When General Motors decides to build a new product, they can go all out. With their budget, vast amount of knowledge, and any resource imaginable, they can create some extraordinary things. A prime example for this theory would be the LS7. The 427 cubic-inch engine was based on the Gen-IV platform. The aluminum block sports a 4.125-inch bore with sleeved cylinders and a 4-inch stroke crankshaft made out of forged steel. Combine that with titanium connecting rods and you have one seriously tough short-block.
For the heads, GM decided to retain the two valves per cylinder rather than four that some of the other car manufactures have migrated to. The intake valves are made up of titanium and are of considerable size at 2.20-inches. The exhaust valves are sodium filled and measure in at 1.61 inches. The result of this combination puts down an impressive 505 hp at 6,300 rpm and 470 lb-ft of torque at 4,800 rpm.
As previously stated, GM did not play around when they decided to build this naturally aspirated titan. So how does one improve on a product that is already cutting edge? Leave it to the crew over at Dart Machinery to be able to pickup the slack where GM left off. Since 1981 Dart has always been know to squeeze every last bit of power out of their combinations and they can usually do this without having to create something new and exotic.
The new Dart PRO1 LS7 compatible heads are made of aluminum and have some obvious differences when compared to the OEM LS7 heads. The CNC rectangular port cylinder heads have been opened up from the factory size of 259cc to 285cc’s for better flow on the intake side. The intake valves are still 2.20 inches but the exhaust valves have been enlarged slightly from 1.61 to 1.625 inch. The biggest difference between the stock design and Dart’s, is in the combustion chamber and in the valvetrain area. The chamber has been reduced from the factory heads’ 70cc chamber down to 66cc’s on the PRO1. The rocker area is machined flat unlike the factory style cast rocker towers, and a billet bar is utilized which allows for the LS7 rockers to be reused. This billet bar actually increases the strength of the valvetrain, thus making it a much more ridged design. Dart also offers a race version of the head, which utilizes Jesel brand rocker arms in conjunction with copper intake and exhaust seats. In this version of the PRO1, the rockers are moved in .0300 of an inch closer to the valves for better rocker arm alignment. Other than these pretty significant changes, the Dart heads retain stock valve angles, stock valve location, and stock valvetrain mounting dowel holes. All of these features will make the install of the heads easy and trouble free.
If you are looking to squeeze every ounce of power out of your engine, Dart also offers a new custom intake manifold to compliment the heads. The intake manifold and cylinder heads work together as an “integrated system to produce maximum performance.” The new Dart LS intake manifold will allow for a seamless transition of airflow from the runners to the heads making sure you get the absolute most out of you combination.
While Dart has not released any dyno numbers in comparison to the stock LS7 heads, we did hear from an inside source that they are excited with the findings. We expect big things from the Dart PRO1 LS7 compatible 12-degree cylinder heads as usual and we are looking forward to a full feature on this new product soon.