Many uber-street-performance enthusiasts—aka street racers—still profess loyalty to the Chevy’s classic Gen I small-block. But making more than 900 horsepower without boost or squeeze—a power number often achieved with naturally aspirated LS engines—has always been an expensive and often challenging task for that beloved architecture. However, a new engine series from Scott Shafiroff Racing Engines using Chevy’s high-flowing SB2.2 cylinder head is giving the Gen I faithful a strong threat to not only the newer GM engine families but any other opposition.
Small-block guys didn’t want to go to a big-block. They just wanted a faster small-block.–Scott Shafiroff, engine builder
Shafiroff reached out to the SB2.2 head because he was running out of options for the Gen I platform.
“For the 23-degree crowd, we’ve stretched it to the edge. Mid to high 700 is where those engines are comfortable and still affordable,” explains Shafiroff. “Then we dabbled with 15-degree, 18-degree and even some 13-degree motors. That just added expense to the engine; yet, it barely got in the low 800s. We were looking for a better mousetrap.”
Shafiroff knew of SB2.2-based motors making over 1,100 horseower but they were all-out powerplants with near unlimited budgets.
“We took that concept to build a reliable and affordable engine that would make 900 horsepower,” says Shafiroff.
The 440ci displacement was favored to take advantage of the breathing capacity of the SB2.2 heads.
“Also, I like the sound of 440,” says Shafiroff, noting the bore is 4.185-inch and the stroke is 4.000-inch.
The foundation is a Dart Iron Eagle block machined to accept the SB2 lifter pattern and a 55mm camshaft.
“Mechanically, I wanted to make sure it was as sound as it could be,” says Shafiroff. “We kept the cam fairly mild because I wanted to use stainless-steel valves.”
The rotating assembly for this engine in they dyno video above comprises a Manley 4340 steel crankshaft, Callies I-beam connecting rods and Diamond flat-top pistons that provide a 15:1 compression ratio.
Shafiroff called on M&M Competition Engines to develop a cylinder head/cast intake manifold package. Although the valves are steel, Shafiroff called for a 5/16-inch stem to help reduce the weight while still being cost effective. Rocker arms are from Jesel. Since the SB2 head was designed as a single 4-barrel engine to compete in NASCAR, Shafiroff retained that arrangement.
“It’s all a package. The head doesn’t work without the manifold,” says Shafiroff, adding that the market also leans heavily towards a cast 4V intake. “M&M worked with runner lengths and angles. That’s the key to the puzzle. It’s even sprayable. I’m not saying you run three kits on it. But you could put a kit or two and it would still be happy.”
As shown in the dyno video, the engine pulled 920 horsepower.
“We can go more if the customer wants titanium valves,” says Shafiroff. “We can get more aggressive with the camshaft. These engine can make close to a 1,000 horsepower. It’s not a torque monster but it made 660 lb-ft around 6,500 rpm. Peak horsepower was right at 7,900 rpm.”
Shafiroff says that while fuel injection could be adapted to the intake, top power numbers would unlikely be affected.
“The secret is in the manifold design,” he stresses. “With EFI you change a lot of the parameters. I wouldn’t expect it to make any more power.”
Shafiroff tried an 1,150 cfm and 1,250 cfm carburetor during testing, both delivering about the same horsepower.
“The choice would depend on the car, transmission and torque converter,” says Shafiroff, noting that the SB2.2 package will start under $20,000 with slightly different equipment but upgrades are always available. Also, the engine does not come with a carb or ignition system. “A race cam would add another $1,300 or $1,400. And we’re saving $3,000 by not going with a timing belt and titanium valves.”
For the future, Shafiroff is developing a street version with the SB2.2 head and a hydraulic roller camshaft. This plan calls for 12.5:1 compression to run on E85 while an 11:1 version is possible to run with 93 octane pump gas.
“I’m sure that would still make 825 horsepower,” adds Shafiroff. “On E85 I would expect it to make 850 horsepower.”
So, for small-block fans there is still plenty of potential in the classic Gen I platform.
“Everybody gets to a certain point they need to go faster,” sums up Shafiroff. “Small-block guys didn’t want to go to a big-block. They just wanted a faster small-block.”