Raptor 4 Could Double Super Heavy’s Outer-Ring Engine Thrust, Musk Says

Elon Musk says he is tempted to build a 500-ton thrust Raptor 4 engine for the outer ring of SpaceX’s Super Heavy booster, replacing the 250-ton Raptor 3 engines that ring is designed around today.

“It is so tempting to make a 500 ton thrust Raptor 4 in place of the 250 ton Raptor 3 for the outer ring of the Starship booster,” Musk wrote on X Friday evening.

That wording matters, since Musk described a temptation, not an approved design change, and SpaceX has not announced a Raptor 4 program, a test schedule, or which Starship version would carry it.

By his own numbers, that would double thrust for each outer-ring engine. It would not double the whole booster, since Musk only mentioned the outer ring and the centre engines are not part of the idea. Musk did not say whether a bigger engine would mean fewer outer engines, a wider booster, or changes to the launch mount and the tower arms that catch Super Heavy.

The post landed as SpaceX prepares for Starship Flight 15, currently targeting November 13, after the company fired all 33 engines on the booster it hopes to catch. Musk has also said SpaceX will try to catch both Super Heavy and Starship.

Doubling per-engine thrust is a huge jump for an engine family that only recently moved to Raptor 3. For now, Raptor 4 lives in a single post, and it is worth treating as Musk thinking out loud until SpaceX puts hardware on a test stand.