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Boost a Junkyard LS Engine Without Breaking the Bank

Boost on a Budget: Assembling a Turbocharged LS Engine With Holley EFI

Tommy Lee Byrd Mar 14, 2016
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We like to think that words such as "cheap" or "easy" apply to some of the things we do with our cars. When it comes to budget builds, the LS family of engines is a great platform, especially when a power-adder is thrown into the mix. Despite the low prices for a junkyard LS engine and an eBay turbocharger, making all of the pieces work in harmony is neither cheap nor easy. However, a little help from Holley EFI made this budget buildup look like a walk in the park.

The combination shown here is a 4.8-liter Vortec truck engine, which is the smallest and typically the most affordable LS-based engine available. The 4.8L truck engine has several big brothers (5.3L, 6.0L, and 6.2L) but the smaller engines tend to work well with boost. And in this case, the engine will feature a budget-friendly single 76mm turbocharger, accompanied by an air-to-water intercooler. All of this is being packed into the engine bay of a 1970 Chevy Nova owned by Kyle Shadden. He built every piece of the turbo system from scratch, aside from the stainless steel headers, which were eBay specials. And though budget has been a concern for the entire build, Kyle realizes that spending money in all the right places will yield great results. Skimping on items such as the fuel system, wiring, and electronics could make a mess of this home-built hot rod.

In this first of two installments, Kyle builds his turbo system and installs a Holley HP EFI system, including a new Holley digital dash to make it easy to swap tunes and monitor the vital signs of his boosted combination. Follow along as he works out some of the bugs and gets the car prepared to run for the first time. The initial "start-up" tune allows Kyle to crank the engine and check for leaks or any other issues before we strap it down on the dyno and pour the coals to it. Check back next time to see what it takes to tune a boosted LS engine with Holley's HP EFI system, and see what kind of numbers this junkyard LS engine puts down.

002 Junkyard Ls Engine Stainless Steel Turbo Headers 2/25

1. Kyle isn't scared of a little fabrication, but he also knows when to spend a few bucks and save a lot of time. He bought these stainless steel turbo headers on eBay—they have thick flanges and bolt on easily.

003 Junkyard Ls Engine Hot Side Piping 3/25

2. Using a series of bends, straight pieces, and a Y-pipe, Kyle built this hot-side piping out of 3-inch-diameter stainless-steel tubing. He incorporated a gusset, which doubles as a mounting flange to keep the piping from bearing a heavy load. The turbo flange is a T4, and the 38mm wastegate is another eBay item.

004 Junkyard Ls Engine 76mm Turbo 4/25

3. The boosted 4.8-liter engine is fed by a 76mm turbo, sourced from eBay. This relatively small turbo will make plenty of power, but there is plenty of room to grow, especially if he steps up to a larger T6 flange. After a few mock-ups, Kyle installs the turbo for the final time.

005 Junkyard Ls Engine Final Assembly Of Intake Manifold And Piping 5/25

4. Although Kyle mocked up the intake to fit the cold-side piping for his air-to-water intercooler, now is the time for final assembly of the intake manifold and piping.

006 Junkyard Ls Engine Oiling Rubber O Ring Gaskets And Working Them In Groove 6/25

5. The Holley Mid-Rise Intake manifold (PN 300-137) is a single-plane intake that features a 4150-style flange. Kyle starts the installation process by oiling the rubber O-ring-style gaskets and working them into the machined groove in the intake runner flange.

007 Junkyard Ls Engine Tightening Intake Bolts 7/25

6. Holley supplies the bolts that go with the intake, and suggests tightening them in a crisscross pattern, starting in the middle and working outward. Kyle set his 3/8-drive torque wrench to 50 in-lb for the first pass and then to 106 in-lb (8.8 ft-lb) for the final torque.

008 Junkyard Ls Engine Holley Efi Rail Kit Fuel Injectors 8/25

7. The Holley EFI Fuel Rail Kit (PN 534-219) is an affordable piece of the puzzle and works in conjunction with a set of Holley 83 lb/hr fuel injectors (PN 522-838). The injectors can supply up to 1,325 horsepower, which provides plenty of room for growth on Kyle's mild-mannered combination.

009 Junkyard Ls Engine Lubricating Fuel Injector O Rings 9/25

8. Kyle uses penetrating oil to lubricate the fuel injector O-rings, but it's still a pretty tight fit, so it took a little effort to seat them properly.

010 Junkyard Ls Engine Installing Fuel Rails And L Brackets For Injector And Rail Assembly 10/25

9. The fuel rails are installed next, and they also rely on an O-ring seal. After the rails are pushed down over the seals, Kyle installs the supplied L-brackets to secure the injector and rail assembly.

011 Junkyard Ls Engine Threading Fuel Lines 11/25

10. From there, the -10 AN fuel supply line and the fuel crossover line can be threaded onto the ends of the rails and tightened. Kyle uses a -8 fuel return line back to the tank. For this combination, Kyle is using dual Walbro 255 fuel pumps and an Aeromotive boost-referenced fuel pressure regulator.

012 Junkyard Ls Engine Mounted Air To Water Intercooler Behind Dash 12/25

11. In this case, Kyle has mounted an air-to-water intercooler behind his dash so the intake elbow is turned rearward. In some builds, the intake elbow can be turned toward the front or even sideways to meet up with the cold-side intake piping.

013 Junkyard Ls Engine Holley Hp Efi Ecu And Harness Kit 13/25

12. Making horsepower with a boosted LS engine is a lot simpler with a plug-and-play style system like this Holley HP EFI ECU & Harness kit (PN 550-602N). It falls under Holley's "HP" series and features a complete ECU and harness designed for a 24x tooth crank sensor.

014 Junkyard Ls Engine Wiring Harness Laid Outand Wires Plugged In Connectors 14/25

13. After Kyle laid out the wiring harness to get an idea of the system, he could start plugging in the connectors. The wires and connectors are clearly marked, so most of the steps are straightforward. The injectors are marked by cylinder (odd numbers on driver-side, even numbers on passenger-side).

015 Junkyard Ls Engine Crank Sensor And Knock Sensor 15/25

14. The crank position sensor and knock sensor are hard to access when the starter and standard exhaust manifolds are installed. Luckily, the turbo headers offer a little easier access.

016 Junkyard Ls Engine Oil Pressure Sensor And Cam Poition Sensor 16/25

15. At the back of the engine you'll find the oil pressure sensor, as well as the cam position sensor.

017 Junkyard Ls Engine Wire To Coolant Temp Sesnor 17/25

16. The coolant temperature sensor is typically located at the front of the engine on the driver-side, but Kyle relocated it to the rear of the passenger-side cylinder head. The Holley wiring harness has appropriate wire lengths to accommodate either position.

018 Junkyard Ls Engine Idle Air Control Connector And Throttle Position Sensor Connection 18/25

17. Kyle moves onto the idle air control connector and the throttle position sensor connection, both located on the throttle body.

019 Junkyard Ls Engine Pressure Sensor Wired To System 19/25

18. It's important to note that on a boosted application you must add a pressure sensor to the wastegate and add a pressure sensor to the fuel line (between the rails). These sensors are available from Holley and feature a connector that can be wired into the system to work with the Holley 557-200 boost control solenoid.

020 Junkyard Ls Engine Zr1 3 Bar Map Sensor 20/25

19. Another note is that the Holley HP EFI system is compatible with the ZR1 3-bar MAP sensor (GM PN 12592525). However, you must buy an adapter harness to connect the main harness to this particular MAP sensor.

021 Junkyard Ls Engine Ecu Mounted Inside Car 21/25

20. Kyle mounted the ECU inside the car in plain sight, but if you want to be sneaky you can hide it behind the dash. The connectors on the ECU are plugged in and the system is nearly complete!

022 Junkyard Ls Engine Hollet Three Port Boost Control Solenoids 22/25

21. Holley offers three-port boost control solenoids, and in many cases an application can require two solenoids even if you're running a single turbocharger. The boost control solenoids come with NPT fittings for vacuum lines and the necessary wiring to tie into the pressure sensors mentioned earlier.

023 Junkyard Ls Engine Holley Efi Digital Dash 23/25

22. The icing on the cake is the new Holley EFI Digital Dash (PN 553-106), which will provide Kyle with all of the engine's vital signs and offer easy tune swaps. Once the engine is tuned and he has a few combinations saved he can toggle—for example—from an economy tune for road trips to an all-out performance tune for the dragstrip without having to deal with a laptop.

024 Junkyard Ls Engine Completed Turbo System 24/25

23. As soon as the system has 12 volts, it boots up quickly and brings you to the main menu screen. The touch screen display is highly configurable, with many different options. We'll show more on how to set up this device in the next installment.

025 Junkyard Ls Engine Main Menu Screen 25/25

24. The turbo system is complete and we're anxious to strap this turbocharged 4.8-liter LS engine to the chassis dyno. The Holley HP EFI system features a start-up tune, which will allow Kyle to get the engine running and check for problems before we start dyno testing.


Bowling Green, KY 42101



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