flush fitement and drag coefficiency
 

Ok i need a little confirm of clarification.

I was always taught, the more the wheel sticks out, the more it affects your drag coefficiency. Im not talking about out way beyond the fenders, im talking about complete flush fitment when the wheels is flush with the fenders. Is this true or have i been mis informed?

This is true

Thanks for the clarification. I figured it was true, but then i see all the wode body race cars and it confused me a bit.

What race cars are you talking about? Look at the Daytona Prototypes , perfect example

Those cars and cars that runs in leman 24 hrs. They have wide body and the wheels are pretty flush instead of sunken in. Thats why i was confuse as to if it hurt or helped if the wheels were flush.

T'bo, why you worried about this? Going for an LSR? Heh.... :icon17:

ANYTHING placed in the airstream creates aerodynamic drag. For our street cars, this is negligible thing to bother considering. No one is driving fast enough to realize a difference between a slippery .28cD and a .50 motorhome. Welllll, that's a stretch but you get the point.

If you are comparing to Enduro prototypes, well, don't bother because they are almost all developed in CAD with specific considerations for aerodynamics and then proto'd and tested in a wind tunnel. Apples, oranges, pigs, cows. All stuff we eat but very different from one another and to compare....ehhh, not so much.

On non-maximized street cars like ours, the under chassis turbulence created by big fat meats and aero gimmicks that don't work at legal speeds add more aero drag - hence, "wind weight" - than they help, despite the marketing that it all helps. And it all looks cool..... :icon39:

So in the grand scheme of things, an interesting point to consider but negligible in reality unless you are on the track or at the Salt Flats. :o

Mic

Sooo youre telling me i need a wind tunnel in my garage... time to start a go fund me haha.

So just to understand it better, is it better, aerodynamic wise, for the wheels to be flush with the car?

And yes mic it matters. Obviously you havent seen fast and furious. "Doesnt matter if you win by an inch or a mile. Winning is winning." Doesnt matter if i feel the increased better aerodynamic, an increase is an increase haha

Not 100% sure on drag racing but for fitment on the wheels themselves overhang or under hang tire on the rim effects the side wall flex. I did a little auto cross in my day, not to name drop but optima challenge. As for drag if you are talking about offset then whatever allows you to get the most amount of tread needed to launch. In 1\4 mile racing there is not such a areo dynamic need. Look old Chevy s10 trucks running 9's in the 1\4 mile and they are shaped like a box.

No wind tunnel to offer but I'll offer my services as a windbag. :o

I'll start with this suggestion.... while you're flushing your wheels to the fenders, add these for extra go fast aero reduction.

https://cimg1.ibsrv.net/gimg/my350z....78bf800144.jpg
Equivalent to adding 55.72bhp. Why, add that to your stickers and you're up over a hundred ponies gained!!

I must be the ONLY guy on the planet who has never seen nor care to see any of the Fast & Furious franchise. I mean, who wants to watch it on a big screen when I'm actually doing it from behind my windscreen, ya? :icon38:

MicSlow&Mellow

I see it this way, out cars and most other cars are designed for performance and economy. Performance cars have an OEM setup that does not sit flush, my jeep did not sit flush and eco only cars do not sit flush. All of these vehicles are wind tunnel tested ( especially my minivan, MPG sells) it is all for aero reason. It may be minimal, but it is for reason.

ok so if i understand it right, the more flush the wheels are, the better it is for aerodynamic but then it will also have more drag? or do i have it the other way around?

basically what i want to know is, when the wheels are flush are they, A) helping with aerodynamic? B) adding drag to the car. C)helping or hurting the car? i understand its minimal. just want to understand it better.

speaking of living a movie, the road you take, to maricopa (butcher that spelling) county, is it the same road that was in the movie "need for speed?" is there a light house at the end of one of the turn off? haha

B. Adding drag and hurting the car when flush. But the added track helps, then on my car I run spats to cover the tire as much as possible for aero reasons

A) Depends on the wheel design.

B) Upsizing tires/wheels always adds drag.

C) Both..... depends on the speed. Low speeds, there's probably enough aero drag and turbulence under the car to choke the car down significantly.... but at the same time, you're going so slow, it's not making any performance difference.

At high speeds, flush fitment MIGHT be helping a tad..... but again, will depend on the wheel design. If you look at a lot of race cars, particularly the prototypes you mentioned earlier, they're running mesh or multi-spoke style wheels (due to weight and strength) but with aero spoke designs to keep them from trapping stagnant air and directing said air flow to the brakes and down/away from the car.

Thanks mic and terra for the help with the explanations. Aerodynamic is such a hard subject since its mostly theory and we cant really test it without a wind tunnel.

Just for fun look at the g10 metro aero mods. people have documented gas mileage increases from moon caps to blocking half of the front bumper air dam. Some people go crazy.

Ive towed some cars that the owner was mpg crazy... Ive seen those stupid hub caps and the fenders covered up... Ive seen some home made hydrogen cells or whatever the hell it was Mickey moused into the intake...

All those mpg cars are ugly as ****, hella flush is where its at... And spacers are on sale for black Friday.... Might need me some 10mm bump outs.

aerodynamics on fleek????

https://cimg6.ibsrv.net/gimg/my350z....09f67fa34b.jpg


https://cimg5.ibsrv.net/gimg/my350z....3c9c69e726.gif