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Discussion Starter #1
Hello,

I just built a splitter and air dam setup. The splitter is a 4" overhang, and the air dam is similar to what the Miata community does.

Has anyone ran a splitter/spoiler (NASCAR style) setup on the E46?
Is there any possibility of balancing this size of splitter with a spoiler?

I was considering making a 10-12" spoiler that can go up to a 75 degree angle at the back of the car from 1/4" polycarbonate sheet.
I have had considerable understeer issues for a while now, but I want to get the car rotating mechanically, not aerodynamically. If this is will produce a huge front aero bias I will use a wing.

Thanks for your input.
 

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Discussion Starter #2
Attached is a picture of my current splitter (ignore the lack of rad/brake ducting), and a spoiler example.
 

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Nice work on the splitter! Did you make it easily removable too?

I don't have much aero experience to offer, but the research I have done overwhelmingly agrees that a spoiler is much less efficient at making downforce than a proper airfoil shaped wing. Wings are much more expensive though, I get it. This is an area that probably doesn't reward DIY too much. I'm certain you will make some downforce with a spoiler like that. I'm also certain that you will wish you had gone with a wing eventually. Might as well start at the end game.

Have you checked out Nine Lives Racing? They make an E46 kit starting at $876, https://9livesracing.com/products/the-big-wang-kit-for-bmw-e46-1997-2006 If you want to do some DIY you can just buy the element and build your own uprights/mounts/endplates. I plan on doing just that this spring. Prices start around $400 for an E46 width slab of wing.
 

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Discussion Starter #4 (Edited)
Nice work on the splitter! Did you make it easily removable too?

I don't have much aero experience to offer, but the research I have done overwhelmingly agrees that a spoiler is much less efficient at making downforce than a proper airfoil shaped wing. Wings are much more expensive though, I get it. This is an area that probably doesn't reward DIY too much. I'm certain you will make some downforce with a spoiler like that. I'm also certain that you will wish you had gone with a wing eventually. Might as well start at the end game.

Have you checked out Nine Lives Racing? They make an E46 kit starting at $876, https://9livesracing.com/products/the-big-wang-kit-for-bmw-e46-1997-2006 If you want to do some DIY you can just buy the element and build your own uprights/mounts/endplates. I plan on doing just that this spring. Prices start around $400 for an E46 width slab of wing.
Yeah I made the air dam removable with two toggle latches (not shown), and the splitter with four bolts for now. I may change two of the bolts to clevis pins to make it even easier. I have already done the "internet test", standing on it. The mounts see almost no flex. The wood sees some, 1/4-1/2", not bad at all.

I'm afraid you might be right. I was hoping to find someone who has done a spoiler. I know that small spoilers can reduce drag from cleaning up air back there, but for me to find any negative lift I would almost certainly be adding more drag...

I'm actually considering making my own wing if I need one... I have laid up carbon fiber before (my sunroof delete), and work at a wind tunnel with guys that have made wings for competition race cars before. I just don't really want to have to start another project right now since I'm falling a bit behind. I have the carbon and epoxy, but would need to make a foam core and stanchions, figure out how everything will work together... That's a big project. I'm hoping someone has gotten away with a spoiler and splitter setup before and has insight. I think I could balance a 2" splitter without adding tons of drag, but a 4" splitter is a lot.
 

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Discussion Starter #5
I've decided to make a wing. Work actually had a leftover carbon fiber symmetric foil, 8" chord 50" span. It's small, but hopefully it'll be enough. I'm going to place it in roughly the same area that the PTG racecars placed theirs. Since it is symmetric I will be cutting the top off and laying up a cambered curve on that side to hopefully help make some downforce without extreme AOA.
Eventually I will likely switch to something larger, since I'm expecting to need to run this small of a wing at an aggressive AOA that won't be very efficient. I was planning to make a 10" chord 60" width S7055 airfoil, so that might still happen.
I'll check back in once the task is complete!
 
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