Meph Posted July 25, 2010 Share Posted July 25, 2010 Hey guys, Im working on cutting down the drag on my Z, so far Ive made up a partial belly pan extending from the air dam to mid engine and make lower grill block from front bumper hight to air dam. After looking at the wind tunnel results it looks as though a rear spoiler actually reduces drag, but this would seem counter productive as it disrupts airflow before the two streams rejoin. I two hatches, one with a spoiler similar tot he 5" one in the wind tunnel testing, with a less aggressive curve. The second is stock. Im looking to install the one with the least amount of drag, does anyone have any experience or knowledge on the subject? Thank you Meph Incase anyone is gonna start flaming, yes I searched first but didn't got a definitive answer. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 25, 2010 Share Posted July 25, 2010 Depends on your spoiler design. The stock BRE/432 whatever you want to call the 'little kick tail' will increase drag to balance the front spoiler and give grip. The same effect can be had by ballasting the rear end of the car. Taking the kick tail off the car gained us 3 mph (140 to 143mph) on the same day at the races, in hotter less dense air (read power lost on the engine). Adding ballast (200#) in the spare tire well regained us traction at speed (half spin at 140 is not fun...) and picked up even more speed. The design of the spoiler is as important as having one there in the first place. Some will give a high drag penalty (the small kick-tail) at the tradeoff of traction. Others, not so much drag but same increase in stability/balance (Rusty Old Datsun style). It pays to experiment. Quote Link to comment Share on other sites More sharing options...
Meph Posted July 25, 2010 Author Share Posted July 25, 2010 racing aside, my biggest curiosity is if a spoiler will reduce drag over a stock hatch (as the wind tunnel tests seem to suggest). As a stock Z is about as aerodynamic as a parachute, I'm trying to find way to maximize efficiency when simply cursing around. Thanks for the input Quote Link to comment Share on other sites More sharing options...
260DET Posted July 26, 2010 Share Posted July 26, 2010 A full G nose would reduce drag more than what you have already done to the front, although that will help. On the rear, why not test the ones you already have? The rate the car slows down from a set high speed will give a useable result. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted July 26, 2010 Share Posted July 26, 2010 If you are only after cruising efficiencey I would not add ballast. It is great for high speed traction and stability, as Tonyd's experience suggests, but for up and down shifting accel/deccel around town driving its not good. There is a reason s30 ls1 cars get amazing mileage numbers eventhough their corvette counterparts have much better aero. The reason is weight. Lugging extra weight around town kills mileage. I am assuming by "maximize efficiency when simply cursing around" you mean mileage. Quote Link to comment Share on other sites More sharing options...
Meph Posted July 26, 2010 Author Share Posted July 26, 2010 Yeah looking to improve the 1jz's mileage. but when looking at the windtunnel results the spoilers all seem to to reduce the drag over stock hatch, dont seem to make sense to me Quote Link to comment Share on other sites More sharing options...
Sideways Posted September 9, 2010 Share Posted September 9, 2010 (edited) Edit: Just adding a link i enjoyed reading, has a bit of input on spoilers and shapes/angle from someone who used to be involved with racing, interesting stuff. http://www.circletrack.com/techarticles/ctrp_0707_stock_car_aero_downforce/index.html Edited September 9, 2010 by Sideways Quote Link to comment Share on other sites More sharing options...
johnc Posted September 9, 2010 Share Posted September 9, 2010 Keep in mind that a stock Z shell generates lift. That takes energy. By reducing lift you're freeing up energy. If you can reduce the lift with very little drag increase then the car can go faster. Quote Link to comment Share on other sites More sharing options...
palauoriginal Posted September 9, 2010 Share Posted September 9, 2010 Yeah looking to improve the 1jz's mileage. but when looking at the windtunnel results the spoilers all seem to to reduce the drag over stock hatch, dont seem to make sense to me what kinda of mpg's does it get anyways? i say get a g nose. your car would look great with it while improving its aerodynamics Quote Link to comment Share on other sites More sharing options...
Sideways Posted September 9, 2010 Share Posted September 9, 2010 Wonder what kind of gains ill see with some aero work i have planned, if any. Currently im getting almost 30 mpg with my turbo z. Quote Link to comment Share on other sites More sharing options...
Meph Posted September 12, 2010 Author Share Posted September 12, 2010 I can squeeze about 35 MPG out of my 1jz right now, thats on 80km/h roads driving it with fuel economy in mind. My goal is 40 mpg when alls said and done. I hope to get there with more tuning but im already on the edge with my ignition. I have left the spoiler on, and confident Ill be able to get to 40 after some more tuning, new diff (3.54 to 3.03 LSD hopefully) synthetic gear oils, new tires and an alignment. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted September 13, 2010 Share Posted September 13, 2010 40 mpg when needed and it looks a hell of a lot better than a Prius. I love it! Quote Link to comment Share on other sites More sharing options...
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