2005 jeep liberty goes diesel

2005 Jeep Liberty
Jeep Goes Diesel: The Diminutive Liberty Takes a Big Step
Towards Raising SUV Fuel Economy
Text and photography by Rob Reaser
Seeking to replace their aging Cherokee mid-size SUV while providing a more compact, stylish
model to entice the growing ranks of urban sport utility vehicle buyers, Jeep released its all-new
Liberty for the 2002 model year. Now, a scant three model years later, the popular Liberty has
been treated to several updates — not the least of which is the first use of a diesel engine in a
mid-size SUV.
Diesel engines are gaining a more prominent position in the minds of the consuming public, as
everyone looks to improve fuel efficiency and reduced operating costs. For Jeep, the timing for
the introduction of its high-tech Common Rail Diesel (CRD) could not be better.
In America, traditionally, diesel engines have meant chuggy powerplants best suited for overthe-road semi and fleet trucks rather than urban daily drivers. Yes, certain European import
sedans and wagons have found a small market here, but loathe as we are to follow any lead
from the continent across the pond, traditional small Diesels have never enjoyed the popularity
here that they do in Europe. Now, however, in the case of the new generation common rail
diesel engines, the wine-and-cheese contingent may indeed show us a better way.
The CRD engine found in the Jeep Liberty Diesel is one of those powerplants that pleases just
about anyone looking into the mid-size SUV market. Although its 2.8L displacement may seem
wimpy at first blush, its numbers quickly dispel such notions. Horsepower is a smart 160 at
3,800 rpm — comparable in performance to most V6 engines in this class. Torque output is
where the CRD truly shines brightest. Coming in at a whopping 295 lb/ft at 1,800 rpm, this
number places the Liberty Diesel in the same ring as V8s which power full-size pickups.
Consider the CRD’s stablemate, the Dodge 4.7L Magnum SOHC. That powerplant has a solid
1.9L displacement advantage over the CRD, yet its torque rating is the same at 295 lb/ft.
However, it doesn’t hit that peak until 3,600 rpm. For its size, the Liberty Diesel is a powder
keg of muscle — and it does most of its grunt work way down in its rpm range, right where you
want it.
You can’t see much of the 2.8L CRD I4 due to the noise-dampening cover, but when in operation there’s no
mistaking the peculiar “tinkle” of a VM Motori of Cento, Italy diesel engine at work.
To pick back up on the European connection, many of you may know the Europeans have been
ahead of the curve in advancing diesel technology in the passenger car market. Most of the best
diesel engines (Cummins notwithstanding) are rolling off that continent’s assembly lines. Such
is the case for the CRD found in the refreshed Liberty. It’s built by VM Motori of Cento, Italy — a
company owned since 1995 by Detroit Diesel, a DaimlerChrysler company, which we all know is
in the hands of the Germans.
(The increasingly incestuous nature of this industry continues to amaze...)
You’re not going to stuff a whole lot of gear in the back of the Liberty with the rear seats in the up position, but
the cargo capacity is good enough for most grocery hauls (note the grocery bag hooks incorporated in the
seatbacks).
Anyway, VM Motori has been a leading diesel technology manufacturer for over half a century,
and has supplied engines for the Jeep Cherokee in Europe since 1994.The CRD powerplant went
into production in 2001. So, in reality, this is nothing new to Jeep from a global perspective. It’s
just new to the North American Jeep marketplace.
The CRD’s hook, if you will, is its common rail direct injection fuel system. To better understand
how it works, let’s run through a quick primer on the mechanics of diesel engines.
For 2005 the rear seats fold flatter to make for a more level cargo floor. In this configuration, cargo capacity
goes from 29 to 69 cubic feet.
As you know, gasoline engines (electronic ignition) utilize a combination of air, fuel and
electrical spark to provide combustion. On its downstroke, a piston simultaneously draws air
and atomized fuel into its combustion chamber. On the piston’s upstroke this mixture is
compressed and ignited by the spark plug to provide the power stroke. Diesel engines, by
contrast, do not use an electric spark for ignition. Instead, the piston draws only air into the
cylinder, which is squeezed on the compression stroke to the point where the air is extremely
hot. At some point in the compression stroke, atomized fuel is delivered into the system. When
the fuel hits the hot, compressed air, the mixture ignites and the power stroke is initiated. This
is why diesels are also referred to as “compression ignition” engines.
The window switches are relocated on the center console for 2005 for a more ergonomic placement.
This may sound a bit crude to those schooled in the EFI arts. In reality, however, current diesel
engines have a whole lot going for them. For example, they excel in fuel efficiency, in part
because they allow for high compression ratios (compare Jeep’s 2.8L CRD compression of
17.5:1 to its sibling 2.4L EFI engine with 9.5:1 compression). Higher compression ratios usually
mean better fuel efficiency in terms of power output and consumption. Additionally, diesel fuel
contains more energy per unit than does conventional automotive-grade gasoline. It’s also less
(should be) expensive because it does not require as much refinement as pump gas.
Back seat passengers don’t fare too poorly in the Liberty. Forward-opening doors, mildly bolstered seats,
integral headrests and 37.2 inches of legroom make rear occupancy tolerable.
Diesel engines have been around for a while (since 1892, to be exact), and to American minds
they’ve always been viewed as loud, clunky, dirty and low on vicarious performance. So what’s
the excitement about now?
It all has to do with ever-improving technology and the incorporation of the common rail direct
injection system. Traditionally, diesel engines used what is called indirect injection, where a
pre-chamber in the cylinder head mixes air and fuel, and begins the combustion process before
the full fuel charge is sent into the combustion chamber. This was necessary in order to
optimize the air/fuel mixture prior to it entering the combustion chamber. The result was a loss
of some fuel efficiencies, noise, heat loss and relatively high particulate emissions, to name a
few of its detractions.
Enter the common-rail direct injection system, such as is found on the new Jeep Liberty Diesel.
The CRD relies on high pressure fuel delivery (rated to 23,000 psi) to send highly atomized fuel
directly into the combustion chamber. All of the cylinder injectors are linked to a single, or
common, high-pressure fuel rail (hence the name) that is fed by a cam-driven high-pressure
pump. The whole operation is run by an electronic control system that is quite similar in
operation to conventional EFI systems. Performance is computer-controlled to deliver the
optimal fuel pressure, injection duration and injection timing to achieve an acceptable balance
of power output and fuel economy. Compared to the indirect injection pre-chamber system,
noise is down, fuel consumption is down, power output is up, and emissions quality is
significantly improved. The 2.8L Liberty engine actually uses two pilot injections, which come on
before the main injection, to further reduce the “edgy” nature of diesels and smooth idle noise.
Furthermore, the Liberty incorporates an electronically controlled turbocharger. This unit uses
moveable vanes to optimize power output and fuel efficiency across the power band.
The next best thing to drop-top off-road adventure is a sunroof, and for $700 you can have one in the Liberty.
So, that’s what all the hype is about. The question is, how does it feel?
Prior to field testing, we had picked up on some Internet chatter about how the Liberty Diesel
was noisy. What a bunch of brie-and-cognac whiners! Yeah, the CRD is no purring kitten, but
then...IT’S A DIESEL! One thing’s for sure...it’s the quietest diesel in a domestic 4x4 we’ve ever
tested. Actually, it’s not bad at all. By tweaking the timing and fuel delivery events, placing the
engine on hydro mounts, adding damping material here and there, stuffing a resonator into the
air induction tract, and dropping a massive engine cover over the four-cylinder, the CRD doesn’t
sound loud to us, just neat...like it’s got some real character going on.
Get over it, already.
On the road the Liberty Diesel isn’t going to win you any streetlight jousting tournaments, but
on the other hand it has a pretty fancy snap for a four-cylinder once the turbo kicks in.
Acceleration, however, isn’t this 4x4’s bag — rather, it’s torque. And torque it has. The max
trailer weight is 5,000 pounds. We can almost see a Liberty Diesel hauling butt to the coast with
a 20-foot runabout in tow, causing gawking passersby to remark something like...“What?”
There’s certainly nothing fancy about the Liberty’s interior décor, but for most off-highway adventurers, that is
as it should be — functional, without being overbearing. New seats and fresh fabric choices are part of the 2005
changes.
The 2.8L turbo diesel option is not available on the Liberty Renegade, only the Sport and
Limited models, and it comes only with a five-speed automatic transmission. ABS is also part of
the diesel package.
After only three model years since its introduction, the Liberty receives some minor body updating for 2005.
The Sport model seen here benefits from higher fog lamp and park/turn lamp placement, a new front fascia,
new body-color grille with fog lamp provisions, and new rocker panel protection.
Do we like the Liberty Diesel? You bet. In fact, given its 22/27 city/highway fuel economy,
pleasing diesel hum, and stump-ripping, rock-rolling torque, our money goes here. After all,
while the Renegade and Limited’s 3.7L V6 may have it in the horsepower department, let’s face
it, the Liberty is no corner-carving SUV. It does a fine job under moderate road driving, but its
real deal is its dual on-/off-road credentials.
If high-end horsepower and slot car handling is what you crave, get a Corvette Z06. If, instead,
you want a maneuverable trail rig that’s got the beef where it counts, the Liberty Diesel is
waiting for your test drive.
What Else Is New?
The CRD engine is not the only new balloon floating at the Jeep Liberty party this year. Inside
and out the Liberty gets a bit of a facelift. Changes include:
•
Renegade - flatter hood, body color grille, new rocker panel protection, molded-in color
front fascia with a Bright Silver Metallic appliqué, standard tow hooks,
body-color bolted flares with chrome-plated attachment details, new
luggage side rack with Brushed Silver Metallic tubular side rails, black offroad light bar is now optional.
•
Limited - chrome grille, chrome bodyside molding (with Liberty name molded in),
chrome side rails, new rocker panel protection.
•
Sport - body-color grille, higher fog lamp and park/turn lamp positions, front fascia,
rocker panel protection.
•
Interior - relocated power window switches, instrument cluster graphics (white letters
on gray background), new seats with dual-density foam, new seat fabrics,
reduced rear seat fold angle.
•
Functional - new NSG370 six-speed manual transmission replaces the five-speed
manual (Sport and Renegade availability).
Ultima generazione
2.8
L
passa i limiti...
has no limits...
he R 428 DOHC 05MY is the
evolution of VM’s current 2.8L
4 cylinder engine. This new
version features a number of significant improvements.
In order to respect the ever more
stringent emission limits and
market demands for high performance engines, the R 428 DOHC
uses the most advanced technological solutions.
The use of Common Rail injection
at 1600 bar, variable geometry
turbo, highly efficient emission
control devices and counter-rotating balance shafts guarantee
impressive performance and fuel
consumption while at the same
time reducing noise and vibrations.
T
The engine’s 120 kW power rating
and torque of 400 Nm (more than
80% of which is available at 1400
rpm) make for outstanding performance and greater flexibility and
responsiveness even on vehicles
such as Minivans and SUVs.
VM Motori is very aware of environmental issues, and has put its long
experience in this field into practice
on this new engine. The result is an
engine that meets the current US
standards (US Tier 2), which heavily
limit NOx and particulate emissions.
Specific attention has been also
dedicated to noise and vibrations.
Double pilot injection, counter-rotating balance shafts and intake throttle valve improve driving comfort.
Fast metallic glow plugs, controlled
by an Electronic Control Unit, assure
immediate engine start-up and
improved combustion not only in the
first few seconds of the engine running but also whenever the ambient
temperature falls below 0°C.
The R 428 DOHC 05MY will be a
further important step towards
public appreciation of diesel engines, and will strengthen VM’s position in the prestigious car sector.
l motore R 428 DOHC 05MY e’ l’evoluzione del noto motore VM a 4
cilindri 2.8L che, già presente sul
mercato, si presenta per l’anno 2005
con significativi miglioramenti.
Per rispettare le normative emissioni sempre più stringenti e le richieste prestazionali del mercato, il
motore e’ stato dotato delle più
avanzate soluzioni tecnologiche.
Il sistema di iniezione Common Rail
a 1600 bar, il turbo a geometria
variabile, dispositivi emissioni ad
alta efficienza, e masse controrotanti consentono di raggiungere
ragguardevoli livelli di prestazioni,
consumi, riducendo, al contempo,
rumorosità e vibrazioni.
La potenza di 120 kW e in particola-
I
re la coppia di 400 Nm (di cui più
dell’80% disponibile a 1400 giri) permettono prestazioni brillanti e grande elasticità di marcia anche su veicoli della categoria Minivan e SUV.
Sempre sensibile ai problemi dell’ambiente, VM ha concentrato su
questo motore la sua lunga esperienza nel controllo delle emissioni
nocive. Il risultato è un motore
capace di rispettare le severe emissioni americane (US Tier 2) che, in
vigore dal 2004, limitano fortemente
il rilascio di NOx e particolato.
Particolare attenzione è stata dedicata anche alla rumorosità e alla
riduzione delle vibrazioni. La doppia
iniezione pilota, le masse controrotanti e la valvola di spegnimento
migliorano il confort di guida.
Le candelette veloci controllate da
una centralina elettronica consentono di avviare il motore senza attesa, di migliorare la combustione nei
primi secondi di avvio e, in generale, in tutte le situazioni con temperature ambientali al di sotto dello
zero.
Il motore R 428 DOHC 05-MY segnerà un altro passo in avanti nel
favore del pubblico per le motorizzazioni a gasolio e rafforzerà la
posizione di VM nel settore dei veicoli prestigiosi.
Turbo VGT
• Incremento prestazioni del 10%
• 80% della coppia massima disponibile a 1400 g/min.
• Incremento efficienza sistema EGR
VGT Turbocharger
• Performance increased by 10%
• 85% of maximum torque available
at 1400 rpm
• EGR system efficiency improvement
Common Rail Gen. II
• Pressione di iniezione: 1600 bar
• Doppia iniezione pilota
• Riduzione dei consumi, rumorosità
ed emissioni
Common Rail Gen. II
• 1600 bar injection pressure
• Double pilot injection
• Redution of fuel consumption,
NVH and emission.
Centralina elettronica
• Controllo motore completamente
elettronico
• Adattamento dei parametri iniezione alle condizioni di guida e
ambientali
• Autocontrollo dei valori di emissione
Electronic Control Unit
• Full electronic control
• Injection parameter control depending on driving and environmental
conditions
• On board diagnostic for emissions
Candelette veloci
• Accensione motore immediata
anche a basse temperature
• Miglioramento della combustione
a freddo
Fast glow plugs
• Immediate engine start-up, even at
low ambient temperature.
• Improved combustion at low
ambient temperature
Caratte
Tipo di moto
Cilindri - Co
Alesaggio e
Rapporto Co
Interasse cil
Cilindrata un
Cilindrata to
...e sbarca in America
eristiche tecniche
Diesel ad iniezione diretta
4 stroke Diesel Direct Injection
Rapporto di Compressione - Com
4 In-linea - In-line 4
Potenza massima - Max Power
94 x 100
Coppia massima - Max Torque
1.06
Sistema di iniezione - Injection S
(mm)
112
Sistema di aspirazione - Air Induc
(cc)
692
Emissioni - Emissions
(cc)
2766
ore - Engine Type
onfiguration
Corsa - Bore & Stroke
(mm)
orsa/Alesaggio - Stroke/Bore Ratio:
lindri - Bore Pitch
nitaria - Unitary Displacement
otale - Total Displacement
...and embarks in America
Prestazioni
Performances
Technical features
mpression ratio
(kW/rpm)
17.5:1
120 @ 3800
[Nm]
[kW]
650
135
600
120
Power
550
(Nm/rpm)
400 @ 1800
ystem
Common Rail Generazione II
Common Rail II Generation
ction
Sovralimentato VGT/Intercooler
Turbocharger VGT/Intercooler
US Tier 2
(Euro IV capable)
Dimension
Dimension
105
500
90
450
75
400
60
350
Torque
30
250
15
2000
2
45
300
200
1000
68
3000
0
4000
[rpm]
54
Valvola EGR elettrica
• Alta velocità di risposta
• Maggiore precisione
• Riduzione delle emissioni nocive
Electric EGR valve
• Rapid response
• High precision
• Reduction of exhaust emissions
EGR Cooler
• Scambiatore di calore ad alta
efficienza per ridurre le
emissioni di NOx
EGR Cooler
• High efficiency heat exchanger for
reduced NOx emissions
Valvola a farfalla
• Incremento ricircolo gas di scarico
• Riduzione delle vibrazioni in fase
di spegnimento
Intake throttle valve
• Increased recirculation of gaseous
emissions
• Reduced engine shake during
shut down.
ni
ns
0
Alberi di equilibratura
682
• Riduzione delle vibrazioni agli alti
regimi
Balance shafts
• NVH reduction at high speed
44042 CENTO (Ferrara) - Italy - Via Ferrarese, 29
Industrial - Marine: Tel. +39 - 051- 6837 511 - Fax +39 - 051- 6837 517
e-mail: [email protected]
www.vmmotori.it
ISO 14001 - Cert. n° 0043A/0
ISO 9001 - Cert. n° 0295/2
ISO/TS 16949 - Cert. n° 2920/0
Azienda di progettazione, produzione e commercializzazione di motori
diesel con Sistema Qualità ed Ambiente certificato.
Company with the Quality and Environmental system certified for diesel
engine design manufacturing and commercialization.
is registered trademark of VM MOTORI.
As technical advancements continue, specification may change. Printed in Italy - VM MOTORI Advertising Department - Cod. 4 250 6017 F - M2 - 11.’04
VM MOTORI preferisce/prefers