Aerodynamic Study: Spoilers & Blunt Nose and Under cover

[SpeedRoo]

@kats it's late here but I'll run the aero figures tomorrow and give you an answer. The Racer Brown 240Z was running around 240bhp so it should be easy to work out. What horsepower do the blue and yellow car have?

[SpeedRoo]

19 hours ago, kats said:

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 The Racer Brown car with the G nose/tail spoiler and using a CD of 0.381 would have had a top speed of 160.81mph.

The standard 240Z with the same horsepower as the Race Brown car and no aero (CD 0.50) would have a top speed of 146.88mph. The G nose with tail spoiler gives a 10% speed improvement.

Standard 240Z with standard 150bhp engine and no aero would have a top speed of 124.89mph

Standard 240Z with BRE front and rear spoilers would a top speed of 129mph.

Edited August 14, 2023 by SpeedRoo

[HS30-H]

9 hours ago, SpeedRoo said:

 @kats The Racer Brown car with the G nose/tail spoiler and using a CD of 0.381 would have had a top speed of 160.81mph.

The standard 240Z with the same horsepower as the Race Brown car and no aero (CD 0.50) would have a top speed of 146.88mph. The G nose with tail spoiler gives a 10% speed improvement.

Standard 240Z with standard 150bhp engine and no aero would have a top speed of 124.89mph

Standard 240Z with BRE front and rear spoilers would a top speed of 129mph.

Lots of "standard 240Z" in the mix there, but what does "standard 240Z" mean? What market variant? What gearing? Emissions-mitigating equipment, or not?

150bhp? A nice figure to put on sales brochures and engine bay tags, but I wouldn't use it for calculations like these. Especially when actual power depended on the territory the variant was made for.  

 

[kats]

Thanks Roo and Alan,

The data which Roo showed is exciting for me, I even don't know how to calculate that. This is just A Wild Guess, however I would say Roo's calculation might be something close to "IF" the car had the G-nose. And other cases too, thank you for the calculations. 

As Alan said, we need to be specific for numbers and units. 150 ps is written in the manual. And the engine performance differs depends on the territory even if the tag says 150 ps.

The front end is 15mm lower for Europe model (except Portugees ) will also make certain difference in Cd and Cl. Gearing too, etc etc. 

Now I am curious about looking back old days, when we were able to buy G-nose from a local Nissan dealership with listed price, would it be the most inexpensive way to get a car faster?  Adding 10 mph top speed, 30% more acceleration performance would cost more than just put a G-nose?  

Fairlady 240Z-L was 1350000 yen, Fairlady 240ZG was 1500000 yen in Oct 1971. The difference is 150000 yen. 

Now in Japan, you will pay 1 million -2.5 million yen for a complete set of genuine G-nose. 

Kats

[kats]

And this is what G-nose performs. Please don't take it seriously my calculations are not accurate. The thesis shows from 140 km/h to 160 km/h,

G-nose took 8.0 sec, Basic nose took 9.5 sec.

When G-nose reached to 160 km/h, Basic nose was almost 200 ft behind. Does it make sense?

Kats 

 

[SpeedRoo]

2 hours ago, kats said:

The data which Roo showed is exciting for me, I even don't know how to calculate that. This is just A Wild Guess, however I would say Roo's calculation might be something close to "IF" the car had the G-nose. And other cases too, thank you for the calculations. 

As Alan said, we need to be specific for numbers and units. 150 ps is written in the manual. And the engine performance differs depends on the territory even if the tag says 150 ps.

The front end is 15mm lower for Europe model (except Portugees ) will also make certain difference in Cd and Cl. Gearing too, etc etc. 

Now I am curious about looking back old days, when we were able to buy G-nose from a local Nissan dealership with listed price, would it be the most inexpensive way to get a car faster?  Adding 10 mph top speed, 30% more acceleration performance would cost more than just put a G-nose?  

Fairlady 240Z-L was 1350000 yen, Fairlady 240ZG was 1500000 yen in Oct 1971. The difference is 150000 yen. 

Now in Japan, you will pay 1 million -2.5 million yen for a complete set of genuine G-nose. 

Kats

@kats glad you are excited. The computations are based on the figures you supplied from the Datsun Japanese aero study and the windtunnel tests done in the USA. The formula used to calculate it is based on published figures, Datsun quoted 150ps for the power, I used their figure. All the data is readily available, no hocus pocus. If you can provide the aero figures for the European 240Z I would be happy to calculate the result.

The aero horsepower required to push the standard 240Z through the air to achieve 125 mph would be around 140bhp, this doesn't take into account parasitic drag losses due to tire friction etc.

Edited August 15, 2023 by SpeedRoo

[SpeedRoo]

2 hours ago, kats said:

And this is what G-nose performs. Please don't take it seriously my calculations are not accurate. The thesis shows from 140 km/h to 160 km/h,

G-nose took 8.0 sec, Basic nose took 9.5 sec.

When G-nose reached to 160 km/h, Basic nose was almost 200 ft behind. Does it make sense?

Kats 

Makes loads of sense @kats  Drag on a car body increases with the square of speed. In other words the energy required per unit of distance to overcome aerodynamic drag increases in proportion to the vehicles speed.

The aero power required for each car to achieve 140kph is G-nose 38.63bhp and Basic 47.35. Basic nose standard 240Z requires 22% more power for same speed.

For 160kph G-nose 58.674bhp and Basic 71.98. Basic nose standard 240Z requires 22% more power for same speed.

From those numbers you can understand why the G-nose can out-accelerate the Basic nose on the standard 240Z.

[kats]

On 8/16/2023 at 12:00 AM, SpeedRoo said:

@kats glad you are excited. The computations are based on the figures you supplied from the Datsun Japanese aero study and the windtunnel tests done in the USA. The formula used to calculate it is based on published figures, Datsun quoted 150ps for the power, I used their figure. All the data is readily available, no hocus pocus. If you can provide the aero figures for the European 240Z I would be happy to calculate the result.

The aero horsepower required to push the standard 240Z through the air to achieve 125 mph would be around 140bhp, this doesn't take into account parasitic drag losses due to tire friction etc.

Thanks Roo,

I don’t see there is a data for the Europe configuration, I mean the data seems didn’t use Europe 240Z (HS30 and HLS30Q etc). Probably the test team used a S30 which has normal suspension set up (basic coil spring rate and length, and normal hight at the front and the rear). And even the engine could have been L20, I will ask these questions to Mr. Miyazaki.

Mr. Miyazaki told me that the test team once tried to reduced Cd as possible as they could. Didn’t need to think about production model, just they tried whatever they could.

Finally they achieved Cd 0.30 for a basic body configurations.

With two people on board, plugged all the holes around the radiator core support, covered the radiator with card boards as much as it was functional, put an air conditioning condenser, fitted much much stiffer coil springs, lowered front end 15mm etc etc. They did many things to the car to keep the car sits lower.

From the words of Mr. Miyazaki  in mind, I re-check the side profile view of the Salt Flats Racer. The car sits lower than normal, it must be a lot better in Cd than normal Fairlady 240ZG. 
 

Kats

 

 

[Carl Beck]

On 8/15/2023 at 11:50 AM, SpeedRoo said:

Makes loads of sense @kats  Drag on a car body increases with the square of speed. In other words the energy required per unit of distance to overcome aerodynamic drag increases in proportion to the vehicles speed.

The aero power required for each car to achieve 140kph is G-nose 38.63bhp and Basic 47.35. Basic nose standard 240Z requires 22% more power for same speed.

For 160kph G-nose 58.674bhp and Basic 71.98. Basic nose standard 240Z requires 22% more power for same speed.

From those numbers you can understand why the G-nose can out-accelerate the Basic nose on the standard 240Z.

Hi Roo Question:  - - 58.674 bhp - - per what?   What is "aero power" or how does that relate to engine HP?

thanks,

Carl

[SpeedRoo]

@Carl Beck aero power is the amount of horsepower required to push the car through the air, rolling power is the amount of horsepower to push the object but taking into account the weight and resistance to movement.