Engine Description - Navistar MaxxForce 7 Operation And Maintenance Manual

Engine Specifications (cont.)

Engine Description

®
The MaxxForce 7 is a V8 engine with a displacement of 6.4 liters
(389 cubic inches). The engine has been designed for increased
durability, reliability, and ease of maintenance.
Air Management System
A two-stage turbocharger provides boost air pressure to the
engine for various speed and load conditions. An electronically
controlled solenoid modulates boost air to a wastegate actuator
that controls the turbocharger discharge pressures.
A chassis-mounted Charge Air Cooler (CAC) is piped into the
air management system between the turbocharger and intake
throttle. The CAC is an air-to-air heat exchanger that cools and
increases the density of the air charge after the turbocharger.
The Exhaust Gas Recirculating (EGR) system includes an EGR
valve and an intake throttle valve. The EGR valve is mounted in
an EGR mixer duct that is part of the EGR valve elbow housing.
The intake throttle valve is mounted on the other side of the EGR
valve elbow housing in the air stream from the CAC.
The EGR system circulates cooled exhaust into the intake air
stream in the intake manifold. This cools the combustion process
and reduces the formation of NO
SECTION 1 – ENGINE SYSTEMS
engine emissions.
X
Cold Start Assist
A relay controlled grid (duct) heater is used in the intake air
stream to aid cold ambient starting.
Crankcase Assembly
The crankcase is comprised of two major matching components.
The upper crankcase half houses the cylinders and main bearing
saddles, with oil and coolant passages either cast or machined.
The lower crankcase consists of a structural plate with the main
bearing caps machined into it for improved load retention and
alignment.
The upper crankcase utilizes Compact Graphite Iron (CGI)
material technology for a lighter and stronger crankcase.
One-piece aluminum-alloy pistons are fitted with one keystone
ring, one rectangular intermediate compression ring, and a
two-piece oil control ring. The combustion bowl is located in
the piston crown to reduce emissions. All pistons are mated to
fractured cap joint connecting rods.
A gerotor lube oil pump, mounted on the front crankcase
bulkhead, is driven by the crankshaft to supply pressurized oil to
engine components. All MaxxForce
oil cooler and spin on oil filter. The oil filter is located at the lower
driver-side corner of the engine where there is a filter header
integrated to the cast aluminum oil pan.
®
7 engines use an engine
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