Belgian F1 GP: McLaren's Button and Alonso have second Honda change

With the drivers both taking on an eighth internal combustion engine (ICE) the FIA has confirmed the matter has been referred to the stewards.

In addition, Alonso has taken an eighth turbocharger and MGU-H, and a seventh MGU-K, while Button is using a ninth turbocharger and MGU-H, and an eighth MGU-K.

It is anticipated the total amount of new penalties to be applied will be 25 apiece, in addition to the 30 handed to Alonso on Thursday and 25 for Button for the initial ICE and other ancillary changes, making a grand total of 105 overall.

However, the total amount of grid penalties is meaningless given the recent change to the rules as the most a driver can now be penalised is to be demoted to the back of the grid.

The FIA decided to eliminate in-race penalties as they were deemed by many to be too harsh.

McLaren and Honda have decided to make the double engine change to ensure they have a stash of systems going forward over the next few races, hopefully without incurring further penalties.

Honda introduced a new power unit for this weekend at Spa-Francorchamps, using a further three of its development tokens.

Explaining the changes, McLaren chief operating officer Jonathan Neale told Sky: "We ran two new engines yesterday, to put new engines in the pool, and then we changed the engines last night because we knew we were going to take a penalty.

"Under the existing regulations we're entitled to take another two [engines] and get them in the pool, so if we're going to take some pain then we'll take it here rather than have some further problems down the line.

"I'm not suggesting we're completely out of the woods, but [it works] in terms of a strategy to get more engines in the pool to give us a clearer run.

"And Honda wanted to introduce this particular engine here, which they've used some tokens for as well, so it's the start of another development path for us with them."

Despite the new engine in place for third practice, McLaren and Honda still encountered problems, with Alonso failing to set a time due to what Neale felt was an exhaust gas issue.