Hi, I'm new here and my cD is .37, can you help me get a .30?

[AutoDeutchland]

Ok, so here is my crossfire. Now I've already checked out the big mod list, but different cars get different amounts of benefit from each mod. So I was hoping you would all take a look at my car and identify the "biggest mods" and estimate how many points they would drop me. Thanks a bunch.

[razordave]

Grille block, air dam and boat tail and you'll be good.

[AutoDeutchland]

Really? I can get down to a .3 with just that? I already pulled my wipers. Whats that good for? .005 cD?

[jeff88]

How crazy are you willing to go? Do you care about looks at all?

I don't think an air dam is going to help you much, since you're already so low to the ground. A grill block on the top would definitely help and blocking as much of the bottom as possible while still having cooling would be good.

The rear hatch looks like it has a sharper angle than the template. Have you tried using the template yet? If you're going for looks a kammback to bring you back to template would be nice. If you don't care about looks, then a boat tail would help.

What does the undercarriage look like? With how low to the ground you are, a full belly pan might be the best way to go assuming you have a lot of parachutes hanging around underneath the car.

Try finding some wheels that are more "covered" or use some coroplast or other material to cover the ones you have. Wheel spats would also be useful.

You might consider running a sheet of coroplast from the hood bent up to the windshield to give the air a better approach angle. You could also hide your wipers underneath it. This would be a finishing touch though, the other stuff is lower hanging fruit.

Good luck!

[AutoDeutchland]

Heres my underside. Also has a front pan. Exhaust has since been removed and routed out the front fenders

[NeilBlanchard]

Removing the wipers is good for almost nothing; especially on this car with the long nose.

To get the Cd down 0.07, you will need smooth wheels, Kamm back, grill block, sealed front seams, mirror delete - at least - and probably a smooth belly pan, and maybe even a boattail, too. The shape of this car is better backward than forward.

[jeff88]

As far as your belly goes, you have a really good start, but you could definitely improve upon it, especially if you moved the exhaust pipes. If there is nothing hot running down the underside anymore, you can do a near complete belly pan to fill all the "holes".

Here is a rough idea of the template on your car. You'll need to fill in the voids as best as possible to lower your cD.



Is there an option for a spoiler from the factory or an aftermarket one that is specific for this car? If you don't want to do a kammback, a spoiler might help fill the void and still look OEM.

A rear diffuser would also probably help considering the sharp, vertical cutoff of the rear bumper. A clean belly transferring to a properly design diffuser would help a lot.

Do you have any pics of the new exhaust setup?

[AutoDeutchland]

ok, well right off the bat, I will completely seal off the mostly fake lower grills and fog lights. I will use bondo and polish the whole bottom half of the bumper. I will also make a completely smooth pan from front to back and make some aero lenses for the headlights. About how many points is each of these good for?

And thanks for taking the time to make that photo!!!!!!!

[jeff88]

Originally Posted by AutoDeutchland

ok, well right off the bat, I will completely seal off the mostly fake lower grills and fog lights. I will use bondo and polish the whole bottom half of the bumper. I will also make a completely smooth pan from front to back and make some aero lenses for the headlights. About how many points is each of these good for?

Sounds like a good starting plan. I would probably start with the grill block and then move on to the belly pan. The other way around will yield the same results in the end, but I imagine the grill block will have a better effect by itself. The belly pan will have a better impact when you have the grill blocked off, forcing the air to go somewhere else (e.g. underneath the car). I'm not sure how many points your plan will get you, maybe NeilBlanchard can help with that.

Originally Posted by AutoDeutchland

And thanks for taking the time to make that photo!!!!!!!

No problem! I forgot to post the link so you can mess around with it: Aero Template

I also found a pic with the spoiler I was talking about. It's not the best photo since it's not a true profile, but you can get the basic idea. Notice how the spoiler helps fill the void and "touch" the line of the template (it probably would if the photo was correct)? Depending on how the spoiler actually works, this might help with the template, but hurt in terms of increasing down force at the expense of drag. I'm sure NeilBlanchard or AeroHead would be able to help in that department.

EDIT: Forgot to add in the pic!

[freebeard]

That's a very nice car. The drivetrain is from Mercedes, is it not? Please don't cover it with coroplast.

What's the use case? Race? Commuter? Show car?

You could possibly push it well below 0.30, but what is working against you is called fineness ration, IOW it's short and stubby. jeff88's overlay doesn't show any extension at all. A complete boattail would be approx. as long as the wheelbase of the car. So it comes down to how much 'pain' you can tolerate.

I'd leave the car completely stock and add a single wheel trailer like BamZipPow's, but finished to a level to match the car.



Else you could consider a hitch mount like HHOTDI:



He saw a positive benefit dragging around a brick. Imagine what an aeropod would do.