1994-1998 Dodge 5.9L Cummins Compound Turbo Kits

Compound turbos on the 1994-1998 Dodge Ram 5.9L Cummins

From the factory, your 12-valve Cummins has a single wastegated Holset HX35, or the WH1C on some 1994 trucks, on a T3 cast manifold with a 3-inch downpipe, making about 18 to 22 psi. Compounds replace that with two turbos working in series. The large atmospheric turbo compresses outside air and hands it to the smaller high-pressure turbo, which compresses it again. The usual street pairing on a 12-valve is an S300-frame turbo over an S400. One documented build ran a wastegated S364 over a T6-flanged S475 and made 70 psi and 700 hp on a stock bottom end with ARP studs.

Why compounds, and when

The stock HX35 has an airflow ceiling. On a truck with added fuel, the factory turbo was documented pushing 35 to 40 psi with the wastegate wide open, with EGTs climbing and the turbo over-speeding. A drop-in 62 to 64mm turbo is the documented answer for towing trucks in the 300 to 450 hp range. An S300-frame single on a T4 manifold is the next step; one took a 12-valve from 390 to 475 rwhp. Compounds come in above that. Competition builds go to S369/S484 or S366/S483 pairings aimed at 1,000 hp.

What we carry

This collection has the ATS Diesel Performance Aurora Compound Turbo System, listed for 1994-2007 Cummins trucks. It is sold as a system rather than a single turbo, which matters because a compound install changes the manifold, the downpipe and the charge-air piping. For single-turbo options, including drop-ins that bolt to the stock manifold, see our turbos page.

Fitment notes

A compound kit is not a bolt-on to the stock T3 manifold. Large S400 atmospheric turbos usually use a T6 flange, and S300 and S400 upgrades in general need a T4 or T6 manifold and an HX40-style 4-inch downpipe, so confirm what the kit includes and what you still need to buy. The ATS listing covers 1994 through 2007, which spans more than one Cummins generation and the 1998 mid-year switch to the 24-valve, so confirm the engine in your truck. Budget for supporting parts too; the 700-hp street build above relied on ARP studs. Call us with your VIN and your power goal.

Frequently asked questions

Do I need compound turbos to tow with my 12-valve?

Usually not. The documented towing choice for 300 to 450 hp 12-valves is a drop-in 62 to 64mm turbo; one 425-hp truck with a Stealth 64 held boost in the mid-20s and EGT near 1,200 F towing 11,000 lb. Compounds are for builds well past that.

How much power do compounds support on a 12-valve?

A street set of a wastegated S364 over an S475 made 70 psi and 700 hp with a stock bottom end and ARP studs. Competition pairings such as S369/S484 or S366/S483 are aimed at 1,000 hp.

Will the ATS Aurora compound kit fit my 1998?

The listing covers 1994-2007 Cummins trucks, but a 1998 can have either the 12-valve or the 24-valve, and details matter on a kit this involved. Confirm your engine: the 12-valve has the P7100 inline pump with the shutoff solenoid on top. Then check the product page fitment, or call us with your VIN.

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.