Unreal Physics Gravity

Okay I have a altitude dependent temperature system which works fine but when I was doing some testing to see if it is correctly working I found some unusual data. I am on the first person template and made one of the boxes z*500 on the scale to make a box 500 meters tall. I jumped off for some laughs and it took forever to hit the ground, 14.46s because I did it again to test my hypothesis that ue4 doesn’t have -9.81 m/s^2 gravity. So at the top of my box I was at 500.4m, at the bottom I was at 2.68m which took me 14.46s. Finding velocity with delta d/delta t I got -34.4m/s, then I took acceleration with delta v/delta t and got -2.38 m/s^2. Then to backwards calculate to find how high I should have been for 14.46s I got just over 2,000m.

Is there anyway to change the engines gravity so that it is correct? Is there something I am missing? I would really like to know since I am creating a game that for some key parts of the mechanics depend on gravity being 9.81 m/s^2. Thank you