Jenson Button and Fernando Alonso will start the Belgian GP from the back of the grid as they have earned a combined penalty of 55 grid places.
Honda arrived at Spa this weekend with engine upgrades that required new parts to be fitted in both McLarens.
As such Button is taking an eighth turbocharger and MGU-H, while he is also using a seventh ICE and MGU-K.
Alonso, meanwhile, is onto his seventh ICE, turbocharge and MGU-H. The double World Champion is also using a sixth MGU-K.
Button's penalty is equal to a 25-place drop while Alonso's is 30.
Good news for McLaren, though, is a rule change means they will just start from the very back of the grid and won't take in-race penalties as well.