here you get a bit better comparison of the two heads changes and the larger and taller SB2 ports
SB2.2 heads – NASCAR’s gift to the small Chevy
A NASCAR engine is one of the most efficient power plants in all motorsports. Next to the NHRA Pro Stock engine it’s the most technologically advanced domestic V-8. A NASCAR engine makes as much as 2.4 horsepower per cubic inch through a restricted inlet and utilizing a flat tappet cam. These engines must also endure over 500 miles of 9500 rpm torture. The mega-dollar budgets of the teams provide for a slew of well researched parts with top notch development. Just because these parts were designed to go in circles doesn’t mean they can’t be slightly modified to fit a drag racing engine. The SB2 head has seen a few different versions since its inception. I’ll discuss the latest and best version, the SB2.2. This head has had years of testing, re-design, and improvement. All of this testing done with near unlimited budgets and the most advanced equipment possible. As you can imagine… these things are pretty darn good.
Most racers are un-aware, but SB2.2 heads will bolt on a standard Chevrolet block. Yep, no need for an overpriced, custom machined piece. Heck, even a plain old stock 400 block will work. They do require several SB2.2 specific parts, but nothing exotic or beyond the normal needs of any engine. Beyond the head assemblies themselves the SB2.2’s require their own cam, rockers, valve covers, intake manifold, valley tray, pistons, and headers. Any of the parts listed are readily available through various outlets.
Let’s take a look at the specifics of the head. While conventional small block Chevrolets use a 23 degree valve angle, the SB2.2 uses an 11 degree intake valve angle and 8º exhausts. The intake valve is also canted at 4 degrees towards the bore centerline. With these angles the intake valve actually moves away from the cylinder wall during the lift cycle. This allows for a much larger valve as well as a shallower chamber. Port volumes for the SB2 are much larger than traditional small block heads. While a typical aftermarket 23* intake runner may fall in the 215-230cc range, the SB2.2’s often fall between 280-300cc. Now don’t be fooled by these numbers. The intake port may sound huge by comparison, but it is much higher and longer than a factory layout and in turn has a larger volume. When comparing heads of different design for the same engine it is more important to use the minimum cross sectional area, or the smallest area of the port. It’s very difficult to produce adequate cross sections for engines over 400†with 23* heads. Pushrod bulges and low port locations on 23* heads often become a restriction on larger engines. SB2.2’s on the other hand have high ports with offset pushrods and are capable of feeding even the biggest small blocks. The valve layout is a bit different than standard with the outside cylinders intake and exhaust valve positions being reversed. The intake ports are also spread, but not symmetrical. The overall concept of the head design was to optimize the use of a single four barrel manifold by pointing the runners toward the center of the engine. Even with this purposeful design the heads do still lend themselves worthy of a well prepared tunnel ram intake with two carbs. I’ve included a chart for a direct comparison a factory style head to the SB2.2.
The potential of the SB2.2 is overwhelming. With intake flow exceeding 400cfm these heads will support a large amount of power. It is quite common for a 440†engine with two carburetors to make in excess of 1000 horsepower using a well prepped set of SB2.2 heads. Dollars spent can also be quite reasonable when they are purchased in kit form. SB2 experienced shops such as M&M Engines in Indianapolis sell top end kits in various forms starting around $5000. A similar 23* setup would only run about $1000 less. That’s dollar per horsepower value anyway you look at it. Both boost and nitrous friendly as well, SB2.2 engines have been dyno tested at close to 3000 hp. As you can easily see these heads work!
23 degree / SB2.2
IN port volume
200-230cc / 270-310cc
Min. cross section
2-2.3†square / 2.4-3.2†square
Chamber volume
64-76cc / 34-50cc
IN valve size
2.02-2.100†/ 2.15-2.2â€
Max ave. IN flow
300-330cfm / 400-440cfm
Power potential
650-750 / 900-1050
Kit cost
$6500 / $8200
Kit includes: Complete ported heads (SB2 heads use titanium valves), shaft rockers, sheet metal valve covers, ported intake, custom pistons, rings, roller cam, roller lifters, pushrods, all bolts, all gaskets, valley tray (SB2) header flanges (SB2)
http://www.derrikecope.com/wcup/98/sb2.htm
http://www.youtube.com/watch?v=UfjYg_mj7GI
http://www.mmcompetitionengines.com/SB22%20Experts.html
http://www.hotrod.com/featuredvehicles/ ... vy_camaro/