Uploaded November 2025 | Updated September 2026, 1 week ago
SpaceX is known for lighting up the sky almost twice a week with rocket launches, and naturally that’s what most people talk about. To be fair, launching a rocket is incredibly difficult, and the company deserves every bit of praise they get for it. But what often gets overlooked is something far more impressive—the engines behind those rockets. SpaceX is one of the very few companies on Earth that builds its engines entirely in-house, from the first bolt to the final test fire. That level of vertical integration is extremely rare in this industry. Most launch companies don’t want to touch engine development at all—it’s expensive, risky, and one mistake can destroy years of work. Companies like ULA spent over a decade relying on engines built by others, including the RD-180 from Russia and the BE-4 from Blue Origin. Buying engines is the “safe” option.
SpaceX didn’t take that route. They chose the hard path. They designed Merlin on their own. They created the full-flow staged combustion cycle Raptor on their own. And they’ve been evolving it aggressively with each generation. That brings us to the latest development—something Musk recently hinted at that caught everyone’s attention: the Raptor 4.
Without making big announcements or glossy presentations, Musk revealed that Raptor 4 is already designed and in development. What makes this interesting isn’t just the name “Raptor 4,” but what he said about its cost and performance. According to him, the engine will deliver more thrust, better efficiency, and—most shocking of all—will be more than ten times cheaper per ton of thrust than SpaceX’s own Merlin engine. That’s insane considering Merlin is already one of the cheapest and most proven orbital engines ever built.
SpaceX is known for lighting up the sky almost twice a week with rocket launches, and naturally that’s what most people talk about. To be fair, launching a rocket is incredibly difficult, and the company deserves every bit of praise they get for it. But what often gets overlooked is something far more impressive—the engines behind those rockets. SpaceX is one of the very few companies on Earth that builds its engines entirely in-house, from the first bolt to the final test fire. That level of vertical integration is extremely rare in this industry. Most launch companies don’t want to touch engine development at all—it’s expensive, risky, and one mistake can destroy years of work. Companies like ULA spent over a decade relying on engines built by others, including the RD-180 from Russia and the BE-4 from Blue Origin. Buying engines is the “safe” option.
SpaceX didn’t take that route. They chose the hard path. They designed Merlin on their own. They created the full-flow staged combustion cycle Raptor on their own. And they’ve been evolving it aggressively with each generation. That brings us to the latest development—something Musk recently hinted at that caught everyone’s attention: the Raptor 4.
Without making big announcements or glossy presentations, Musk revealed that Raptor 4 is already designed and in development. What makes this interesting isn’t just the name “Raptor 4,” but what he said about its cost and performance. According to him, the engine will deliver more thrust, better efficiency, and—most shocking of all—will be more than ten times cheaper per ton of thrust than SpaceX’s own Merlin engine. That’s insane considering Merlin is already one of the cheapest and most proven orbital engines ever built.
