Interior Exterior
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Anyone have Shinoo's rear CF diffuser or front splitter installed? Any pix or comments?
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yup, I have the Reverie versions. Good quality parts. Front spoiler is very easy to scrape on driveways even at stock ride height.
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RAC'S!!!! Yummy!!!!!!
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yup, I have the Reverie versions. Good quality parts. Front spoiler is very easy to scrape on driveways even at stock ride height.
Gorgeous car, and the spoiler looks sweet. I'm always at stock height, and still have to negotiate an angle entry to my driveway...so, that would probably be an issue here. Too bad. Thanks for posting the pix. PS: Great video with the C6. Your car is loaded...do you plan to turbo?
You have to love tight canyons
I'm still trying to find those here in Ohio. Weather forecast has me finding snow on Thanksgiving
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The CF rear diffuser is advertised as having improved downforce compared to stock.
How does it do that?
JnC (unfamiliar with auto diffuser design)
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Hey dave you might want to give Bretts' overpriced chin guards a shot . I scraped lightly while leaving the dealer right after I bought this thing . Now that it's lowered Bretts' sliders do work....My ride height would make this a great dive way snow shovel.........Take care....Frank
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The CF rear diffuser is advertised as having improved downforce compared to stock.
How does it do that?
JnC (unfamiliar with auto diffuser design)
Diffusers help to create low (or even negative; like on some race cars) air pressure under the car. The key is for it to be lower than the air pressure above the car. It works together with the front spoiler of a car which splits the air above and below the car. If the underside of the car allows the air to occupy more space toward the rear, compared to the small space in the front, you achieve lower air pressure. Also, by forcing the air to travel a longer distance under the car, you also reduce the air pressure under it. So, generally, the longer the front spoiler and the longer the rear diffuser, the greater the effect.
Basically, it is like the inverse of how wings allow a plane to fly (the air pressure is lower above the wing than it is below the wing).
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Gorgeous car, and the spoiler looks sweet. I'm always at stock height, and still have to negotiate an angle entry to my driveway...so, that would probably be an issue here. Too bad. Thanks for posting the pix. PS: Great video with the C6. Your car is loaded...do you plan to turbo?
I'd rather do the supercharger, so am waiting to see which kit is the most reliable and which one does not blow the motors under heavy track use.
I'm still trying to find those here in Ohio. Weather forecast has me finding snow on Thanksgiving
That's a bummer! The beauty of the West Coast is that it's always decent enough for a good drive... I'm headed to the track with my Elise tomorrow...
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The CF rear diffuser is advertised as having improved downforce compared to stock.
How does it do that?
I believe the curve (side profile) of the CF diffuser is the same as stock. The downforce advantage should come from the vertical pieces, which you'll note extend closer to the ground and the rear edge of them is more vertical. This helps trap the air in that channel to maximize the diffuser's efficiency, which will translate into more downforce.
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Have you noticed any instability compared to stock? This is with both pieces installed.... Do you think a wing spoiler on the trunk would change things?
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The stock exhaust exiting at the middle diffuser also accelerates the air in that area, creating more downforce. F1 cars and the like which utilized this property had a problem with downforce decreasing too much as throttle is closed, so this feature needed to be adjusted/designed accordingly.
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Diffusers help to create low (or even negative; like on some race cars) air pressure under the car. The key is for it to be lower than the air pressure above the car. It works together with the front spoiler of a car which splits the air above and below the car. If the underside of the car allows the air to occupy more space toward the rear, compared to the small space in the front, you achieve lower air pressure. Also, by forcing the air to travel a longer distance under the car, you also reduce the air pressure under it. So, generally, the longer the front spoiler and the longer the rear diffuser, the greater the effect.
Basically, it is like the inverse of how wings allow a plane to fly (the air pressure is lower above the wing than it is below the wing).
Yo, Sleepless. The rear diffuser are sometimes referred to as venturi channels. As the flow excelerates under the car, the pressure decreases as dictated by Barnoulli's Relation. This low pressure air then slows down through the channels at the same time air enters the channels from the side of the car. If the outer walls are close to vertical a strong vortex will form in the channel. This vortex will keep the flow attached within the channel while helping to stabilize the flow beneath the entire vehicle. Therefore these channels increase the downforce and decrease the drag of the vehicle. Because we do not have channels under the car, a rear slant is added behind the rear axle. This slant generates the same effect as the underbody channels, only to a smaller degree. A well designed rear wing with proper wing tip design known as a Gurney flap increases the effective camber of the airfoil. The result is greater downforce with only a small increase in drag. For example, look at the wing tips of newer and more efficient aircraft. Or, look at the Benetec wing..........Hell, but then, that could just be my opinion.......Hey Sleepless...if you really want to get faster lap times with your "Track Only" Elise, you could lighten her up by removing your street plates and passenger....10 pounds = one horsepower.
P.S. You must fly upside down alot. Check your silhouette. Were you absent that day? The airdam is designed to decrease drag and therefore, increase downforce......Ronin.
deleted by RandyC... ronin, please chill out, thanks
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Hey dave you might want to give Bretts' overpriced chin guards a shot . I scraped lightly while leaving the dealer right after I bought this thing . Now that it's lowered Bretts' sliders do work....My ride height would make this a great dive way snow shovel.........Take care....Frank
Already have Brett's maxi-pads on - LOL. They do a decent job I guess. Hey, when are you going to give me a ride on that yacht? Well, gotta go out and mount the tire chains on the Elise....
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Hey let me know if your ever coming out this way....We have canyons that Elise were made for.......Canyons in the morning.....when the winds come up sail past all the yachtees with there stinkin rules.......On the Ronin 15 knots feels like 140 in an Elise....No Rules............The only salt I see is on my deck....
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Have you noticed any instability compared to stock? This is with both pieces installed.... Do you think a wing spoiler on the trunk would change things?
Frankly, I've seen no verified proof that any of the after market spoilers, diffusers and wings improve anything; however, many, including the ReVerie and Benetec items look to be designed to be functional.
For me, none of them will do much for me because none of the tracks around here have fast enough sweepers to benefit from such addons.
I bought the rear diffuser for two reasons: 1) I wanted to get rid of the holes left by the stock exhaust system, and 2), the CF diffuser weighs less than stock.
I bought the front spoiler simply to balance out any effect the diffuser might actually have on the car; of course this added weight to the car, not much, but it negated the weight loss from the diffuser. So, weightwise, no net difference but at least I got rid of the rear holes from the exhaust system. If the spoiler/diffuser actually do anything, it's an added bonus.
I haven't noticed any difference compared to stock.
As far as wings go, there are other threads that discuss their possible effectiveness.
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I keep checking Ragnorak Racing's site to look for pictures of their front spoiler and rear diffuser. Also CF and slightly cheaper than the ReV pieces.
Brett, please post pics if you are reading this. BTW, the ReV pieces are very nice when viewed in person. Fit and finish is excellent.
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Thanks guys!! This thread provided hours of entertainment where I work.
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Yo, Sleepless. The rear diffuser are sometimes referred to as venturi channels. As the flow excelerates under the car, the pressure decreases as dictated by Barnoulli's Relation. This low pressure air then slows down through the channels at the same time air enters the channels from the side of the car. If the outer walls are close to vertical a strong vortex will form in the channel. This vortex will keep the flow attached within the channel while helping to stabilize the flow beneath the entire vehicle.
Not quite...
On a typical wing air flowing over the top has a longer way to travel compared to the air traveling under the wing. The faster air has a lower pressure, above a wing and higher pressure under the wing - the wing is "sucked up/pushed up" by the difference in air pressure. This is all basic aerodynamics - Bernoulli's Principle. The vertical winglets on the end of a wing are to prevent the higher pressure air from under the wing from going "around" the end of the wing and flowing to the lower pressure air on the top of the wing. Air moving in such a way has two effects - it reduces the overall lift (some of the air pressures are equalizing), and it greatly increases the drag caused by the vortexes generated at the end of the wing. The winglets don't increase the lift, they reduce the loss of lift, and eliminate/greatly reduce the vortexes. To put it simply, vortexes are bad, and are to be avoided when possible.
Now, for a car, we flip the aerodynamics upside down. In the case of the Elise, the underside of the car is flat until you get to the rear diffuser. At this point it curves upward, and like a wing, causes the air flow to speed up and consequently generate "downward lift". The strakes on the diffuser are not to generate vortexes, they are to prevent them. They serve the same function as winglets on aircraft wings - to keep the air from "spilling over" (or in this case from sneaking in from the sides).
Front air dams by itself, do not "reduce drag" (if anything they may create some) and they do not create "downforce". The purpose of an air dam is to redirect the air flow from passing under the car - instead directing the air around the sides and/or over the top. Air passing under a car tends to be "compressed" into the small space, and this in turn causes two potential problems. First, the "compressed" air (it's not actually compressed, just higher pressure than the faster moving air around the rest of the car) tends to generate "lift" - the air pressure under the car is higher than above the car, just like a wing. Second, it causes drag because of the higher pressure turbulent air flow under the car (this is greatly reduced by the flat under tray of the Elise). Using an air dam reduces all of this, and overall usually reduces drag and especially "lift".
A splitter is another version of the air dam. A splitter has a horizontal component that sticks out from the car. This "splits" the air flow above and below, and reduces the air flow that would normally pass under the car just like a regular air dam. The stock Elise has a very low front end, so the body itself acts as an air dam. The strakes on the sides also direct the air up and to the side, helping to reduce the amount of air that would normally pass under the car. All of it seems to work quite well considering that the Elise generates "negative lift" all by itself with no add-ons (although the numbers are small, consider that most cars generate "positive lift" - so the relatively small numbers for "negative lift" generated by the Elise are relatively huge compared to the larger numbers of "positive lift" that most cars generate).
There are such things as Vortex Generators (or turbulence generators), and they are often very useful. Remember that vortexes are bad (they disturb the air flow and create drag), but sometimes they can serve a good purpose. For instance, if you have something down stream in the air flow that will create a terrible disturbance to the air flow, making a smaller disturbance farther upstream may, overall, be better by making a little drag instead of a bigger drag downstream. You can often see generators on the wings of commercial airliner - they are the little flaps of metal that stick up for no apparent reason (there is a reason).
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Nevermind what they say about you Tim. Your OK.
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You say Bernoulli, I say Newton.