New member looking for aero advice Saturn SL1
 

I envy all of you that drive hatchbacks.

Who has an idea for how to slightly modify a sedan? I have a Saturn SL1 that I would consider modifying slightly on the rear end.

The only two things I can think of are a possible spoiler on the trunk, if it was the right shape, to help with aerodynamics. Or, I've seen spoiler-like things go on the back of a lot of newer cars right above the rear window. That would be similar to a mini-camback? Right? Would something that small even make a noticable difference?

Welcome to the site Raysp30. I would suggest you start your own intro thread. You can post all your info there and we can barage you with info. :)

Raysp30 -

If I had an SL1, I would either be :

1 - Studying the "Evo Vortex Generator" solution (what you are talking about). The idea would be to have vortex generators that help "bridge" the gap to a spoiler that helps your aerodynamics. Here's the Evo paper :

Research on Aerodynamic Drag Reduction by Vortex Generators
http://www.mitsubishi-motors.com/cor...004/16E_03.pdf

But, the likelihood of MPG payoff would be much less because the Evo solution was designed for downforce (I think), and was heavily engineered.

2 - Trying to fab a removeable Kamm-Back, probably using lots of magnets. The roof and trunk lid on the SL1 is metal, so you could work with that. The key would be a design that gives you a correct shape *and* ( relatively ;) ) easy access to the trunk.

If I can find a good side view picture of an SL1, I'll do a mockup.

CarloSW2

Yes, welcome to the forum.

I split the Saturn discussion into a new thread. Hope you don't mind.

CarloSW2, you're right that the Mistu VG's were designed to get more airflow onto the downforce-producing spoiler. But even without the spoiler, they had a very small positive effect on reducing Cd (though not likely enough to show up clearly at the pump). The change was less than 0.01, if I recall.

Wheel skirts would be a good place to start as well.

Metro - No problem at all to move to a new thread.

I'm not really into hacking up an otherwise nice looking Sedan, so creating a full Kamm-back is out of the question -- even if it was somehow removeable.

I'm already planning rear wheel skirts. And a partial undertray. I have a sheet of ABS Plastic sitting in my garage for when I have some extra time. I expect that to help some, but I'm still stuck with the stock body. By the way, anyone have a cd coefficient for the SL1 or similar car?

Raysp30 -

Here's the closest I have (1997 model year) :

http://img253.imageshack.us/img253/8...aturncdgx6.jpg

1997 SL1 was 0.315

CarloSW2

I doubt a spoiler will have much effect on aero. It looks like the 2000 SL1 and SL2 have the same CD of .32. I think the only major difference (exterior) between them is a spoiler, fog lights, and alloy wheels. Maybe an aftermarket flush/lip spoiler would be more effective, though I doubt it would be cost effective. My 1997 SC1 on the other hand, would benefit from an SC2 spoiler (SC1/.33 - SC2/.31).
I do have Vortekz brand vortex generators and smooth (full moon) hubcaps. I think I have $25 shipped (plus paint) into the VG's and $35 shipped into the hubcaps. There are pics in my garage.

www.manufacturersdepot.com Browse By Manufacturer:Vortekz Category

cripedistributing.com : 14" Stainless Hubcaps 81130-41 (4 pieces) [81130.41] - $18.00

Welcome Raysp30.If you can tell us where you're at,mpg wise,and your target mpg,that will give us a "performance envelope" to think about.Unfortunately for you,the notchback style body is the least efficient aerodynamically,however has great utility.36-percent of your future potential mpg is locked up in the air behind the Saturn.Without some changes to the back of the car,that savings will be beyond your reach.

Currently, I'm consistently getting 49-52 mpg on the highway. I have a goal of 60. So far, aerodynamically, I've only taken off the side mirror.

I didn't know these rear ends were so bad. 36% is huge!

Still interested in mods that would be aesthetically pleasing to the eye for a car like this.

On another note, and a new post in a day or so, I'm in the process of making a permanent grill block and I just finished a front belly pan. Belly pan took a couple hours to make. The grill block is a bit more complicated. I'll start a new thread when I take the time to download the pictures.