posted on June 15, 2014 14:01
Building the Ultimate Turbo Small Block Chevy-Part 1
The Small Block Chevy is a dead outdated hunk of iron that is best left to old guys puttering around restoring muscle cars in their garages, or is it?
The venerable Small Block Chevy was first introduced to the motoring public in 1954 and was installed on the assembly line until 2003 and is still in production as a replacement motor. This means that the good old small block has been around for 60 years, making it one of the longest lived and most produced engines of all time with over 100,000,000 units having been built to date.
The longevity of the Small Block speaks volumes to the genius of the original design. With a lightweight for the time 90 degree, thin walled, short skirt block and overhead valves, the Small Block was exceedingly compact and could pack a lot of displacement and power into a compact lightweight package. By being produced in such huge numbers for such a long time the Small Block also enjoyed what is perhaps the largest aftermarket following of any engine ever made by several orders of magnitude.
The Small Block Chevy was updated and modernized many times during its long life cycle but by the new millennium it had become painfully apparent the the old war horse was getting long in the tooth. Its single cam in block overhead valvetrain and iron construction became a symbol of how out of touch the domestic carmakers were with modern technology as the Japanese then European manufacturers pumped out lightweight alloy DOHC multivalve motors by the bushel.
GM responded with the all alloy world class LS series of V8 engines and those of us on the cutting edge forgot all about the Small Block. Until recently.
When looking to do an engine for Darren McNamara's Formula D S14, Team Falken was looking to do something new. As the professional drift world has become more competitive, more and more power has been needed to keep up with the pace of competition. Long gone are the days when a 200 hp AE86 Corolla could win a drift event.
At first a 450 hp Nissan SR20DE was considered to be a big power motor, then as suspension and tire technology evolved, 550 hp then 650 became necessary. At this point the Chevy LS motor in naturally aspirated form started to become the dominant engine. With little stress, a big LS could reliably last an entire season and engine problems disappeared.
All looked relatively stable in the engine world until a Japanese guy by the name of Daigo Saito came on the scene. With a turbocharged and nitrous injected 2JZ engine packing an unheard of maximum of 1300 hp, Daigo shredded the FD field in his rookie year. Thus the power wars were triggered with 850 to 1000 hp becoming the new norm.
When looking for a way to develop 1000 hp reliably, the Falken team looked towards turbocharging a V8 engine. It would potentially be less stressful to run low boost through a big V8 instead of trying to develop super high compression and high revving motors to respond to Formula D's current power demands. In addition, turbocharging made it easy to get more power in case future developments in tire and suspension technology dictated the need for more power.
When looking for a base engine to turbocharge, at first the Chevy LS engine was considered with its modern all alloy construction but with its 4 bolt per cylinder design, cylinder head sealing at more than 10 psi of boost was an issue, Racing versions of the LS can be had with 5 bolts per cylinder for better seal but those engines were prohibitively expensive. That being said, attention was focused on the latest developments in the Small Block Chevy racing world and after looking at stuff developed for Sprint Car and NASCAR racing, it was discovered that the Small Block could potentially be smaller, lighter and just as powerful as the LS.
Falken had lots of Small Block Sprint Car engine parts in inventory from older cars so the decision was made to build a turbo motor from some of these parts. Is the Small Block old and outdated? Not at all, let us show you how the modern Small Block racing engine is not what it was in 1954!
Team Falken's turbo wonder engine starts with not your junkyard old Small Block pulled from a wrecked Camaro, but this totally modern racing block constructed from Aluminum by Dart Manufacturing. Even though it was made of cast iron and had 5 bolts per cylinder, the old Small Block would flex and be stressed out with the power levels a modern drift car needs. The Dart block has a thick deck for good head gasket sealing and a lot of beef around the main webs to help support the crank. Thin iron liners can be bored, in this case to a larger 4.166" which is a little marginal for a turbo engine due to gasket sealing in between cylinders but use of existing parts in the Team Falken inventory was a priority and low boost was anticipated. An interesting feature is the thick plate bridging the lifter valley. This bolts to thick buttresses and serves to stiffen the block. In Sprint Cars and in the Falken S14 the engine is a stressed member of the chassis so block stiffness is important. Stiff blocks also distort less in the cylinders and crack bores while making more power. The Dart block is lightweight and strong.
Flipping the block over reveals the thick and strong pan rails and main caps. The Dart block uses stiff billet steel main caps bolted in 4 places to the block vs the stock cast iron caps attached which are only attached with 2 bolts. The stiff pan rails are due to the oil pan being part of the block structure for additional strength, more on that later. If the background looks familiar, it's because we're in the MotoIQ HQ building and Technosquare's Howard Watanabe is serving the engine's builder.
The Dart block has some more modern features when seen from the front. The cam spins in roller bearings on non standard 50mm journals. The roller bearings need less oil and have much lower friction. This is important due to the loads that a modern aggressive high lift roller cam can place on the bearings due to the high seat pressures required. The cam is also higher in the block than your old Chevy to accommodate stroke lengths up to 4 inches. In our case we are running a 3.8 inch stroke for a total displacement of 413 cubic inches or 6.77 liters. In older motors, the crank would hit the cam or a special reduced base circle cam could be ground for more clearance. Of course this would be less than desirable for valvetrain stability. Raising the cam higher in the block fixes the issue of cam/crank interference.
Since racing engines actually "breathe", they tend to flex and distort under high stress and in race engines it is not uncommon to run really high coolant pressures of over 25 psi. As a result our block uses super heavy duty screw in freeze plugs. Your traditional stamped steel press in plugs tend to fall out under racing conditions which is no bueno but they sure won't on this engine!