AdelaaR, you should get a powermeter. For TT, you want to get as close as possible to Variability of Intensity = 1.0. (Normalized Power/Average Power) and be running the TT at your functional threshold or slightly higher, depending on how long the TT is of course.

Only a power meter will show you the short-duration variability in your power output to help you train to that level of consistency, as well as to know what your FTP is and where your output stands in relation. One of the revelations to me when I started training with power was how much my output had to change to maintain a specific pace with what are very small changes in grade on the road.

How else are you going to take down Tony Martin?