Aero-dynamics

Z

zedhead260

Well-Known Forum User
Anyone know anything about the aero-dynamics of a 240z / 260z ?? Read anything anywhere ??
I'm thinking of ditching my rear spoiler when I get my tailgate repaired - purely for cosmetic reasons.
Also, what effect does a deep chin spoiler have on the car ??
Drag co-efficient anybody ??
 
I've read that the 240 and 260Z have a drag coefficiency of  0.467 the 280ZX benefitted from better air tunnel testing which lowered its drag coeff to 0.385.

If you do remove the spoiler bear in mind that all the racing 240Z's 260Zs all have a rear spoiler, either the original one or a wider one. It definately has a purpose, mainly to keep the rear wheels onto the tarmac.

Also the lack of rear spoiler (I think, after chatting to a US guru) would mean more exhaust fumes entering the vehicle.

Just some thoughts. <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>
 
I think drag co-efficient is something to do with the amount of makeup you wear when you go out for the night!
 
Hi,
&nbsp; I stand to be corrected..But I think that air dams and rear spoilers on road cars are generally used by the manufacturers as more of a marketing tool, rather than to improve aerodynamics.
&nbsp; However...the un-spoilered versions of sports cars are often the most visually appealing too!
&nbsp; Some original spec spoilers are very heavy too, which obviously has a detrimental effect on the overall car weight.
&nbsp; Unless you're going to drive on the track I wouldn't think that at sane <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'> road speeds it will make much difference.
JEZ
 
Time for a serious reply tonight . The standard US spec 240Z cars like mine were sold without front or rear spoilers. the lack of a front spoiler leads to front end lift at high speed which makes the car feel a bit light and unstable ie it does a sort of high speed wander if you are not watching it carefully. Quite scary sometimes. I know the rear spoiler is there to increase rear end downforce but I defy anyone to be able to detect the difference on a normal road car.
My personal preference visually is for my US spec car witout any plastic add on stuff. But really its all down to individual preference. Its your Zed, just do what you fancy. Try looking at the colour pics in Brian Longs book Fairlady to 280Z or in Colin Shipways book Essential Datsun Z
 
I read the thread on the Hybridz forum and there are some interesting views. After pondering on it over the past few days, it really boils down to how the car will look. The deep front spoilers that you find fitted to some Zed's don't really do anything for me. They look ok from the front, but from the side it all goes a bit pear shaped at the front of the arch and spoils the lines (is that why they are called spoilers ?). I have the one piece front valance with original size chin spoiler (fibreglass), so think I'll stick with it. I don't really get front end lift at speed as the car has been lowered. In fact, high speed stability is very good.
Still in two minds about the rear one though. I like the look of it, but I also like it without. Hmmmm &nbsp;<img src="http://www.zclub.net/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'> The problem with it, is that it acts as a water trap. If I go to all the expense of repairing the lower edge of the tailgate, I wouldn't want to do it all over again some years down the road.
So the jury is still out on that one. I have started to do track days, but essentially it is a road car (something I have always considered before a modification), so I am prepared to compromise a slight loss of rear downforce.
What's the definition of sane road speeds ?
70mph ? 100mph ? 130mph+ ??
Anyone got a wind tunnel ?
 
in my view the Samuri spoiler is the best looking from the side as when it is fitted correctly it follows the line of the front of the wheel arch and dosn't look like an add on
I know Tim Riley used to seal f/g replicas that were quality
Just my 2 pence worth
 
hi late addition to the fray but from personal experience &nbsp; the front end WILL go light at about 60mph+ with quite spectacular results when running a Z without a front spoiler. even the small inoffensive black rubber ones help channel the airflow round the car not under it. the rear spoiler is more for show but adds somewhere in the region of110 psi downforce to the rear of the car at 60mph+ as for drag co-efficients &nbsp; unless you are intending to run the Z in the F1 championship &nbsp; dont worry about it just add an extra coat of polish and cut out the junk food.
 
Thanks chaps,
Like I said before, with the standard front spoiler and the fact that the car sits low, I don't suffer front end lift at any speed so will keep as is.
After lots of thought, I think I will keep the rear spoiler as well. I like the sound of 110 psi of downforce above 60mph.
 
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