Aero Advice on 260z

[sopwith21]

I am road racing a 1974 Datsun 260z. I have the option of either removing the front windshield and rear hatchback to save weight, or leave them in and have a more streamlined, aerodynamic body.

 

I have no idea what to do. Would love to really do my homework here and make a good decision.

 

The car makes approx. 160 hp. It weighs 2213 lbs without driver. The car has been scaled and the weight is evenly distributed via coilovers. Anticipated top speed is 90-120 mph on straightaways at places like Iowa Speedway and Texas Motor Speedway. Overall average speeds on these road racing tracks will be around 65-80 mph.

 

Remember, all side windows have been removed for driver ingress/egress. The only question here is what to do with the front and rear windows.

 

Essentially, I can either save 40-60 lbs (weight being the enemy of speed) and have a car with the aerodynamics of Swiss cheese, or leave both windows in place, keep the extra weight, and streamline the car's aero profile.

 

Which is better?

 

If anyone can lend any support or help, it would be most appreciated. Thank you!

Edited November 11, 2010 by sopwith21

[AkumaNoZeta]

I would think that the car would have less drag without the windows since it will reduce the frontal area and get rid of the high pressure area on the cowl.

[cygnusx1]

  I dunno, without the front glass or hatch, and the roof panel acting like a big lifting body???  I would think drag may be slightly reduced, if any, but lift is going to increase quite a bit...just a wild guess.  Personally, I would keep the glass for safety, and what we know works.  

Edited November 11, 2010 by cygnusx1

[burninator]

What about replacing the glass with Plexiglas or lexan or some similar transparent plastic? You'd save most of the weight, and likely have better aerodynamics than leaving the windows out. Everything inside the car is so odd shaped that I couldn't see the air having an easy time passing through, and when you factor in the interaction with the roof and hatch... it'd take quite a bit of testing to know how it would work. Over time the lexan will get scratched up and may need to be replaced, but it's pretty cheap.

Edited November 11, 2010 by burninator

[AkumaNoZeta]

You have the glass now so you can do it in stages. Record your times with the glass, then see how your times change after taking all the glass out, and then check the change in times again after installing lexan windows. Then you have hard data to play with.

[JMortensen]

Could also just run the windshield. Don't use plexi, it's a ***** to cut. Lexan cuts really easy with a jigsaw.