Considering about swapping that restrictive factory charger for an lb7 s400 kit is definitely usually the first big step toward producing real power with your old-school Duramax. If you've invested any time from all within the diesel forums or browsing social media groups, you've probably realized that the LB7 masses has a little bit of a love affair with the BorgWarner S400 frame. There's a good reason for that. Whilst the stock IHI turbocharger that arrived on the 2001-2004 trucks was decent for its time, it really starts to struggle as soon as you ask it to accomplish something beyond basic commuting or light dragging.
The particular LB7 is a renowned engine, mostly mainly because it doesn't have all the complex exhausts equipment that later models were saddled with. But that will stock turbo? It's a bottleneck. As soon as you start pushing for 500 or six hundred horsepower, the backpressure climbs, the exhaust system gas temperatures (EGTs) go through the particular roof, and you're basically just throwing out hot air. That's in which a solid S400 swap comes straight into play.
Precisely why move away from the stock IHI turbo?
The stock turbo upon an LB7 is usually a fixed-geometry unit. It's small, which makes it spool up quickly, but it runs out of breath incredibly fast. If you've added a tuner, maybe some larger injections, along with a lift pump, you've likely noticed that the vehicle feels great straight down low but falls flat on the face as the Rpm climb.
Installing an lb7 s400 kit adjustments the entire character of the truck. By moving to a larger T4 mount frame, you're allowing the engine to breathe. It's not just regarding the peak horsepower quantities, though those are fun to brag about. It's about efficiency. When you reduce that restrictive backpressure, your motor doesn't have to work nearly simply because hard to push exhaust out. This may lead to cooler operating temperature ranges and, in numerous cases, a much more dependable setup for long-term abuse.
What's actually within the kit?
You can't just buy a BorgWarner S400 turbo and bolt it onto your manufacturing plant manifold. It doesn't work like that will. An lb7 s400 kit is basically a conversion package that will provides all the particular hardware needed to bridge the space between your motor and the new turbo.
Most high-quality products are likely to include a T4 pedestal. This particular is the item that sits in the "valley" of the engine and provides the mounting surface for the brand-new charger. You'll furthermore get a new downpipe, since the S400 outlet is definitely different from the stock one, and a set of intercooler water lines (hot and chilly side).
Don't forget the particular small stuff, possibly. A good kit should come with the oil feed and deplete lines, gaskets, and all the shoes and clamps. A few of the more premium options also incorporate a custom consumption pipe because the particular massive inlet upon an S400-frame turbo won't even think about mating up to your stock airbox. It's a great deal of plumbing, nevertheless it's all organized on the garage floor, it begins to make sense why these kits are usually priced how they are.
Deciding on the best turbo size for the goals
This is where people usually get stuck. "S400" describes the body size, but you still have to choose the actual compressor wheel size. In case you pick something too big, your own truck will experience like a pig off the line. When you go too small, you're making power on the table.
- The S464: This could be observed as the "towing" choice. It spools up remarkably quick for a large-frame turbo. If a person still occurs LB7 for work or pulling great van, the S464 is definitely a fantastic match up. It's snappy, keeps EGTs in check, and can easily support around six hundred horsepower.
- The S467. 7: This is arguably the "sweet spot" for most Duramax owners. This offers a little more top-end punch than the 464 but doesn't sacrifice too much on the bottom end. It's a great all-arounder for a daily motorist you want to become genuinely fast.
- The S472 and larger: Now we're getting into the particular "fun" territory. In case you're building a dedicated track truck or a weekend gadget, an S472 or even S475 will shift massive amounts associated with air. You should be cautioned: you're going to encounter some turbo lag. Without the right fueling and tuning, it might feel a bit lazy until the boost hits, and then it's like a shipment train hitting you from behind.
Supporting mods a person shouldn't ignore
I've seen it happen too several times—someone spends their own whole budget on an lb7 s400 kit and after that wonders why the truck isn't carrying out like they anticipated. You need to remember that will a bigger turbo needs more fuel to spin it up.
In the event that you're still working stock injectors and also a stock CP3 pump motor, a large S400 turbo is heading to be extremely laggy. You'll most likely want at minimum 30% or 45% over injectors to really wake that will turbo up. A lift pump, like the FASS or AirDog, can also be pretty much mandatory to maintain the fuel system joyful.
After which there's the transmission. The Allison 1000 is usually a great gearbox, but it wasn't designed to handle 600+ horsepower. If you plan upon actually utilizing the energy that an S400 kit provides, you'd better have a "built" transmission upon your grocery list. Otherwise, you'll be limping the truck home the first time you decide to show off.
The installation process: Expect a few bruised knuckles
Installing an lb7 s400 kit isn't exactly an one-hour job. Because the turbo sits within the valley of the engine, you're going to be leaning more than the grille for quite a whilst. Getting the old IHI out will be half the battle—those factory bolts have been heat-cycled for twenty years and usually aren't interested in moving.
The "while you're in there" rule definitely applies here. Since you're tearing down the particular top end of the engine, it's the perfect time to check your energy rails, look intended for any weeping injector lines, and maybe even set up some high-flow consumption bridges.
One of the biggest hurdles will be often the downpipe clearance. The S400 is a very much larger physical device than the share one, so issues get tight close to the firewall. You may need to accomplish a little "massaging" of the metal to obtain everything to sit just right without rattling. It requires patience, but as soon as you hear that first whistle upon startup, the aggravation usually melts apart.
How exactly does this feel on the road?
Driving an LB7 with an S400 is a totally different experience. The particular first thing you'll notice is the particular sound. The stock turbo has a little bit of a hiss, but an S400 includes a deep, rhythmic whistle that noises like a jet engine warming up.
Whenever you roll into the throttle, there's a brief moment of calm, and then the boost gauge starts ascending. Once it hits about 15-20 PSI, the truck just will take off. Unlike the stock turbo, which usually feels like it's striving at high speeds, the S400 just keeps pulling more difficult the faster a person go. It turns the LB7 in to a highway creature.
Even regarding daily driving, it's surprisingly civil. As long as your tuner knows what they're performing, you can possess a truck that's smooth and simple to operate a vehicle in visitors, but absolutely crazy when you find an open stretch of road.
Conclusions upon the swap
At the end of the day, opting for a good lb7 s400 kit is one regarding the best methods to modernize an older Duramax. It moves system away from its "work truck" roots and straight into the realm associated with high-performance diesel territory. It's a substantial investment in both time and money, but the reliability and power gains are usually hard to argue along with.
Simply make sure you're honest with your self about your targets. If you just would like a reliable tow line rig, stick with the smaller S400. If you need to melt tires and chase timeslips, move big. Either way, you're going in order to end up with a truck that's the whole lot even more exciting than the particular day it rolled off the assembly line. Plus, there's just something irrefutably cool about taking the hood plus seeing that substantial BorgWarner charger sitting in the valley. It's a statement item that truly backs up its looks along with performance.