Engine, PowerTech Plus™ 6.8 L external, efficiency, and performance features
Efficiency and performance features
 

Owners of row-crop tractors have high expectations for fuel economy and field performance.  John Deere research and development has engineered an engine that has met these customer requirements and met stringent emission regulations.  With the PowerTech Plus 6.8 L engine you can expect superior performance in any application.  These engines deliver proven operation, with countless hours of laboratory and in-field usage to verify it can carry the John Deere name.

 

This section will describe the key performance and economy components that are visible from the exterior of the engine.

VGT (Variable Geometry Turbocharger)
 

For excellent economy and load response, a Variable Geometry Turbocharger (VGT) is used on all models.  (See fig. A for its location under the hood).  The “variable” part of the turbo provides performance by electronically positioning exhaust airflow vanes.  The external actuator (fig. B) has a mechanical linkage to move the vanes to the appropriate position. 

VGT vanes in exhaust flow

VGT vanes in exhaust flow

The vanes are in the exhaust flow.  The opening or closing of the vanes changes the outlet volume and airflow speed against the turbocharger impeller.  The ability to keep the airflow going at the optimum point provides more consistent engine boost pressure and the ability to respond to load quickly.  You will find this system to be without turbo “lag” found on some competitive tractor engines.  Boost pressure in the intake manifold is controlled at its optimum point to provide economy and performance regardless of rpm or load.

 

Think of the ability of the VGT to create boost pressure as a transmission is to load - a 16-speed transmission can respond quickly to more situations than an 8-speed. 

Unlike many competitive engines, there is not a “wastegate ” used on the 9.0 L engine to control maximum boost pressure.  Wastegate turbochargers can increase fuel consumption.  


 

The VGT provides these overall benefits:

  • Increase low-speed torque
  • Quicker response to load
  • Increase peak torque
  • Improved fuel economy
  • Improve performance at high altitudes
Fuel injection system, single injector control via common rail
 
Right-hand side of engine contains fuel system

Right-hand side of engine contains fuel system

Common rail and high pressure fuel pump

Common rail and high pressure fuel pump

Every PowerTech Plus 9.0 L engine uses a common rail to supply fuel pressure to the injectors.  The gear-driven high pressure fuel pump instantly responds to requirements for more or less fuel flow or pressure.

 

The common rail (see fig. A above) contains extremely high pressure fuel and is the channel flowing fuel to each injector.  The pressure is generated by the gear-driven piston pump (see fig. B above).

 

Each injector is controlled individually via the engine control unit (ECU).  The ECU turns the injector on and off several times per firing cycle to control the fuel delivery into each cylinder.  The (ECU) can sense engine rpm and load changes 100 times per second and respond instantly to them. Load and speed sensing allows each cylinder fuel delivery rate to be adjusted independently at the individual injector.  With each injection cycle, the (ECU) can make the following adjustments on-the-go: 

 

  • Number of injections
  • Fuel pressure in the common rail
  • Start of injection
  • Duration of injection

 

Cold weather and high altitude compensation are also precisely controlled for good starts regardless of weather and proper power levels at high elevations.

Noise reduction
 

The injection system also provides a way to have the engine run with a decreased noise level via a process called “pilot injection.”  With the precise fuel injection capabilities, there can be a small amount of fuel injected early in the combustion process.  This helps lessen the “combustion knock” that is commonly heard on many diesel engines.  While the combustion noise reduction is most obvious at lower rpm, pilot injection continues to function at any engine speed.

 

Integration of this state-of-the-art fuel injection technology into the John Deere 9.0 L engine provides the necessary means to achieve improvements in operating performance, fuel economy, and exhaust emissions.
Vari-Cool™ system
 
Variable speed fan

Variable speed fan

This patented fan drive system replaces the viscous and vistronic systems used in prior 8000 Series tractors.  The cooling fan and how it is driven is very important to control precisely because it takes horsepower to move air across the coolers and radiator. The Vari-Cool system gains in efficiency are coming from two main elements:  A) A belt replaces the viscous clutch where there is always some “slippage”.  The belt drive used in Vari-Cool, transfers almost 100% of the power.  B) The fan rpm can be controlled to the exact speed required for the operating conditions.  The fan speed can be controlled exactly to the rpm that is required to cool the water from engine, hydraulic oil, and assure good air conditioning operation. 

 

The Vari-Cool system has proven to add value by increasing the overall efficiency of the tractor via automatic control of its speed.  The key to this efficiency is the integration of engine and tractor functions only John Deere can offer.

Vari-Cool is integrated into the hood design
 
Hood airflow

Hood airflow

The Vari-Cool system is an integrated part of the hood design.  Intake and outflow of air from the coolers is diverted to key openings in the hood structure. 

 

An additional benefit of this new design gives the operator of an 8030 Series:


  •  No change in the hood width for continued best-in-class crop visibility
  • Improved forward visibility due to the slope in the hood profile
  • Improved airflow dispersion to lessen dust and crop kick-up
  • Hot cooling system airflow is directed away from the cab, putting less load on the air conditioning system

Hood air entry and exit points are shown below.   Engine intake airflow opening in the hood allows air into the engine from a cool area.  

How Vari-Cool works
 
This electrohydraulic system uses similar and familiar-looking components from variable speed drives.  As an example, it is similar to what a combine uses to drive the separator and other functions.  The diagram explains the functioning parts.   The operating principal of the Vari-Cool fan drive system is shown as follows.
 

Fan rpm is determined by the ratio of top to bottom operating diameters.

 

Variable speed fan drive

Variable speed fan drive

The ECU opens the valve on the top of the upper assembly.  Engine oil pressure is directed to the piston that pushes top inner sheave out (A), creating a narrower gap and a larger working diameter.

 

Bottom sheave (B) responds by compressing the coil spring, widening the gap between the two sheave halves, creating and a smaller working diameter. The fan speed increases.

 

To slow the fan, the valve opens, allowing oil to leave the piston, widening the upper sheave halves. The fan speed slows by the above process reversing.

 
Fuel and oil filters
 
Fuel filter system with electronic pump

Fuel filter system with electronic pump

There have been two significant improvements in the 8030 Series fuel filtration system. 

 
Fuel filter capacity is increased.
 
Fuel filter system requires no special procedures for bleeding.  It's as simple as 1-2-3!

Here are the specifics for the improvements to change the filter elements:

  1. Open the water/fuel drains on both the 10 micron primary filter housing (B) and 2 micron secondary filter cartridge (C ).
  2. Remove and replace both filters following the operator’s manual instruction procedure.
  3. Turn on the key in the cab and wait 60 seconds.  Start the engine.
While the filter change interval is unchanged at 500 hours of operation, not knowing if a filter is plugged prior to that interval can cause unnecessary changes and expense.  To eliminate this potential, there is a pressures switch (D ) that monitors the restriction of the filter.  If it requires attention, a message will show on the CommandCenter™ display.  To further enhance the life of the filters, the electronic fuel pump (A) runs at a variable speed that corresponds to the load on the engine.  This means only the fuel being used by the engine is being filtered, without recirculation back to the fuel tank.
Oil filter change
 
Top-loading oil filter

Top-loading oil filter

The proven, vertically mounted, top-load filter element is contained in a permanent canister.

 

The top-load oil filter provides quicker, easier oil filter changes.  There is easy element disposal due to elimination of the metal filter casing.  When the filter top cover is loosened, oil held in the the canister can flow into the sump of the engine.  You will make a “clean” swap of the filter element.

 

Bypass valve is integral to the canister.  The valve opens for continued lubrication should the filter plug or oil temperature is extremely cold. 

 

Large oil sump provides oil capacity for long, 250-hour change interval (375 hours when John Deere PLUS-50™ oil and a John Deere oil filter are used after engine break-in).

Engine coolant deaeration tank
 

The deaeration tank on the 8030 Series has been relocated onto the right front corner of the engine.  Easy access with the hood up provides accessibility to the engine fill if needed. The deaeration tank provides an area where coolant level is maintained and air is allowed to separate from the coolant during operation.

Base Equipment On : 8030 Series Tractors
 
Last Updated : 24-Jul-2013