Jenson Button is set for a massive 50-place grid penalty for this weekend's Mexican GP.
McLaren have been the hardest hit by penalties governing engine changes as Honda have struggled with reliability while also introducing upgrades.
This weekend's changes relate largely to the latter.
Button will run Honda's 'phase four' engine for the first time so he'll get a new engine, turbocharger, MGU-H and MGU-K on Friday morning. That means a 25-place penalty.
But in order to stock up on components, Honda plan to change all those again ahead of second practice adding another 25-place penalty.
As for his team-mate, Fernando Alonso is getting a new ICE which means a 10-place drop for the Spaniard. A new gearbox, yet to be confirmed, will mean another five-place drop for Alonso.
To date McLaren-Honda's biggest penalty was 105 places which they incurred at the Belgian Grand Prix.