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Chevy Small-Block - Two Timing With Turbos

Can Your Chevy Small-Block Make Over 1,000 Hp? It Can. Here's How.

Mike Harrington Aug 6, 2007

When people achieve power, they often want more. For extreme examples, think of history's many tyrants. For less extreme examples, think about hot rodders. While it's true that we hot rodders are slightly less deviant that the Napoleons of the world, we are fairly consumed with increasing our power-horsepower that is.

A little power under the hood leads to ambitions of more, much more. (Insert evil laugh here.) After the first grab and taste for horsepower, there's no choice but to become a local tyrant at the dragstrip or on the street.

For those who lust for domination, Gale Banks Engineering has taken the small-block Chevy and given it more power than any reasonable person could want. Perfect! When it comes to musclecars, are any of us horsepower junkies truly reasonable? Banks' twin turbo-powered small-block Chevys have the capability of producing up to 1,100 horses at the flywheel.

Super Chevy magazine hasn't run many turbo builds, so let's take a kindergartner's view of what a turbo system is and what it does. We all know that the more fuel and air that enters the cylinder and gets burned, the more power an engine is capable of producing. Unlike a supercharger, which derives its energy from a series of pulleys that are directly connected to the engine's crankshaft, turbos use exhaust gasses to spin their turbines. Being connected to the engine's crank means there's an amount of parasitic energy taken from the engine to power the supercharger. Why a twin turbo? Banks Engineering uses two moderate sized turbos for the express purpose of creating more boost pressure from the engine's exhaust pressure, eliminating much of the turbo lag ... and it just looks darn cool, too.

Banks Engineering has several turnkey twin turbo engines that it builds, ranging from 700 hp to 1,100 hp. We asked Banks engine builder Mauricio Lindoro what the difference was between the different turbo-powered engines and the horsepower numbers. Mauricio informed us all the engines are built to the same exacting standards; the difference lies in the valvetrain selection, i.e., cam profile, lifters, springs, etc. The rest is intercooled vs. non-intercooled, fuel octane ratings and the amount of boost that's stuffed into the engine.

Let's not fool ourselves. We all know that creating serious horsepower requires serious money. One of these Banks Engineering 6.0L (374 ci) twin turbo turnkey engines runs just shy of $40,000. That may be out of reach for a majority of us (editors included), but it still makes for amazing eye candy to see a small-block push the 1,000hp mark. Even tyrants have an eye for beauty. (Kim Jong Il's hairdo and wardrobe notwithstanding.)


Each build starts with a Dart 4-bolt main iron block. And from there the Dart block is further bored and machined to the tolerances set by the engine builders blueprint. For this application, the bore is 4.125-in. and the stroke 3.50-in.


After machining and cleaning, the Dart block is painted black or red and ready for assembly.


The freeze plugs are not just pressed in and left there. Each plug is also riveted once it's in place.


As good as the Scat crankshaft is, the cranks are also machined and mic'd according to the build sheet.


The oil galleys on the crank are also chamfered and de-burred according to spec. This enhances oil flow as it returns to the pan.


The main caps are measured and honed checking for the right size between the crank journal and block.


Once all the chamfering, de-burring and honing is done, the crank is ready for install.


Only ARP bolts are used in the build-up of this small-block.


This is a surface roughness meter. After each cylinder in the block is bored, honed and smoothed, the surface roughness meter measures the surface of each cylinder and then gives a print out of what it detects. If the numbers fall within an acceptable range, the block is good to go.


The most common way to verify that the cam is installed correctly is via the intake centerline method. At the risk of over-generalizing, we'll just say that this measures the crankshaft angle where the cam's intake lobe reaches maximum lift. Install a lifter into cylinder number one's intake lifter bore, and mount the Powerhouse Products fixture so that the dial indicator's tip touches the lifter. Every part of this fixture must be secure and tight for accuracy, and the dial indicator's stem needs to be parallel to lifter travel. Zero the dial indicator at maximum lifter travel out of its bore.


All piston rings are end gapped and de-burred, then test fit into their corresponding cylinders.


At a separate workstation, the connecting rods are also being cleaned and de-burred.


Every wrist pin is measured to fit the piston and rod.


The same measuring goes for the piston as well. Nothing on this build is left to chance and nothing is assumed no matter the quality of the said part. Banks engine builders follow the blueprint, then measure and record the numbers of each fitting.


Another tool employed by the engine builder is this rod bolt free length tool. Essentially this measures the length of the bolt before torque is applied.


After the connecting rod bolt is torqued into place, the bolt length is measured again to check how much it may have stretched. Serious engine builders like those at Banks are almost more concerned with bolt-stretch numbers than torque numbers.


Dart aluminum cylinder heads that are cast specifically for Banks Engineering with custom CNC'd combustion chambers and exhaust ports are used in every turbo engine build. The cylinder heads receive the same precise degree of measuring as everything else in the build. Every combustion chamber is measured for an accurate displacement of cubic centimeters (cc). These heads feature 2.060-inch intake valves, 1.600-inch exhaust valves and 78.8cc chambers. Compression is a boost-friendly 8.3:1.


Prior to install, each valvespring is pressure tested to make sure the right spring load is used for the right horsepower engine.


Each valve is checked and measured for travel and spring height.


A Cloyes adjustable cam sprocket is used on all the Banks engines. The really neat thing about these is the fact that they do just what they say. Setting the timing on the cam has never been easier.


The bottom half of the engine is now completely assembled and the rest of the engine build accelerates from this point on.


Before the lifters are put in the lifter bore the lifters are also measured and recorded.



After measurement, each lifter is assigned a specific location in the block.



The custom cast Dart heads are next on the blueprint, then the lifters, pushrods and rocker arms.


Banks uses an ACCEL Pro Ram polished aluminum intake that has been port matched to the heads.


Here's what the build is all about. The turbocharger and exhaust manifold are all built in-house, making quality control easy to manage. The turbo's wastegates are the only things not made at Banks.


After the turbo units are installed, the Vintage Air serpentine system, compressor, hardlines, fuel lines, etc., are installed during the next hour. In the interest of space, we won't show every photo of every part involved in this build.


The moment of truth: somewhere underneath all these wires and tubes lies the twin turbo 1,000-plus horsepower small-block. The long tubes you see coming out the front are for the intercooler. Once the engine is hooked to the dyno, Banks' techies spent a decent amount of time mapping and tuning the EFI system. Every fuel injector is examined and monitored. After breaking in the engine, the spark plugs are removed and each cylinder is examined with a microscopic camera to check the valves, pistons, etc.


Afterward, a few more break-in pulls were made while Super Chevy was there with its camera. While we didn't witness the small-block reach its peak of 1,100 hp (work continued on the EFI programming after our deadline) we did see it make 911 hp at just 5,785 rpm with 827 lb-ft of torque to match. That just might be enough speed to fill your shorts. Even though these engines may be out of reach of most budgets, they are still being built, sold and installed into Chevrolets around the globe. This particular engine is destined to make its way to Australia where a '69 Camaro is waiting for it.



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