McClaren and Honda have warned against expecting any big performance jumps from them at this weekend's Belgian Grand Prix, with more grid penalties expected as they prepare to introduce a revised engine.
On the back of a morale-boosting two-car points finish in Hungary, Honda have been using the summer break to work on a new specification power unit and have placed particular emphasis on improving the internal combustion engine (ICE) via the spending of an as yet unspecified number of development 'tokens'.
Yasuhisa Arai, the Japanese manufacturer's motorsport chief, says F1's return to action at Spa will therefore be a key test of their work, but he is still expecting a challenging weekend.
"As we planned, Honda has updated our combustion characteristics to further improve our power units for Spa and the second half of the season," Arai said.
"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."
Having already exceeded their penalty-free allocation of engines for the season - which was retrospectively increased to five last month - McLaren's drivers will pick up further grid demotions any time they run fresh ICEs between now and the end of the season.
Team boss Eric Boullier insists the Woking outfit are "refreshed and determined to continue improving our form", but is also aware that high-speed Spa and Monza, the next two tracks on the calendar, are not likely to suit the MP4-30.
"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," the Frenchman said.
"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."
With 70 per cent of the undulating Spa circuit spent at full throttle, Fernando Alonso is expecting a "tricky" few days, but has stressed the importance of the race weekend to McLaren.
"The next few races will be important for us: we need to continue our forward momentum, and, with the addition of some tweaks to the car and power unit, we will be looking for more progress and good correlation between the simulator and our on-track performance," the Spaniard said.
"That might not necessarily appear above the surface in either Spa or Monza, but we'll keep pushing development forward at each race."
