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Old 01-13-2020, 11:49 AM   #1
Weste46
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Join Date: Dec 2011
Location: Noblesville, IN
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My Ride: Has 280k mi.
Year: 2001
Model: 330ci
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Balance a Splitter with Spoiler

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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Suspension: Fortune Auto 500 10k/14k, TMS ARB's, Meyle FCA's, 95A FCA, 75D subframe, 95A RTA, 95A RUICA
Drivetrain: LTW FW, MFactory helical LSD, S65 mounts, 95A 5sp, 88A diff, I/H/E, open-loop EU2 tune
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Old 01-13-2020, 11:56 AM   #2
Weste46
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Attached is a picture of my current splitter (ignore the lack of rad/brake ducting), and a spoiler example.
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Suspension: Fortune Auto 500 10k/14k, TMS ARB's, Meyle FCA's, 95A FCA, 75D subframe, 95A RTA, 95A RUICA
Drivetrain: LTW FW, MFactory helical LSD, S65 mounts, 95A 5sp, 88A diff, I/H/E, open-loop EU2 tune
Brakes: Hawk DTC60/StopTech309, ECS front lines, DIY ducts
Interior: Corbeau FX1 Pro & CR1, Jaffster knob, suede wheel
Exterior: Custom CF sunroof delete
Wheels: 17x8.5 M68, 245 RS3
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Old 01-13-2020, 02:36 PM   #3
Strebor
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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/th...-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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Old 01-13-2020, 03:42 PM   #4
Weste46
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Quote:
Originally Posted by Strebor View Post
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/th...-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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Suspension: Fortune Auto 500 10k/14k, TMS ARB's, Meyle FCA's, 95A FCA, 75D subframe, 95A RTA, 95A RUICA
Drivetrain: LTW FW, MFactory helical LSD, S65 mounts, 95A 5sp, 88A diff, I/H/E, open-loop EU2 tune
Brakes: Hawk DTC60/StopTech309, ECS front lines, DIY ducts
Interior: Corbeau FX1 Pro & CR1, Jaffster knob, suede wheel
Exterior: Custom CF sunroof delete
Wheels: 17x8.5 M68, 245 RS3

Last edited by Weste46; 01-13-2020 at 03:44 PM.
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