So my current race class allows for a full front airdam with maximum 5* angle, and a splitter with 4" maximum protrusion past said air dam. I'm currently running a splitter with 4" of protrusion, and a GV lip, but no air dam. I also normally run a set of spats that fully cover the front tires, but those are not legal in class so I have to pull them off for race weekends. Photo of current front end setup below:



I'm curious to get some input from the aero overlords (or anyone with some solid aero knowledge in general) regarding potential gains to be made by making a full-size airdam for an NC1. I've only seen one NC track car do it, and the front bumper on the car is already a lot flatter/less pointy than an NA/NB. Seems like the full dam would net less drag loss/downforce increase compared to an NA/NB, but there may still be worthwhile gains. If nothing else, I'd be able to partially cover the front tires without the need of spats. And all the materials needed are a $40 roll of ABS and a bunch of rivets.



Only photo of an airdammed NC I could find. Long story short, do you guys think making an airdam is worth it? Or do we just not see any NC's with these because the juice isn't worth the squeeze?

And yes, I'm aware it's ugly as sin. I'm willing to make my car uglier if it means shaving tenths off the table

 

The class rules allow a full air dam, but don't allow you to use cheaper, less effective, and easier to install spats on the stock bumper?

 

No sir! That'd be too easy. The GV lip is technically not legal in this class either, since it's not an OEM piece. Luckily, our local chapter lets those slide, but that would probably get audited at Nationals as well.

That being said, the rules are the rules, and I can't change that. I'm just trying to make the car as quick as possible while staying within them.

 

If it gets you spats, do it.

It will clean up the front, so there should be gains there. Also look at your radiator opening. IIRC Emilio reduces the opening on, eg Crusher, that may be experiment driven rather than a formula, but in your case you would have to consider street driven car and I suspect that might require a larger opening than for the track - not that that is difficult with a removeable piece to enlarge the opening when needed.

 

Ah, knew I was missing something! Smaller radiator opening should net some gains too, huh. I remember seeing multiple posts from Emilio on here mentioning minimizing mouth opening.

Yeah I think between that ability of the dam to act in place of spats, the airdam's probably worth making. Thanks for reiterating what I was thinking/hoping for.

Roll of ABS ordered.

 

HDPE is a better material than ABS. Much tougher and more crack resistant.
Plastic wraparound airdams aren't always pretty but they are very effective. Maximize the area covered by the undertray as allowed by the rules. Best to have your splitter and undertray be all one piece if possible.

 

Ahh, thanks Emilio. My bad, the stuff I ordered is HPDE. Got a 10ft roll of it off Summit. Just so used to referring to all plastic sheets as ABS.

Splitter/undertray is currently all one piece, but I'm going to have to build a bigger one as the airdam will cover more of my current one. I'll post updates on here once finished

 

Look up Rapscallion Motorsports on FB/IG/google. They have multiple NCs with plastic airdams and splitters and they've been pretty successful in WRL. The black car you posted was built by MER, and MER is now Rapscallion.

 

I agree that it's worth it if you get spats out of it, no question. Weird rules, but sounds like a win to me. Plus your car with the fender cuts and all will really pull off the look. Send itttttt

 

I can vouch for Rapscallion. I have been to their shop multiple times and seen their various NCs. They are a high-quality shop. They like to swap the ZF 8 speed autos into them.

 

Man, why do people keep telling me that the ZF8 swap is possible and straightforward in these cars? I specifically said when I bought this car that I would NOT do a drivetrain swap in it

In all serious, thanks for the feedback guys. Those rapscallion cars look mean! Dunno how I've never seen a pic of them especially having looked around for NC's with airdams.



I ordered a roll of HDPE from Summit Monday, which somehow ended up arriving overnight. Got it yesterday evening and started cutting.



It's perfect. I think I'll just leave it like this.

 

Recommend calculating the open area of your radiator. Thats usually about 2/3rds of core dimensions. The smaller the opening, the less drag and more downforce you will have. You can always open it up more at the track if it's not running cool enough. In our experience, with good ducting, sealed undertray, and all other cooling system optimizations, the bumper opening can be very smol.

 

Gracias, Emilio! Some buddies and I were just discussing bumper opening area yesterday, because of a couple of your previous posts on here about it haha.

Definitely gonna start small on the bumper opening. This car's already got more cooling capacity than it needs. Still haven't seen coolant temps get above 190* on track with the current setup (although highest ambient temps have only been 75-80*). Ducting is only about ~80% sealed currently, so I'll get that fully sealed up before cutting an opening and driving it.

I'll measure the core area tonight. Thanks for that stat!

 

Another thing to factor in; Most HPDE/TT builds seem to have no screen. In w2w, a screen (wire mesh) is a must to protect the core. But I think a screen should be installed regardless. Screens have their own open area to factor in. Mcmaster screen material actually lists open area. Again, start minimal and open it up as needed. On our NA/NB's we hack away the lower half of the bumper and build our own ducts. Reduces weight, makes service easier and generally make room for activities. Remove bumper beam and anything else in the way of a direct path to entire core.

 

Not NC, and not traschan bumper, but I also went with the 1:3 ratio after reading about it from Emilio and others. Not track tested yet.. but with the ducting this seems super effective and plenty of airflow.. (and the opening could probably be a little smaller)

 

Hang on, is it 1/3 ratio or 2/3 ratio?

Also still stoked on how your ducting came out Nate haha.

Emilio if I can pose another question, what density mesh do you guys use? There's about a billion mesh options on McMaster's website and a few options on Pegasus's site below. I guess the density used will just dictate bumper inlet size, but I'm curious to know what you guys have gone with in the past if you happen to know off the top of your head.

 

Emilio will set this straight I'm sure, but my understanding was that the bumper mouth opening should be between 1/4 to 1/3 the size of the radiator effective core size. Though I did re-read his comment and now I'm confused as well!. 2/3's sounds HUGE.

Also in for discussion on mesh size. All I know is that it affects your airflow more than you'd think.

 

I could have my math backwards, it's been years since we did that research and data collection. oops.
I think you're right though, 1/3rd sounds familar. I'll have to look at my old posts written when the data was fresh off the griddle.

I do recall by one of every mesh mcmaster sells covering a wide range of open areas. Tested at the track mid summer and discovered we could really block off a lot and still run cool when we had the rest of the system optimized. The racecars would overcool with a stock bumper in all but the hottest weather, tstat never opening.

 

I think what Emilio said was that the open area of the radiator itself was usually about 2/3rds of the core size, I think he was referring to the area of the core vs the area of the core + endtanks, but it's not 100% clear. Then the opening of the bumper should be about 1/3rd of of that core radiator opening size, or roughly 2/9ths of the radiator size.

 

Spent a good hour this morning searching for my notes and old posts on the recommend area ratios. Couldn't find anything..

The specific info is out there though, google search. Overall the actual opening needed is much smaller than most people think. Our S2 Supermiata road racer (7,000rpm 140whp BP6D on E85) had an HDPE skin with probably less than half the core dimension for an opening and barely cracked the tstat in 110° weather.

N/A 140whp


220whp BP6D turbo, with a FMIC further clogging the airflow. No overheating in Socal w2w