AFR 195cc CNC Street
With a strong reputation for building killer cylinder heads, we had some high expectations for the AFR 195cc CNC Street heads, and as usual, AFR did not disappoint. For this particular test, Tony Mamo of AFR sent us the least expensive head offered by AFR for this application, which he believes offers the best bang-for-the-buck. These heads, called the 195cc Street, feature a very nice CNC job and a 23-degree valve angle. They ship from AFR with lightweight 8mm 2.050-inch intake valves and 1.600-inch exhaust valves and flow an amazing amount of air for such an affordable unit. With a retail price of $1,849.00 these AFR heads offer excellent value. On the dyno, AFR sealed the deal, taking home the honors of both highest horsepower and torque. It would be very interesting to see what the "Competition" CNC heads would do as they outflow and outperform the "Street" castings on the bench.
Dart PRO1 200cc LT1
As the only "as cast" head in the shootout, the Dart 200cc cylinder heads really did quite well. Featuring 200cc intake ports and 54cc combustion chambers, 2.020- and 1.600-inch intake and exhaust valves, these bring all the good stuff to the table. Since Dart Machinery uses "wet flow technology" to develop these heads, they have some very nice back-cut valves that help promote fuel suspension in the combustion chamber. All of this helped them make good power, especially considering that absolutely no CNC work has been done to these heads. Retailing for $875 each ($1,750 total), they offer a good value but would need some extra work to make big horsepower. We believe that these heads in a CNC version would have been highly competitive, but we are still very impressed by the "as cast" offerings. These are perfect for someone looking to get a nice casting and go from there.
Edelbrock RPM Xtreme 195cc CNC LT4
The Edelbrock LT4 CNC heads were the only heads in the group that feature a hybrid CNC/cast intake and exhaust port. Both the intake and exhaust are CNC-blended, a process where Edelbrock cuts the ports to match the very large LT4 race port gasket intake side and a large header on the exhaust. While this is great for someone wanting to hand port and smooth these heads, it does leave a little power on the table in stock form. Of course, without doing a full CNC program, Edelbrock can offer these at a very reasonable $1,029.50 for the pair. For that price, we feel this is an excellent starting point for someone looking to put in a little elbow grease and make some big power. With 2.020-inch intake valves and 1.570-inch exhaust valves, they are a little smaller than some others in the group but still performed quite well. It is important to note that the combustion chamber is completely CNC'd and looks great. As a package with the excellent Edelbrock RPM Air-Gap LT4 intake manifold, we feel that this represents a great bargain buy for someone building a high-400 to low-500 horsepower street motor.
Golen Engine Service CNC 185cc LT1
As a stock casting, 185cc LT1 head, the Golen CNCs really didn't sound like they would stack up to the stiff competition. Fortunately for the crew at Golen, these heads feature a great CNC port job by Competition CNC of Bethlehem, CT, and fell right in line with the group average, making 493 horsepower and 476 lb-ft of torque. Starting with a brand-new LT1 casting, these heads ship with Manley 2.02/1.60-inch valves, 54cc combustion chambers, and 185cc runners. Obviously, the CNC port work is excellent, which allows the stock casting to really shine. Even more impressive is the fact that this is only a 185cc intake runner, much smaller than some of the other 200cc entries. For a sneaky racer or someone looking to port a set of existing stock castings, these would be a great choice.