The easiest way to swap the heads and cam is to yank the motor. A head swap is easy in the
It took less than 30 seconds for the performance industry to respond to the power potential of the new generation of LS engines with a raft of cylinder heads, camshafts, and intake manifolds. Among the companies that offer parts, Trick Flow Specialties (TFS) has come up with a package called the GenX Top-End Engine Kit that includes a pair of complete CNC-ported cylinder heads, a matching hydraulic roller camshaft, pushrods, head bolts, and even head and exhaust gaskets that make the swap a bolt-on affair. TFS offers three different levels for the typical 346ci LS1 engine rated at 485, 500, and 515 hp. Because this is Car Craft, we chose a slightly different route, using TFS Fast As Cast heads with the second-biggest cam.
Our volunteer victim for this quick horsepower upgrade was none other than the '04 GTO LS1 engine that has been quietly hiding in Editor Glad's '64 El Camino. He yanked the motor and, along with a pile of shiny new parts, dropped it in the back of our little blue Project S-10 pickup for the trip out to Westech's SuperFlow engine dyno/polygraph room. The LS1 made an impressive 414 hp on the baseline run, but it was the near-500 hp we made with just a swap of cam and heads that made the biggest impression. And we made all this power on pump gas.
Here's our LS1 motor ready for the dyno with the TFS GenX system parts arrayed on the tail
The phrase LS engine has been overused to the point that it has become almost meaningless. But in our case, our test victim truly is an LS1 that was originally destined for use in an '04 GTO before a detour found it in Editor Glad's green-hued El Guapo ("How To Swap a Gen III into a '64-'72 A-Body" May '08). Glad's only change to the engine was to add a Street & Performance oil pan to clear the engine crossmember. For the purposes of our test, we yanked the EFI manifold, replacing it with a carburetor mainly to make the test easier and minimize the electronic hassles. The factory rates this 10.2:1-compression, 346ci engine at 345 hp at 5,200 and 345 lb-ft at 4,800. With a 3.89-inch bore and a 3.62-inch stroke, it is considered a small-bore engine. Despite the small bore, it is capable of some impressive power numbers. The easiest way to make power is to add cam timing, since the stock LS1 cams measure in at 198 degrees at 0.050-inch tappet lift with around 0.475 inch of valve lift. As you'll see, with the addition of just an Edelbrock intake, a Holley 750-cfm carb, and a set of headers, even a stock LS1 is capable of more than 400 hp.
The TFS GenX Top-End Kit
The simple elegance of the TFS kit is that the company has done the work of dyno-matching the components for you with three different horsepower levels based on cam timing and cylinder heads. The kits range in horsepower ratings from 485 to 515. In our case, we used a pair of TFS Fast As Cast 220cc intake port cathedral-port heads to save a little money compared with the CNC-ported heads. These heads offer a valve size small enough to not interfere with the LS1's rather small bore size, yet the intake ports will flow 300 cfm at 0.600-inch lift. Combine the high-velocity intake port flow with a camshaft that's 30 degrees longer in duration, and you have the makings of a pretty solid performance package. The cylinder heads come with a 13.5-degree valve angle, which is even more vertical than the 15-degree production heads. And they are equipped with dual valvesprings that are installed with 150 pounds of seat load and 438 pounds of open pressure and can handle up to 0.600-inch valve lift. Combine that with a set of titanium retainers that help keep the weight down, and we have all we need to make some serious power. With the dual valvesprings' larger upper diameter, TFS also had to include a set of Harland Sharp 1.7:1 roller rockers with the kit because the OE rockers will not clear the bigger springs.