Chevy LR4 4.8 Vortec 4800 Engine Specs, Problems And Reliability

Being very alike from a mechanical point of view, GM’s LS motors and Vortec ones, built on their framework, were employed for almost every brand of the company, comprising Chevrolet, Pontiac, Buick, GMC, Cadillac, Saab, Izuzu and Hummer.

As both LS and Vortec motors are pretty widespread, they are treated as contemporary motors of high efficiency. Having fantastic output, these motors can be susceptible to various modifications, including turbo and superchargers, high-flow cylinder heads, intake systems, camshafts plus nitrous oxide. Besides, many aftermarket details are in stock for sale for LS swap motors. Crate engines are obtainable and you are free to get an old motor pretty cheap at the junkyard.

Summit Racing has made some guidelines for each motor of the series for engineers, tuners, and just car enthusiasts to have a better idea of the peculiarities of LS motors.

Key Facts:

• Keeping manual transmission, LR4 motors, released between 1999 and 2000, featured a crankshaft with a rear flange of 1.250 inches. (Casting #12553312)
  The further versions were equipped with a crankshaft with a rear flange of 0.857 inches. (Casting #12553482)
• In 2001, LR4 plus LM7 motors gained MLS gaskets.
• LR4 and LM7 motors, released between 1999 and 2003, kept return-type fuel injection systems.
• In 2004, motors turned returnless (Express is the only exception).
• GM/ Chevrolet LR4 is a 4.8-liter (293 cu in) natural aspirated V8 90-degree 4-cycle gasoline motor, pertaining to the Gen III small-block V8 truck engine lineup.
• Being often called Vortec 4800 and serving as a substitute for GM’s L30 with 5.0-liter displacement, this motor was manufactured at St. Catharines, Ontario, and Romulus, Michigan, from 1999-2006.
• Keeping V8 90-degree cast iron cylinder block with the five-bearing crankshaft, 2 aluminum heads, one-piece cast camshaft plus 2 valves per cylinder, LR4 featured a sequential multi-port fuel injection system plus a throttle body of 78 mm (3.07 inches). Moreover, it gained a Coil-Near-Plugs ignition system.
• Featuring Cylinder bore of 96 mm (3.78 inches) and a piston stroke of 83 mm (3.27 inches), its compression index equals 9.4. The output is 255 hp (258 PS or 190 kW) – 285 hp (290 PS or 213 kW) with the torque of 386 Nm (39.4 kg/m or 284.9 ft/lb) – 400 Nm (40.8 kg/m or 295.2 ft/lb).

4.8 Vortec Specs

Being first produced in 1999, LR4 was one of the first engines of the LS series for trucks along with LM7 and LQ4. LR4 was applied for General Motor’s vans, pickups plus SUVs till 2007. The motor with 4.8-liter displacement is also referred to as Vortec 4800.

These motors are reliable and can boast of great strength and are even more efficient with boost or nitrous. They can achieve 1000 hp if some updates are made.

Cylinder Head

Great cooling is provided to the cylinder head thanks to the light but solid aluminum alloy it’s built of. A single chain operates a camshaft while the timing chain conveys rotational movement from the crankshaft to camshafts. Rocker arms, located on a pedestal, ensure valves functioning.

Inlet valves are 48 mm (1.8898 inches) while exhaust ones are 39.4 mm (1.5512 inches). The intake duration is 190 degrees with an 11.60 mm (0.457 inches) valve lift. Exhaust duration equals to 191 degrees with an 11.84 mm (0.466 inches) lift.

Cylinder Block

LR4 ‘s cast-iron cylinder block features a five-bearings crankshaft supported system. The diameter of the crankshaft journal equals 65 mm (2.55 inches) while the crankpin is 53.3 mm (2.09 inches).

With a compression ratio of 9.4, the motor has a cylinder bore of 96 mm (3.78 inches) and a piston stroke of 83 mm (3.27 inches). Moreover, LR4 utilizes 2 compression and 1 oil control ring plus connecting rods of 159.38 mm (6.275 inches).

4.8 Vortec Engine Problems And Reliability

• Fuel Pump Failure
• Intake Knock Sensor
• Intake Manifold and Gasket Leaks
• Water Pump Failure

The 4.8 Vortec engine was typically a good Workhorse of an engine for Chevrolet. Many drivers were able to keep the engine functioning properly for up to 300,000 miles or more as long as it was properly maintained. Despite Chevy’s replacement with a 5.3 L engine in 2013, many drivers reported that the replacement engine was far less trustworthy owing to issues with an active fuel management system, which had been known to cause significant oil consumption problems.

On the other hand, in terms of performance, the 4.8 Vortec and the 5.3 Vortec are almost identical, with the exception that because of their lack of active fuel management, they didn’t have an oil consumption problem. In reality, owing to this fact, it becomes a substantially better engine in terms of performance than the 4.8 Vortec.

However, comparing the potential advantages and drawbacks of these two engines is hit-and-miss at this point since there are several drivers who believed that the 5.3 would be a superior option due to performance differences.

The 4.8 Vortec, as previously stated, has a few issues that rose above the others and are worth noting but were never really significant across the board. It was not the case that every Sierra or Silverado produced had these problems. With this in mind, it’s reasonable to believe that if you’re searching for a Chevrolet with a 4 on the engine before 2011, it may be operational and have a lot of miles left on it.

It’s also a good idea to have a professional mechanic check it out before you buy anything, especially the water pump and the fuel pump, because if they’re original components after so many years, there’s a chance they’ll fail soon and will need to be replaced. There’s no sense in buying a used car that will require lots of new parts right away if you don’t have to. So keep that in mind.

What Is The Difference Between A 4.8 L And 5.3 L Engine?

Many people may find it difficult to tell the 5.3L and 4.8L apart because the blocks are similar. However, there is a significant difference within. The 4.8L features an 83mm stroke, whereas the 5.3L has a 92mm stroke. Displacement can be determined by looking at the top of the pistons, either with a head or while using a borescope

For the pistons, you have a 5.3L for the dish and a 4.8L for the flat-top piston. You’ve got yourself either a 4.8L or a higher-output, Gen IV 5.3L if you choose the flat-top piston with a 4.8L displacement (and no cylinder head). The crankshaft is next to be looked at. If you find that casting number 12553482, it’s a 4.8L (and not another engine type such as a turbocharger). The crank casting number for the 5.3 L will be 12552216 like other 3.62-stroke LS engines

What’s The Horsepower Of The 4.8 Engine?

The 4.8-liter V8s in the Ram 3500, Dodge 2500/3500, and Durango can produce anywhere from 270 to 295 horsepower and 285 lb./ft. to 305 lb./ft. of torque depending on the model year and vehicle.

What Cars Have The LR4 4.8 Vortec Engine?

Most Common Bolt-On Updates For LR4 Engine

This motor is frequently used in engine swaps because of its low cost at car dumps despite the fact that it’s not so widespread in commercial vans. If you are eager to add some modifications to your motor, you will face no troubles as LR4 is a great basis for many upgrades.

The choice of the bolt-ons for vans isn’t very vast while much more additions are obtainable for trucks. Moreover, you can find some good variants for a 5.3-liter modification.

Pretty often, car enthusiasts update the cold air intake plus exhaust system. However, be ready that your motor’s sound will become so great that you won’t resist the temptation of riding faster. You will cope with all these updates yourself, but note that the tune will be non-optimized.

So, it’s advisable to turn for assistance from a chassis dyno tuner and computer programmer. In such a way, a specialist will attune the ECM and make it work more efficiently no matter what fuel you buy (low octane or high quality one).

The 4.8-liter motor is prone to revving. That’s why it’s better to increase the rev limit plus offset points. Moreover, by doing that, you will cope faster with larger camshaft and injectors tuning. Moreover, it’s crucial to mount a colder thermostat before making any further updates.

LR4 Intake Manifold and Throttle Body Modifications

Owning a power booster, intake, and throttle body modifications can be postponed. But, in case your motor is naturally aspirated, deal with them before heads. Original manifold for trucks features long runners, ensuring efficient low-end torque. It’s also great that intake is ported.

Frequently, it’s undesirable to opt for a single plane way. Nevertheless, it’s reasonable if you use much nitrous as it’s prepotent and contributes to enhanced cylinder-to-cylinder mixture allocation. It’s a cool option if you apply it for an old automobile or in case you aren’t aware of the injection process. You are free to clap your carburetor on it and manage a programmable ignition box, plugging directly into the original coil harness and cam sensor.

Seeking increased power, F.A.S.T. LSXRT intake is compatible with throttle bodies of 102 mm and bigger. Moreover, truck motor bays comprise tunnel rams, changing some torque down low for more torque up high.