Speed dating with the pistons

How fast can a racing piston go?

Special racing pistons weigh in at less than a pound, but imagine trying to accelerate one to 6,800 fpm (350 Chevy at 7,500 rpm) max piston speed at mid-stroke and then slam it to a dead stop and reverse direction in about 13⁄4 inches (stroke/2). At TDC the piston is headed for the moon and the rod has to stop it and yank it back the other way.

How do you find the mean piston speed?

The formula for mean piston speed yields an average speed based on two times the stroke (up and down for one revolution), times the engine speed (RPM) divided by 12 to convert to feet per minute (fpm). To simplify the formula, divide the numerator and the denominator by 2.

What is mean piston speed and why is it important?

Mean piston speed has long been used as an indicator of component durability under severe service. It is a good rule for evaluating engine potential and it is even more instructive if you calculate maximum piston speed since one of the axioms of engine performance dictates that power comes from engine speed.

What happens to the piston when it comes to a stop?

Since the piston actually comes to a complete stop at the top of the stroke (TDC) and at the bottom of the stroke (BDC), its speed and acceleration at any given point is always changing. The piston is always accelerating from or decelerating to zero speed.

What is the piston speed of a car engine?

Piston speed, measured in feet per second, is the limiting factor in reciprocating piston engines. That’s why racing engines use short strokes and lots of cylinders… 4000 ft/min used to be an astronomical speed, achieved only by the most exotic of racing engines. Now there are production cars that reach and even exceed this piston speed.

How to choose a piston for a racing engine?

Choosing a piston for a racing engine requires careful evaluation of the final application in terms of engine speed and the sustained piston motion, velocity, and loading that occurs. Hence a brief discussion of piston speed is warranted.

How fast can a cast piston Rev?

When the piston is exactly at either top or bottom dead center it is stopped and there is no acceleration. Using the formula for mean piston speed we calculated 3,000 fpm or 34.09 mph for our 302 Ford. Now let’s find the maximum piston speed at 6,000 rpm. A stock cast piston in a 350 Chevy revs to 6,000 rpm just fine.

How many stops per second does a piston make?

In the Honda S2000 2.0 liter engine previously mentioned, at 8300 rpm the piston makes 276 stops per second. The piston is then accelerated at several thousand g, also twice per crank rotation.

What happens when a valve hits the piston?

Due to a particular cause that can only be realized after the diagnosis of the engine, the valve might hit the piston. In most cases, the valves end in the losing point. A piston is more robust than a valve and functions under tremendous pressure. Therefore, the valves might bend while the piston gains some scratches.

What are the most common problems with piston rings?

Common problems with pistons: 02 Worn piston rings Piston rings eventually start to wear and the seal between the piston and cylinder is no longer air tight. As a result, oil makes its way from the crankcase past the piston and into the firing chamber. Symptoms of this are white smoke coming from the tailpipe and a drop in engine oil level.

What are the symptoms of a bad piston on a car?

Symptoms of this are white smoke coming from the tailpipe and a drop in engine oil level. If the noise doesn’t go away once the engine is up to temperature, the piston or the cylinder could be worn. A noisy piston is caused by too large a gap between the piston and the cylinder wall.

What is a piston?

In its basic form, a piston is a cylinder that moves up and down inside the engine block. Air and fuel mixture explodes inside the combustion chamber, and this causes the movement.