docjohn said:
You'll get the most aerodynamnic benefit with the least penalty with a front splitter, under panels, diffuser, and a ducted hood/shroud. IMO, that is the best place to start with most production racers as in stock trim most vehicles have near zero downforce, pretty crappy turbulant aero, and these mods tend to be a great low-cost improvement point versus slapping on a big a$$ expensive CF JDM wing.
The reason being that unlike the other trimmings wings generate good downforce but with the added penalty of significant drag. More power as always is desirable to overcome this affect. The amount required can be calculated on paper but I have discovered is typically not as high as one might otherwise think. You'll often see production racers even in the low 300hp range with lots of aero working for them. The reason being is that it is an exponential equation so it thus tends to result in a net benefit for most road course speeds, and even wind tunnel tuning although ideal isn't always an immediate priority herein when your speeds are under about a buck 30.
In practice / seat of your pants testing, the Taitec JGTC wing was functional for me, just noticable, and did help keep the rear end planted at several points along the course. I would characterize its drag penalty, even in its full upright position which is where I left it most of the time, as being most definitely acceptable and its overall affect as 'ok'. All I can really say is "it was a little better." The S-Tai was about on par as well.
The Kawagen picnic bench coupled with the trunk lid has far more surface area, and is located up an over the roof line for maximum affect, typically locked into one of the lower positions as I had to really rein it in a little due to its sheer size.
Coupled with everything it does produce very significant usable down force. Absolutely most definitely noticable, with many co-driver comments to that affect. You can literally feel the affect during acceleration, or lift off the gas and feel the added drag during braking. During hard cornering, it tends to inspire a lot of driver confidence. In its full rake position it is entirely over kill. In its minimal position it is already noticable and you can just start to feel the added grip and hear it working as your speed increases up past 65.
For a short road course with relatively short straights like PIR (top speeds around 125-140mph) sacrificing top speed and some acceleration for cornering all in all is an excellent compromise, and the downforce benefits so amazingly noticable even at the lowest course speeds (~55 through the chicane) it is literally a night and day difference over stock.
The obvious downside to the system is drag, which combined with the frontal area of a wide front bumper, etc.. raises the vehicles coefficient of drag greatly. From some rough math, I'm would guess quite likely double of the .3-.32 range of stock trim. In comparison, a typical family sedan is in the range of .3-.4 and an F1 car's drag is about .75-.8
However, overall, my top speed/ entry speed into the braking zones is about consistent with before. Close enough not to really matter for non-timed events.
Everything told, I would argue that what is really important IMO is the feeling of confidence you get as driver having good usable downforce on a production racer. IMO, improving on aero is definitely worth the investment. Especially in the wet.
