LT1 Cylinder Head Comparison - LT1 Head Shootout!

We Test The Best Off-The-Shelf Lt1 Heads On The Market And The Results Are Quite Surprising

Justin Cesler Aug 1, 2009 0 Comment(s)
0908gmhtp_01_z Lt1_cylinder_head_comparison Project_motor 1/27

Picking a cylinder head for your latest project motor really is a tough, somewhat confusing situation. With prices ranging from hundreds to thousands of dollars, slick advertising talk skewing the facts, and little to no reliable independent testing, it is no surprise that people end up with some pretty wacky combinations.

With head technology constantly evolving and a fiercely competitive market always pushing development, it is time we sat down, built a nice short-block, and put them to the test. It is important to note that, while tempting to name a winner, each head in this particular test has its advantages and disadvantages. While peak horsepower is important, we recommend you also look at your specific goals, budget, and future modifications before picking a cylinder head. Much like life, it is important to figure out what is best for you and go from there.

The Test
For this test, we turned to our friends at Golen Engine Service in Hudson, NH, to help us build and dyno each combination. Based on what most people would build, we assembled a mild 383 LT1 capable of making good, streetable power on pump gas. With a target compression of 11:1 we had each head decked to 54-55 cc combustion chambers. Since this was going to be a street engine, Comp Cams sent us a very mild 280XFI camshaft, which features 230/236 degrees of duration, 0.576/0.570-inch lift with 1.6 ratio rocker arms on a lumpy 113 LSA. We felt that most of these heads would do quite well with this camshaft, and with a group average of 495.4 hp, we were quite impressed. All of the heads, except for the Edelbrock RPM Xtreme LT4, were tested using a hand-ported LT1 intake manifold. Chad Golen has perfected the art of the LT1 manifold and feels it offers a great upgrade to any performance LT1 build. The Edelbrock heads were tested using the excellent Air-Gap LT4 manifold, since they ship port-matched to the much larger raised-runner LT4 race port intake manifold gasket. To make all of this happen, you need a lot of gaskets and we thank Fel-Pro for coming through with five sets of head and intake manifold gaskets. Without these, we would never have been able to complete such a test. With the engine assembled and bolted to the dyno, we will let the heads do the rest of the talking.

All testing was done with 38 degrees of timing, 43.5 lbs of fuel pressure, Standard correction, and a consistent 12.5-13.0:1 air/fuel ratio. Had we chosen to adjust timing for the differences in each head, most likely we could have increased peak outputs, but would run the risk of human error. A variable we, instead, chose to keep constant.

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.

Total Engine Airflow / Trick Flow 200cc CNC LT1
These TEA-ported, TFS LT1 heads performed extremely well in our testing and offer a great value for anyone looking to make big power. Up top, these heads made 511.5 horsepower, which was the second highest out of the group. Built on a Trick Flow casting, TEA is responsible for the CNC work, which is truly second to none. Each head comes complete with 2.020- and 1.600-inch intake and exhaust valves and a set of 0.650-inch lift dual valvesprings. At a retail price of $1,799.00 it is almost impossible to choose between these and the AFR heads for all-out performance. Due to time constraints, we could not test the newest 21-degree head from TEA/TFS, but we have no doubt it would have made a ton of power.

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