Alfa Romeo 4C Forums banner
881 - 900 of 939 Posts

·
Vendor
Joined
·
1,417 Posts
Discussion Starter · #882 · (Edited)
We are about to finish the prototype set of GMS carbon rear hood with integrated ducktail and optional race wing. The hood is in the finishing phase and the carbon race wing is already waiting to get the proper alu CNC'd mounts. GMS hood assembly (carbon rear hood + carbon rear louver = 3,9 kg) is more than 3x lighter than OEM hood assembly (SMC rear hood + glass + steel meshes = 12,5kg) and that is quite some weight saving right there at the top back end where we want it the least. We've shed 8.3kg of the top rear of the car and added downforce and cooling. Let's go...

Automotive tire Hood Motor vehicle Bumper Tread Automotive parking light Hood Automotive tire Automotive lighting Tread
 

·
Vendor
Joined
·
1,417 Posts
Discussion Starter · #883 · (Edited)
Slight correction...GMS hood assembly (carbon rear hood + carbon rear louver = 3,9 kg) is more than 3x lighter than OEM hood assembly (SMC rear hood + glass + steel meshes = 12,5kg).

Here is the sneak peak preview of the prototype.

Stock one looks like something is missing, isn't it? And don't mind the gaps, the parts are just put on a car, not tightened and adjusted.

Car Wheel Vehicle Tire Vehicle registration plate Automotive lighting Wheel Vehicle Hood Light Land vehicle Car Vehicle Wheel Tire Vehicle Car Hood Automotive tire Motor vehicle

http://instagr.am/p/COgFWKClQbW/
 

·
Vendor
Joined
·
1,417 Posts
Discussion Starter · #884 ·
With provisional mounted race wing and some details of the GMS carbon rear hood.

It is one of the most detailed and precisely build carbon part I've ever seen in aftermarket motorsport world. Height adjusters, cable guides, tapers, locks, heat treated engine compartment, high gloss visible interior parts and the most important. Perfect fit!

Tire Automotive tire Black Motor vehicle Wheel Automotive tire Grey Helmet Pattern Snout Liquid White Drinkware Black Automotive lighting Automotive parking light Automotive lighting Hood Grille Automotive tire Car Vehicle Automotive lighting Hood Motor vehicle
 

·
Vendor
Joined
·
1,417 Posts
Discussion Starter · #892 · (Edited)
You probably mean downforce numbers? The GMS race wing (1700mm span / 300mm chord) numbers are provided by the wing manufacturer data and the GMS rear hood numbers are CFD estimates of similar designs (991 GT2 RS).

The downforce numbers are:
  • GMS rear hood with ducktail 20kg - 30kg of downforce at 160 km/h (CFD estimate)
  • GMS race rear wing 30kg - 40kg of downforce at 160 km/h at 0° AOT (angle of attack)
  • GMS race rear wing 70kg - 90kg of downforce at 160 km/h at 12° AOT
  • GMS race rear wing at 12° of AOT mounted on GMS carbon rear hood with integrated ducktail = 100kg+ of downforce at 160 km/h
The exact figures for our wing are measured in free air stream, not on the car, so the raw numbers below are slightly higher than numbers we are stating.

Angle (°) / Df (N) / Drag (N) / -L/D (ratio) / Drag (BHP):
  • 0° / 461N / 32N / 14.62 / -1.9 bhp
  • 4° / 672N / 48N / 13.89 / -2.9 bhp
  • 8° / 857N / 71N / 12.01 / -4.2 bhp
  • 12° / 954N / 95N / 10.02 / -5.7 bhp
  • 14° / 966N / 108N / 8.93 / -6.4 bhp
  • 16° / 964N / 126N / 7.67 / -7.5 bhp
*There is a slight mistake in video description ("30kg - 40kg") of downforce for hood only, up above are correct numbers...
 

·
Registered
Joined
·
1,058 Posts
You probably mean downforce numbers? The GMS race wing (1700mm span / 300mm chord) numbers are provided by the wing manufacturer data and the GMS rear hood numbers are CFD estimates of similar designs (991 GT2 RS).

The downforce numbers are:
  • GMS rear hood with ducktail 20kg - 30kg of downforce at 160 km/h (CFD estimate)
  • GMS race rear wing 30kg - 40kg of downforce at 160 km/h at 0° AOT (angle of attack)
  • GMS race rear wing 70kg - 90kg of downforce at 160 km/h at 12° AOT
  • GMS race rear wing at 12° of AOT mounted on GMS carbon rear hood with integrated ducktail = 100kg+ of downforce at 160 km/h
The exact figures for our wing are measured in free air stream, not on the car, so the raw numbers below are slightly higher than numbers we are stating.

Angle (°) / Df (N) / Drag (N) / -L/D (ratio) / Drag (BHP):
  • 0° / 461N / 32N / 14.62 / -1.9 bhp
  • 4° / 672N / 48N / 13.89 / -2.9 bhp
  • 8° / 857N / 71N / 12.01 / -4.2 bhp
  • 12° / 954N / 95N / 10.02 / -5.7 bhp
  • 14° / 966N / 108N / 8.93 / -6.4 bhp
  • 16° / 964N / 126N / 7.67 / -7.5 bhp
*There is a slight mistake in video description ("30kg - 40kg") of downforce for hood only, up above are correct numbers...
Wing from Reverie ?
 

·
Registered
Joined
·
1,116 Posts
And now the answer to the biggest question ever asked on the forum (“When will the ARB be launched?”)… 😂
 

·
Administrator
Joined
·
17,255 Posts
And now the answer to the biggest question ever asked on the forum (“When will the ARB be launched?”)… 😂
And the biggest question ever asked on the internet - when will the GMS exhaust be able to accommodate them? :D :p ;) :ROFLMAO:
 

·
Vendor
Joined
·
1,417 Posts
Discussion Starter · #897 · (Edited)
Wing from Reverie ?
Calin, I'd rather not disclose all the details as we've put a lot of effort in selecting the wing and persuading the manufacture to make us a small batch of custom shaped wing to fit within the 4C's body limits without loosing too much of effectiveness. The wing is curved according to the 4C's rear bumper (looking from the top), it has 300mm of chord width in the center section and a bit less on the side sections, 1700mm of span width and it is heavily cambered towards the edge, to make it act as a gurney flap. Due to this (curved, narrower side sections), we are a bit down on downforce and a bit up on a drag but with heavily cambered profile we stall at a bit higher speeds, compared to the wings already available on the market.

And now the answer to the biggest question ever asked on the forum (“When will the ARB be launched?”)… 😂
As soon as we are sure our current material selection is the thing. By spending lots of testing hours on design and materials especially, I am confident to say that improper selection of material for ARB will affect the effectiveness of the ARB on a long term to the point you might end up with nothing but well over 10kg of ballasts on your car. Thick, mild steel tube will drop its yielding characteristics after a long time use and because the 4C has short travel suspension and movement of the ARB's on the 4C is very limited this is a very important aspect when it comes to proper material selection.

And the biggest question ever asked on the internet - when will the GMS exhaust be able to accommodate them? :D :p ;) :ROFLMAO:
As mentioned the new, revised GMS 3" Dual center out is compatible with OEM, aftermarket and GMS ARB's. And by the way, it's slightly less loud. We plan to have the first batch finished this weekend and then they are off to customers. When we get the next batch done, I'll make it available again in online store.
 
881 - 900 of 939 Posts
Top