Crossplane
Encyclopedia
The crossplane or cross-plane is a crankshaft
design for V8 engines with a 90° angle between the cylinder banks.
The crossplane crankshaft has four crankpins, each offset at 90° from the adjacent crankpins. The first and last of the four crank pins are at 180° with respect to each other as are the second and third, with each pair at 90° to the other, so that viewed from the end the crankshaft forms a cross. The crankpins are therefore in two planes crossed at 90°, hence the name crossplane. A crossplane crank may have up to five main bearing
s, and normally does, as well as large balancing weights. Crossplane V8 engines have uneven firing patterns
within each cylinder
bank, producing a distinctive burble in the exhaust
note, but an even firing pattern overall. Their second-order balance means no additional balance shaft
is necessary to achieve great smoothness.
The other design for a V8 crankshaft is the flatplane crankshaft, with all crankpins in the same plane and the only offset 180°. Early V8 engines, modern racing engines and some others used or use the flatplane crankshaft, which is similar to that used in a straight four
or flat-four engine. Flatplane V8 engines may use any angle between the cylinder banks, with 60° and 90° the most common. They lack the V8 burble and the superior mechanical balance
of the crossplane design, but do not require the large crankshaft balancing weights. Inherent balance of the big ends is like a straight four, and modern designs often incorporate a balance shaft for smoothness. But without balance shafts, flatplane designs have the least flywheel
effect of any V8s, which allows them to be more free-revving.
The crossplane design was first proposed in 1915, and developed by Cadillac
and Peerless
, both of whom produced flatplane V8s before introducing the crossplane design. Cadillac introduced the first crossplane in 1923, with Peerless following in 1924.
motorcycle uses the crossplane crankshaft and utilises a specially designed balancer to counteract the unusual vibration found in this type of crank when not used in conjunction with a V8 engine.
This type of crank has been used in Yamaha's M1
MotoGP racing models in the past. Yamaha claims advances in metal forging technologies make this a practical consumer product.
Crossplane cranks can be combined with big-bang firing order
for improved power delivery.
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
design for V8 engines with a 90° angle between the cylinder banks.
The crossplane crankshaft has four crankpins, each offset at 90° from the adjacent crankpins. The first and last of the four crank pins are at 180° with respect to each other as are the second and third, with each pair at 90° to the other, so that viewed from the end the crankshaft forms a cross. The crankpins are therefore in two planes crossed at 90°, hence the name crossplane. A crossplane crank may have up to five main bearing
Main bearing
In a piston engine, the main bearings are the bearings on which the crankshaft rotates, usually plain or journal bearings.All engines have a minimum of two main bearings, one at each end of the crankshaft, and they may have as many as one more than the number of crank pins...
s, and normally does, as well as large balancing weights. Crossplane V8 engines have uneven firing patterns
Firing order
The firing order is the sequence of power delivery of each cylinder in a multi-cylinder reciprocating engine.This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine...
within each cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
bank, producing a distinctive burble in the exhaust
Exhaust system
An exhaust system is usually tubing used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes...
note, but an even firing pattern overall. Their second-order balance means no additional balance shaft
Balance shaft
In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...
is necessary to achieve great smoothness.
The other design for a V8 crankshaft is the flatplane crankshaft, with all crankpins in the same plane and the only offset 180°. Early V8 engines, modern racing engines and some others used or use the flatplane crankshaft, which is similar to that used in a straight four
Straight-4
The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....
or flat-four engine. Flatplane V8 engines may use any angle between the cylinder banks, with 60° and 90° the most common. They lack the V8 burble and the superior mechanical balance
Engine balance
Engine balance is the design, construction and tuning of an engine to run smoothly. Improving engine balance reduces vibration and other stresses and can improve the overall performance, efficiency, cost of ownership and reliability of the engine, as well as reducing the stress on other machinery...
of the crossplane design, but do not require the large crankshaft balancing weights. Inherent balance of the big ends is like a straight four, and modern designs often incorporate a balance shaft for smoothness. But without balance shafts, flatplane designs have the least flywheel
Flywheel
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed...
effect of any V8s, which allows them to be more free-revving.
The crossplane design was first proposed in 1915, and developed by Cadillac
Cadillac
Cadillac is an American luxury vehicle marque owned by General Motors . Cadillac vehicles are sold in over 50 countries and territories, but mostly in North America. Cadillac is currently the second oldest American automobile manufacturer behind fellow GM marque Buick and is among the oldest...
and Peerless
Peerless
Peerless was a United States automobile produced by the Peerless Motor Company of Cleveland, Ohio from 1900 to 1931. The company was known for building high-quality, precision luxury automobiles. Peerless' factory was located at 9400 Quincy Avenue in Cleveland...
, both of whom produced flatplane V8s before introducing the crossplane design. Cadillac introduced the first crossplane in 1923, with Peerless following in 1924.
Inline-four crossplane cranks
Inline-4 engines can also use the crossplane concept. The 2009 Yamaha YZF-R1Yamaha YZF-R1
The Yamaha YZF-R1 is an open class sport bike, or superbike, motorcycle manufactured by Yamaha Motor Company since 1998.-1998–1999:Yamaha launched the YZF-R1 after redesigning the Genesis engine to offset the crankshaft, gearbox input, and output shafts. This "compacting" of the engine made the...
motorcycle uses the crossplane crankshaft and utilises a specially designed balancer to counteract the unusual vibration found in this type of crank when not used in conjunction with a V8 engine.
This type of crank has been used in Yamaha's M1
Yamaha YZR-M1
The Yamaha YZR-M1 is an motorcycle specifically developed by Yamaha Motor Company to race in the current MotoGP series. It succeeded the YZR500 by the 2002 season and was originally developed with a engine...
MotoGP racing models in the past. Yamaha claims advances in metal forging technologies make this a practical consumer product.
Crossplane cranks can be combined with big-bang firing order
Big-bang firing order
A big bang engine is an unconventional motorcycle engine designed so that most of the power strokes occur simultaneously or in close succession. This is achieved by changing the ignition timing; sometimes in combination with a change in crankpin angle. The goal is to change the power delivery...
for improved power delivery.
External links
- V8 Engines - The characteristics of V8 engines.