Wind tunnel testing of Z's with common aftermarket parts:

Windtunnel Test Data - Windtunnel Test Results and Analysis - HybridZ

Windtunnel Testing the Datsun S-30 Z - Windtunnel Test Results and Analysis - HybridZ

Here is a little larger copy of the Car & Driver Aero Article from 74

http://zhome.com/CarDriverAero/CDAero74.htm

FWIW,

Carl B.

.... what would be the net effect of a spook in front and a clear rear end? Are front and rear spoilers a package deal aerodynamically?

I have a Blue 72 and I have both BRE Front & Rear spoilers on it. Rock solid at speed.. Built L28/triples/cam/headwork etc. I tend to drive it faster than I should - for some reason. Freeway runs between Clearwater and Atlanta nights - typically made at 100 mph.{just to keep the trucks from running over me}. On that Z I like having the pair.

I also have a White 72 - mostly bone stock - I find myself driving it at a much more relaxed pace. Typically 70-80 mph on the Freeways. I have only the Front BRE Spook and the car is very solid on the road.

So from my personal experience - I'd say you would be perfectly happy with only the front Spook.

FWIW,

Carl B.

Reducing lift increases fuel mileage. It takes energy to lift the front and rear of a car and that energy comes from the engine. In a corner at the traction limit an additional 20 lbs. of less lift on the back can be the difference between the exiting the corner under control or having the rear end break loose. Turn 9 at Willow Springs will teach you that. Formula 1 teams spend tens of thousands of dollars to generate an additional 10 lbs. of downforce.

I have neither the front or rear spoiler on my 72, and do have mild instability at highway speed, and thats only 100 km in NZ. Funny thing is, it seems to stabilize at speeds above that.

Got to watch out for curbs with the spook. Carbon fiber is tough, but concrete always wins.

Does it really matter on a car of that age ?

Thanks for all the input and great references. In my past Z experience, I think the car definitely needs help with high speed stability at freeway speeds (Southwest US freeway speeds of 80+). As for the rear, the car is used as a daily driver and occasional long-distance GT so, in the interest of esthetics, I'll see how things go without it. Thanks again for all the input!