A basic limitation on lap times is the driver's use of throttle and brake. This is very visible in formula cars, and is definitely one of the things that currently still limit my catching up with the leading pack in the Finnish Formula Ford Championships.
Formula cars are very close to eachother in performance, and nowhere is that so visible as in the Formula Ford class. Tenths are crucial, and slightest execution below the limit will show painfully in slow laptimes. Having no aerodynamic downforce, exploiting mechanical grip is paramount in FFs. This is imperative across all types of turns, but the big lap time differences appear in two areas - turns leading to long straights (exit speed is crucial) and high speed turns (where maintaining max speed is absolutely necessary to be competitive).Once these types of turns are managed proficiently, the next level of performance requires perfect braking. The braking needs to be firm and "full-on", yet such that it does not sacrifice the exit speed from the corner. As the FFs have no aerodynamic downforce, there is no need to account for that in braking. In F3s for example, as the driver initiates braking he has more traction (due to higher speed and thus higher aero downforce) whereas when the speed decreases so does downforce. Thus braking initially can be "super hard" and then wane off. In FFs this phenomenon is not as marked, due to the absence of aero downforce.
Below some examples of how these two behaviors appear in data logging. I have taken some data from Alastaro (you will perhaps recognize that in the track map on the picture), looking at the midsection of the two long straights with bends. In the first section we look at throttle lift off (the driver may think he only "slightly" lets the throttle up, but the truth is he is almost completely off the throttle - big room for improvement here!), and in the second section we study braking (driver shows some hesitance here).
The picture on the left is taken from Race Technology's Analysis software, and I have encircled the location of the car (upper part shows track map - this is one of the high speed turns at Alastaro where FFs go through with full throttle). The lower part of the picture shows the throttle position (in percent, 100% being fully open). The driver may think he only momentarily lifts off the throttle, but the data clearly shows he is completely off for a while, and then hesitates further. This is a big penalty in laptime (we are talking about a second here)! The data is taken using the DL1 data logger and an ECU interface to the Motec unit. As a smaller detail, note that there are small vertical "blips" (one appears to the left of the lift-off, one in the next part) which indicate that the driver takes throttle off when switching gears. This is another area that could be improved, the FFs and the Hewland transmission do allow for gear switching with throttle on (provided engine is at the top of its rpm area).
The second example shows braking at the end of the mid section at Alastaro. On the top we see the track map with the car's position encircled, and on the bottom the front brake pressure. We can see that the driver hits the brakes hard, but then hesitates and comes back. It may be that the driver experienced a lock-up here, this could explain the pattern. However, the driver seems to consistently lift off braking at the end (similar to what one might expect in an F3 or other winged formula, where this stems from the decreasing effect of aero downforce). This should not be necessary in an FF, and thus brake pressure could be maintained at a higher level longer, with shorter braking distance as a (much desired) result. The lowest part of the picture shows brake balance, and the singular line across the section indicates that the brakes maintain their balance reasonably well. Typically this plot is made for the full driving session, and any deviation from the diagonal is used to detect potential brake malfunction or failure. Thus it is a good safety check. The data used was logged with an DL1 logger, connected to two Bosch pressure sensors.
