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5.9 12V Cummins | 1988 – 1993

First Gen 5.9 12-Valve Cummins Parts (1989–1993)

Keep your 1st Gen working hard with upgrades that improve spool, airflow, and towing power while protecting reliability. Diesel Power Source designs clean-fit turbos and exhaust manifolds for 1989–1993 Dodge Ram 5.9L 12-valve Cummins.

This page highlights first-gen specific parts and fit notes. If you need 24-valve or common-rail components, or universal turbo categories, use the links at the bottom. Detailed specs and year-specific contents are listed on each product page.

Why upgrade your 1989–1993 12V Cummins

  • Quicker spool and response: Flow-optimized manifolds and right-sized turbos help the VE-rotary pump builds pull sooner.
  • Lower EGT on grades: Better exhaust flow reduces drive pressure and heat when towing.
  • Durability: Thick-wall castings and flat-machined flanges resist warping and leaks through repeated heat cycles.
  • Clean fitment: Parts are modeled around first-gen bay clearances for service access and repeatable installs.

How to choose parts for a 1st Gen 12V

  • Towing and daily use: Choose a stock-replacement manifold and a quick-spooling turbo. Monitor EGT on first towing runs.
  • Street performance: Step to a slightly larger compressor with the correct turbine housing to hold speed on grades without excessive lag.
  • Higher fuel builds: Plan airflow headroom with appropriate turbine A/R, quality intercooling, and a converter or gearing that matches the goal.

Fitment checklist for 1989–1993

  • Confirm T3 vs T4 turbo flange on the manifold you select.
  • Verify downpipe route, intercooler path, and clearance at steering shaft and A/C lines.
  • Plan new gaskets, hardware, heat shielding, and sensor ports if you log EGT or drive pressure.

Install and first drive notes

  • Use new gaskets and quality hardware. Torque in sequence on a cold engine.
  • Pressure test the charge-air system before first start. Check for any pre-turbine leaks.
  • Monitor boost and EGT on shakedown. Re-check fasteners after heat cycles if specified.

Shopping related categories? 5.9 Cummins Manifolds (12V, 24V, common-rail) | S300 Single Turbos | S400 Single Turbos | Add-A-Turbo Kits. For later engines, see 6.7 Cummins Manifolds.

Frequently asked questions

Do I need tuning on a 1989–1993 12V after a manifold swap

A manifold alone does not require tuning. If you change turbo size or fueling, plan to adjust fuel delivery and monitor EGT for safe operation.

Will a performance manifold help tow temps on a first-gen

Yes. Lower drive pressure and smoother flow typically reduce EGT on long pulls and help the turbo stay in an efficient range.

T3 or T4 for a 12V

Use T3 for most stock-frame or quick-spool goals. Choose T4 when stepping to larger airflow with future power headroom.

What should I inspect during install

Manifold and turbo sealing faces, downpipe alignment, intercooler boots, and any soot traces that indicate a pre-turbine leak.

 

5.9 12V Cummins FAQ's

Yes. Lower drive pressure and smoother flow typically reduce EGT on long pulls and help the turbo stay in an efficient range.

A manifold alone does not require tuning. If you change turbo size or fueling, plan to adjust fuel delivery and monitor EGT for safe operation.

And here is the body that is a little longer

If you own a 93 Cummins, you're working with one of the most iconic 12-valve engines ever made. The 1993 Cummins, often found in the 93 Dodge Cummins trucks, features a T3 turbo flange stock—important to know if you're upgrading to a T4 aftermarket turbo. 

 

Most '93s came with a VE rotary injection pump, known for its simplicity and fuel economy, though many enthusiasts swap in a P7100 for better fueling and horsepower. 

 

Engine bay space in these first gens is tight, making Diesel Power Source’s compact compounds or Add-A-Turbo kits a perfect fit. Since most 1993 Cummins trucks didn’t come with a factory intercooler, adding one is crucial for EGT control and performance. 

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