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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.

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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