Power is torque×angular velocity. Say for same power, torque for big engine is more thus angular velocity is less , thus less RPM . Torque for small engine is less thus to get that same power they have to work Faster thus more RPM.
Why can’t v8s rev high?
Without extra valves, the engine can’t take in enough air at higher rpm and it becomes starved for air. Thus, it can’t rev as high. The number of camshafts and valve timing are the final reasons pushrod engines don’t rev very high. … That means valve lift and duration can’t be adjusted for higher rpm needs.
Is it better to have higher or lower rpm?
Running at lower RPMs equates to higher torque and thus lower horsepower, while making higher RPM power outputs less torque and higher top horsepower. In a straight line race, higher RPMs take precedence.
Is low rpm good for engine?
Low RPMs are fine if you’re just cruising or slowing down, but when you accelerate, low revs leave your engine with a gearing disadvantage. To get your car up to speed, the engine has to work a lot harder. Engine temperature will rise, and cylinder temperature will rise. This is where things can start to go screwy.
Do 4 cylinder engines rev higher?
4L/cyl) with a shorter stroke than the 3.8L V6 so it redlines slightly higher, at 7k. However, because of this shorter stroke, it puts out 115hp but only 110lb-ft of torque. The reason why Ferraris can rev so much higher than other large engines is because their engines are small for the number of cylinders they have.
Why do American engines rev so low?
1. American pushrod engines generally have lower redlines than overhead cam engines. … The limiting factor to how fast an engine can rev is usually the valvetrain. The valves are held in the closed position with springs, until they get a bump from the cams, causing them to open.
What limits an engine’s RPM?
The maximum RPM of an engine is limited to the airflow through the engine, the displacement of the engine, the mass and balance of the rotating parts, along with the bore and stroke of the pistons.
Does torque beat horsepower?
Horsepower equals torque multiplied by rpm, divided by a constant. Because there is generally a limit on how fast you can spin an engine, having higher torque allows for greater horsepower at lower rpms. This is also why people talk about “low-end torque” being important for better power at slower speeds.
What Does BHP stand for horsepower?
What is Brake Horsepower (bhp) However, Brake Horsepower (bhp) is often used as a more realistic measurement of power. This is because bhp considers the power left after other car parts are working such as the gearbox, alternator, and water pump as well as any loss of power due to friction.
Is horsepower better than torque?
The more horsepower a car has, the faster it’s going to burn fuel, both on acceleration and under normal driving conditions. Conversely, the more low-end torque a vehicle has, the slower it may burn fuel, depending on your typical driving and hauling habits.
Is it bad to drive 5000 RPM?
5000 is where the fun starts. It’s not staying there for extended periods. You’ll be fine. The reason it’s so sluggish is that the transmission is programmed to save fuel so it’s always in a higher gear.
Is bogging engine bad?
At the most basic level, lugging your engine doesn’t make much sense because it puts your engine at a disadvantage. That means it has to work harder to do the same amount of work. But that also means it runs less efficiently, increases engine temperature, and can even cause issues with the engine’s timing.
Is driving in 4th gear bad?
5 Answers. To answer your question, no it isn’t bad for your car to keep it in as high a gear as you can while still maintaining speed. As long as you are above idle in RPM and your engine isn’t lugging, you aren’t doing any damage.
Why do bigger engines make more power?
It’s a simple matter of being able to burn more fuel to raise cylinder pressure. More cylinder pressure pushes down on the piston harder, which in turn rotates the crank faster and harder and = more power. It’s that simple.
Why do F1 engines rev so high?
Lower piston speeds means less stress on the connecting rods and crankshaft as well as acceptable flame propagation speeds, allowing the engine to rev even higher. … Formula 1 engines and motorcycle engines often have very high bore/stroke ratios, allowing for higher engine speeds (and thus more power).
Why is 7000 rpm the limit?
Petrol engines usually redline at 7000-8000 RPM while diesel hits the peak at around 4500 RPM. This is because diesel engines are not made for high RPM in the first place. They are slow to combust than petrol and are mainly focused on more torque rather than RPM.