Explore and find Blog
31 January, 2019
Let’s face it, the only people who don’t love boost are people who haven’t tried it. Okay, maybe the “everyone” part is a bit of an overstatement, but there is certainly no denying either the potential or popularity of boosted motors. While superchargers certainly have their place, turbos seem to be all the rage. Credit, at least in part, might go to the availability of inexpensive, off-shore turbochargers, intercoolers, and the associated plumbing. While turbos have been with us for decades, never in the history of automotive performance has boost been both so readily available and affordable. Nowhere is this more evident than in the LS market. Given the propensity, one might conclude that GM actually offered turbos on their LR4 and LM7 motors, but such was not the case. With turbochargers, intercoolers and aluminum tubing so readily available, the question now becomes, how do you get a turbo (or turbos) mounted to supply all that wonderful boost? Enter the low-buck DIY turbo kit!
Truth be told, there are a number of complete turbo kits available for a variety of factory LS (and some popular swap) applications, but the cost of these is often not what the typical junkyard dog would deem acceptable. Given the popularity of LS swaps, kits may or may not be available for your exact hybrid combination—at any price. For the low-buck crowd or those looking for an application not covered by the aftermarket, the best route is the down-and-dirty DIY route. As luck would have it, the purchase of a used LS from the wrecking yard comes with what amounts to most of the turbo kit already. That’s right, your homebrew turbo kit is sitting in the junkyard just waiting for you to pick it up with your $300 race motor! Interested? We thought so.
The key to the DIY turbo is actually in the exhaust, as the factory truck manifolds employed on most 4.8L, 5.3L, and 6.0L motors work perfectly as boost builders. They offer everything you would want in a turbo manifold, including plenty of strength (they will never wear out), excellent heat retention (originally to speed up converter light off), and plenty of flow (guys easily exceed 1,000 hp and already run 7s with them). While most complete take-out motors come with the factory manifolds, there is another little trick to inexpensively completing the homebuilt turbo kit.
While the stock cast-iron manifolds are a no-brainer for the turbo kit, what really makes the DIY system affordable is securing the short sections of exhaust connected to each manifold. The reason for this is that the short sections contain the necessary mounting flanges to facilitate completion of the Y-pipe. The Y-pipe is used to connect the two sides of the V8 together to channel the exhaust to a common exit. Flowing the exhaust from both sides maximizes the energy to the turbo, so the Y-pipe is a critical element in the kit. Many junkyards cut the catalytic converters off. Most wrecking yards use giant pinchers to make the job easier, and cut the exhaust between the converters and factory exhaust manifolds. This provides not only two of the necessary Y-pipe flanges (see photos), but also oxygen sensor fittings and sections of stainless exhaust tubing to start the Y-pipe. The only thing better than getting a cheap race motor is having them throw in most of a turbo kit along with it! Makes sure when choosing your junkyard jewel that you select one that has the sections of the exhaust with it. Search around; sometimes they are removed along with the manifolds. Nothing says you can’t add these to complete your motor.
Though major pieces, the manifolds and exhaust sections are obviously only part of the equation. Now that you have the manifolds and exhaust, it’s time to make a Y-pipe. Most LS turbo motors position the turbo in front of the motor. The actual position will be determined by the chassis and engine position, so a little mock up time will be necessary after reversing the manifolds (they need to be positioned to flow toward the front of the motor). From there, it’s just a matter of positioning the turbo of your choice and connecting the Y-pipe to mount the turbo in the proper position. For our needs, the Y-pipe simply needed to fit the cooling tower and electric water pump on the engine dyno. Your position might vary from ours to allow fitment around the accessories, radiator, and inner fender well. We used mild-steel and stainless exhaust bends were sourced from a local muffler shop. The throw-away sections of exhaust were both cheap and plentiful. Using the sections, we fabricated the Y-pipe which ended in a single 3-inch V-band clamp. Most will simply end in a T4 or T6 turbo flange, but we opted for the V-band to allow us to install any turbo we wanted on the system for future testing using simple fabricated adapters. The common T4 and T6 flanges (T3s will be too small for a single turbo application on an LS) are available from a variety of sources online; we purchased ours from CXRacing.
The final installation step includes mounting the wastegate flanges. The flange(s) are generally included with the wastegate, though it was necessary for us to weld on a small section of tubing to stand off the wastegate from the Y-pipe. The exhaust tubing exiting the turbo will be a function of the turbo chosen. Most are equipped with a V-band exit and require a matching V-band fitting and clamp, along with the appropriate size exhaust tubing. A word to the wise: turbos love a free-flowing exhaust (exiting the turbo). Don’t worry so much about the size of the Y-pipe, anything from 2.0 to 3.0 inches in diameter will work, but try to maximize the exhaust flow after the turbo! It should be pointed out that though this DIY turbo kit was done for an LS application, the same basic rules apply to any other motor in the junkyard, from a SBC to a late-model Hemi. You will need oil fittings, and pressure and return lines, but all of that is available on line. Our guys at CXRacing once again came through with oil feed and drain fittings to complete the kit. This DIY turbo kit was put to good use on a variety of different LS test motors; the most recent being a modified 6.0L equipped with TFS Gen X 225 heads, a mild cam, and Dorman LS6 intake. Combining a Borg Warner S480 from LJMS with an air-to-water intercooler from Procharger allowed us to increase the power output of our test motor from 514 hp and 465 lb-ft to 977 hp and 807 lb-ft at 12.9 psi. The DIY Turbo Kit FTW!
On The Dyno
While the power output of the naturally aspirated motor and choice of turbo have much more to do with the outcome, this test was run with our DIY turbo kit. The kit was more than capable of supporting the tested power level, as racers have combined the factory LS truck manifolds and custom Y pipe to runs deep into the 7s. The combination powers a great many turbo LS motors out there, many of which are swap vehicles. To illustrate that the cheap-date system does indeed work, we applied the DIY kit to a simple 6.0L truck motor equipped with a mild cam, TFS 225 heads, and Dorman LS6 intake. Run in naturally aspirated trim, the 6.0L produced 514 hp and 465 lb-ft of torque. After adding the DIY turbo kit with a Borg Warner S480 turbo and Procharger air-to-water intercooler, the power output jumped to 977 hp and 807 lb-ft of torque at a peak boost of just 12.9 psi. Obviously there was considerably more power to be had with higher boost levels, but the test was merely to illustrate that the DIY kit was fully functional and ready for action.