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4.7 liter HO Engine

Introduction & History / Feature differences / Manifold / Cams kit
Manifold / Cams part #'s / HO Intake system / HO engine Specifications

See also:Chrome exhaust tips

The 4.7-Liter HO engine
A performance enhanced "HO" version of the popular 4.7-Liter V8 engine made its premier in the 2002 Grand Cherokee. The HO engine was a Grand Cherokee exclusive for the 2002-2004 model years, available as an option on Limited models and standard on the Overland - but not available on the Laredo. For the 2004 model year, Jeep added the HO as an option on three new special models, the Freedom Edition, Columbia Edition and the Rocky Mountain edition.
The performance modifications (listed in the chart below) added 30 horsepower and 30 Ft.-Lb. of additional torque. The HO engine is designed to run perfectly on standard octane fuel, but for maximum performance Jeep recommends premium fuel.
The HO engine was discontinued in the Grand Cherokee at the end of the 2004 model year. The all-new 2005 model Grand Cherokee's offered the new 3.7 V6, the standard 4.7, the 5.7 Hemi and the new 6.1L Hemi SRT engines. Starting at the end of the 2005 model year, the 4.7 HO engine became availble in the Dodge Dakota.
Ho engine model availability - Grand Cherokee
Year / Model / Laredo / SE / Sport / Limited / Overland / Freedom / Columbia / Rocky Mtn
2001 / N/A / Pilot models
2002 / N/A / N/A / N/A / Optional / Standard
2003 / N/A / Optional / Standard
2004 / N/A / N/A / Optional / Standard / Optional / Optional / Optional
2005 / N/A / N/A / N/A / N/A
"N/A" = Not Available
2001 Grand Cherokee HO
What no onesrealizes, and being revealed here for the first time, is that the HO engine was originally planned for the 2001 model year. Several 2001 Grand Cherokee models were built with the 4.7 HO engines back in 2000!
Plans for a "future" HO version of the 4.7 were put together when the new engine was original designed for the 1999 model year, back in 1996/1997. The first HO engines were assembled in the fall of 1999 and put into 2001 model pilot Grand Cherokee's in early February 2000! Twelve of these models were built, complete production versions right down to the HO badges. Colors were Stone White, Patriot Blue, Flame Red, Sienna and Champagne.
These special 2001 HO models also included an exclusive "Sport suspension", different than that of the Up Country package. Components included exclusive springs (ZKN/ZKT front and ZYN/ZYT rear), Goodyear P235/65R17 BSW AS/P tires, chrome tow hooks and the skid plate package. Even more interesting is the axle ratio, which has never been used on any other Grand Cherokee model, 3.91!
For reasons unknown, the HO engine was held back until the 2002 model year. It's possible that for marketing reasons Jeep wanted to introduce the HO with the new Overland model, and to have a key option added to the list of new features being implemented for 2002, the start of the second half of the WJ generation. New features for 2002 included side air bags, adjustable pedals, the Rain Sense wiper system and the Tire Pressure Monitor System. The HO engine was the "icing on the cake" and turned out to be a very popular and successful option.
Summary of HO engine feature differences
(Compared to standard 4.7 liter engine)

1. Block - Detonation sensor bosses in the valley / 10. Intake - low-restriction intake system (different resonator, air filter, air filter hose and housing)
2. Camshaft - custom profile lobes (designed for increased performance) / 11. Knock sensors - two, stereo
3. Connecting rods - modified, with floating wrist pins (vs pressed-fit pins in standard V8) / 12. Main bearings - tri-metal (vs bi-metal in standard V8, designed specifically for the HO engine)
4. Crankshaft - forged steel (vs cast iron in standard V8) / 13. PCM calibration - unique programming
5. Crankshaft damper - unique to H.O. / 14. Pistons - dome shaped for increased compression ratio
6. Cylinder heads - different shaped combustion chambers (for improved airflow). The letters "H.O." are cast on the front end of the heads. / 15. Spark plugs - platinum tipped
7. Exhaust tip - chrome (2002 models only, decontented for 2003 models. Available only as a one-piece assembly with muffler) / 16. Valves - unique exhaust valves (same lift as standard V8)
8. Fuel injectors - higher flow (+3.3 lb/hr) / 17. Valve springs - upgraded valve springs (intake & exhaust. Larger diameter wire and more coils)
9. Intake manifold - modified (shorter runners)
HO manifold and cams upgrade

Notes: When the HO was first introduced in the summer of 2001, DC service training literature featured statements and warnings that the upgraded parts used on the HO engine were NOT interchangeable with the standard 4.7L engine. So we found it interesting that later on Mopar introduced a "HO" performance cams and manifold kit, considering that these are the exact same parts that the factory used for the 2002 4.7L HO. The Mopar kit includes gaskets and typically takes from 4-8 hours or more to install. It is recommended that BOTH the manifold and the camshafts be installed together if doing this upgrade (not just one or the other).
Quite a few Dodge truck owners have successfully installed the manifold and cams into their standard 4.7 engines without any major problems. Most have reported horsepower gains from 5% to 15%, varying at different RPM's. Anyone interested in doing this upgrade or learning more about it should visit the message boards at DodgeDakotas.com and search through the HO related posts. Some Jeep owners are now considering this upgrade, we'll report on the results as info becomes available.
The Mopar Manifold/Cams kit is available from Multitronics ("Kolak")
Manifold and Cams OEM Part numbers:
HO Camshafts:
Left (2002-2004): P/N 53021411AB
(superseded by P/N 53021411AD. MSRP: $188.00)
Right (2002-2004): P/N 53021412AB
(superseded by P/N 53021412AD. MSRP: $188.00)
HO Manifolds:
Note: All manifolds are currently on national back-order or discontinued (as of November 2008)
2002: P/N 53031739AC
(superseded by P/N 53031739AD. MSRP: $248.00. Used only in HO engines for model year 2002)
2003: P/N 53013403AB
(superseded by P/N 53013403AC, then P/N 53013403AD, then P/N 53013403AE. MSRP: $141.00. Redesign of 2002 version, used in both standard 4.7 and 4.7 HO engines for model year 2003)
2004: P/N 53013403AC
(superseded by P/N 53013403AD, then P/N 53013403AE. MSRP: $141.00. Very slight non-performance changes from the original 2003 version. Used in both standard 4.7 and 4.7 HO engines for model year 2004).
(NOTE: Prices listed are for reference purposes only and may vary by dealer. MSRP prices are current as of May 2009. Parts are not available from this web site.)

Starting with model year 2003 production, a new manifold was introduced and used for both the 4.7 and the 4.7 HO engines.
For more photos of the WJ manifolds, see WJ Manifolds
HO low restriction intake system

HO intake system components /
HO manifold and throttle body
HO intake system OEM part numbers

/ Resonator / Quantity: 1 / P/N 53013417AA
(2002)
P/N 53013417AB
(2003-2004) / List price: $ 58.35
List price: $ 66.55

/ Air cleaner hose / Quantity: 1 / P/N 53013418AA
(2002-2004) / List price: $ 28.75

/ Upper cover / Quantity: 1 / P/N 5018321AA
(2002-2004) / List price: $ 71.25

/ Lower cover / Quantity: 1 / P/N 5018322AA
(2002-2004) / List price: $ 78.25

/ Filter element
Top: 9-5/8" x 10-11/16"
Bottom: 9" x 10-1/8"
Thickness: 1.5" thick / Quantity: 1 / P/N 5015610AA
superseded by
P/N 5015610AC
(2002-2004) / List price: $ 24.85

/ Breather tube
(Same as standard 4.7) / Quantity: 1 / P/N 53031667AC
(2002-2004) / List price: $ 15.50
(All parts listed above, except for the Breather Tube, are unique to the HO engine. Prices listed are for reference purposes only and may vary by dealer. Prices are current as of May, 2009. Parts are not available from this web site.)

HO engine with K&N FIPK installed.
For more information of Fuel Injection Performance Kits see our FIPK page.

Underside view showing the WJ's muffler and catalytic converters.
4.7 HO Specifications
(see also:WJ 4.0 / 4.7 / 4.7 HO engine specifications comparison chart)

/
Dome shaped HO piston and RC7PYCB4 platinum-tipped spark plug
General:
Camshaft: Custom profile lobes (designed for increased performance)
Compression Ratio: 9:7.1
Crankshaft: Forged steel, with custom damper
Cylinder Block: Cast-iron block with modified aluminum alloy heads. Detonation sensor bosses in the valley
Cylinder heads: Different shaped combustion chambers (for improved airflow)
Displacement: 4.7 Liters / 287 C.I.
Engine type: 90° SOHC V-8 16-Valve
Engine Power (SAE net): 265-270 BHP @ 5100 RPM
Engine Torque (SAE net): 325-330 LB-FT @ 3600 RPM
Engine Bore x stroke: 93.0 mm (3.66 in.) / 86.5mm (3.40 in.)
Firing Order: 1-8-4-3-6-5-7-2
Injectors: Flow = 25.8 lb/hr @ 49psi
Knock sensors: Two (Stereo)
Lead Cylinder: # 1 Left Bank
Main bearings: Tri-metal construction
Manifold, Intake: Modified (shorter runners)
Oil Capacity: 6 Quarts, 10W30 recommended
Oil pressure: At curb idle: 04 psi min. @3000 rpm, 25-110 psi
RPM Engine speed, maximum: 6000 RPM
RPM Engine speed, tachometer redline: 5700 RPM
Spark plugs: Unique platinum-tipped spark plugs. Type SPRC7PYCB4, .040 in. gap
Throttle body size: 68mm (same as 2002-2004 standard 4.7 engine)
Pistons:
Piston diameter: 92.975 mm (3.6606 in.)
Piston material: Aluminum Alloy, Symmetric pop-up design (for improved compression)
Piston weight: 383.5 grams (13.52 oz.)
Piston pins, type: Full floating
Piston pins, clearance: 0.010 - 0.019 mm (0.0004 - 0.0008 in.)
Piston pins, diameter: 24.017 - 24.020 mm (0.9455 - 0.09456 in.)
Valves:
Valve system: Chain-driven SOHC, 16 valves, hydraulic end-pivot roller rockers. Unique exhaust valves
Valve springs (intake and exhaust): 7.30 coils, 4.77 wire diameter
Intake - Opens (ATDC): 3.0°
Intake - Closes (ATDC): 233.0°
Intake - Duration: 236.0°
Exhaust - Opens (BTDC): 235.0°
Exhaust - Closes (ATDC): 15.0°
Exhaust - Duration: 250.0°
Valve Overlap: 18.0°
Valve lift, Intake (at 0 lash): 12.0 mm (0.4724 in.)
Valve lift, Exhaust (at 0 lash): 10.90 mm (0.4292 in.)
Valve lift (zero lash): Intake 12.0 mm (0.4724 in.), Exhaust 10.90 mm (0.4292 in.)
Speed:
0-60 mph: 6.9 (Motor Trend)
0-62 mph: (0-100 km/h): 8.3 (DCX)
1/4 mile / speed: 15.4 / 86.6 mph (Motor Trend)
Top speed (w/ limiter): 118 mph
Top speed (w/o limiter): 128 mph (DCX)
Fuel:
Fuel Economy mpg (EPA est., City/Hwy): 14/19
Fuel requirement: Regular unleaded, 87 octane. For maximum performance, Unleaded premium, 93 octane.

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