How to Build a Chevy Turbo Motorby Richard Rowe
Introduced in 1955, Chevrolet's seminal small-block engine has powered everything from street cruisers to land speed bruisers. This design has long been known for its versatility and ability to withstand huge amounts of horsepower, especially when built using a high-strength aftermarket block. In the late 1980s, history hit technology square in the face when hot rodders began adding turbochargers and electronic fuel injection to Chevrolet's stalwart old block. With modern turbo engineering and the vast array of aftermarket parts available for this engine, even the average builder can bolt together a 1000+ horsepower combination for the street or strip.
Assembling the Engine
Start with a high-strength engine block. There isn't a chance that the stock Chevrolet block will handle the kind of horsepower the turbos are capable of making, so you'll need to start out with a high-strength aftermarket unit from Dart, Merlin, Bowtie or any other you prefer. Make sure to specify one pre-clearanced for a stroker crankshaft.
Install a forged billet steel stroker crankshaft with 3.75 inch arms for 383 to 400 cubic inches (depending on the bore size of the block you've specified). Eagle, Crower and Kellogg all sell such cranks. Install a set of matching forged H-beam connecting rods (available from any number of manufacturers, including Crower and Oliver) and utilize a set of no higher than 8.5:1 forged pistons for pump-gas compatibility when cruising. Use a set of 1/16, 1/16 and 3/16 inch piston rings for best sealing.
Utilize a set of aluminum cylinder heads flowing a minimum of 300 to 330 cfm on the intake side, preferably with high angle 18 degree ports, 2.18 inch intake valves and at least 1.6 inch exhaust. Consider a set of titanium or sodium-filled valves. Install a full race-spec shaft-style valvetrain, utilizing roller-tipped rockers and high-strength 5/16 inch pushrods.
Install a camshaft measuring at least 230 degrees intake duration with a 115 degree lobe separation and over 0.50 inches of lift, and install the matching valvesprings and retainers onto your heads. Crower, Crane and Indy all sell such cams.
Install a fabricated sheetmetal intake manifold. You can use the manifold supplied by your fuel injection manufacturer (be it Holley, Accel, Edelbrock or any other), but you'll need a custom manifold if you use the 18 degree heads. Install the fuel injection system, computer (if engine mounted), distributor and control box suggested by or provided by your fuel injection system manufacturer.
Install an electric water pump (like those made by Meziere, Proform and Moroso) and whatever ancillaries (like the belt drive, alternator and starter) and custom touches (like valve covers and engine covers) you wish to use. Install an endurance racing-spec oil pump set to deliver about 60 psi, and install whatever oil pan fits your application.
Install the turbochargers (a set of Precision Turbo GT4067S units will work, or you can use the equivalent from Garret, Banks or Vortech) and all associated plumbing and oiling system provisions. These provisions will vary by application, but will include at least a set of oil pressure feed lines, reservoir tanks and drain lines. You'll need to wait to connect the turbocharger's pressure outlet to the engine if using a front-mount intercooler.
- This basic combination should produce about 1,200 horsepower on racing gas, and around 900 on 93 octane. When building an engine from all new parts, remember to check your clearances twice before installing anything, and always use a chrome-moly based assembly lube on friction surfaces like bearings and rocker arms. Standard motor oil will drip out of the bearing before you get it running, resulting in potential damage and premature wear to your all-new stuff.
Items you will need
- All required engine parts
- Full set of ratchets, sockets and wrenches
- Torque wrench
- Screwdrivers and pliers
- Dial calipers and measuring equipment
- Piston ring file
- Assembly lube
- 20W-40 racing oil
- Oil pump primer
- chrome engine image by Thomas Czeizinger from Fotolia.com