Navistar MaxxForce 7 - Engine Description

SECTION1–ENGINESYSTEMS
EngineSpecications(cont.)
EngineDescription
TheMaxxForce
®
7isaV8enginewithadisplacementof6.4liters
(389cubicinches).Theenginehasbeendesignedforincreased
durability,reliability,andeaseofmaintenance.
AirManagementSystem
Atwo-stageturbochargerprovidesboostairpressuretothe
engineforvariousspeedandloadconditions.Anelectronically
controlledsolenoidmodulatesboostairtoawastegateactuator
thatcontrolstheturbochargerdischargepressures.
Achassis-mountedChargeAirCooler(CAC)ispipedintothe
airmanagementsystembetweentheturbochargerandintake
throttle.TheCACisanair-to-airheatexchangerthatcoolsand
increasesthedensityoftheairchargeaftertheturbocharger.
TheExhaustGasRecirculating(EGR)systemincludesanEGR
valveandanintakethrottlevalve.TheEGRvalveismountedin
anEGRmixerductthatispartoftheEGRvalveelbowhousing.
TheintakethrottlevalveismountedontheothersideoftheEGR
valveelbowhousingintheairstreamfromtheCAC.
TheEGRsystemcirculatescooledexhaustintotheintakeair
streamintheintakemanifold.Thiscoolsthecombustionprocess
andreducestheformationofNO
X
engineemissions.
ColdStartAssist
Arelaycontrolledgrid(duct)heaterisusedintheintakeair
streamtoaidcoldambientstarting.
CrankcaseAssembly
Thecrankcaseiscomprisedoftwomajormatchingcomponents.
Theuppercrankcasehalfhousesthecylindersandmainbearing
saddles,withoilandcoolantpassageseithercastormachined.
Thelowercrankcaseconsistsofastructuralplatewiththemain
bearingcapsmachinedintoitforimprovedloadretentionand
alignment.
TheuppercrankcaseutilizesCompactGraphiteIron(CGI)
materialtechnologyforalighterandstrongercrankcase.
One-piecealuminum-alloypistonsarettedwithonekeystone
ring,onerectangularintermediatecompressionring,anda
two-pieceoilcontrolring.Thecombustionbowlislocatedin
thepistoncrowntoreduceemissions.Allpistonsarematedto
fracturedcapjointconnectingrods.
Agerotorlubeoilpump,mountedonthefrontcrankcase
bulkhead,isdrivenbythecrankshafttosupplypressurizedoilto
enginecomponents.AllMaxxForce
®
7enginesuseanengine
oilcoolerandspinonoillter.Theoillterislocatedatthelower
driver-sidecorneroftheenginewherethereisalterheader
integratedtothecastaluminumoilpan.
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