Ground effects for 180 mph

Jess said:

Well lets start with 5500 rpm, 28 inch tall tires, 3.73 rear gears, final drive of .63, and a whole lot of horse power???

Jess

Click to expand...

The theoritical equation works out to about 178-180
http://www.corral.net/tech/gearcalc.html

However, to properly align expectations the car will never see that speed because of tire friction, wind drag, etc....top speed will be sub 140 IMO. Another thing to remember is the OD gear in trannys are rarely (if ever) designed to allow the car to acheive 5500 RPM while in them. The car's top theoricial speed is best calculated using the 1:1 tranny ratio since in a race you would not be using OD.

Here is a theoretical speed graph I made for my car so I could have an idea of speed based on RPM since the speedo hasn't been hooked up. If I stepped up to a 28 inch tire from a 25.5 I would have very similar numbers to yours. While no one has yet to pass the car 5000 in OD feels extremely unsafe because of lift and I know I am not going anywhere close to what the theory says I should be (I would guess sub 110). So to answer the core question at higher speeds and air damn/spoiler on the front will help you prevent lift (until a point) I see little benefits in side skirts.

http://www.dodgestang.com/speedchart.jpg

One thing I would keep in mind for high speed running. If you look at the 'super cars' that are designed to actually run above the 130-140 mark. They have smoother undersides with vents in strategic locations to create a pressure change under the car thereby using this pressure change created by the passage of air at high speeds under the car to 'suck' it down.