top of the engine cover for the scoop's plastic seal to rest upon. Now shining a bright light into the hoodscoop shows the entire TMIC is open for cooling. Link to comment Share on other sites More sharing options...
SSpeed Posted December 5, 2008 Author Share Posted December 5, 2008 I should do the same, can you give a little more details or even pictures on how you sealed the closest to windshield end after you opened up that row of fins? Link to comment Share on other sites More sharing options...
SeeeeeYa Posted December 9, 2008 Share Posted December 9, 2008 I should do the same, can you give a little more details or even pictures on how you sealed the closest to windshield end after you opened up that row of fins? Here you go: http://legacygt.com/forums/showthread.php?t=101673 Link to comment Share on other sites More sharing options...
SSpeed Posted December 23, 2008 Author Share Posted December 23, 2008 For anyone following, you might be thinking of going the same route, the controller is actually made be elabtronics, supported by elabtronics, and for sale a good deal cheaper from elabtronics. http://elabtronics.com/products_cat_accandapp_intspraycontroller.htm Link to comment Share on other sites More sharing options...
WhatV8 Posted December 23, 2008 Share Posted December 23, 2008 You guys just make my a** want to chew tobacco sometimes, really. Hey, whatever floats your boat. Now, remove your engine cover and things change. Remove your undercover and things change even more. Take both off and Subaru's billion dollars worth of R&D has been replaced with ......... ...real world experience/experimentation. Ford had invested millions in its racing programs, yet they still put the hood scoop in one of the worst locations for airflow at speed. One of the Engineers in the SVO program spoke at one of our meets and admitted that the airflow changes from in to out of the scoop above 35mph due to the low pressure zone in the middle of the hood. The early SVO prototypes had FMIC's because they worked, they received TMIC's because of cost/production demands. Subaru and its parent company started building aircraft in 1917. Do you REALLY think they do not understand aerodynamics??!! For example, the 2005 Subaru LegacyGt has a Coefficient of drag: 0.29. This is the same as the same model year Corvette. Subaru also has Sales & Marketing folks that influence the shape/style of a vehicle as well. Do they know anything about aerodynamics...not likely. I would be willing to bet a paycheck that the hood scoop design/location was chosen by a S&M member and cost dictated the TMIC. Look under your car, see those tiny 'winglets' near the wheels? More aerodynamic engineering in action. The design of the hood and hood scoop to promote laminar airflow INTO the scoop is not so obvious. That is why I stated to tape some yarn strings to your hood around the scoop and drive it around. You will see 'real world' results, no interpretation there. This technique is not all that uncommon when trying to see what the airflow is doing. Become educated, don't guess. I guess my BSME degree and senior level work with the wind tunnels on campus don't count... Link to comment Share on other sites More sharing options...
praedet Posted December 24, 2008 Share Posted December 24, 2008 ^^^Honestly, I could care less what your degree is in. There is a video of the strings on the hood idea. The hood is pulling in air in a stock set-up. I promise, this has been covered beffore... Now, is it in the ideal location to take advantage of the car's aerodynamics? I don't know. I don't have the time to do a CAD design to find out... Link to comment Share on other sites More sharing options...
700watts Posted March 13, 2009 Share Posted March 13, 2009 It seems to me that it would behoove us to have front fender vents to evacuate air from under the hood....thus lowering under the hood pressure... Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.