Aerodynamic Study: Spoilers & Blunt Nose and Under cover

[Carl Beck]

3 hours ago, SpeedRoo said:

Found it @Carl Beck https://forums.hybridz.org/topic/55944-windtunnel-test-data/

@SpeedRooThanks - the old links in my bookmarks wouldn't load.... so I used the image I had saved at the time.

[kats]

13 hours ago, AK260 said:

This is my new FAVOURITE all-time thread.

Thanks Kats and Alan for sharing such brilliant info.

What I don’t understand is - and bear with me pls, I know little about aerodynamics - given that the engine bay pressurises does the blunt nose improve cooling also? And does the standard under tray improve the pressurisation situation? (Apologies if it’s covered in the magazine articles that I haven’t had a chance to read yet).

A very experienced member of the UK club (the late Mr. F) used to tell me that the under tray also affect the cooling efficiency, so I’m wondering if this was the reason?

Hi!

SpeedRoo and Alan described it well,  I didn't even think about the under cover does such a great job for reducing Drag and Lift.

Takeuchi-san (Z432-R owner) used to say he put an undercover on his car but he took it off in a few days. He said it wasn't good for engine cooling. Takeuchi-san, he takes his car on the road no matter how far his friends live, how hard rain falls from the sky. But he normally doesn't need to push his car over 100 MPH. Last time I visited him I saw the cover on his wall like an interior decoration.

Me, maybe the same. I want to put it in my car but don't want to make the engine hot in the daily driving. Or winter only will work for me.

Kats

Edited August 12, 2023 by kats

[kats]

11 hours ago, Carl Beck said:

The test data from HybridZ... the numbers for a stock Z (test #2)  Cd /CL etc  are pretty close to what Kats Posted.

Hi Carl,

Thank you for the data, I have never seen it before. I visited the link provided here, I saw they tested various kinds of body configurations. 

I am curious about the car stayed on the floor, Nissan engineers set the actual car on the block which makes the car sit higher than sitting on the floor.

We know this car, Salt Flats Racer 240Z. Most of people never knew (including me) the G-Nose can be attached with the Europe front spoiler like this car. I think this car has perfect aero dynamic package available from Nissan back in 70's Except one thing, an undercover.

If this car had an undercover on that day, it could have much faster top speed on the plaque. Nissan engineers tested a G-nose with a front spoiler in the thesis I showed here.

More surprising for me is the car did 152 MPH in 1972 without G-nose.

Kats  

Edited August 12, 2023 by kats

[w3wilkes]

On 8/11/2023 at 8:07 PM, kats said:

Hi Carl,

Thank you for the data, I have never seen it before. I visited the link provided here, I saw they tested various kinds of body configurations. 

I am curious about the car stayed on the floor, Nissan engineers set the actual car on the block which makes the car sit higher than sitting on the floor.

We know this car, Salt Flats Racer 240Z. Most of people never knew (including me) the G-Nose can be attached with the Europe front spoiler like this car. I think this car has perfect aero dynamic package available from Nissan back in 70's Except one thing, an undercover.

If this car had an undercover on that day, it could have much faster top speed on the plaque. Nissan engineers tested a G-nose with a front spoiler in the thesis I showed here.

More surprising for me is the car did 152 MPH in 1972 without G-nose.

Kats  

Just looking at the 2 pictures Kats posted it looks to me like... With the way this G-nose is configured and with the raised hood center at the rear of the hood it looks like a venturi entrance in the nose to accelerate and condense the air entering the front of the car and the hood configuration should create a low-pressure area at the rear of the hood to provide suction for air exiting the engine bay.

[SpeedRoo]

On 8/11/2023 at 7:07 PM, kats said:

Hi Carl,

Thank you for the data, I have never seen it before. I visited the link provided here, I saw they tested various kinds of body configurations. 

I am curious about the car stayed on the floor, Nissan engineers set the actual car on the block which makes the car sit higher than sitting on the floor.

We know this car, Salt Flats Racer 240Z. Most of people never knew (including me) the G-Nose can be attached with the Europe front spoiler like this car. I think this car has perfect aero dynamic package available from Nissan back in 70's Except one thing, an undercover.

If this car had an undercover on that day, it could have much faster top speed on the plaque. Nissan engineers tested a G-nose with a front spoiler in the thesis I showed here.

More surprising for me is the car did 152 MPH in 1972 without G-nose.

Kats  

 

@Kats  the early record car had the spook front spoiler, faired in headlights and tail spoiler. What was even more remarkable it had the early rear diff setup with the forward mounting point and angled driveshafts. Considering these supposedly caused vibrations in the standard 240Z they obviously weren't a problem at 150mph!

 

[Carl Beck]

On 8/11/2023 at 10:07 PM, kats said:

Hi Carl,

Thank you for the data, I have never seen it before. I visited the link provided here, I saw they tested various kinds of body configurations. 

I am curious about the car stayed on the floor, Nissan engineers set the actual car on the block which makes the car sit higher than sitting on the floor.

We know this car, Salt Flats Racer 240Z. Most of people never knew (including me) the G-Nose can be attached with the Europe front spoiler like this car. I think this car has perfect aero dynamic package available from Nissan back in 70's Except one thing, an undercover.

If this car had an undercover on that day, it could have much faster top speed on the plaque. Nissan engineers tested a G-nose with a front spoiler in the thesis I showed here.

More surprising for me is the car did 152 MPH in 1972 without G-nose.

Kats  

Hi Kats:

As I understand it:

GT Class is Grand Touring Sports

Class “F”  Engine Size is:    123 CID (2015.61cc)  to 183 CID (2998.83 cc)

 

152.134 mph 1972    (L24 BRE Front Spook and Rear Spoiler)

166.037 mph  1976   (L28 G Nose with chin spoiler)

168.721 mph  1985   (308QV  Ferrari)

172.974 mph  2010   (L28 - Rebello 3.0L - slight body rake) 

 

Between 152 mph and 166 mph two things changed.  1) L24 to L28 and 2) BRE/Spook/spoiler changed to G Nose.

I have to think that the L28 accounted for the additional speed.

 

A Wild Guess - about setting the Z on blocks:

There could be a significant difference between the Wind Tunnel in Japan 1971 and the one used by HybridZ in 2008 was it?   The Wind Tunnel in Japan may have had a limited number of sensors spaced in the floor - so the Z there was set on blocks - on the sensors.  The Wind Tunnel used by HybridZ has sensors more easily movable / or more of them in the floor - so the tires could set directly on them.

 

 

 

 

 

 

 

 

 

Edited August 13, 2023 by Carl Beck

[Carl Beck]

3 hours ago, SpeedRoo said:

@Kats  the early record car had the spook front spoiler, faired in headlights and tail spoiler. What was even more remarkable it had the early rear diff setup with the forward mounting point and angled driveshafts. Considering these supposedly caused vibrations in the standard 240Z they obviously weren't a problem at 150mph!

I believe that they caused vibrations only in a specific RPM range - AIR the test team driver said he needed to maintain a certain specific higher speed range long enough for the vibration to show up and get worse.  Slower or faster was not a problem.  

[SpeedRoo]

@Carl Beck that makes sense, was just surprised to see such a standard 240Z break the speed records. Even the 2010 record breaker had the standard bodywork rather than the G nose.

[kats]

10 hours ago, w3wilkes said:

Just looking at the 2 pictures Kats posted it looks to me like... With the way this G-nose is configured and with the raised hood center at the rear of the hood it looks like a venturi entrance in the nose to accelerate and condense the air entering the front of the car and the hood configuration should create a low-pressure area at the rear of the hood to provide suction for air exiting the engine bay.

Seems good for reducing pressure in the engine bay!

Kats

[SpeedRoo]

Actually it does the opposite, the opening to the rear of the hood brings air into the engine bay rather than venting it. It's a common place to draw air into the interior of the car for ventilation, hence the vents on the panel there. It's also used to feed air into the carbs on many race cars. Here's a good example.

 

 

 

[kats]

7 hours ago, Carl Beck said:

Hi Kats:

As I understand it:

GT Class is Grand Touring Sports

Class “F”  Engine Size is:    123 CID (2015.61cc)  to 183 CID (2998.83 cc)

 

152.134 mph 1972    (L24 BRE Front Spook and Rear Spoiler)

166.037 mph  1976   (L28 G Nose with chin spoiler)

168.721 mph  1985   (308QV  Ferrari)

172.974 mph  2010   (L28 - Rebello 3.0L - slight body rake) 

 

Between 152 mph and 166 mph two things changed.  1) L24 to L28 and 2) BRE/Spook/spoiler changed to G Nose.

I have to think that the L28 accounted for the additional speed.

 

A Wild Guess - about setting the Z on blocks:

There could be a significant difference between the Wind Tunnel in Japan 1971 and the one used by HybridZ in 2008 was it?   The Wind Tunnel in Japan may have had a limited number of sensors spaced in the floor - so the Z there was set on blocks - on the sensors.  The Wind Tunnel used by HybridZ has sensors more easily movable / or more of them in the floor - so the tires could set directly on them.

 

 

 

 

 

 

 

 

 

Hi Roo and Carl,

By the way, yes if we have a car serviced properly for drive train and suspension components, properly tightened bolts and nuts, assembled carefully just they required in the manual would certainly reduce the chance of the shake issue. The test drive in U.S. and Canada late 1969 the crew noticed the vibration around 80 MPH constant speed cruising.  The decision of Tokyo office was anyway just keep making cars, with balancing tire. They knew what they had to do thoroughly by the report of the test crew but needed a year and half for production ready.

Let's play Another Wild Guess- about the top speed of "RACER BROWN" 1972 :

If the car had a G-nose (with a chin spoiler), what the top speed would have been? How much speed would have been increased from 152.134 mph?  

Fairlady -Z brochure says G-Nose will give you 5% more top speed, 30% more mid-range speed acceleration. In the brochure, top speed of Fairlady-240Z is 205 km/h. Fairlady-240ZG is 210 km/h. Fairlady-Z432 is 210 km/h too (I think we have to guess there was something behind).  Basically, I think it is a Japanese way of thinking. Listing data (numbers and values) must be correct and proved in many ways. Better is acceptable, worse is unacceptable. So, usually those performance data have certain margin in there. 

Kats    

[kats]

One more quiz, how fast is the G-nose? I always imagine what a great driving experience for Mr.K would be. Now owned by Mr. Kenny Ueda, his car would pass my car easily on the road.

The thesis provided the data, acceleration of mid range speed. Please think the yellow car and my blue car have the same gears.

Kats