Presented by Nine Lives Racing
Tazz9924
Tazz9924 New Reader
6/13/22 8:30 p.m.

Im curious about the effects the relative position of a wheel in a wheel well has on drag in a relative sense. In road course racing its not as much of a relevant question because wider wheels and track widths are the norm. In different forms of racing like drag racing and land speed you don't have a 325 tire in the front and can then decide where the tire must land. Usually i see the tire on drag cars sunk in like an old vw instead of as wide as possible. I asked a chassis builder and he said he makes them like that because they look cool. What do the aero people think?

RACINGNUT
RACINGNUT New Reader
6/22/22 9:55 p.m.

I think the first question I have is; - what is the exact racing you're going to be doing?  Road course or drag racing?  Cool factor aside, it all depends on what you're trying to do.  

I'm aware of the NASCAR folks who were trying to build as narrow of a body as possible, (when you could still build your own bodies), and they would put the contour of the wheel opening to meet up as flush as possible with the bulge of the sidewall of the tire.  

You're intentions will make all the difference in the answers you may get.

sleepyhead the buffalo
sleepyhead the buffalo PowerDork
6/22/22 11:07 p.m.

the reason drag cars... we'll, rwd ones... have the tires close together in the back is primarily about 'differential thrust'.  Based on some comments Andrew Nelson has made in the past:  On big power cars, there's basically no guarantee that both tires will make the same traction at the same time.  So, keeping them close together means the moment (force x arm) of this difference in traction will have less of an impact on the lateral trajectory of the car.

aero is kinda a secondary consideration, afaik.

from a purely aerodynamic perspective, the best solution is to have a wheel tightly encased (ensconced?) in as much of a fairing as possible.  Unfortunately, many practical, physical, performance, and litigious limitations preclude doing that.

Tazz9924
Tazz9924 New Reader
6/24/22 2:45 p.m.

In reply to RACINGNUT :

This is in reference to drag racing

Tazz9924
Tazz9924 New Reader
6/24/22 2:50 p.m.

In reply to sleepyhead the buffalo :

That and the rear is narrow as well to allow for the wheels to come off. Try removing a 16-20" rim out of a wheel well, especially without taking the air out. Sometimes its nearly impossible. We are considering a narrower rear end to allow us to run bigger rims easier. My questions lie mostly with the fronts where as far as traction goes is almost a non factor. We do let the suspension droop a lot to allow steering while doing wheelies. but track width in the front is unregulated. The only regulations as far as the front wheels go is: wheelbase, and stagger. 

sleepyhead the buffalo
sleepyhead the buffalo PowerDork
6/24/22 8:03 p.m.

off hand... weight is usually more important for a 1/4mile pass than drag is... just because {royal} "you" spend so little of the pass above 60mph.

Beyond that, there's a bunch of little elements that could influence wheel position within some 'wheel well' volume.  Like, how likely (and to what deflection?) do you expect the front wheels to be turned to... lets say "beyond 500ft"?

Further, each potential car and ruleset has some nuances that might influence things.  So, there's not really a definitive "put it there", beyond makings sure a "steering only, front wheel/tire" is not sticking out in flow outside of the fender/wheel-well... and probably inset a bit so that 'normal corrective steering actions' keep the tire concealed within the wheel well.

Our Preferred Partners
vmTkafFKqwy1WEzxhYQMhT3XRmTdUFGkVDSnBoM5nIrrkfXp2XRHq6Za4iWNYdEc