Straight-seven engine
Encyclopedia
A straight-seven engine or inline-seven engine is a straight engine
with seven cylinder
s. Wärtsilä
, with their RTA96-C
, and MAN Diesel produce crosshead two-stroke diesel engines in this configuration. Wärtsilä also produces regular trunk engines in this configuration. It is more common in marine applications because marine engines are usually based on a modular design, with individual heads per cylinder.
Only one straight-seven engine for land propulsion is known to be in production, the AGCO
Sisu 7-cylinder diesel engine. This engine configuration was chosen because of size, parts commonality, and power range issues. A straight-8 would be too long for the farm machinery application the engine was intended for, whilst a V engine
would require a higher investment compared to the expected low sales volume for this power range. The straight-7 configuration is a lower investment because Sisu has reused cylinder head
s from their I3 and I4 diesel lineups. This is possible because the cylinder volume, pistons and con rods are identical across the Sisu model range.
Straight engine
Usually found in four- and six-cylinder configurations, the straight engine, or inline engine is an internal-combustion engine with all cylinders aligned in one row, with no offset...
with seven 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...
s. Wärtsilä
Wärtsilä
Wärtsilä is a Finnish corporation which manufactures and services power sources and other equipment in the marine and energy markets. The core products of Wärtsilä include large combustion engines...
, with their RTA96-C
Wärtsilä-Sulzer RTA96-C
The Wärtsilä RT-flex96C is a two-stroke turbocharged low-speed diesel engine designed by the Finnish manufacturer Wärtsilä. It is currently considered the largest reciprocating engine in the world, designed for large container ships, running on heavy fuel oil...
, and MAN Diesel produce crosshead two-stroke diesel engines in this configuration. Wärtsilä also produces regular trunk engines in this configuration. It is more common in marine applications because marine engines are usually based on a modular design, with individual heads per cylinder.
Only one straight-seven engine for land propulsion is known to be in production, the AGCO
AGCO
AGCO is an agricultural equipment manufacturer based in Duluth, Georgia, USA. As a leading global manufacturer of agricultural equipment, AGCO offers a full line of tractors, combines, hay tools, sprayers, forage and tillage equipment, which are distributed through more than 2,700 independent...
Sisu 7-cylinder diesel engine. This engine configuration was chosen because of size, parts commonality, and power range issues. A straight-8 would be too long for the farm machinery application the engine was intended for, whilst a V engine
V engine
A V engine, or Vee engine is a common configuration for an internal combustion engine. The cylinders and pistons are aligned, in two separate planes or 'banks', so that they appear to be in a "V" when viewed along the axis of the crankshaft...
would require a higher investment compared to the expected low sales volume for this power range. The straight-7 configuration is a lower investment because Sisu has reused cylinder head
Cylinder head
In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket...
s from their I3 and I4 diesel lineups. This is possible because the cylinder volume, pistons and con rods are identical across the Sisu model range.