SCCA CAM-C Thread

[NightmareMoon]

In other sanctioning bodies this is determined by the plan (top) view of the bumper, not the stock splitter.

If you were to take a plumb-bob & hang it over the bumper, that would define your datum. The splitter is allowed to protrude 6" beyond that (imaginary) line.

The GCR would have the proper SCCA definition, but I'm away from home presently & don't have one available to check.

Yeah, I'm just struggling with the factory splitter/airdam/lower valance versus 'bumper'. I think you're right, but that messes up my plan . Lets see if the SCCA will respond to an email for absolute clarification.

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[TeeLew]

Yeah, I'm just struggling with the factory splitter/airdam/lower valance versus 'bumper'. I think you're right, but that messes up my plan . Lets see if the SCCA will respond to an email for absolute clarification.

I've never actually put eyes on this particular rule, so I hesitate to make any real statement, but rules generally tell you what you don't want to hear.

To share an unrequested thought, I think you could produce the downforce you need without resorting to a splitter longer than 6" by working under the nose & in the wheel wells. I have no idea what you've already done, but I know it's quite a bit. Splitters can be a mixed blessing. They're powerful as hell, but they also introduce ride height & pitch sensitivity issues which can make the overall setup difficult to drive and tune.

 

[SteveW]

On my GT PP the most the factory splitter extends forward of the bumper is 1 5/8"ish at the pointy parts on each corner. Most of it is barely a half in forward of the bumper.

 

[NightmareMoon]

Finished my DIY CAM aero project. I did get an email replay from scca rallysolo (unsigned so I don’t know who), to my question about the splitter and they indicated that their read on the CAM rules was the splitter would measure from 6” from the plastic cover over the crash bar (implying not from the lower bumper plastic or front valence), so I cut back my original splitter to conform. The rear lexan spoiler is just less than 10” too, but it looks massive.

I’m satisfied with how it all turned out and I’ll get to test it all at a local event tomorrow to find out how the balance has changed at speed.

 

[Dana Pants]

That looks so bad ass. Good luck.

 

[kz]

I’m satisfied with how it all turned out and I’ll get to test it all at a local event tomorrow to find out how the balance has changed at speed.

Did you have to drill the trunk for the spoiler rods ?

 

[NightmareMoon]

Did you have to drill the trunk for the spoiler rods ?

Yeah, I found a cheap deal on a black take-off factory deck lid with the stock spoiler holes so I used all of those for the brackets (and widened a couple), and then drilled 4 additional holes for the support rods.

Its not too bad to swap trunks, so the plan is to switch back to my stock trunk when I'm not in race mode. You can see my factory deck lid in the background here.

 

[shogun32]

got a bigger pic? I note a distinct lack of sponsorship decals, friend.
are the 'tabs' on the front/leading face or on the trailing? Would seem ripe for flutter and pulling thru.

 

[Dana Pants]

Made up sponsors only please.

Perhaps the most primitive tool utilized in the making of the vehicle.

Recently I honored the discoverers of the tetanus vaccine as I raced the rustiest Miata I’ve ever seen.

 

[NightmareMoon]

Made up sponsors only please.

Perhaps the most primitive tool utilized in the making of the vehicle.

Recently I honored the discoverers of the tetanus vaccine as I raced the rustiest Miata I’ve ever seen.

Well its sort of the other way around. In this project I sponsored Home Depot, Lowes, McMaster, Fellers...

A local guy has a big "Thanks Mom" on his new neon green D-Street Camaro XD.

Most primitive tool was probably the BFH to bend some of the brackets. Hard to get more crude than a sledge hammer. The part I'm secretly the most proud of is the $10 garage door weatherstripping and $4 in plastic push clips that makes up the airdam (sshhh don't tell anybody)

 

[NightmareMoon]

got a bigger pic? I note a distinct lack of sponsorship decals, friend.
are the 'tabs' on the front/leading face or on the trailing? Would seem ripe for flutter and pulling thru.

no movement at all at 80mph, haven’t tested it at higher speeds yet, but these 8mm bolts and large washers on the back of the rod supports seem pretty sturdy. The base of the spoiler is supported from behind so IDK.

Its my first try at something like this and I have plenty of Lexan left over so if it flies off, its no big deal.

and yes you can stand on the front splitter . Scary to try that on something that took as long to build as this took me but it was fine. A rod collet slipped when I did so I’m glad I tested it.

 

[TeeLew]

That looks really good on both ends, Nightmare. I've got to think you'll be able to feel it. How close are you to the top of the spoiler protruding beyond the rear bumper? Leaning it back will gain plan view surface area, but you can only go so far. Side fences on the spoiler might gain a bit of pressure & add rigidity.

I love the approach. Drag be damned...we're gonna make some stick! It's almost always the way to go...unless you happen to be at Daytona.

 

[shogun32]

how much downforce does such a rear spoiler create? I thought the idea was to trap air in the 'pocket' so the air coming off the roof stayed laminar and didn't tumble in a vain effort to follow the window down. The chaos behind the vertical trunk plane has gotta be horrible.

 

[NightmareMoon]

Today looks really good on both ends, Nightmare. I've got to think you'll be able to feel it. How close are you to the top of the spoiler protruding beyond the rear bumper? Leaning it back will gain plan view surface area, but you can only go so far. Side fences on the spoiler might gain a bit of pressure & add rigidity.

I love the approach. Drag be damned...we're gonna make some stick! It's almost always the way to go...unless you happen to be at Daytona.

I've got about 2-2.5 inches horizontally before it protrudes past the bumper edge, so it could be leaned back maybe 5 or 10 more degrees. I'd loose drag, but I'd also loose downforce at a shallower angle (from what little I've read). Good info on wacky CAM legal spoilers is hard to find, but I did find a little.

 

[NightmareMoon]

how much downforce does such a rear spoiler create? I thought the idea was to trap air in the 'pocket' so the air coming off the roof stayed laminar and didn't tumble in a vain effort to follow the window down. The chaos behind the vertical trunk plane has gotta be horrible.

How much? No idea. I did collect some info which mapped the coefficient of (negative) lift to cornering speeds, but getting actual coefficient data for these types of spoilers is difficult to find.

Its gonna be horrible for drag, but as TeeLew said, its almost always worth it to gain grip for the corners. How often can you actually use the power we have available? Once or twice on any given autox course? Everywhere else we have surplus engine power to plow through the extra drag and need the cornering speeds.

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