set datafile separator ","
set title  "Horsepower vs. Altitude"
set ylabel "HP"
#set y2label "Pressure Pa"
#set y2range [40000:102000]
#set y2tics border
set xlabel "Altitude"

plot "aaa-100.csv" every :10:110 using 12:3 notitle  with lines 2, \
     "pegasusiv-power2600-2.dat" using 1:2 notitle  with lines 3 

pause mouse key
if (MOUSE_KEY != 27) reread