[shwayne5]

At the risk of being esoteric, I’m putting this out there even if the chances of someone who’s done this are pretty remote.

I have turned my g80 m3 into a dedicated track build. I’m right at the limit of mechanical grip, weight savings (minus carbon) thus far. I am looking to add meaningful aero to the car. The problem is, no one has created a “bolt on” kit for our cars. And I’m getting the feeling from many of the usual companies that the g87 is their only priority. I get it because if someone is going to turn their g8x into a track/time attack car most of them will be g87 owners at this point.

I am looking for anyone who has done an aero scan of a G80 M3. It’s an intensive process that I was quoted 3 full days of labor on. And even if I did pay for it, I’d be giving the R&D to whatever company I use to create the aero. That’s not my goal unless they’re going to pay for the labor.

To be clear, I’m not looking for huge aero which will make the car non-street drivable. This mainly comes down to the splitter not sticking out from the front more than 4-6 inches. The wing can be relatively big as long as it’s not wider than the widest part of the car. Thanks!

[NYG]

I work with wind tunnels often but for structures. Be prepared to spend ridiculous money on this. I'm assuming you were quoted to see what the current flow characteristics of your car are including drag/vertical loads. The problem with this is that the moment you tweak one aero component, the behavior and flow characteristics for the entire car changes - sometimes A LOT. Especially if you're on stock suspension. You really need a stiff racing suspension to be able to tweak things properly.

I know my fluid mechanics but I'm not an aerodynamicist so I can't give you a real deep look into this but just some general advice.

The most cost effective way is to lower the car as much as you can and seal the underside as much as you can paired with a good diffuser. It's a low drag, highly effective method of getting downforce. Then determine on the track where you're lacking grip (front or rear) and adjust to your driving preferences.

Another thing I've seen a lot of TT guys do and actually most of the lower-mid range aero manufacturers do this as well, is to work entirely off CFD models but those things are extremely easy to screw up, especially if an amateur is modeling it and sometimes even if the model is good, it doesn't always provide 1:1 results in reality. Software is getting a lot better. A few years ago, getting an accurate CFD model was a pain in the ass.

Either way, my clients spend 40-75k on wind analysis for scaled models of 40-50 story buildings so I really don't advise you go this route unless you're racing professionally and it's a dedicated race car.

[shwayne5]

Originally Posted by NYG

I work with wind tunnels often but for structures. Be prepared to spend ridiculous money on this. I'm assuming you were quoted to see what the current flow characteristics of your car are including drag/vertical loads. The problem with this is that the moment you tweak one aero component, the behavior and flow characteristics for the entire car changes - sometimes A LOT. Especially if you're on stock suspension. You really need a stiff racing suspension to be able to tweak things properly.

The quote was informal but looked like 3 days of labor rate just for the scan. Not sure that would provide drag or vertical loads. This is something I’m unfamiliar with.

I am on full SPL, MCS 3-way, with H&R sway bars (only sway bars offered a few months ago, not sure this has changed) This is a dedicated track build. Don’t have a car hauler at this point so street driving to and from track is still required.

I know my fluid mechanics but I'm not an aerodynamicist so I can't give you a real deep look into this but just some general advice.

The most cost effective way is to lower the car as much as you can and seal the underside as much as you can paired with a good diffuser. It's a low drag, highly effective method of getting downforce. Then determine on the track where you're lacking grip (front or rear) and adjust to your driving preferences.

It’s as low as it can go with the suspension/tire setup I have. 305/35/19 x4. But I appreciate the point you’re making. I do wonder if I add a cf hood with louvers if it would cut down on lift. Also lower IAT. This is theoretical…

Another thing I've seen a lot of TT guys do and actually most of the lower-mid range aero manufacturers do this as well, is to work entirely off CFD models but those things are extremely easy to screw up, especially if an amateur is modeling it and sometimes even if the model is good, it doesn't always provide 1:1 results in reality. Software is getting a lot better. A few years ago, getting an accurate CFD model was a pain in the ass.

CFD is probably the best bet. Thanks for all of the helpful info.

Either way, my clients spend 40-75k on wind analysis for scaled models of 40-50 story buildings so I really don't advise you go this route unless you're racing professionally and it's a dedicated race car.

See answers next to comments etc

[NYG]

Originally Posted by shwayne5

See answers next to comments etc

So you'd essentially be looking for vertical deflections @ various speeds on each spring/tire to understand where your aerodynamic center is and how many lbs of force are being applied.

Nice setup on the suspension! Seems like you know what you're doing.

Are you dealing with front end lift? If so is it in the corners or at higher speeds the front end gets light?

[shwayne5]

Originally Posted by NYG

So you'd essentially be looking for vertical deflections @ various speeds on each spring/tire to understand where your aerodynamic center is and how many lbs of force are being applied.

Nice setup on the suspension! Seems like you know what you're doing.

Are you dealing with front end lift? If so is it in the corners or at higher speeds the front end gets light?

Honestly it’s not terrible at higher speeds, just looking to mitigate any that I am getting plus add additional downforce. And I’m guessing that if I add a wing without adding downforce or reducing lift in the front, I’ll be getting more lift. But I’ll be the first one to admit that I am way outside of my knowledge base. And given the complexity of aerodynamics, no one locally is very well suited to address it. So it’s either wait until someone finally addresses it properly or pay way too much money to have my car be the guinea pig. That doesn’t sound like a good route to go.

[NYG]

Originally Posted by shwayne5

And I’m guessing that if I add a wing without adding downforce or reducing lift in the front, I’ll be getting more lift.

For sure. You'll move the aerodynamic center toward the back and have more vertical deflection on the rear springs. You'll get way better traction on power but your turn-in will suffer. I also prefer more front end. I ran a pretty aggressive front rake on my F82 and it helped a lot.

Trial and error is the best way to go.