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Why did GM decide not to add a lower diffuser, even on the ZR1X?
Without an aero analysis, can we only guess?
My guess would be these strakes help speed up the under-chassis airflow and add performance, whether downforce or top speed is unknown, yet?
I added a diffuser to my 2017 Grand Sport. In my case for "Looks." But there is a lot of info on how they work. This is a Doc I made from what I found: http://netwelding.com/Rear_Diffuser.pdf
Here are a few of the many Pics with long captions:
Lots ofComputational Fluid Dynamics (CFD) software that can show and calculate aero effects.
The basic principle involves counter rotating vortices on the sides of what some refer to as Fences.
This C8.R has 8 Fences. But to be effective they must be low to the ground. Possibly why not added to the ZR1 street model!
I added to my C7 Grad Sport for looks
They also supplied what was referred to as an Undertray that helped create some downforce without the "Fences" having to be close to the ground.
This fellow makes a case that counter rotating vortices are not over the whole diffuser and not the reason for "strakes," "fins," or "fences." His contention is one reason they are effective is they help manage air flow I never considered, air coming from the bottom of the tires that is pulled down and squirts out as it rotates! Worth a look.
Super easy. I did not do it, had it installed when I had the side skirts installed. But it slips right over the existing rear diffuser. There are four holes you have to drill underneath to fasten the fins and the rest is held on by 3M tape. The fitment is excellent.
pic looks good but it says it’s glossy black. Doesn’t it clash in the sun with the cf black? I looked at a different one on Amazon but it had poor reviews.
pic looks good but it says it’s glossy black. Doesn’t it clash in the sun with the cf black? I looked at a different one on Amazon but it had poor reviews.
It is glossy black. Unless you look up close you would never see the difference. My new side skirts are also glossy black and again unless you look really close you would not see a difference. The EOS diffuser is well made. The fitment is excellent.
I assume it is strictly for show, especially at the speeds most of us drive at.
I considered the one on Amazon, glad to get feedback - I missed the 2 bad reviews. Like just about everything on Amazon now, if it is important, medical, pharmacy, DO NOT USE Amazon - the product will probably be a scam.
Thanks for all the comments.
I watched all the links and further delved into Utube C8 aero videos.
I still do not know why GM did not install strakes on the rear?
Especially when the ZR1 and Z06 are perhaps defined as race cars.
Yet, I can envision some GM aero planning of directing the airflow in a straight line to exit the rear of the car... perhaps for heat exit, as opposed to downforce.
The front splitter and flat underbody seem aerodynamically very good.
Of interest was the rear wheel/tire air wake control designed by GM.
The rear undercarriage seemed weak, again, unless the design is for heat extraction and mpg coefficients.
On my SR, for example, there is a small wing design under the center muffler.
Further, there are small strakes on the inner vertical exhaust tip bezels.
Yet, if looking for a functional (downforce) rear diffuser, the underbody rear panel needs "work"/ extending to complete the flat undercarriage.
FWIW in my research, there was much knowledge about rear wings and extended front splitters on the C8
Would love to find GM engineer discussions on the rear aero.
As is, I am considering the diffuser I posted as cosmetic
Thanks for all the comments.
I watched all the links and further delved into Utube C8 aero videos.
I still do not know why GM did not install strakes on the rear?
Especially when the ZR1 and Z06 are perhaps defined as race cars.
Yet, I can envision some GM aero planning of directing the airflow in a straight line to exit the rear of the car... perhaps for heat exit, as opposed to downforce.
The front splitter and flat underbody seem aerodynamically very good.
Of interest was the rear wheel/tire air wake control designed by GM.
The rear undercarriage seemed weak, again, unless the design is for heat extraction and mpg coefficients.
On my SR, for example, there is a small wing design under the center muffler.
Further, there are small strakes on the inner vertical exhaust tip bezels.
Yet, if looking for a functional (downforce) rear diffuser, the underbody rear panel needs "work"/ extending to complete the flat undercarriage.
FWIW in my research, there was much knowledge about rear wings and extended front splitters on the C8
Would love to find GM engineer discussions on the rear aero.
As is, I am considering the diffuser I posted as cosmetic
Again thank you all for commenting.
Doubt a GM Aero Engineer will comment but perhaps a race car aerodynamicist might. From what I have read they're not effective unless low enough to the ground or can have some effect with an undertray at bottom. Most sold for the C8 are for "Looks."
Usually believe "Form Follow Function" but added the diffuser to my 2017 Grand Sport for Appearance!
As has been mentioned, the CF on Amazon has bad reviews, the "decent" ones linked above are glossy black, not CF like the Chevy rear that is CF in appearance only. A search has CF rear diffusers at $$$$. Is there anything at a lower price point that is worth the money?
I picked up a glossy black one off eBay and then had it painted in carbon flash to match…that was before the carbon flash one appeared on Amazon…I’ve got around $400 in mine doing it that way…
As has been mentioned, the CF on Amazon has bad reviews, the "decent" ones linked above are glossy black, not CF like the Chevy rear that is CF in appearance only. A search has CF rear diffusers at $$$$. Is there anything at a lower price point that is worth the money?
Originally Posted by PurdueDoc
That is my favorite diffuser, but I want it in CF to match the rest of the rear.
Is there an answer to the Question?
A reasonably priced CF painted (does not need to be or desire a real CF) Rear Diffuser.
Why did GM decide not to add a lower diffuser, even on the ZR1X?
Without an aero analysis, can we only guess?
My guess would be these strakes help speed up the under-chassis airflow and add performance, whether downforce or top speed is unknown, yet?
Also thought about adding the diffuser fins. But feel they're only cosmetic and prefer not to convolute the Corsa exhaust/X-Pipes. The fins are still cool looking though!
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
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Rear Diffuser
- I missed the 2 bad reviews. Like just about everything on Amazon now, if it is important, medical, pharmacy, DO NOT USE Amazon - the product will probably be a scam.
