1st Gen 12 Valve Cummins Specs

When it comes to diesel vehicles, the first-generation Cummins is a name that most people are acquainted with. With the 7.3L Powerstroke as a close second, I believe it to be the most dependable diesel engine ever installed in a pickup truck. Numerous first-generation 5.9L Cummins vehicles are still on the road today, 30 years after their introduction.

In this 1st gen 12 valve Cummins article, we’ll go into further depth to learn more about this engine.

Is A First-gen Cummins A 12 Valve?

Yes, the first-generation Cummins engine is a 12 valve. It was available in both 6 and 8 cylinder versions and offered great performance and reliability. Many of these engines are still in use today and can be found in a variety of applications.

A new bar for OEM diesel performance was set when the 5.9L 12-Valve Cummins engine was introduced to the Dodge D/W truck series. In the first-gen 5.9L Cummins, direct fuel injection and a Holset fixed-geometry turbocharger were seen on a diesel pickup truck for the first time. Dodge’s D/W 250 and 350 trucks now have better handling and throttle response thanks to their best-in-class 400 lb-ft torque.

For its day, the 160 horsepower and 400 lb-ft of torque were a lot more remarkable than it is now. We now know that the first-generation Cummins is capable of achieving high horsepower and torque ratings with ease.

The 6BT engine is more than capable of handling more power without requiring too many support changes, therefore high-performance figures may be accomplished on a budget as well.

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1st Gen 12 Valve Cummins Specs

Generation 1 Cummins can also be called 12V or 12 Valve Cummins, 6BT Cummins, and 1st Generation Cummins. Has an inline-6 Cylinder engine design with a cast-iron block. Its cylinder head is a cast iron and per cylinder has 6 head bolts.

  • Displacement: 5.9 Liters or 359 Cubic Inches
  • Bore: 4.02″
  • Stroke: 4.72″
  • Compression Ratio: 17.0:1
  • Fuel Injection: Mechanical injection pump (Bosch VE44), direct-chamber fuel injection, mechanical injectors
  • Turbocharger: (VGT) Holset Fixed Geometry Turbocharger
  • Valvetrain: Overhead Valve Engine (OHV) 2 Valves Per Cylinder
  • Governed Speed: 2,500 RPM
  • Torque: 400 lb-ft @ 1700 rpm
  • Weight: 1,100 pounds dry
  • Capacity of Engine Oil with Filter: 11.4 Liters or 12 Quarts
  • Fuel: Diesel
  • HP: 160 horsepower @ 2,500 rpm

1st gen 12 valve cummins

How Much Is A 1st Gen Cummins Worth?

The value of a 1st gen Cummins depends on many factors, such as the year it was manufactured, its mileage, and its overall condition. However, you can expect to pay anywhere from $3,000 to $5,000 for a used 1st gen Cummins engine.

How Much Horsepower Can A 1st Gen Cummins Make?

Generation 1 Cummins can make 160 horsepower at 2,500 rpm.

While the factory rating is 160 hp, many people have reported that their 1st gen Cummins made more power. It is not uncommon for a first-generation Cummins to make over 200 horsepower with some simple modifications.

A stock 1st gen Cummins will usually make around 700-800 ft-lbs of torque, but with some modifications, you can increase that number to over 1,000 ft-lbs of torque.

What Is The Best Year For A 1st Gen Cummins?

The best year for a 1st gen Cummins is often considered to be 1989. This is because the the1989 model was the first year that Dodge used the 5.9L Cummins engine. The 1989 model also featured several improvements over the previous models, such as a higher compression ratio and a new injector pump.

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How Much Horsepower Does A 12 Valve Cummins Have?

With an inline injection pump of P7100, the Cummins 5.9-liter 6BT 12 valve offers 230 HP and torque of 440 lb-ft. There are several Jeep, Rat Rod, Muscle Car, and Dragster projects powered by 12-valve engines.

1st gen 12 valve cummins

Why The 12-valve Cummins Is The Best Diesel Engine?

Simplicity in Design

From 1989 to 1998, the 5.9L Cummins was available in a 12-valve variant. An engine engineered to withstand the rigors of time and use has a cast-iron head and block, forged steel crankshaft and connecting rods, mechanically regulated direct injection, and an inline-six design. Low-rpm torque of 359 cubic inches may be achieved thanks to a 4.72-inch stroke and 4.02-inch bore.

Along with its inherent ability to create massive amounts of torque, inline engines are also simpler to service than their V8 counterparts. The water pump may be swapped out in under an hour by a beginner technician in the time it takes to remove the turbocharger. The 12-valve is notorious for wreaking havoc on gearboxes and axles if it isn’t modified to its full potential. As a result, the remainder of the engine is generally bolstered to handle the 5.9L’s increased output.

Connecting Rods with a Durable Material

With the 12-valve 5.9L (and ’98-’02 24-valve engines), the connecting rods are made of forged steel and can handle 800 rwhp in factory condition. Many aftermarket firms produce polished, shot-peened, and balanced versions of the original rod for drag racing and sled pulling purposes. These rods can endure 1,200 rwhp (plus or less) before bending.

Heavy-Duty Rod Bolts

For a long time after that, the stock rod bolts are on borrowed time since they may back out with age and greater engine speeds, even though the factory rods are capable of handling over 800 rwhp. Fortunately, ARP produces heavy-duty rod bolts for the ’89-2002 5.9L, which give roughly 23% more tensile strength than the original parts (PN 247-6303).

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Additional Horsepower

The 12-valve Cummins is a mechanically-injected engine, so you don’t need to communicate with the ECM while making fuelling adjustments. With a few basic hand tools and your own two hands, you can increase the horsepower of your vehicle. You may start by modifying the P7100 injection pump’s AFC (air-fuel control) housing, illustrated in the image below, which sits on top of the pump.

The AFC housing can be moved all the way forward (toward the truck’s front), the star wheel under the AFC housing can be turned to the passenger side of the engine, the fuel plate can be removed, and the turbocharger wastegate can be disabled to increase horsepower. All of these methods are possible. Completing all of the aforementioned steps often yields a 100-hp boost, if not more.

Parts Are Interchangeable

The ’89-’93 5.9L and the ’94-’98 5.9L are not interchangeable, however, a large number of components may be switched over. It is possible to install a P7100 injection pump (in lieu of the rotating VE pump) in the ’89-93 engines (with the necessary components and know-how) with the right parts and components. The truck’s rwhp goes from 350 to 600 with the addition of a P7100 to the first generation 12-valve engine. To get those types of benefits, it’s well worth the time and effort of tracking down all of the conversion components that you need.

Final Thoughts

If you’re looking for a high-performance engine, the 1st gen Cummins is a great option. With its durable construction and powerful performance, it’s no wonder these engines are still in high demand today. Whether you’re looking to replace your old engine or upgrade to a more powerful one, the 1st gen Cummins is a great choice.

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