{"product_id":"verus-engineering-aggressive-rear-diffuser-2015-2021-subaru-wrx-sti-91w57m","title":"Verus Engineering Aggressive Rear Diffuser - 2015-2021 Subaru WRX \/ STI","description":"This rear diffuser was designed for those who want an extremely functional piece that dramatically reduces drag and increases downforce.\r\n\u003ch4 align=\"center\"\u003eABOUT THE AGGRESSIVE REAR DIFFUSER\u003c\/h4\u003e\r\n\u003cdiv class=\"container\"\u003e\r\n\u003cdiv class=\"leftColumn\"\u003e\r\n\r\n\r\n\u003cp\u003eJB Autosports, parent company of SubiSpeed and FT-86 SpeedFactory, has been working closely with Verus Motorsports for the last two years.  This is the fourth aerodynamic project between our companies.  Notable projects include the a rear diffuser for the 86 platform (\u003ca href=\"\/2013-subaru-brz\/exterior\/rear-diffusers-and-lips\/ft-86-speedfactory-rear-diffuser-2013-ft-86\"\u003esee here\u003c\/a\u003e) and front splitter (\u003ca href=\"\/2013-subaru-brz\/exterior\/front-lips\/ft-86-sf-street-performance-front-splitter\"\u003esee here\u003c\/a\u003e).\r\n\r\n\u003c\/p\u003e\n\u003cp\u003eThe main difference between Verus products and other products is in the way they are developed.  Actual data is analyzed and plays an important roll in the final design.\u003c\/p\u003e\r\n\r\n\u003c\/div\u003e\r\n\r\n\r\n\u003cdiv class=\"rightColumn\"\u003e\r\n\u003cdiv class=\"video-container\"\u003e\r\n         \u003ciframe src=\"https:\/\/www.youtube.com\/embed\/e5Bgavn2-14\" frameborder=\"0\" width=\"560\" height=\"315\"\u003e\u003c\/iframe\u003e\r\n\u003c\/div\u003e\r\n\u003c\/div\u003e\r\n\u003c\/div\u003e\r\n\r\n\u003cdiv id=\"clear\"\u003e\u003c\/div\u003e\r\n\r\n\u003chr\u003e\r\n\r\n\u003ch4\u003eSubiSpeed Installation \/ Comparison Video\u003c\/h4\u003e\r\n\r\n\u003cdiv class=\"video-container\"\u003e\r\n         \u003ciframe src=\"https:\/\/www.youtube.com\/embed\/0-E_QkIYcco\" frameborder=\"0\" width=\"560\" height=\"315\"\u003e\u003c\/iframe\u003e\r\n\u003c\/div\u003e\r\n\r\n\r\n\u003chr\u003e\r\n\r\n\u003ch4\u003eDesign\u003c\/h4\u003e\r\n\r\n\u003cp\u003eIn this latest iteration of projects, the focus has been turned to the very popular 2015+ WRX \/ STI.  The rear diffuser was designed for those who want an extremely functional piece that dramatically reduces drag and increases downforce. We believe this to be the highest downforce producing unit on the market at this time. The aesthetic goal was to blend into the vehicles exterior and integrate as if an OEM piece. We used cutting edge technologies to deliver the best fitting, best performing, and most integrated unit possible.\u003c\/p\u003e\r\n\r\n\u003cp\u003eWe started by laser scanning the entire underbody of a 2015 WRX STI. Using this scanned data in CAD, we are able to design a product that fits well, looks great, and performs with a purpose.\u003c\/p\u003e\r\n\r\n\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--yWY8ORh---\/f_auto\/v1\/content\/xvpdvozeh0nofpcgwhhe\"\u003e\u003c\/p\u003e\r\n\u003chr\u003e\r\n\u003ch4\u003eCFD Analysis\u003c\/h4\u003e\r\n\r\n\u003cp\u003eThe design was optimized through CFD analysis. Each analysis was done using a half-car analysis since no yaw testing was completed. This is done using symmetry down the centerline of the car. Significantly less computational processing power is necessary when using a half-car model and was the reason behind this analysis approach. The meshing of the car is done using first a surface mesh and then volume mesh. To find a suitable mesh size for the analysis, a grid convergence study was done. A volume mesh count of 10 million cells was considered within the room of accuracy using mesh sensitivity analysis.\u003c\/p\u003e\r\n\r\n\u003cp\u003eHow do we know we are somewhere in the realm of potential results? We use past knowledge, compared results with published aero analysis (Perrinn LMP1 model, Ahmed model, and DrivAer models to name a few), and finally we use published values for the WRX. We analyzed the stock body and compared this to the drag numbers published by Subaru; we were within a few percentages. For a CFD analysis, this is good and within the accuracy necessary to predict real world performance. This analysis was performed at stock ride height.\u003c\/p\u003e\r\n\r\n\u003cp\u003eThe CFD post-processing offers both visualization of the flow and numerical data. Using both of these we can make educated guesses as to the changes to make to optimize parts of the system to reach design goals. Surface pressure plots allow us to visualize the location of high and low pressure very easily and shows where and how the component is working.\u003c\/p\u003e\r\n\r\n\r\n\r\n\u003chr\u003e\r\n\r\n\u003cdiv class=\"container\"\u003e\r\n    \u003cdiv class=\"leftColumn\"\u003e\r\n               \u003ch5\u003eFig. 2: Rear Diffuser with Pressure Plot on Surface, With and Without Contour Lines\u003c\/h5\u003e\r\n\r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--ySmZrJ5T--\/f_auto\/v1\/content\/qblxhn5pmuxjajhe9d6n\"\u003e\u003c\/p\u003e\r\n\t\u003c\/div\u003e\r\n    \u003cdiv class=\"rightColumn\"\u003e\r\n\r\n                \u003ch5\u003eFig. 3: Air Pressure Plot of WRX Rear Diffuser\u003c\/h5\u003e\r\n               \r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--MUFfF1WX--\/f_auto\/v1\/content\/cxejbrywyxihv4xi7j1x\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\r\n              \u003cp\u003eAir pressure plots allow us to see how the parts are influencing the air around the vehicle.\u003c\/p\u003e\r\n\t\u003c\/div\u003e\r\n\u003c\/div\u003e\r\n\r\n\u003cdiv id=\"clear\"\u003e\u003c\/div\u003e\r\n\r\n\u003chr\u003e\r\n\r\n\u003ch5\u003eFig. 4: Air Velocity with Contour Lines\u003c\/h5\u003e\r\n               \r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--IPz05pGx--\/f_auto\/v1\/content\/pzo3dthzjutj95zebmkq\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\r\n               \u003cp\u003eAnother powerful visualization is air velocity.\u003c\/p\u003e\r\n\r\n\u003ch5\u003eFig. 5: Side View Air Velocity Plot with Streamlines on Body\u003c\/h5\u003e\r\n               \r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--4z8Oey3s--\/f_auto\/v1\/content\/pfbf9m1cbdrkxdbctkvn\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\r\n \u003chr\u003e\r\n\r\n\u003cdiv class=\"container\"\u003e\r\n    \u003cdiv class=\"leftColumn\"\u003e\r\n               \u003ch5\u003eFig. 6: Surface Streamlines With and Without Pressure Plot on Diffuser\u003c\/h5\u003e\r\n\r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--3XwXLvtU--\/f_auto\/v1\/content\/tceqrnzqkneyv5mbqavx\"\u003e\u003c\/p\u003e\r\n\r\n              \u003cp\u003eFinally, we get to vector plots with the CFD analysis, which allows us to view magnitude and direction of air velocity.\u003c\/p\u003e\r\n\r\n\t\u003c\/div\u003e\r\n    \u003cdiv class=\"rightColumn\"\u003e\r\n                 \u003ch5\u003eFig. 7: Air Pressure Plot with Vectors Included\u003c\/h5\u003e\r\n               \r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--8qII7GVT--\/f_auto\/v1\/content\/wleah5uncll9nzv0dhma\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\r\n              \u003cp\u003eFinally, we get to vector plots with the CFD analysis, which allows us to view magnitude and direction of air velocity.\u003c\/p\u003e\r\n\t\u003c\/div\u003e\r\n\u003c\/div\u003e\r\n\r\n\u003cdiv id=\"clear\"\u003e\u003c\/div\u003e\r\n\r\n\u003chr\u003e\r\n\r\n\u003ch5\u003eFig. 8: Vector Arrows on Symmetry Cut Plot\u003c\/h5\u003e\r\n               \r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--tCRsYX5i--\/f_auto\/v1\/content\/alkhcrq8k9qhrf9muc32\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\r\n               \r\n\r\n\u003ch5\u003eFig. 9: Comparison plot, OEM on Top, Diffuser Added on Bottom\u003c\/h5\u003e\r\n               \r\n\t\t\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--bbRLSuc7--\/f_auto\/v1\/content\/n8gwsnrayuzne2thj47m\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\r\n                \u003cp\u003eOne last view we wanted to see was a before and after.\u003c\/p\u003e\r\n\r\n\u003chr\u003e\r\n\u003ch4\u003eData\u003c\/h4\u003e\r\n\r\n\u003cp\u003eThe rear diffuser decreases lift dramatically and reduces drag quite a bit. It also shifts the aero balance rearward which is a good thing with a front weight biased vehicle. The lift coefficient decreased significantly but is not negative yet; which means the WRX is not creating downforce but is very close to.\u003c\/p\u003e\r\n\r\n\u003cp\u003e\u003cimg src=\"https:\/\/images.jbautosports.com\/image\/upload\/s--uj0M7vHM--\/f_auto\/v1\/content\/vebkvsynurf1rmlizthq\" width=\"98%\"\u003e\u003c\/p\u003e\r\n\u003chr\u003e\r\n\u003ch4\u003eConclusion:\u003c\/h4\u003e\r\n\r\n\u003cp\u003eThese results are logical to us and are reasonable gains in aerodynamic performance for a component of this nature. Most OEM cars produce lift in stock form, which our analysis backs up. This is the floating feeling you feel when reaching triple digit speeds. A 4% reduction in the coefficient of drag is actually quite large for a product of this nature and an 81% reduction in lift is a plausible result from such a component as well. Logically, the results above make sense to us.\u003c\/p\u003e\r\n\r\n\u003cp\u003eReal world benefits may differ as this is a computational analysis which simulates real world results. Simulations, both computer (CFD) and real world (wind tunnel) generated, are inherently riddled with inaccuracies which can skew results. Something as simple as ride height or wheel choice can vary results, as well as various other aspects. Real world results could be better or worse than what is shown above. We must remember though, given the model we started with, the above data is accurate and should translate to a real world benefits.\u003c\/p\u003e\r\n\r\n\u003cp\u003eVery few companies perform CFD or wind tunnel analysis on any of their aerodynamic pieces. As a consumer you can rest assure that you are receiving a quality component with an engineering analysis that has proven to benefit the vehicles characteristics.\u003c\/p\u003e\r\n\u003chr\u003e\r\n\u003ch5\u003e\u003cul\u003eConfirmed Exhaust Fitment:\u003c\/ul\u003e\u003c\/h5\u003e\r\n\r\n\u003cp\u003eStock Exhaust - STI and WRX\u003cbr\u003e\r\nAgency Power Exhaust\u003cbr\u003e\r\nBlitz Nur Spec\u003cbr\u003e\r\nBlitz Nur Spec F-TI\u003cbr\u003e\r\nBorla Exhaust\u003cbr\u003e\r\nCobb Exhaust\u003cbr\u003e\r\nCorsa Exhaust\u003cbr\u003e\r\nETS Exhaust Sysemts\u003cbr\u003e\r\nGreddy Supreme SP\u003cbr\u003e\r\nHKS Hi-Power (all)\u003cbr\u003e\r\nHKS Legamax\u003cbr\u003e\r\nHKS Super Turbo\u003cbr\u003e\r\nInjen\u003cbr\u003e\r\nInvidia N1 single and dual\u003cbr\u003e\r\nInvidia Q300 dual\u003cbr\u003e\r\nMagnaflow Exhaust\u003cbr\u003e\r\nMilltek Exhaust System\u003cbr\u003e\r\nMishimoto\u003cbr\u003e\r\nNameless axle and cat backs\u003cbr\u003e\r\nPerrin\u003cbr\u003e\r\nRCE Clubsport\u003cbr\u003e\r\nSubiSpeed \u003cbr\u003e\r\nTurbo XS\u003cbr\u003e\r\nX Force\u003c\/p\u003e\r\n\r\n\u003chr\u003e\r\n\u003ch5\u003e\u003cul\u003eConfirmed Exhausts that do not fit:\u003c\/ul\u003e\u003c\/h5\u003e\r\n\r\n\u003cp\u003eInvidia N1 Single  ( trimming needed )\u003cbr\u003e\r\nTomei Type 80 ( trimming needed )\u003c\/p\u003e\r\n\r\n\u003ch4\u003eInstructions\u003c\/h4\u003e\r\n\r\n\u003cp\u003eSee \"additional\" tab.\u003c\/p\u003e","brand":"Verus Engineering","offers":[{"title":"Default Title","offer_id":45712674717782,"sku":"VERA0028A","price":273.88,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0741\/0411\/1190\/files\/loxo8cgoppkt_1c588514-26d5-4d6c-ba72-4d4900d44fab.jpg?v=1788783908","url":"https:\/\/truegearus.com\/products\/verus-engineering-aggressive-rear-diffuser-2015-2021-subaru-wrx-sti-91w57m","provider":"TrueGear","version":"1.0","type":"link"}