11 Reasons Why Your 6.7L Cummins Needs an S400

April 16, 2018
Story By
Mike McGlothlin

Eleven years into the 6.7L Cummins’ production run, the benefits of the 5.9L’s descendant are crystal clear: its block is stronger, it makes more torque and (thanks to its displacement advantage) it can drive a fairly large turbocharger with virtually zero negative side effects. While compound turbo systems were extremely common—and virtually a requirement—on a highly modified, street-going 5.9L Cummins, adding a big single charger is standard operating procedure for daily driven 6.7L Cummins mills making similar power. In particular, most ’07.5-present Ram owners install a fixed geometry, S400-based BorgWarner turbo in place of the factory variable geometry unit.

Why Scrap the VGT?

Although the variable geometry Holset HE351VE that comes standard on the 6.7L Cummins provides instant response and a highly-effective exhaust brake function, its complex design doesn’t lend itself to long-term durability. The vanes used to vary exhaust flow across the turbine wheel in the turbine housing often stick due to excessive soot and carbon buildup, and the electronic VGT actuator is notorious for doing the same. Add to that the fact that it produces excessive drive pressure and doesn’t support more than 500rwhp very well and you have all the justification you need for scrapping it.

Added Performance AND Reliability

Not only does a fixed geometry, S400-based turbo add more reliability to the equation (fewer moving parts to fail and less drive pressure making life easier on the head gasket), but it can also support considerably more horsepower than the stock VGT. In fact, depending on how it’s sized, an easy 600rwhp to a very streetable 800rwhp can be had. So what’s it take to get an S400 bolted to your 6.7L Cummins? The most feasible option is to purchase a complete Second-Gen turbo swap kit. These all-inclusive systems are designed around the use of a ’94-’02 style 5.9L Cummins exhaust manifold (hence the term Second-Gen), which—due to mounting the turbo in the center of a divided manifold—provides equal, more efficient exhaust gas flow for each cylinder.

Below, you’ll find 11 of the most popular second-gen turbo swap kits available in the aftermarket. While the price, featured components and fit and finish varies from system to system, each one aims to achieve the same end goal: make your 6.7L Cummins more reliable and powerful.

1. Stainless Diesel

Features:

Stainless Diesel 24-valve exhaust manifold
Your choice of S400, from a cast wheel S463 to a billet, 5-blade S475 with a race cover
5-inch high flow cold air intake kit with IAT and MAF sensor bungs, S&B filter
3-inch diameter, bead-rolled intercooler pipe
4-inch diameter aluminized downpipe and V-band clamp
High-torque T-bolt clamps
All oil supply and feed lines/fittings (including -6 AN braided stainless supply line)
All gaskets, mounting bolts and studs
Optional polished exhaust manifold

Price: From $2,425 (’07.5-’12, S463 turbo included)

*Piping-only kits are also available

2. Fleece Performance Engineering

Features:

Optional ATS Diesel or Steed Speed T4 flange exhaust manifold
Your choice of a cast wheel S463 (63/83/.90), cast S467 (67/83/.90) or billet S468 (68/87/.90)
Fleece Performance Engineering 5-inch ManTake intake with IAT and MAF sensor bungs, air filter included
S400 90-degree cast-aluminum discharge adapter
Hot-side intercooler pipe, boots and clamps
Stainless steel downpipe
VGT coolant delete plugs (16mm and 18mm included)
Oil feed line kit
Oil drain line kit
T4 turbine flange studs and gasket
OEM Cummins exhaust manifold gaskets

Price: From $2,358.83 (’07.5-’09, cast S463 turbo included)

*Piping-only kits are also available

3. BD Diesel Performance

Features:

BD T4 Race exhaust manifold with provision for wastegate
S467.7 with forged milled wheel (FMW) compressor (67.7/83/1.10)
BD-exclusive 90-degree compressor housing discharge
BD hot-side intercooler pipe
Turbine housing blanket included
5-inch cold air intake with 8-inch (od) air filter
BD composite intake tube with IAT and MAF sensor bungs
4-inch downpipe
Automatic transmission dipstick tube relocation bracket
Oil feed line kit
Oil drain line kit
All required boots, clamps, mounting bolts and studs
Exhaust manifold gaskets

Price: $2,925 (’07.5-’16, turbo included)

*Piping-only kits are also available

4. Wehrli Custom Fabrication

Features:

Optional ATS Diesel 3-piece or Steed Speed exhaust manifold (T4 flange)
Your choice of 14 different turbos, from a cast wheel S463 (63/83/.90) to a billet S475 (75/87/1.0)
5-inch intake with S&B dry filter, IAT and MAF sensor bungs
One-piece, 3-inch diameter hot-side intercooler pipe
3.5- or 4-inch downpipe (diameter depends on model year)
-6 AN stainless oil feed line and fitting
-10 AN stainless oil drain line and fittings
Coolant lines and fittings
T-bolt clamps
Silicone boots
All necessary hardware

Price: From $2,125 (’07.5-’09, cast S463 turbo included)

*Piping-only kits are also available

5. Industrial Injection

Features:

3-piece T4 flange exhaust manifold
Your choice of various S400s (S464, S467.7, S471, S475)
One-piece, 3-inch diameter hot-side intercooler pipe
Composite intake tube with IAT and MAF sensor bungs
4-inch downpipe
Grid heater drop bracket
Coolant plug kit
Automatic transmission dipstick tube relocation bracket
Oil feed line kit
Oil drain line kit
All required boots, clamps, fittings and hardware

Price: From $2,474 (’07.5-’09, S464 turbo included)

6. Maryland Performance Diesel

Features:

BD Diesel 3-piece T4 flange exhaust manifold
Your choice of S464 or S467.7
MPD hot-side intercooler pipe with crush-proof ends
Stainless steel intake tube with IAT and MAF sensor bungs, air filter
Downpipe adapter allows for reuse of factory downpipe
All required boots, clamps, gaskets, fittings and hardware
Automatic transmission dipstick tube relocation bracket

Price: From $2,799

7. G&R Diesel

Features:

3-piece T4 flange exhaust manifold
One-piece, 3-inch diameter hot-side intercooler pipe
5-inch welded aluminum intake with IAT and MAF sensor bungs, air filter
4-inch downpipe with flat V-band clamp
Braided stainless oil supply and oil drain lines
All required boots, clamps, gaskets, fittings and hardware
Billet-aluminum fitting and coolant lines for EGR coolant riser

Price: From $1,699 (’10-’12, turbo not included)

8. Deviant Race Parts

Features:

ATS Diesel 3-piece T4 flange exhaust manifold
Your choice of S464 or S467.7
5-inch powder coated intake with oiled/reusable filter, pre-molded intake boot, IAT and MAF sensor bungs
3-inch powder coated hot-side intercooler pipe
HX40 style 4-inch downpipe
Oil supply and drain lines
Exhaust manifold gaskets
Exhaust manifold bolt kit
All required boots, clamps, plugs, fittings and hardware

Price: From $2,300 (’07.5-’09, S464 included)

9. Source Automotive

Features:

3-piece T4 flange exhaust manifold standard, 1-piece stainless manifold optional
S463 turbo (63/83/.90)
6-inch mandrel bent intake with S&B filter
Custom bent hot-side intercooler pipe
S400 90-degree cast-aluminum elbow or 90-degree Nomex/silicone elbow
Custom 4-inch downpipe with stainless V-band clamp and exhaust hanger
MLS exhaust manifold gaskets
Nomex intercooler boots
Stainless steel T-bolt clamps
All required plugs, fittings, gaskets and installation hardware

Price: From $2,400 (’07.5-’12, turbo included)