Car engines and jet engines have almost nothing in common, other than the purpose of making a vehicle move forward. The fuel is different, the average speeds are not even in the same ballpark, and the prices are not even on the same planet. Plus, good luck finding jet engine parts at your average junk yard.
What about rotational speed? You can go out to your driveway right now and look at the tachometer of your car and see that it redlines likely somewhere between 6,000 and 7,000 rpm. If you drive something a little spicier and higher-strung like a Honda S2000, 9,000 rpm might be the limit, whereas a motorcycle or an F1 car might reach 15,000 rpm.
How do those rotational speeds compare to a jet engine’s? Well, the answer isn’t all that clear-cut, because there are many spinning parts in your average modern turbofan engine, mainly the high-pressure and low-pressure turbines. Even for those components, the actual rotating speed isn’t too far off from a car, with the maximum speed of a high-pressure turbine reaching 15,183 rpm in the CFM 56 series of airliner engines.
High speed and low speed
The CFM 56 series of engines is the best selling jet engine ever. It powers mass-market airliners like variants of the Boeing 737. The 56-7 variant puts out a maximum of 27,300 pounds of thrust. There is no direct translation from thrust to horsepower, but given a Boeing 737’s cruising speed of over 500 miles per hour, it’s safe to say it’s more powerful than a car engine.
Going into specific speeds, according to CFM and Stanford University, the maximum rpm of the CFM 56 is broken up into the high-pressure turbine speed and the low-pressure turbine speed. As mentioned earlier, the high-pressure turbine redlines at 15,183 rpm. The low-pressure turbine redlines at a slower speed of 5,380 rpm. Those two speeds put a jet engines maximum rpm near the absolute pinnacle of F1 cars and the low speed somewhere near that of a commuter sedan.
