disclaimer: I'm not trying to be an a$$, I'm genuinely interested and intrigued. I'm also an engineer (mech eng in the auto industry) who has a few questions so I'm playing the Devil's Advocate here
First, why? The reason most 'diffusers' on todays cars are cosmetic is because a real one isn't necessary for the target demographic or function of the car. If you are tracking your car, do you have a problem with high-speed grip that you require more downforce for stability? On track, are you even achieving speeds where it will operate? I get that it is cool, and we all want something functional, but do you need it and are you going to truly notice the improvement?
How will you know it works (besides the 'butt-dyno'
), do you have sim data (Fluent, StarCCM, CosmosWorks?) to evaluate and tune the design? The only true way is to plan a day at a wind tunnel to prove that it actually works (especially if you plan to sell it)
For full effectiveness, you shouldn't just add the diffuser at the rear. You should incorporate it with the whole aero design: beginning from the front of the car, then having an entirely smooth undertray to avoid stagnation, then entering the diffuser.
Will you even have enough space to build this in the rear? Are you planning to build it underneath the muffler cans? A potential idea, perhaps use the exhaust to 'feed' the diffuser?
Again, I'm genuinely interested! I think just a couple legitimate questions, please don't take this the wrong way!
