drag coefficient needed

[CaptTrev]

hey guys

I just got an OBD II Scan tool and Dyno tester for a Palm Pilot. (Got it off eBay)
its made by Auterra.

In order to utilize the dyno functions of the unit, i need to enter in my XJ's stats (height, weight, gear ratios, etc)
i also need the drag coefficient, or a way to calculate it.

my XJ is lifted, with 31's. I was wondering if their was a way to figure out this #, or if anyone knows the drag coeff. of a stock XJ and I could tweak that # slightly maybe?

any help would be appreciated!

CaptTrev

 

[explorer]

A generic number for vehicle type out of one of my textbooks is in the .35 to .42 range. Any dyno or calculator is typically only useful for comparing setups. They can give variable #'s between different machines.

 

[MaXJohnson]

.55 to .60 will get you in the ballpark

 

[Dr. Dyno]

A stock XJ has a drag coefficient of 0.45 and a frontal area of 27.8sq.ft.

 

[MaXJohnson]

A stock XJ has a drag coefficient of 0.45 and a frontal area of 27.8sq.ft.

That sounds like the specs I have for a '95 Grand Cherokee

Bricks don't get under .50

 

[CaptTrev]

A stock XJ has a drag coefficient of 0.45 and a frontal area of 27.8sq.ft.

yes, i needed frontal area too, thanks!

im definately not expecting a perfect result with this thing, I'm really just going to mess around with it for fun.

I bought the unit mostly for its OBD II scanner abilities--the dyno part of it will be just a toy for now.

I'm going to guess if stock is .45, my 4" lift + 31X12.5's will up that # to at least .55 maybe.

How much do you think the frontal area would increase with my setup?

thanks for all the info everyone, keep it coming!

CaptTrev

 

[Dr. Dyno]

How much do you think the frontal area would increase with my setup?

About 8-9%. Since you've also added bigger/wider tires as well as a 4" lift, figure on the drag coefficient being nearer to 0.60.

 

[2offroad]

I would think just south of a barn's or maybe a Great lake tanker.

 

[Wolf]

Drag coefficient of an XJ = drag coefficient of

 

[Wolf]

I think someone needs to build a Charger Daytona-esque nose cone for the XJ.

 

[Wolf]

cars.com shows the drag coefficient for a 2000 XJ as 0.51, they don't list it for a 96.

 

[casm]

cars.com shows the drag coefficient for a 2000 XJ as 0.51, they don't list it for a 96.

*Only* 0.51? For the brick on stilts? Guess we got off lucky