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S30 Aerodynamics not really that bad?


rudypoochris

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BJ, that mirrors what we see in the Land Speed Car. We ended up adding 200# of lead shot to the spare tire well, and it netted us a nice jump in top speed simply due to stopping tire spinning at speed. Andy almost spun the car during one run after we dropped the spoiler off the back, just couldn't keep power to the ground. Added the weight and stuck like glue. Picked up something like 6 mph on that run.

 

On the FairladyZ with 205-60-14's it pulls something like 5300rpm with the early 280 five speed, in fifth, with a 3.9 rear gear. That's with, or without my little "tagalong trailer" being towed (don't ask why I do these tests, I just do....)

 

Similarly, the wife's 260Z with a late ZX five speed, the same tire/rim combination, and a 3.70 gearset topped out at 4750rpm. For like an hour leaving St. Louis across Missouri...

 

Both engines are basically stock. eeh...

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ahhh now remember Mike, my above statement was "unmodified front end", and the speed was "above 150"...

 

I am not disputing anyones claims when they have done "real" modifications to the vehicle involving airflow, etc.

 

But when someone comes up to me with a hackjob bonestock Impala Stationwagon 350 conversion, with absolutely no modification to the front end, underneath, and indeed has raised the car for "tire clearance" or "looks" and in the same breath claims the car "easily does 165 all day long" with that TH400 and 3.36 rear end...

 

Well, Mike, I'm sure you're in my camp in saying in this case "We will smile politely and move on to the next subject!" LOL

 

This happens far more often that you might think. Especially when hanging around people bitter that their V8 is slower than "a puny little six"! But that is another discussion altogether!

 

I mean this is not limited to the Z-Community in any srot or stretch of the imagination. i know someone who claimed their B-60 14 shod Chevelle with a 4.11 gear "spun a rod doing 160 racing a turbo Porsche"... BS is not limited to us Z-Car guys, no, not at all! LOL

 

Tony, I'm fully in your camp on this post. The reason I made my comments was only to validate the numbers I've repeatedly spoken of. Quite honestly, my own crude methods of data collections back in the 90s were extremely dangerous and extremely risky. We were on public highways that had (At the time) little to no traffic and utilized several people and an off duty police officer who just so happened to be a good college buddy and fellow car nut.

 

Mike

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"my own crude methods of data collections back in the 90s were extremely dangerous and extremely risky."

 

Great minds thought alike during that very same time period! LOL

 

My static pressure probes and Magnahelics, Manometers, and Omega Rotary Switch Thermocouple reader rocketing down the road coming to realizations of "Oh, that's interesting OH SH*T! BRAAAAAAAAAAAAAAAAAAAAAAKES!"

 

A wind tunnel will be much more empirical, and more importantly SAFE!

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Rewind 30 years.........

The Primadonna addressed many of the aerodynamic issues associated with the S30.

prima172yo9.jpg

 

 

zcar1jpgyu4.png

Forget about the wing for just a minute.

Low frontal area nose, small radiator intake, evacuating ducts in the hood, and fenders. These were all elements that Jack took in to account when designing the body mods(again 30 years ago). Combine that with (if your paying attention, and not staring at the wing) a re-profiled windshield (made longer, and at a softer angle), aero skirting, and the absents of drip rails, make the car clean and very stable at speed. The mirrors are terrible for aerodynamics, but offer great visability. Many will remember seeing early pictures of the car wearing BBS aero cooling fans in the wheels. Frankly, I have several sets of them, but are not partial to their appearance

The modifications were done to a highly modified Scarab V8 car. This car is so well built that unless you have personally inspected the car, you probably don't get it.

As for the rear wing, it is functional.....the weight alone is guaranteed to keep the ass firmly planted.

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Primadonna,

 

You make some good points. I have some questions though, is the black on the sides behind the front wheel and infront of the rear wheel functional? And more importantly is the one behind the front wheel a vent? I can't tell from the pics.

 

It would seem pointless to add the small wheel well vent at the top when the place strip is exactly where it should be. There are always a number of improvements to any design that can be made, and the primadonna Z is no exception.

 

Not bad for 30 years ago though?

 

Dave

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The black that you see in front of the rear wheel is chip guard. With all of the widebody cars alot of rocks are thrown up against the rear fender extremities. What you are seeing is a bed liner type of material that is painted black to protect the fenders.

In the rear of the front fenders are two evacuation points. The upper is an evacuation duct, the lower an expanded metal grill. Both are to evacuate air in the front wheel housings. Probably do a pretty good job of getting air out from under the car, and aid in brake cooling as well.

The vents located on the hood are to evacuate underhood heat, and air build up in the engine compartment.

Thats my read anyway.

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Hey guys,

 

I found these links that I thought you might find interesting. I don't know if they've already been posted.

 

1) This page has a huge table of Cd for tons of different cars!

http://www.mayfco.com/tbls.htm

 

2) A neat page for how to measure Cd on your car.

http://www.geocities.com/plymouthsd1950/testing/dragforces.html

 

:mrgreen:

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I thought that windshield looked non-stock. When you compare the S30 windshield to the S130 windshield, you see Nissan recognized that was a big area that they could get easy payback aerodynamically.

 

Man, that Custom Windshield has to be $$$$$!

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Here are my attempts at redirecting air from the airdam/hood opening into only the i/c and rad.

 

On a side note. My hood used to quiver/shake/lift while driving at normal and above normal highway speeds. After these two aluminum pieces were added, it completely stopped shaking at speed.

 

 

DSC01061.jpg

 

 

DSC01071.jpg

 

BTW with my old L6 (highly modded if anyone cares to remember) Saw sustained speeds of 7400rpm in 5th with a 4.11 rearend, and 24.5" diameter tires. My calcs at the time put it around 148mph. That is with suspension mods, lowered, airdam, bellypan, rear wing, etc.

 

I am watching intently with these aero mod discussions, as I have been interested and working with them for some time now. I am by far NOT an aero expert. I do know that our speedo's are no good for testing, but I also have not been afraid to cautiously experiment. I'll have to get involved to some extent with this wind tunnel stuff. Heck I'd pay to have some good info to help me make some intelligent mods. (granted that not all of my mods have been with aero in mind..my big flares being the big one)

 

Thanks,

Scott.

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If there is sufficent interest I could do a post outlining the Primadonna windshield mod.

Actually it is quite simple. The biggest part would be modifying, or making a new cowl panel to work with the windshield. Since the windhield is Race Glass (lexan) the cost of the project is not huge.

 

The windshield does extend forward at the very front center about 8 inches from the stock position, so retaining your stock wipers is not an option.

 

Let me know

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PRIMADONNA Z... I'm interested too. I have a fake 250 GTO and your windshield mod would make it look more like the original. In addition, the decreased weight is welcome, especially that high on the car. It's a daily driver and Texas insists on working wipers though.

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Haven't given it much thought. The car is not my daily driver, so it's pretty much fair weather only (who wants to clean up the mess?).

However, if you look towards the top of the hood center you will see that the car does have a wiper (928 porsche rear wiper) that acts soley as a law enforcement decoy.

zcar7dr7.png

Because the windshield extends so far forward, the wiper would have to mounted on the hood. Volkswagen (I believe?) used a wiper motor that had a long cable that attached to the motor that allowed the motor to be mounted in a remote location out of the way (I have this system on another car, and no it's not a VW!). Perhaps with a little work this could be used to drive a wiper transmission for a single wiper like the one shown. The Race Glass ought to be tough enough to take the abuse from the wiper, they demonstrate it's durability by giving you a piece of steel wool and allowing you to rub on it. Tuff stuff!

Below is a picture if the re-profiled windshield 30 some years ago on car "01" during the orginal build. As you can see a dash panel needs to be fabricated to fill the area inside between the new windshield profile, and the old. Also the darker gray on each side of the windshield shows the mods necessary to the exterior cowl panel. The picture really illustrated the windshield extension. Great shape to reduce the wind resistance.

balconyshothq9.jpg

Frankly, as soon as I get some other projects out of the way I plan on doing this mod to my other car. Short of the wiper issue it's pretty simple and straight forward.

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PRIMADONNA Z... Thanks for the pics and info!! All cars are inspected here and must have working wipers. I guess I'm on my own with the wiper issue since it's an Alpha one with a pull-off hood. D@mn state interference...

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