I'm starting to go down the aero rabbit hole with my Hyundai Tuscani (Tiburon). I've already done some ducting and blocking off of useless holes. I'd like to decrease drag, increase cooler efficiency and make a little bit of downforce. However, I want the car to look stock or near stock and it has to clear speed bumps and sit happily in traffic.
Here's what I've already done. https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/rocinante-the-hyundai-avante/101123/page3/
One place to start is the rear bumper. Many older stock rear bumpers create a nasty parachute effect at speed, so you can either cut it upward for better flow or eliminate the parachute by using coroplast or a similar material to block wind from entering. It's a common ecomodder tweak.
I want to see the airflow or some before/after testing to see if it's actually a "parachute" effect. It's a popular viewpoint for sure.
Looking at the car, I think you'll get the majority of your gains from some different wheels and as flat an underbody as you can manage. If you're trying to improve cooler efficiency and front downforce, some venting in the hood is an easy option.
Keith Tanner wrote: I want to see the airflow or some before/after testing to see if it's actually a "parachute" effect. It's a popular viewpoint for sure.
Didn't GRM have an article about this recently? I added one of these to my amazon cart after reading it (I think it was specifically about spoilers, and hood vents on their Mustang IIRC).
Maybe poke around with one of these and see if there arent any obvious areas in need of improvement.
Edit: it wasn't an article, it was a live feed on facebook. You'll need access to the books of faces, but it's definitely worth a watch. video
In reply to Keith Tanner:
I plan to flatbottom this car eventually but I'm worried about overheating. I'd definitely need a vented hood first but I'm not sure how aggressive I need to be on that front. How much venting do you think a track driven, 300~ish horsepower turbo car would need if the heat can't escape downwards anymore?
The main purpose of venting the hood is to increase the flow across the radiator by increasing the pressure differential. Better cooling. It also helps increase the pressure on top of the hood, so more downforce. And if that pressure goes out the top, it won't go anywhere else. A track driven 300 hp car can benefit from some very big holes in the hood because it needs a lot of flow across the heat exchangers. I'd probably aim for a couple of square feet of hole.
The biggest concern I have with heat control on an flat underbottom is trapping the radiant heat from the exhaust and what that means for the diff and transmission - especially on a RWD.
The magnehelic gauge can help you locate the most effective location for the vents. I've got one in the shop, they're a really fun toy. Haven't tried putting one near the rear bumper. I suspect the improvements people might be seeing by putting a flat panel underneath is not from prevent a parachute but from giving a smoother surface for the air and a more gradual transition from undercar to behind the car.
even a flat underbody under the engine can be louvered with some fairly aggressive flaps. Think of the louvered hood that GRM recently put on their mustang track car. I bet something like that UNDER the car would help cooling and help airflow across the bumpy bottom
As for the rear bumper, if it is causing drag and you want to keep the car looking mostly stock. I would think some sort of vent in the license plate area would look pretty factory normal
Just use a hole saw on the bumper like the Honda bros do. Do a before and after at the 1/4 mile. Compare results. No change? No help. And you ruined that bumper for life. Lol.
Trackmouse wrote: Just use a hole saw on the bumper like the Honda bros do. Do a before and after at the 1/4 mile. Compare results. No change? No help. And you ruined that bumper for life. Lol.
Yeah those holes are never a good idea...even when they do help (they can make things worse), blocking off the bumper from below with a coroplast flat bottom is just as aerodynamically effective and aesthetically better.
More on-topic about streetable aero stuff, supercars are a good example of the most you can get away with. They have splitters, flat bottoms and diffusers, but the splitters aren't big and they have 4" of ground clearance, which I consider to be the bare minimum for safe street use. Less than that and you get beached on speedbumps.
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