The NPR/W-Series Gasoline vehicle features a low cab forward design that is ideally suited for inter-city applications. The low cab design minimizes overall length for a given body length and in conjunction with the set back front axle positioning provides excellent weight distribution. The 42.5-degree inside wheel cut angle coupled with integral power steering makes it an extremely maneuverable truck.
The NPR/W-Series Gasoline vehicle is powered by the GMPT-V8 gasoline engine. The basic features of the Vortec 6000 V8 are 8 cylinders, 4 stroke operation , and 365 cubic inch displacement. (Gen IV Engine).
Engine Data: GMPT-V8 w/50 State Certification
| Power: | 325 HP at 5000 RPM |
| Torque: | 360 lb.-ft at 4400 RPM |
| Injection: | Sequential port fuel injection |
| Displacement: | 365 CID/6.0L |
| Cylinder Bore: | 4.00 in (101. mm) |
| Cylinder Stroke: | 3.62 in (92.0 mm) |
| Cylinders: | 8 |
| Operating cycles: | 4-cycle |
| Compression: | 9.4:1 |
| Cooling : | Water-cooled |

The LY6 GMPT Vortec 6000 V8 truck engine has been designed to deliver better performance, high fuel economy, less noise, lower emissions and reduced maintenance than its predecessor. The engine will offer many enhancements featuring:
The LY6 offers GM’s patented sequential port fuel injection. This system provides precision fuel control for optimal fuel distribution to each cylinder. One injector per cylinder is used to deliver fuel through flexible fuel transport tubes to the inlet port. The precise amount of fuel is delivered to a fuel atomization nozzle at each cylinder during each combustion cycle. The precise control of fuel by the SFI system improves cold start, hot restart and fuel control at idle. This system helps the truck engine achieve its maximum power and torque in an efficient manner while improving fuel economy. Increased durability of the fuel atomization nozzles is achived by a compound installation angle and special coating on the nozzle.
The LY6 incorporates mass airflow metering. This system eliminates the variables created by changes in altitude and temperature. This metering system improves fuel economy, acceleration, and engine idle.
The LY6 offers several long life systems. The ignition system is virtually maintenance free for the first 100,000 miles. The system includes platinum tipped spark plugs, low resistance spark plug wires, a composite distributor housing, and a high voltage switch which does not require timing adjustment. The cooling system includes a long life coolant that is rated for 5 years or 100,000 miles. An extended life accessory belt and Magna-quench starter are standard equipment. These “Maintenance free” systems are design goals for this engine, and are in place to provide greater customer satisfaction and increased durability of the product.
A new exhaust manifold design provides higher engine performance and improved tailpipe emissions. The exhaust manifold features a three bolt flange to reduce leakage. The dual exhaust system has 3-inch pipes flowing into catalytic converters and a single muffler. Engine Control
The vehicle has been equipped with an ECM (Engine Control Module). This module is used to control the Engine, the vehicle performance parameters, and The onboard diagnostic systems. The ECM monitors a wide variety of emission systems and components for the slightest level of deterioration or malfunction. The system monitors fuel delivery and catalytic Converters. To monitor these systems the ECM uses Oxygen sensors, Crankshaft and Camshaft Position sensors, a MAP sensor, manifold temperature sensor, Knock sensors, Throttle Position sensor, Engine Coolantsensor, and an Engine Oil Pressure sensor. The ECM also includes a starter control.This control will ensure that; 1, if the key is prematurely released the starter motor will continue to crank until the engine starts, 2, if the key is held for an excessive period the ECM will disengage the starter preventing overheating and damage to the starter, and 3, if the key is switched to crank while the motor is running the ECM will not allow the starter motor to crank. All input information is analyzed by the ECM to determine if engine emission levels and current operating status of the engine are within the operating levels that are required to meet today’s increasingly stringent emission requirements. The ECM is also capable of storing and retrieving diagnostic codes to help technicians diagnose and fix problems faster and with more accuracy.
The vehicle has been equipped with a Transmission Control Module (TCM). This module is used to control the transmission, The vehicle performance parameters and the on board diagnostic systems. The TCM analyses data from the ECM and TCM shift algorithms and selects the most efficient transmission shifting for the given environment. All input information is analyzed by the TCM to determine if the transmission operating status is within the operating levels that are required to meet today’s increasingly stringent emission requirements. TheTCM is also capable of storing and retrieving diagnostic codes to help technicians diagnose and fix problems faster and with more accuracy.
The system features a controlled by-pass thermostat that enhances overall system performance. The system design improves bank-to-bank coolant flow balance, and expedites warm up and overall heater performance. The water pump bearing is designed to extend water pump life. The radiator is a 2-row tube and fin type with an area of 506 square inches. The engine uses a viscous fan clutch hub.
Paper element with cyclone action, 11-in. diameter, back of cab location. Vertical intake stack on back of cab.
Use regular unleaded gasoline rated at 87 octane or higher that meets specification ASTMD4814 in the
U.S. Blended gasoline is suitable for use in the Isuzu NPR NPR-HD Gas Chassis. MTBE is “methyl tertiary-butyl ether.” Fuel that is no more than 15%. MTBE is fine for your vehicle. Ethanol is ethyl or grain alcohol. Properly-blended fuel that is no more than 10% ethanol is fine for your vehicle. Methanol is methyl or wood alcohol.
NOTICE: Fuel that is more than 5% methanol is bad for your vehicle. And even at 5% or less, there must be “co-solvents” and corrosion preventives in this fuel to help avoid damage to the fuel system from methanol.
Fuel filter is located inside the fuel tank.
This system features an activated carbon storage canister that collects fuel vapors that are retained when the vehicle is not in operation. When the vehicle is operating these vapors are drawn in to the engine where they are consumed in the normal combustion process.
The NPR/W Series gasoline vehicle is powered by the GMPT V8 gasoline engine. The engine configuration supplied in the vehicle (LY6) is not compatible with propane, compressed natural gas, or liquid natural gas.
The vehicle is certified to the following levels: Federal Emission Certificate & California MD ULEV Emission Certificate 12,000 GVW Gas NPR/W3500
Federal Emission Certificate & California HD Emission Certificate 14,500 GVWR Gas NPR HD/W4500
The propeller shaft assembly is made up of a first and second shaft. The propeller shaft center support bearing is an oil seal type dust seal which is attached to the rear of the first shaft and is mounted to the crossmember by a rubber cushion and steel support bracket. The sliding spline, located on the front portion of the second shaft, is an involute spline type. Attachment of the propeller shaft assembly is by flanged couplings with four bolts each.
| Model: | 4L80-E Hydra-Matic |
| Gear and Ratios | |
| 1st | 2.482:1 |
| 2nd | 1.482:1 |
| 3rd | 1.000:1 |
| 4th | 0.750:1 |
| Rev. | 2.077:1 |
| A/T Fluid | 13.2 qts. |
| Weight/Wet | 254 lbs. |
| Features: |
For good vehicle performance under load, the NPR/ WSERIESGAS uses a 4L80-E Hydra-Matic 4-speed automatic transmission with lock-up converter and overdrive.
The key drivetrain components in the NPR/W-SERIES GAS engine, transmission and rear axle are all engineered and matched to operate as a team to provide optimal performance and economy.
The 4L80-E transmission does not have a PTO gear or opening.
The NPR/W-SERIES GAS front axle is a drop forged steel, reverse Elliot, “I”-Beam.
| Front Axle Specifications: | |
|---|---|
| Type | Steel Drop Forged |
| Reverse Elliot, | |
| “I”-Beam | |
| Rated Capacity | 6,830 lbs |
| Tread Width | 66.1 in |
| King Pin Type | Bronze Bushings |
| Thrust Bearing | Ball Type (RH) |
| Roller (LH) | |
| Hub Lubrication | Grease |

The front suspension is tapered leaf springs with stabilizer bar and shock absorbers.
Front Suspension Specifications:
| GVWR | 12,000 lbs | 14,500 lbs |
| Type | Semi Elliptical Springs | |
| Capacity | 8,440 lbs | 8,440 lbs |
| Effective Length | 51.2 in | |
| Width | 2.8 in | |
| Deflection Rate | 731.0 lbs/inch | |
| No. Leaves | 2 | |
| Leaf Thickness | 1 @ 0.65 inch | |
| 1 @ 0.71 inch | ||
| Stabilizer | ||
| Bar Dia. | 1.65 in | |
| Thickness | 0.16 in | |
The NPR/W-SERIES GAS is equipped with integral power steering with a 18.8-20.9:1 gear ratio and a variable ratio pump. This provides power assist when turning while providing good road feel and feedback driving straight ahead.
The system also features a tilt and telescopic steering column that allows adjustment of the 109.0 in 33.5 ft 38.8 ftsteering wheel location for driver comfort and convenience.

The NPR/W-SERIES GAS steering also features a 42.5inside wheel cut angle. This, coupled with the integral power steering, makes the NPR/W-SERIES GAS an extremely maneuverable truck.
| WB | Curb to Curb | Wall to Wall |
|---|---|---|
| 132.5 in | 40.7 ft | 46.0 ft |
| 150.0 in | 45.3 ft | 50.6 ft |
| 176.0 in | 51.9 ft | 57.2 ft |
The NPR/W-SERIES GAS has full floating rear axle with a banjo type housing and separable carrier. The wheel bearings are tapered roller type for long service life and feature oil bath lubrication.
The rear suspension consists of a multi leaf spring with shock absorbers designed to handle the loads. The long effective spring length design provides excellent ride characteristics.
Rear Suspension Specifications:
| GVWR | 12,000 lbs | 14,500 lbs |
| Type | Multi Leaf Spring | |
| Capacity | 9,880 lbs | 9,880 lbs |
| Main Springs | ||
| No. Leaves | 5 | |
| Effective Length | 51.2 in | |
| Width | 2.8 in | |
| Leaf Thickness | 1@ 0.43 in | |
| 5@ 0.51 in | ||
| Deflection Rate | 919 lb/in | |
| Auxiliary Springs | ||
| No. Leaves | 2 | |
| Effective Length | 33.5 in | |
| Width | 2.8 in | |
| Leaf Thickness | 2@ 0.63 in | |
| Deflection Rate | 2,661 lb/in | |
| Main + Auxiliary | ||
| Deflection Rate | 3,580 lb/in | |
A limited slip differential is available from the factory. This LSD will help provide additional traction under conditions where road surface traction has been decreased.
Oil Type: Multi purpose gear oil SAE90 GL-5 for limited slip differential together with limited slip differential lubricant additive (Part No. 8-01052-358-0) or equivalent.
The frame in the N/W Series Diesel is a ladder-type, channel section, straight rail from bumper to end of frame with a rivet-less top flange.

| WB | 109 | 132.5 | 150 | 176 |
| Side Rail Sec. | 8.50 in X 2.76 in X 0.24 in | |||
| Combined Section Modulus | 7.20 in3 | |||
| Yield Strength | 44,000 psi | |||
| Rated RBM | 316,800 lb-ft/in | |||
| (per Rail Combined) | ||||
| No. Crossmembers | 5 | 6 | 6 | 6 |
| Frame width | 33.5 | |||
The fuel tank is mounted in the rail behind the rear axle, within the suspension area. This location enhances vehicle safety while providing easier installation of vocational bodies.
The fuel tank is steel and rectangular in shape. It is equipped with a fill hose, electric fuel pump (mounted within tank). Through the rail fuel fill.
The Fuel Tank Size is 30.0 gal. rect.
The service brake system is a dual circuit vacuum assisted hydraulic system with a metering valve in the front brake circuit that promotes brake application timing. The NPR, NPR-HD Gas /W3500, W4500 Gas are standard with front disk brakes and self-adjusting outboard mounted rear brake drums. The system incorporates an Anti-lock Braking System (ABS) and Electronic Braking force Distribution. The ABS is designed to avoid the locking of the wheels and ensure the stability of the vehicle during deceleration for a stop. The system has a fail-safe mode that will turn the ABS brake system off if a malfunction in the system is detected. The ABS system has a self-diagnostic function that will improve the ease of serviceability of the system. The system offers excellent stopping power, long service life, and non asbestos brake linings. The Electronic Braking force Distribution (EBD) suppresses an excessive rise in rear brake pressure based on wheel speeds and brake pressure sensors. EBD provides the best balance for a given load to provide maximum brake lining life based on wheel speeds and brake pressure sensors this in turn extends maintenance intervals and lowers operating costs.
The ABS control unit increases,decreases, or keeps brake fluid pressure the same by operating the brake actuator unit in response to the wheel speed sensor signals. The control unit also calculates wheel speed, wheel deceleration and vehicle speed. When the brakes are applied in a manner that the wheel rapidly decelerates and the difference between wheel speed and vehicle speed becomes larger that a predetermined value the control unit senses that the wheel is about to lock up and the unit keeps the fluid pressure as it is.

If the wheel further decelerates the control unit senses that the wheel is locking up and reduces the brake fluid pressure. When the control unit senses that the wheel is unlocked, the unit maintains or increases brake fluid pressure repeatedly.
The power assist for the system is supplied via a separate vacuum pump that is driven by the engine off of the back of the alternator.
The NPR-HD / W4500 gas is equipped with an additional electric vacuum pump to back up the system.
The parking brake is a drum/shoe type that is mounted on the rear of the transmission and is operated by a manual lever actuated cable.
Battery Specifications:
A 12 volt Delco maintenance-free type battery is standard and is located outside the frame rail on the RH side aft of the air cleaner. The electrical system is 12 volt negative ground. The battery is rated at 750 CCA.
Starter Motor: Sliding Pinion type solenoid controlled with over running clutch. Bearings are oil-free, graphite-filled bronze.
Alternator: 12V-145 AMP output with integral regulator.
Lighting Specifications:
The exhaust system routes through Oxygen Sensors to dual horizontally mounted stainless steel catalytic converters and muffler on the left side of the chassis. The exhaust tail pipe then exits to the rear of the muffler well ahead of the rear axle on the driver's side.
The N/W series cab has been updated for the 2008 NPR/W3500 and NPR-HD/W4500 Model Year. The new design brings an exciting fresh new look to the N/W series product. Based on the “Hexapod Design Concept” the cab has been completely redesigned to meet new emerging market demands. Cab panels, radiator grill, headlights, and bumper have been completely redesigned to embrace the design concept that brings maximum space to the cab interior while creating a bold look on the outside of the cab. The sleek new design conveys a solid clean vehicle with a bold presence in the market place. With these enhancements the product continues to bring many customer driven improvements in low cab forward design. The cab interior features improved driver comfort with increased head room, leg room, storage room, and a wider door opening and larger step for easier access to the cab. Once inside the driver is greeted by a new interior color scheme and enhanced visibility of a new instrument cluster. This cab has been designed to meet all current and future market trends.
The low cab forward (LCF) design used by the N/W Series Gas has been recognized in urban centers throughout the world for the following features:
The Hexapod cab offers additional value to the customer in many other areas.

The N/W Series Gas tilt cab design provides complete and easy access to the engine area for service. By following the procedure shown in the owners manual the cab can be tilted a full 45o with great ease on improved cab mounts. More engine access is provided with the tilt cab than by any conventional or van cabs offered by the competition. This ease of access allows quicker service that will translate to lower maintenance costs leading to a lower cost of operation for the LCF design. The engine compartment is protected from road spray by splash shields mounted under the cab. The cab floor is insulated to improve the drivers cab environment by reducing engine noise and heat in the cab interior. A rear engine cover improves the cabs appearance and further reduces noise. Convenience of operation and service are highlights of the improved cab. The hydraulic brake reservoir is located at the left end of the dash for easy inspection and service.
Fuses and electrical relays are located behind a removable panel below the center of the dash. This location is within easy reach for access by the driver or technician. The windshield washer bottle is located on the end of the dash on the passenger side. The washer bottle feeds intermittent wet arm wipers that put the washer fluid directly on the windshield where it is needed. The cab roof cap is designed to channel water off of the roof to the side not down the windshield to improve driver visibility in wet weather. The windshield is bonded to the cab for increased cab rigidity, less wind noise, and no leaks. The windshield has a upper tinted area for improved visibility and safety. The coolant reservoir is located at the back of cab and is also easily checked without tilting the cab.


The cab environmental system has been re designed to provide enhanced air flow through the ventilation system in the cab. The system provides plenty of air flow and heat to keep the driver comfortable, ventilate the cab, and keep the windshield glass clear. The air conditioning system uses environmentally friendly 134a refrigerant. A new larger air-conditioning condenser has been relocated vertically and raised for greater protection of this component for improved operation and less maintenance.
Performance:
ITEM DESCRIPTION
Heater 16,400 BTU/hr
Air Conditioner 16,000 BTU/hr

The N / W Series Hexapod cab has been designed for the person who spends all day on the road. The drivers will find the cab has a spacious environment with increased shoulder and head room. The cab is standard with a high back drivers seat and passenger seat. The center passenger seat has a tray mounted on the back side to provide a convenient work area for the driver inside the cab out of the elements.

To enhance driver comfort the seat cushions, have been designed for maximum support. The seat material is a durable Tricot and Jersey knit combination material, which breathes for enhanced driver comfort in hot or cold climates. The drivers seat travel fore and aft has been increased allowing more room to tilt and adjust the seat for maximum driver comfort. Additional storage for maps and other papers is provided in easy to reach door pockets, seat backs as well as several built in storage areas in the dash. An overhead storage shelf is now standard equipment on all N/W series chassis. Power windows and door locks are also standard on all models. Seat belt design is enhanced for easier operation. A new interior dome light is installed for a brighter cab in night time operations. Heavy duty floor mats are standard.

The steering wheel is constructed to provide maximum visibility of the instrument cluster. The column tilts and telescopes to adjust for varying driver profiles.
The parking brake handle is located between the drivers seat and the center passenger seat. This location provides an unobstructed floor for increased driver comfort. The rubber floor mat is durable and easy to maintain. The automotive style instrument panel has a low profile design for improved downward visibility. The cab is fully trimmed to provide a quieter environment. A cup holder is mounted between the seats within convenient reach of the driver and will handle large convenience store cups. A slide out, dash mounted cup holder accommodates two smaller sized coffee cups. The rear cab panel incorporates a coat hook as well as a rear storage organizer for improved driver comfort.
The Hexapod cab includes redesigned steering wheel which greatly enhances instrument visibility. Frequently used switches are styled for easy operation, and illuminated for operation at night. ISO symbols are used on the switches and instrument panel for standard recognition of control components. The combination switches are designed to fit more naturally in the hand. Their function is clearly marked on the lever for easy recognition. The odometer has a check switch to read the mileage without turning on the ignition switch. The fuel level can also be read without the key in the ignition by pushing the odometer check switch for rapid yard checks of parked vehicles.
Cornering lights have been added to improve night time visibility when the turn signals are operated and headlights are on. Cruise control is standard and the controls are post mounted for easier operation and greater driver comfort. An optional AM/FM/CD radio can be ordered. The dash also has a “5 DIN openings suitable for other electronic equipment.
The Hexapod cab has undergone improved anticorrosion treatment to ensure a long service life. This treatment begins with extended use of galvanized steel panels in the cab construction. In addition to more galvanized. panels the galvanizing thickness has been increased. The cab receives a cat ion electro deposit primer “E coat” and a strong alkali-proof paint for full protection against corrosion. Undercoating has been added in the wheel wells to further protect the cab from road spray and rock chipping. A self cleaning resin doorstep has been used, combined with a plastic support to protect against corrosion in the step wells. All of these added features will result in a cab that will withstand the elements for an extended length of time.
The cabs exterior features a chrome grill to complement the new cab and a removable front service panel for easy access to wiper motor, wiper linkage, cab air intake filter, and electrical connections. New side view mirrors have a breakaway function to protect the cab doors. These large 17 x 8 west coast style mirrors heads incorporate a 11x7 inch flat glass mirror and a 4x6 inch convex mirror in one mirror head. There is an option for extended mirror brackets for use with 102 inch wide bodies. Heated mirrors are an available option. Cab door handles are the large paddle type that protect the door paint and are easy to operate by a gloved hand.
The cabs structural strength is vastly improved for the 2008 N/W Model. The side sill is now a closed section and the under-frame is now constructed of high tension-resistant steel. In making these changes we accomplish 2 important goals, (1) structural strength is maintained in case of a collision and (2) weight is reduced so as not to affect payload.
The cab durability has also been enhanced by passing structural elements through the closed sections at the under-frame connection point to the chassis in the vehicle width direction. This arrangement of components improves cab rigidity.
Additional reinforcement in front pillar area from the cowl to rocker panel area has been accomplished. Gussets have been enlarged to increase the connecting rigidity between the pillar area and the cowl. This change reduces cab deformation in case of a collision.