How is bore ratio calculated?
Divide the diameter of the cylinder bore by the piston stroke length. For example, if your cylinder bore were 4 inches and the piston stroke length were 3 inches, you would perform the following equation: 4/3 = 1.33. This is the bore-to-stroke ratio of your engine.
What is the best rod ratio?
Some engine builders say a “good” rod ratio is anything 1.55 or higher. Production engines may have rod ratios that range from 1.4 to over 2.0, with many falling in the 1.6 to 1.8 range. Four cylinders tend to have lower rod ratios (1.5 to 1.7 range) while many V6s have somewhat higher rod ratios of 1.7 to 1.8.
When do you measure piston to cylinder bore clearance?
Engine assembly requires the measurement of several components to ensure adequate clearances. Piston to cylinder bore clearance is one of those critical areas. Although the clearance is typically set by the machinist during cylinder honing, it is imperative that the assembler knows how to take the measurement to double-check the machinist.
Why does a piston need more clearance than a rod?
Highly loaded engines like these tend to experience greater heat loads and much higher cylinder pressures that can increase piston deflection and require more clearance. While the piston and rod are the mechanism by which force is transferred to the crankshaft, the piston is also tasked with maintaining a stable platform to support the rings.
How does Mahle measure piston to bore clearance?
In this example, Mahle set up the bore gauge to measure the actual bore size. The bore gauge reads zero at 4.040-inches. An alternate method is to measure the clearance without having to do any calculations by setting the bore gauge to read zero at the piston measurement. The reading on the bore gauge will be the piston to bore clearance.
What is the piston to cylinder clearance for a VHM?
When you know the exact cylinder bore size, you can check what piston diameter you need. With all VHM pistons, a packing list is included in the box. The minimum piston to cylinder clearance is indicated on this list. For example: your cylinder bore is Ø54.02 mm and the minimum piston to cylinder clearance is 0.07 mm.
Engine assembly requires the measurement of several components to ensure adequate clearances. Piston to cylinder bore clearance is one of those critical areas. Although the clearance is typically set by the machinist during cylinder honing, it is imperative that the assembler knows how to take the measurement to double-check the machinist.
In this example, Mahle set up the bore gauge to measure the actual bore size. The bore gauge reads zero at 4.040-inches. An alternate method is to measure the clearance without having to do any calculations by setting the bore gauge to read zero at the piston measurement. The reading on the bore gauge will be the piston to bore clearance.
Highly loaded engines like these tend to experience greater heat loads and much higher cylinder pressures that can increase piston deflection and require more clearance. While the piston and rod are the mechanism by which force is transferred to the crankshaft, the piston is also tasked with maintaining a stable platform to support the rings.
What is the bore to stroke ratio of a car?
The ratio of cylinder bore to piston stroke is most of the time defined as the Greek letter zeta ζ: For passenger road vehicles the bore to stroke ratio is usually from 0.8 to 1.2. When the bore is equal to the stroke, B = S, the engine is called square engine.