240Z Airfoil Analysis

[acf321]

Is anyone aware of any airfoil/spoiler analysis having been conducted on the 240Z?

 

That is, we know the CD is quite significant for a 240Z from the factory, but what I have not read, but am very interested in knowing are answers to questions such as these;

 

1) what happens to the downforce and Coefficient of Drag to a 240Z with a '432' style duck tail spoiler, and corresponding front 'lip spoiler?

2) how much downforce is added to a 240Z by the use of a 'Bre' style front 'lip' spoiler, versus a larger full front spoiler?

3) How does chassis / aero dynamics and CD change with the use of a front only spoiler, or rear only for that matter?

4) what is the effect on downforce at 100mph (or any other pre-determined speed) for a 240Z with factory option or Bre spoilers?

 

Reason for asking is that since looking at the 432 style rear spoiler, I have considered using one on my project, but I want to know if the use of this spoiler on the rear alone will unsettle the balance of my car at speed. I was first introduced to this issue when reading the history of the 911, in which engineers tested and printed all the downforce / lift statistics when designing the front and rear spoilers on the early seventies cars? For example, Porsche very much shun the use of a rear 'ducktail' or later 'whale-tail' spoiler without the corresponding 'lip' spoilers of the day, purely as the cars do become dangerous without the aerodynamic 'balance' offered by the corresponding set. Infact, 1980's porsches are frankly dangerous if the whale-tail is removed (for cosmetic purposes) with the driver leaving the front 'lip' in place.

 

SO ... if I go and whack a 432 rear spoiler on the Hornet, because it looks good, what will that do to the handling of my car at speed ? This is a genuine question and something I wonder if anybody, here or abroad has made any investigation into. Would be intrigued to know.

 

 

Regards

 

Adam

 

 

 

 

 

 

[Riceburner]

I have a motorsportauto 'victory' rear spoiler, it's the same as bre style but 2 inches higher. They have a warning listed with the item saying not to run the victory rear spoiler without a front spoiler...... Also I remember reading standard 240z's were supposed to wander/lift at high speeds so I guess adding a rear spoiler would only make this more of a problem  :-\ 

 

But I'm just a plumber so 'pipes' and 'stuff' is where my expertise ends 

[NZeder]

Adam on hybridz.org there is a section on wind tunnel testing this has all the answers to your questions - but generally most rear spoiler on the rear of a zed are cosmetic only unless they are a certain height/size. I think one of the best setups was like the one John Cofery made of this 240z - flat alloy at the right height and angle.

[Whittie]

The thread NZeder is talking about

 

http://forums.hybridz.org/index.php?/topic/55944-windtunnel-test-data/

[sco_aus]

There was also one recently started on this forum that refers to the hybridz one... Perhaps a search next time?

[PZG302]

From my experience zeds suffer with lift at anything over 140km/h without a front spoiler.

 

I don't know how well the BRE or spook type blade spoilers work, but the MKII type front spoiler works well at keeping the front end down.

 

For rear spoilers, the standard Nissan motorsport, or BRE, bob tail does work, just not as well as others. The most effective rear spoiler I have used is a Mazda RX7 bird bath made from a genuine Group C motorsport body kit. It sat at just over 150mm high from the base of the hatch and created a low pressure area behind the car that literally sucked the bum to the ground. It did create extra drag, but was very effective when you saw the muck that was stuck to the back of the car after a race.

 

When I get some time i will be looking at putting the bird bath back onto my Z as the rules for production/Marque Sports cars has changed and the spoiler is now legal again.

 

Another thing to look at regarding keeping the front down, especuially if using the MKII type front spoiler is to also use a fibreglass undertray back to the standard stone tray if you can find one. This helps keep air from the engine bay and the air that does get into the engine bay is reasonably effectively dragged out. Not sure how effective this would be using the blade type front spoiler.

[Zedman240®]

I'm running one of those BRE style spoilers on the front and at a recent Philip Island event donw the straight doing approx 130mph (who knows how inaccurate my speedo is!) the zed never drifted or lifted the nose in a bad way.. I've experienced the drifiting without a spoiler at a low 50-60 mph so I could imagine at anything higher what it would be like.

[260DET]

Here is a link to a aero topic I started at Ozdat http://www.ozdat.com/forum/viewtopic.php?f=37&t=22074 which may help a bit. Do not ever underestimate the downforce generated by quite simple aero devices and their importance in keeping your Zed on the deck and going fast, drag generated by the stock S30 is mostly ignored yet steals power and speed too. Front and rear spoilers are a start, there is a lot more that can be done after that though.