Follow the explanation
Back to the model ↑How the parts work together
A V with real bores
The two rows of bores are 90° apart. Turn the model to see the sectioned surfaces and the pistons inside them. L and R are labels for this model, not a manufacturer’s numbering convention.
Two rods share one pin
The two big ends sit beside each other along a crankpin. Their pistons follow different bore directions. Scrub slowly and check that both eyes remain attached.
Count the power starts
Our generic sequence is L1–R4–R2–L2–R3–L3–L4–R1. The strip advances every 90°. Two cylinders are in their ideal power strokes at a time; this is cycle timing, not a torque plot.
Give one cylinder two turns
At 450° L1 is on intake, after power and exhaust. Its blue valve opens while the piston descends. Compression follows, and power begins again at 720°. The schematic valves omit lead, lag and overlap.
The main parts
- Sectioned block & bores
- Eight real openings in the castings align with the piston axes. Sectioned surfaces reveal the moving parts; removed material still exists in the ideal mechanical model.
- Heads & valve seats
- Each head closes the four bores in its bank. Ports lead from manifold flanges to the chambers. Sectioning exposes the valve seats.
- Crankshaft & shared pins
- Four offset journals sit in two perpendicular planes. Two rods fit between each pair of crank webs. Five main journals support the shaft between the throws.
- Connecting rods
- Each large eye surrounds a crankpin; the small eye surrounds the piston’s wrist pin. The I-shaped beam moves as one rigid part.
- Intake & exhaust valves
- Blue intake valves open during intake; graphite exhaust valves open during exhaust. Spring and stem motion follow an ideal lift schedule. Camshafts and their drive are omitted.
- Intake plenum & runners
- The blue plenum branches into eight passages at the inner faces of the heads. No air or fuel flow is calculated.
- Exhaust headers
- Eight outer runners join two collectors. These passages are illustrative, with no exhaust acoustics or tuning calculation.
- Cylinder R1
- Station 1, R bank. Its power stroke starts at 630° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder R2
- Station 2, R bank. Its power stroke starts at 180° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder R3
- Station 3, R bank. Its power stroke starts at 360° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder R4
- Station 4, R bank. Its power stroke starts at 90° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder L1
- Station 1, L bank. Its power stroke starts at 0° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder L2
- Station 2, L bank. Its power stroke starts at 270° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder L3
- Station 3, L bank. Its power stroke starts at 450° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.
- Cylinder L4
- Station 4, L bank. Its power stroke starts at 540° in the declared teaching sequence. Selecting it opens the mechanism and highlights its piston.