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GC8 Track Aero - Double Deck Rear Diffuser

Old 01 August 2017, 09:54 AM
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MY94BlueWRX
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Default GC8 Track Aero - Double Deck Rear Diffuser (amongst other things!)

Morning Guys,


After lots of design, development and fabrication, we have eventually got close to the completion of the underbody aero for our GC8 track car, or at least the latest version of it anyway!


Many iterations of exhaust placement and diffuser configurations have led us to our latest version of the front splitter, flat underfloor and double deck rear diffuser. We have completed some tuft testing (albeit fairly crude) however the results speak for themselves, in terms of the airflow that we are now getting through both upper and lower parts of the rear diffuser.

Version 1 Airflow -


Version 2 Airflow -

Two venturi tunnels have been added into the flat floor to provide an airflow path for the upper deck, as we had a big issue with exhaust fumes entering the car with the previous design. This has hopefully been resolved with a side exit exhaust and the redesigned double deck diffuser.


Any questions, comments or suggestions, from anyone that has also travelled down the Aero path would be gratefully received?


Cheers,
Kim.








Last edited by MY94BlueWRX; 14 August 2017 at 02:18 PM. Reason: Added video links
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Old 01 August 2017, 05:50 PM
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Nice floor and diffuser.
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Old 05 August 2017, 07:15 PM
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Henrik
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Very nice! What are you doing underneath the engine, and where are you venting air from the radiator etc?

I'm thinking of doing something similar, but not sure if I'll stay with front mount rad or go rear. I fancy having a flat floor starting from the front bumper backwards, and I also want to vent my fmic just after the leading edge of the bonnet. The fmic would ideally become fully enclosed, but that leaves little space for a rad, at least to have it vented in the same way.
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Old 05 August 2017, 07:18 PM
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I went a slightly different route for the exhaust.
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Old 05 August 2017, 10:07 PM
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Thanks Makkink 👍

Hi Henrik,

We have a front undertray/splitter that leads into the flat floor, this makes the underside completely flat from front to back. Although we have added some sidewalls or channeling on the entire length to encourage some rolling vertices to form.

In terms of the radiator, I have fabricated a full shroud for the back of the rad that completely closes it off from the engine bay. We have gone back to the original Subaru rad as it's a thinner core than the toyo one we were using, which wins us a few valuable cm's.

I am in the process of cutting a rather large hole in the bonnet which will be used to evacuate the rad airflow, this will be on the leading edge where the pressure differential is the most favourable, and will hopefully draw the hot air out from behind the rad.

Your exhaust looks good, we were originally thinking about exiting out of the side door, then decided to keep it under the floor so no fumes could possibly enter through the clearance gap... though a side door exit has less of a chance of this happening than our original rear upper diffuser deck exit! 😉
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Old 06 August 2017, 03:11 PM
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Thanks for the detailed description, I might copy some of your ideas

What material did you use for this? It looks kind of like some aluminium honey-comb material or similar? Any reason why you didn't just go with aluminium sheet? I'm thinking something like 2mm, but it's entirely possible that the material you have there is lighter and stronger than a plain sheet (so might copy your material choice as well..)
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Old 06 August 2017, 08:16 PM
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We started with the front engine undertray/splitter and did use 2mm aluminium for that, strengthened with 'L' section aluminium extrusion. This was ok but could be improved with the material that we chose for the underfloor and diffuser... it's an aluminium honeycomb composite called aerolam, same stuff used on aircraft and is extremely light and strong.

I will remake the front undertray at some point with the aerolam material, but for now it is holding up well enough.
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Old 06 August 2017, 08:41 PM
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Great work Kim, love the fabrication on the exhaust also!

I may be a bit ****, but is there anything to be gained by forming sculpted sections over the underbody bracing rather than cutting an opening for it?

Last edited by sunny1989; 06 August 2017 at 08:45 PM.
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Old 07 August 2017, 05:32 AM
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WOW WOW WOW please make me some I'm sure you could make some money making these great work supcribed
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Old 07 August 2017, 07:08 AM
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Thanks Sunny1989... if I'm honest that is something that has been overlooked and could very well be worth doing, as even the smallest irregularity can upset the airflow. Granted we're not at F1 levels here, but if a job is worth doing etc etc 😉

@Johnnybon, thanks for the compliment, but from my experience people are seldom prepared to pay for one off fabrication items... I know I'm not, that's why I make everything myself! Lol

That said, if there is anything in particular that you were looking for, drop me a pm with some details and I'll get back to you 👍

Knocked up a new hard pipe turbo inlet over the weekend, to replace the original restrictive Subaru item. Have tried silicone pipes and they tend to get sucked closed under high boost conditions, unless you go for a samco or rcm one... but I struggled to part with £200+ for a silicone pipe! 😳

So I fired up the tig and got creative with my bandsaw!






Last edited by MY94BlueWRX; 07 August 2017 at 02:37 PM. Reason: Incorrect name
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Old 08 August 2017, 01:00 AM
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Hi mate I will be pm you when I return from holidays defo a rear defuses and maybe the flat floor to 👍
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Old 11 August 2017, 10:00 AM
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Got back onto the intercooler/oil coolers & radiator venting the last few nights, and finished up the front sealing of the front bumper to the intercooler.


They are hand fabricated aluminium panels, the side ones are secured to the bumper and the bottom one to the intercooler itself. Sealed with some high temp closed cell foam.


These should encourage a higher pressure to form on the front side of the intercooler, and then when the radiator shroud is in place and vented through the bonnet, the low pressure area over the bonnet vent should promote a better flow of air through the various cooling cores. That's the theory anyway!


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Old 14 August 2017, 12:53 PM
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Default Radiator/Intercooler Bonnet Venting

Made some progress over the weekend on the bonnet venting for the various cooler cores... was a nervous moment when I fired up the angle grinder and sunk it straight through our aluminium bonnet!!


I still have various infill panels to fabricate yet, seals to measure & fit, and finally paint finish everything... but it's a start.












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Old 31 August 2017, 03:04 PM
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Look a project like this, looks great!

Lovely work on the inlet!! Ever thought about making more to sell?
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Old 08 September 2017, 10:23 AM
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Default Radiator bonnet venting

Thanks Rice Rocket, I hadn't thought of making more to sell, but you never know?

We got round to finishing up the radiator shroud install and the bonnet venting the other night... really pleased with how it's gone as when the fans kick in the air displacement and direction is spot on.




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Old 08 September 2017, 11:35 AM
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nice work on the shroud/vent.

Regarding your fog covers are they custom made?

Is the main scoop an ETS or RCM item?
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Old 08 September 2017, 07:12 PM
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Hi Sunny,

I had the fog light covers made a few years back, they're actually the inlets for the brake ducts, and the reverse vent was from a chap on eBay so not sure of the make... but it's definitely not an RCM item.

Next on the list of fabrication is a replacement set of canards/dive planes, probably just going with one large set instead of two smaller ones. Then a set of new end plates for the splitter, again larger and more functional than the vortex generator we currently have.

Last edited by MY94BlueWRX; 08 September 2017 at 10:37 PM. Reason: Additional info
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Old 09 September 2017, 09:05 PM
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looks like an ETS one, had one on mine
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Old 17 September 2017, 09:49 AM
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Proper; great to see something new on here for a change
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Old 17 September 2017, 09:06 PM
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Thanks trails... we're trying our best to keep it original.

Knocked up a new switch panel over the weekend that houses two temp gauges for gearbox & rear diff, 4 latching switches for fuel pump, fans, rain light and a spare. Plus the toucan screen and tyre temp monitoring screen will be fixed to the top half... information overload!! Lol
​​​

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Old 30 September 2017, 06:16 PM
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Default Gauging opinion?

Evening people,

I have in my possession a set of replacement headlight covers from ABW, one of which includes a naca duct in the drivers side which will serve as an inlet feed for the turbo induction filter...

Question is what colour do I paint them?

Black, Satin Chrome, Blue or Pink?





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Old 01 October 2017, 09:37 PM
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i say blue......
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Old 02 October 2017, 12:30 PM
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surprising myself here, but I really like the satin chrome; closest to actual headlamps. The black looks super mean though
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Old 02 October 2017, 08:29 PM
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Black.
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Old 03 October 2017, 05:42 AM
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black and do you have a extra scoop on the right side of the headlamps.
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Old 03 October 2017, 06:49 AM
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Yes the drivers side does have an inlet scoop, just not shown in the pics as they are photoshopped images.

I originally thought the satin chrome as it matched the headlights, but the black is growing on me?
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Old 04 October 2017, 02:00 PM
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+1 for Satin Chrome. Black or blue hides the fact the car should have headlights, ruins the look of the car. Like having a face with no eyes!
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Old 05 October 2017, 12:05 PM
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Black or Satin chrome I'd say. great progress mate.

I'm going to scan the original fog covers, then integrate the brake ducts and 3D print them myself.

Seems like the easiest way to get exactly what I need.
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Old 07 October 2017, 05:55 PM
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Sounds like a good idea, what modelling software do you use Sunny?
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Old 07 October 2017, 06:07 PM
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Default Enginetuner Mapping Session

We had a very busy day yesterday... set off at 2:30am for sunny Plymouth, 5 hours later we were sat outside Enginetuner waiting for Martyn.

As soon as he arrived he was straight onto it, and a few hours later we we’re all mapped and setup... the results speak for themselves and the new Wideband Alcatek was a pleasure to map (Martyn’s words). The Anti Lag was also set up, more for a nice ‘toy’ feature than an actual positive pressure system, but it sounds so nice on overrun! 😜

Then a long drive back last night made for a very long day, but the big smiles on our faces more than made up for it... enjoy!





Last edited by MY94BlueWRX; 07 October 2017 at 06:08 PM.
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