Increasing downforce while reducing drag?

[Bicycle Bob]

I'll just add that lift, like drag, increases as the square of speed, so there is 4X as much lift at 120 as at 60. I doubt that there is a production sedan that can ever loose as much traction to lift as it does to mild rain, let alone ice.

[lunarhighway]

i'd exeriment with an undertray, wheeldams op perhaps an airdam.

especially an undertray is a great update to any car, as it smooths out the air going underneath, but it has the added benefit of blocking out road and windnoise, and keeping your engine bay much cleaner. subjectively i'd also say that it makes my car feel a bit more stable. everytime i drove the car without it since it was fitted it felt as though the car was less stable. could just be the noise, but it's a great thing to have.

i've once experimented with windstrips for doors to seal up the panel lines between the hood, and while i didn't see a massive FE increase from this and they didn't stand up to the rain, i'd swear the car was a little more quite, wich made it feel... smoother.

experimenting with wheel airdams i found certain setups can also alter the feel of the car... these things are difficult to get right especially since the low drag and a stable feel sometimes come from different designs.

if you want to drive a normal car hard, than the first thing you'd need to upgrade are the suspention , the breaks and the tires... these things keep you from going of the road. but keep in mind that widers tires are a huge source of aero drag

the opel calibra went from 0.26 to 0.29 because wider tires where fitted, and the new mercedes e class coupé has Cd's from 0.24 up to 0.29 depending on what size tires are fitted.

[MadisonMPG]

I suggest you do this, using 3/4" plywood for stability. Don't forget your K&N.

[winkosmosis]

Originally Posted by RobertSmalls

Lift creates drag, and so does downforce. Some aerodynamic improvements (such as a kammback over your trunk) will reduce drag and lift at the same time, others (such as deleting cosmetic wings) will reduce downforce and drag.

Downforce and lift are mostly a distraction here. A few lbs added to or lifted from the tires will have a tiny effect on mpg. Pursue drag reduction whether it removes lift or removes downforce.

A kammback creates lift while reducing drag. A "diffuser" at the rear underside creates downforce while reducing drag.

[aerohead]

Originally Posted by Hermie

I know there's got to be some ways to reduce lift and give downforce while reducing drag.

Tire spats are one of them, and I've installed a pair on the rear end of my '91 Ford Tempo using material from my front license plate holder (which actually cover the whole width of the tire!)

I've seen data showing that vortex generators allow air to stay on the surface of the rear of the car better, and improving the effectiveness of spoilers (as shown by studies on the Mitsubishi Lancer Evolution VIII).. But what if you don't have a wing?

Discuss lift-reducing and downforce-making aero tricks!

Ford has already spent a few million dollars in wind tunnel development time to make sure the Tempo won't have stability issues at posted speeds.It's good that you're thinking safety,it's just that Ford can't afford for you or anyone else in a Ford product to get out of shape in a crosswind gust.

[Hermie]

TO STAY ON TOPIC: THE LIST SO FAR!

1. Roof-mounted vortex generators when a rear wing/spoiler is present

2. Tire spats

3. Rear diffuser

4. Front Air Dam

[Hermie]

I'm taking in the information, thank you very much. No need to be rude.

I was also trying to steer things back on topic.. I'm sure at least the moderators would appreciate that.

[2000mc]

Originally Posted by Hermie

TO STAY ON TOPIC: THE LIST SO FAR!

1. Roof-mounted vortex generators when a rear wing/spoiler is present

2. Tire spats

3. Rear diffuser

4. Front Air Dam

i think lunarhighway pretty much hit it on the head already

#1 you dont have one so dont worry about it
#2 try it
#3 make an undertray instead, then you could try it, without a smooth underbody it could only create drag
#4 try it unless youre trying #3

personally on my saturn i've extended the air dam so that its wider, and extends in front of the tires so its like i have tire spats in front. i haven't been able to detect any change in mileage good or bad. but i kept it on because the car seems less affected by cross winds when driving on the highway or interstate. if it improves handling any other way, it has been undectable to me.

i would also like to improve my mileage while improving handling of my own car (or as you think of it, reduce drag and improve down force) but i don't think down force or lift matters much below triple digit speeds, and if you're going that fast, you'd probably let down force trump drag anyway. if you have plenty of ground clearance for where you normally drive, and if lowering springs are available for your car, buy some. i'd like to when i can afford doing it... my tires are needing to be replaced soon, so i've been looking for tires that have the best grip and least rolling resistance.

btw, anyone know of a better tire for that in a 175 70 14 than michelin harmony that isnt worthless in snow?

[Hermie]

Tire Search Results

There's two studless ice and snow tires on the bottom, and some sticky summer treads on the 1st page for 175/70/14. Enjoy!

[NeilBlanchard]

Hi

Are you trying to improve FE, too? The spats you are referring to -- are they wheel skirts, or deflectors? (A pic or two would help.)

Nobody has mentioned a front upper grill block and/or a gasket under the front edge of the hood to seal the gap. This will reduce drag and it may even improve cooling. It might reduce front end lift, too?

A rear deck spoiler will only increase drag and it'll do squat for lift. Turbulators will add more drag, and do squat for lift.

A front belly pan (or a full length belly pan) will lower drag much more than a chin spoiler, and it would not increase the frontal area.

A Kamm back would reduce drag, and probably lower rear lift.