The Woking squad secured a season-best finish of fifth with Fernando Alonso at the last race in Hungary, but know that the high-speed nature of the Spa-Francorchamps circuit is likely to expose the weaknesses of their current package.
However, both McLaren and Honda are determined to learn as much as possible over the three-day event in order to maximise performance for the remaining races.
“Honda has updated our combustion characteristics to further improve our power units for Spa and the second half of the season,” said Honda's motorsport boss Yasuhisa Arai. “This weekend's free practices will be important to test the pairing of the power units to the cars.
“The Belgian race, however, will surely be a difficult one for the team and drivers, with expected grid penalties and a long and unforgiving power circuit.
“Nevertheless, McLaren-Honda's focus is to improve race by race. We know we can learn a lot from the circuit for immediate future, and hope that we can come out of the weekend with some positives.”
McLaren’s racing director Eric Boullier added: "Spa is a truly spectacular circuit - arguably the best on the calendar for many - but, given the unique power and downforce package required, the track won't play to our strengths.
“Therefore, of course, we must be measured in our optimism, and we will need to wait for Singapore and beyond before we can see the fruits of our labours reflected on track."
Historically, McLaren have enjoyed an enormous amount of success at Spa. The team took their very first win at the Belgian circuit in 1968, and have registered 11 further victories there since - a record matched only by Ferrari.