Why SpaceX's new Raptor 4 is the Best Engine Ever Made...

This is the most dangerous rocket on earth. The SpaceX Starship. A machine so powerful that even a single static fire test can unleash sonic booms strong enough to rattle parked cars, shake nearby buildings, and occasionally remind local windows that life is temporary. And the craziest part, that violence comes from only one section of the rocket. Firing together beneath Super Heavy. Enough power to launch your entire neighborhood into low earth orbit if zoning laws were a little more flexible. But today, we're not even talking about Raptor 3. No. Today, we are diving into something even more extreme. Something that could make today's engines look conservative. I'm talking of Raptor 4. The next generation engine SpaceX is preparing for Starship version 4. An engine that may completely rewrite the limits of rocket propulsion. So what exactly is Raptor 4? And why are aerospace engineers already quietly losing sleep over it? Let's dive in. But first, a quick favor. Over the past two months, about 73.7% of viewers watching these videos still have not subscribed. And somehow that number keeps climbing faster than Starship's propellant budget. The goal is to get that number down to 60%. So if you've been enjoying the channel so far, please show your support by hitting that subscribe button. It genuinely helps us a lot and keeps these episodes coming. Thank you. And now, let's talk about rocket insanity. By now, you probably already know what Elon Musk is ultimately trying to accomplish. And it's not simply reaching orbit. His long-term goal has always been making humanity multi-planetary. Specifically, putting humans on Mars. That vision is exactly why SpaceX refused to stop after the success of Falcon 9 and the Merlin engine family. Back in 2008, SpaceX was dangerously close to collapse. The company nearly ran out of money entirely before Falcon 1 finally succeeded. But instead of slowing down afterward, Musk pushed even harder. Eventually leading to Starship, the largest and most powerful rocket system humanity has ever attempted to build. And at the center of that monster sits the Raptor engine. To understand how extraordinary Raptor really is, you need a comparison point. For decades, the king of rocket engines was the legendary F-1 engine used on the Saturn V moon rocket. The same engine that helped send humans to the moon during the Apollo era. Each F-1 produced roughly 680 metric tons of thrust. And the thing was enormous. You could practically park a small car inside the nozzle bell. For generations, aerospace engineers viewed the F-1 as the benchmark for raw rocket power. Now compare that to Raptor. The current Raptor 3 produces around 280 metric tons of thrust. Roughly 40% of an F-1's output. But that's not the absurd part. Raptor is dramatically smaller. Only about three meters tall with a nozzle diameter of one and a half meters. A tiny fraction of the F-1's size. And that compactness is exactly the point. Because it allows SpaceX to cluster 33 engines together beneath Super Heavy. The closest modern comparison would probably be the RS-25 engine used on the Space Shuttle and NASA's SLS rocket. The engine produces around 190 tons of thrust while being physically much larger than Raptor. More size, less output. Exactly the opposite of what SpaceX wants. So, even today, Raptor 3 already ranks among the most advanced rocket engines ever built. But SpaceX isn't stopping there. Musk has repeatedly confirmed that Starship is moving toward V4. And with it comes Raptor 4. This is not just a routine upgrade. It's an engineering requirement. Because Starship V4 is expected to become absolutely gigantic. When fully stacked with Super Heavy, the vehicle could stand around 142 meters tall. Roughly the height of a 35-story building. Fully fueled, the entire stack may weigh approximately 6,350 metric tons at liftoff. And payload capacity could exceed 200 metric tons per mission. That is an astonishing amount of mass. The problem is that Raptor 3 was never really designed to support those margins comfortably. You cannot constantly operate rocket engines at their absolute maximum limits and expect reliable long-term reuse. Especially not if your goal is flying hundreds of times. You need performance headroom. And that is where Raptor 4 enters the picture. This leads us to one of the most important numbers in rocketry. The thrust to weight ratio. Or TWR for short. The rule is simple. If the ratio falls below 1.0, the rocket does not leave the ground. Which honestly would make for a very disappointing live stream. For healthy acceleration during ascent, most rockets aim for something between 1.3 and 1.5. With Raptor 3, a fully fueled Starship V4 stack would generate around 8,877 tons of combined thrust. That creates a TWR of approximately 1.4. Which isn't bad, but definitely tight. And that assumes every engine performs perfectly at full output simultaneously. Which almost never happens in reality. During launch, SpaceX deliberately throttles engines down to reduce stress on both rocket and launch pad. Even small performance losses can quickly eat into those margins. Now imagine replacing those engines with Raptor 4. At a conservative estimate of 300 tons of thrust per engine, total liftoff thrust climbs to roughly 9,900 tons. That pushes TWR to approximately 1.56. And if SpaceX reaches the more aggressive 330 ton target, the TWR jumps to around 1.72. That is no longer just a performance upgrade. That is a massive operational advantage. It means the engines no longer need to operate constantly at the edge of destruction. They finally gain breathing room. Which is critical if Starship is expected to fly repeatedly like an aircraft someday. And yes, this gets even crazier when you step back and look at the full picture. 33 Raptor 4 engines together could generate more than 3 times the thrust of the Saturn V moon rocket. At chamber pressures potentially reaching between 350 and 380 bar. That is difficult to even visualize. Imagine compressing the weight of a fully loaded school bus onto an area the size of a postage stamp. While somehow convincing the metal not to explode. At that point, it almost stops feeling like engineering. It starts feeling like physics is being held hostage. So how is SpaceX even attempting this? A huge part of the answer comes from one of Elon Musk's most controversial decisions early in Starship development. Abandoning kerosene entirely in favor of liquid methane. Traditional rocket fuel like kerosene leaves behind thick soot deposits inside engines during combustion. Engineers call this coking. For expendable rockets, that is not a major issue. The rocket gets thrown away afterward anyway. But for a fully reusable system like Starship, constantly cleaning soot after every flight would become a nightmare. Methane solves that problem beautifully. Its molecular structure burns extremely cleanly, leaving almost no residue behind. However, that clean combustion comes with an enormous engineering price. Because to fully exploit methane's potential, SpaceX adopted one of the most terrifying engine cycles ever attempted. Full flow staged combustion. Even NASA has never successfully operated the cycle in routine spaceflight. The first major challenge is pressure. Absolutely insane pressure. To force methane and liquid oxygen into the combustion chamber, Raptor relies on independent turbopumps, compressing propellants under crushing loads. The chamber pressure exceeds 300 atmospheres. For comparison, the pressure of the bottom of the Mariana Trench is tiny by comparison. At these levels, even microscopic flaws can become catastrophic instantly. A tiny crack, a split second timing error, one unstable turbopump, and suddenly the engine becomes a thermobaric bomb, sitting beneath the largest rocket ever built. But somehow, that's not even the scariest part. To generate these pressures, Raptor runs both propellants through separate pre-burners simultaneously. One side for oxygen, one side for methane. Each side partially combusts propellant into ultra-hot gas streams that drive their respective turbines. Both systems feed into each other continuously in what can only be described as controlled violence. No operational rocket engine in history has ever done this successfully with both propellants simultaneously. The Soviet RD-270 came close back in the 1960s, but it never flew. That is the full-flow part of full-flow staged combustion. And the oxygen side becomes especially horrifying. Because hot, high-pressure oxygen stops behaving like friendly, breathable air. It becomes an incredibly aggressive oxidizer capable of igniting metals that normally seem fireproof. In simple terms, Raptor operates in a near-constant state of controlled self-destruction. The propellants are continuously trying to destroy the engine from the inside while the engine desperately tries to survive long enough to reach orbit. To handle this environment, SpaceX reportedly developed proprietary super-alloys specifically designed for these brutal oxidizing conditions. Because ordinary materials simply would not survive. And the complexity extends far beyond the engines themselves. Unlike many traditional rockets, Starship does not use on-board helium pressurization systems in the same way older designs did. That reduces mass and simplifies some systems. But it also transfers enormous startup complexity directly into the launch infrastructure itself. Every single ignition sequence must be perfectly choreographed through the launch tower systems, all 33 engines, at exactly the correct timing. That is why Starbase's launch infrastructure is referred to as Stage Zero, because the launchpad itself has effectively become part of the rocket. It handles propellant loading, engine chilldown, turbopump startup, ignition timing, clamp release, and dozens of synchronized operations simultaneously. One mistimed sequence across even a single engine could potentially trigger a rapid, unscheduled disassembly within seconds. Which is the aerospace industry's very polite way of saying everything exploded. And honestly, knowing all this somehow makes Starship's successful flights feel even more unbelievable. Wouldn't you say? Every mission that does not end in a fireball represents another step toward taming one of the most violent machines humans ever created. And here is what makes SpaceX's approach even stranger. They're not solving problems by adding complexity. They're solving them by removing parts. Just look at the evolution of the Raptor program itself. Raptor 1 looked unbelievably complicated. Pipes everywhere, valves stacked on valves, wiring wrapped around the engine like somebody lost a fight with industrial spaghetti. Building a single Raptor 1 reportedly took around 11 days, and it produced roughly 185 to 200 tons of thrust at around 250 bar chamber pressure. Impressive at the time, but far too complicated and expensive for large-scale production. Then came Elon Musk's famous philosophy, the best part is no part, and SpaceX applied it aggressively. Raptor 2 simplified huge portions of the plumbing by integrating pipes directly into the structure itself. The engine lost roughly 450 kilograms of mass while increasing thrust to around 230 tons. Same overall combustion principles, but lighter, cleaner, and more powerful. Then came Raptor 3, the version that genuinely shocked the aerospace industry. When the engine first appeared publicly, Tory Bruno reportedly thought it looked unfinished. Not because it looked bad, because it looked too simple. The external heat shielding was almost entirely gone. Not because SpaceX stopped caring about heat, but because the regenerative cooling systems had become so efficient that flowing propellant through the engine walls was enough to keep the metal from melting. No extra shielding required. With that design, Raptor 3 achieved roughly 280 tons of thrust at around 350 bar chamber pressure, breaking nearly every internal record SpaceX had previously established. And if you compare early Super Heavy boosters equipped with Raptor 2 against newer vehicles using Raptor 3, the visual difference is dramatic. The engines genuinely look cleaner, tighter, and more refined. Like the technology is evolving faster than the human eye can comfortably process. And now, SpaceX appears ready to repeat the cycle again with Raptor 4. If history repeats itself, Raptor 4 will not just become more powerful, it'll become simpler too. And in the world of rocket engines, achieving greater performance through simplification is basically the holy grail of engineering. Right now, no other company on earth appears to be moving at this pace. And honestly, that may be the most terrifying part of all.