HUGE difference in FTP outdoors vs indoors (Page 2)

ok here is the whole indoor test:

Power-Tap #1:
    Duration:      42:43
    Work:          375 kJ
    TSS:           70.8 (intensity factor 0.998)
    Norm Power:    151
    VI:            1.03
    Pw:HR:          0.08%
    Pa:HR:          -1.68%
    Distance:      11.321 mi
        Min    Max    Avg
    Power:           0    245    146     watts
    Heart Rate:      154    183    177     bpm
    Cadence:         45    146    83     rpm
    Speed:           6.4    19.5    15.9     mph
    Pace             3:05    9:22    3:47     min/mi
    Hub Torque:      0    89    60     lb-in
    Crank Torque:    0    257    149     lb-in

and here is CBTT

Duration:      29:39
    Work:          299 kJ
    TSS:           58.9 (intensity factor 1.092)
    Norm Power:    186
    VI:            1.1
    Pw:HR:          n/a
    Pa:HR:          n/a
    Distance:      10.615 mi
        Min    Max    Avg
    Power:           45    584    168     watts
    Cadence:         32    166    82     rpm
    Speed:           2.7    32.5    21.5     mph
    Pace             1:51    22:27    2:48     min/mi
    Hub Torque:      11    270    55     lb-in
    Crank Torque:    32    1028    181     lb-in

so yes, VI is higher on CB,

I think now that I have had all this great input and time to examine that it is a combination of indoors without adequate fans, after long day at work, and 3 days after the outdoor effort and not resting rather swimming and lifting the days before the indoor....

so will look ahead to when the next one is - the remainder of the OS I am doing indoor TTs.

meanwhile I am tempted to use my last VO2max/LT testing for my power numbers (FTP 170) as it is inbetween.....

I would tend to agree that it probably comes down to cooling indoors.  I've watched even my own "easy" days drop 20W for the same RPE just because I forgot to open the patio door and turn on the fan.  Closely followed by consistency.  As you described, training load, rest, workload, motivation, environment, and duration were different between the two tests.  It makes sense to just choose a date and change over to the method that most closely resembles the majority of your training locations.  If you mainly train indoors, test indoors so the zones are applicable.  

 If your familiar with design of experiments (DOE) it comes down to holding constant all the variables you can so you can use the results to make conclusions about the variables you can't hold constant.