Top down speed limit? - Page 2 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Xorshaik · 10-09-2011, 09:58 PM

So, I suspect Corvette programs probably do high speed testing, but I haven't been involved with those as a convertible engineer. Where I have been with convertibles involved I haven't been involvled with high speed testing, but I have with other components.

The way I've heard it, governing of speed is set at the speed rating of the stock tires. I believe from what I'm seeing on Tire Rack you guys are getting Z rated tires, and that means they're rated for over 186 MPH. I'm not sure that my knowledge about high speed testing falls in the domain of what I can disclose, but wikipedia states that the banked circle track at the Milford Proving Grounds has a speed limit of 120 MPH. And Corvette was certified in 2009 to 205 MPH on a track in Germany.

Regardless of the top speed of a vehicle during driving tests, there is also always wind tunnel testing which acording to this article can run up to 160 MPH:
http://deansgarage.com/2009/gm-wind-...-and-brochure/

I know that probably didn't help at all about the OP question, but I figured it would be interesting to hear that cars get tested to pretty high speeds.

Here's something to consider in terms of aerodynamic lift. I was originally going to go into aerospace engineering, but after my first year of that and seeing my roommate graduate and not find a job, I decided to go mechanical and get into automotive for more job security (ha!) So at any rate, there are those who grasp aerodynamics better than I do. With that said, here's some relevant aerodynamic basics:

Aerodynamic lift is generated when air flowing around an airfoil has high velocity and low pressure above the airfoil and low velocity and high pressure below the airfoil. Taken to the extreme, a car moving at high speed has air moving at high speed over the top of it and no speed under its surface or in its interior. So at any rate, there are lift generated on things like a lowered convertible top.

You can probably alter the airflow at the top, thus reducing the lift and maybe avoiding it catching wind like a sail, if you had a wind deflector accessory... I don't know if they have those from the OEM but they're probably available aftermarket.

chozn4service · 10-09-2011, 10:43 PM

I don't know on this one. This past August I had the opportunity to ride with 2011 Indy500 Winner Dan Wheldon in a 2011 convertible at Indianapolis Motor Speedway with the top down and we hit speeds of 145-150MPH and it was all good!

He and I held conversation the entire time and I was surprised how nice the ride was with minimal wind noise and buffeting. Hearing what the backseat passenger was saying was impossible unless she raised her voice and you turned your ear toward her but otherwise it was all good!

Dale Jr. elected to keep his top up if I'm not mistaken and so did Clint Bower.
EDIT Dale Jr. did in fact have his top down as I thought he might loose his ball cap but he didn't. Clint Bower had his top up the entire time as did Jeff Gordon.

RAWarrior · 10-10-2011, 11:50 PM

I drive mine on the interstate, commonly 85ish and yeh, there is a small amount of flutter but it never lifts up. So far knock on wood, I'm still good as the top issues are concerned. Now, the boot is another story.

OrangeVert · 10-11-2011, 09:31 AM

Quote:

Originally Posted by chozn4service

I don't know on this one. This past August I had the opportunity to ride with 2011 Indy500 Winner Dan Wheldon in a 2011 convertible at Indianapolis Motor Speedway with the top down and we hit speeds of 145-150MPH and it was all good!

He and I held conversation the entire time and I was surprised how nice the ride was with minimal wind noise and buffeting. hearing what the backseat passenger was saying was impossible but otherwise it was all good!

Dale Jr. elected to keep his top up if I'm not mistaken and so did Clint Bower.

Way cool, chozn. Thanks for sharing!!

Drop top ride to Cape Cod last weekend. Some buffeting of the tonneau, but nowhere near coming off. Great driving and weekend, everyone loves this car!!

Nasty1970 · 10-11-2011, 02:52 PM

been around 140 with the top down, just flapped a little, nothing major. Sounds like a problem to me....

10-09-2011, 10:43 PM	#16
chozn4service Drives: 2016 SS w/2SS A8 Blue Velvet Join Date: Dec 2009 Location: 39.793153,-86.238223 Posts: 3,678 View My Garage	I don't know on this one. This past August I had the opportunity to ride with 2011 Indy500 Winner Dan Wheldon in a 2011 convertible at Indianapolis Motor Speedway with the top down and we hit speeds of 145-150MPH and it was all good! He and I held conversation the entire time and I was surprised how nice the ride was with minimal wind noise and buffeting. Hearing what the backseat passenger was saying was impossible unless she raised her voice and you turned your ear toward her but otherwise it was all good! Dale Jr. elected to keep his top up if I'm not mistaken and so did Clint Bower. EDIT Dale Jr. did in fact have his top down as I thought he might loose his ball cap but he didn't. Clint Bower had his top up the entire time as did Jeff Gordon. Attached Images __________________ Never grow up, it's a trap! Last edited by chozn4service; 10-11-2011 at 10:01 AM.

10-10-2011, 11:50 PM	#17
RAWarrior Drives: '11 CGM/IOM 2SS 'vert '02 GMC Envoy Join Date: Oct 2010 Location: Springfield IL/Indy IN Posts: 461	I drive mine on the interstate, commonly 85ish and yeh, there is a small amount of flutter but it never lifts up. So far knock on wood, I'm still good as the top issues are concerned. Now, the boot is another story. __________________ Cyber Grey/Black Conv 2SS IOM interior 12/07/2010 - (1100) Order Placed 12/10/2010 - (2000) Order Accepted by GM Dealer 12/15/2010 - (2500) Order Preferenced Order 12/15/2010 - (3000) Order accepted 01/29/2011 - (3100) Order available to sequence. 01/29/2011 - (3300) Order Scheduled for Production 01/29/2011 - (3400) Order Broadcast 02/07/2011 - (3800) Order produced, 02/07/2011 - (4000) Vehicle available to ship 02/07/2011 - (4104) Bailment Invoice Created 02/07/2011 - (4B00) Your car is bayed 03/12/2011 - She's finally Home!!!!

10-11-2011, 02:52 PM	#19
Nasty1970 Drives: 2011 Red 2SS RS Convertible Join Date: May 2011 Location: Houston TX Posts: 377	been around 140 with the top down, just flapped a little, nothing major. Sounds like a problem to me.... __________________ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1970 Camaro ,2011 Red Convertible 2SS,2008 Saturn Sky,2012 Jeep Wrangler

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10-09-2011, 09:58 PM	#15
Xorshaik An engineer Drives: 4 wheels and a motor Join Date: Aug 2011 Location: Michigan Posts: 43	So, I suspect Corvette programs probably do high speed testing, but I haven't been involved with those as a convertible engineer. Where I have been with convertibles involved I haven't been involvled with high speed testing, but I have with other components. The way I've heard it, governing of speed is set at the speed rating of the stock tires. I believe from what I'm seeing on Tire Rack you guys are getting Z rated tires, and that means they're rated for over 186 MPH. I'm not sure that my knowledge about high speed testing falls in the domain of what I can disclose, but wikipedia states that the banked circle track at the Milford Proving Grounds has a speed limit of 120 MPH. And Corvette was certified in 2009 to 205 MPH on a track in Germany. Regardless of the top speed of a vehicle during driving tests, there is also always wind tunnel testing which acording to this article can run up to 160 MPH: http://deansgarage.com/2009/gm-wind-...-and-brochure/ I know that probably didn't help at all about the OP question, but I figured it would be interesting to hear that cars get tested to pretty high speeds. Here's something to consider in terms of aerodynamic lift. I was originally going to go into aerospace engineering, but after my first year of that and seeing my roommate graduate and not find a job, I decided to go mechanical and get into automotive for more job security (ha!) So at any rate, there are those who grasp aerodynamics better than I do. With that said, here's some relevant aerodynamic basics: Aerodynamic lift is generated when air flowing around an airfoil has high velocity and low pressure above the airfoil and low velocity and high pressure below the airfoil. Taken to the extreme, a car moving at high speed has air moving at high speed over the top of it and no speed under its surface or in its interior. So at any rate, there are lift generated on things like a lowered convertible top. You can probably alter the airflow at the top, thus reducing the lift and maybe avoiding it catching wind like a sail, if you had a wind deflector accessory... I don't know if they have those from the OEM but they're probably available aftermarket.