1989-1993 Dodge 5.9L Cummins Drop-In Turbos

Drop-in turbos on the 1989-1993 RAM 5.9L Cummins

From the factory, every first gen ran a single Holset H1C on a T3 divided manifold flange, with turbine housings in 18 cm and 21 cm sizes. Trucks from 1989 through early 1991 have no intercooler; trucks from mid-1991 through 1993 have a front-mounted air-to-air unit. A drop-in turbo is built to use that factory mounting. That is different from the big-frame builds in the magazines, which bring head studs, a new manifold and an intercooler upgrade along with the turbo.

Replace or upgrade?

If your H1C is worn and you want the truck stock, the OEM-style route is a reman exchange H1C, sold separately for 1989-1990 and 1991-1993 (18.5 cm) trucks. Commonly reported signs of a tired 30-year-old turbo are shaft play, oil in the intake or intercooler boots, blue smoke and a whine, though the documented 620,000-mile survivor still ran its original. If you want more air, an HX35-frame 60/64 turbo is a common bolt-on upgrade for first gens, and Diesel Army's first-gen buyer's guide puts a larger Holset or BorgWarner turbo in the mid-range tier, after the budget steps. Anything bigger than that is built-truck territory.

What we carry

Calibrated Power supplies the drop-ins in this collection: the CPS200125 Stealth STR and the CPS200228 HX35 Stealth 64 Performance Turbo, both listed for 1991.5-2002 5.9L Cummins trucks. The Stealth 64 is an HX35-frame turbo, the frame size first-gen owners commonly step up to. Gaskets, oil lines, clamps and heat blankets for the install are on the turbo accessories page for this truck, and the full turbos page and Cummins catalog cover other years.

Fitment notes

Both CPS units carry a 1991.5-2002 listing, so a 1989-1990 truck, or an early 1991 truck without the factory intercooler, needs a call to us before it gets one. Intercooled and non-intercooled trucks differ in compressor outlet plumbing as well as pump and injector calibration. Match the flange gasket to the manifold on the truck, not the year. If the oil feed line is original, inspect it while the turbo is off, since feed lines leak and crack with age. Verify by VIN.

Frequently asked questions

Will a CPS drop-in fit my 1990 Ram?

The CPS200125 and CPS200228 are listed for 1991.5-2002 trucks. A 1990 is non-intercooled and plumbed differently on the compressor side, so call before you order. We will check your truck against the listing.

Should I rebuild my stock H1C or upgrade?

If you want the truck stock, a reman exchange H1C is the OEM-style path, with separate units for 1989-1990 and 1991-1993. If you want more airflow, an HX35-frame turbo is a common bolt-on step. Either way, the factory turbo has a long record, so confirm it is actually worn before you replace it.

What else do I need with a drop-in turbo?

Fresh MLS flange gaskets, a sound oil feed line and good clamps are the usual supporting parts. Put a pyrometer, boost gauge and fuel pressure gauge on the truck too, so you can see what the new turbo is doing to exhaust temperature and boost.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.