As Europe makes the transition to the new tougher Euro V exhaust emission standards, Volvo Buses is taking the step of replacing the previous 12-liter engine with a new 13-liter engine, the Volvo D13C, in the Volvo 9700 and Volvo 9900 coaches and for the chassis Volvo B13R.
This is the same basic engine that has been used by Volvo Trucks for several years and is thus one of the world’s most-sold heavy diesel engines. Volvo Trucks’ experience shows that the Volvo D13C is an engine with robust technology and very high reliability. Because it has been used on the road for many years, work shop mechanics already have good knowledge of how to maintain it.
Volvo Buses’ new engine is a straight six-cylinder diesel engine with turbo and intercooler. It has a one-piece cylinder head, overhead camshaft, four valves per cylinder and electronically controlled unit injectors.
The engine will be offered in 420hp and 460hp versions, and has more torque than its predecessor. The 420hp engine has 2100 Nm at 1100-1400 revs/min, while the 460hp engine has 2300 Nm at 1050-1400 revs/min.
Despite the higher displacement, engineers have successfully reduced the engine’s weight by about 80 kilograms compared with the 12-liter engine. The combination of lower weight and higher torque provides the opportunity for a higher average speed, further increasing cost-efficiency.
The new engine combined with an adapted gear shifting strategy in the popular I-shift gearbox means that the bus can be driven at a lower number of revs, which reduces fuel consumption.
“Low fuel consumption is one of the absolute key factors for our customers,” says Håkan Karlsson, President, Volvo Buses. “It was the main reason why we chose the SCR technology to meet the Euro IV requirements.”
That decision helped ensure that Volvo Buses succeeded in significantly reducing fuel consumption. Buses equipped with Volvo’s 12-liter engine and I-shift are among the most fuel-efficient vehicles in the market today.
“As we shift to the new, modern 13-liter engine, we have succeeded in reducing fuel consumption even more,” says Håkan Karlsson. “Our field tests indicate a further reduction of up to 5 percent.”
The respons is rapid both in high and low engine revs. This results in faster acceleration and better driveability with fewer gear changes. Thanks to the higher torque, Volvo Buses can use faster rear axel ratios, which further reduces the engine’s revs and thereby also noise and consumption.
The new 13-liter engine is vertically mounted. A lot of efforts have been put in to the installation of the engine to make it easy to access for service, making it more cost-efficient in the aftermarket.