LS2 Dyno Thrash -- Technical Article -- GM High Tech Performance Magazine

The intake ports of the Livernois...        read full caption The intake ports of the Livernois heads come in several different flavors. The Stage I heads get a complete port job with work on the intake. The Stage II heads get a 220cc intake runner to help promote better breathing with a larger camshaft, stroker kit, or power adder.

Like the intake side, the...        read full caption Like the intake side, the exhaust ports are fully ported to enhance airflow through the head. Bowl-blended and ready-to-go, the stock head offers up a great value when worked up right and assembled with good parts.

Nevin Saum is the man in charge...        read full caption Nevin Saum is the man in charge of the CNC machine at Livernois Motorsports. A computer numerical control port job is an exact copy of a hand-ported head. Here, Nevin showed us the actual CNC-port model that will be cut into the heads on the company's five-axis machine.

The CNC bits and machining...        read full caption The CNC bits and machining fluid fly at Livernois as Nevin commands the machine to go to work. In a few hours, out pops a perfectly ported LS2 head ready for assembly and installation on an awaiting hot rod.

By this time, Dominic had...        read full caption By this time, Dominic had no problem taking the LS2 apart and putting it back together. We bet him he couldn't do it blindfolded, but he refused. The head swap went quickly with the good access that you have to work on the engine.

Head Games
Without question, the LS2 responds very nicely to a high performance camshaft. With that data firmly in our pocket, we got to work examining the different cylinder head options an LS2 owner has. The stock heads are obviously working well on the production engine, but head porting is one proven method to extract more horsepower/torque through better airflow velocity and volume. Livernois Motorsports employs several master head porters, and their computer numerical control (CNC) porting is a state-of-the-art duplication of their designs. In addition, once you start playing with camshafts, other pieces of the engine (most notably the valve springs) need to be upgraded to deal with increased lift.

Like their camshaft selection, Livernois Motorsports offers their clients different stages of port work (please see the flow chart for specific air flow capabilities). Their Stage I CNC-ported LS2 head starts as a new GM casting, which is treated to a full port job on the in-house five-axis CNC machine. That port work includes porting and smoothing of the intake port, exhaust port, and bowl area. The head comes with 2.000-inch intake and 1.550-inch exhaust valves, and you get custom single-coil valvesprings that are good for up to a .580-inch lift camshaft. Fully assembled, they are ready to install for only $949. If you are going to use this head with a camshaft that has .610- to .620-inch lift, Dan recommends using the upgraded valvesprings from COMP Cams (COMP 918). That upgrade bumps the price of the ported head to a very reasonable $1,049. Milling is also available if you are looking for an increase in compression ratio.

If you are going to run an LS2 with a power adder, larger cubic inches, or a high-lift camshaft, Livernois Motorsports recommends their Stage II CNC-ported LS2 cylinder head. This head receives the same port work as the Stage I head with the addition of a larger, 220cc intake runner and larger (2.02-inch) intake valves to handle the increased demand for airflow. With the Livernois single-coil valvesprings, the Stage II heads cost $1,199 for a full-assembled set. The COMP 918 valvesprings upgrade bumps that to $1,299. Or, for $1,499, you can get the Stage II ported LS2 heads with Manley 221426 dual-coil valvesprings for camshafts of up to .670-inch lift and Manley 23623 titanium retainers.

For this test, we wanted to look at what the Stage I CNC-ported head had to offer the LS2 enthusiast. This is a dynamite cylinder head choice if you want to run a smaller camshaft (less than .580-inch lift) for a combination that will deliver a 100 horsepower gain. In test cars, Dan reports no chugging or "trailer hitching" on the street in sixth gear and generally great drivability. We got a ride in a C6 Corvette outfitted with the smaller cam and these heads, and we can attest to their voracious performance and surprising civility at anything other than aggressive driving.

On the dyno, the Stage I CNC-ported heads helped our LS2 pump out 520.3 hp at 6,300 rpm and 467.7 lb-ft at 5,100 rpm. The Stage I heads gave us a solid 10- to 20-lb-ft increase in torque across the rpm range with the real meat of the engine digging in well before the peak. A nice flat torque curve that wants to steamroll you past 7,000 rpm--we like it!

The Livernois Stage II CNC-ported head matches up nicely with the aftermarket aluminum pieces, so we'll save that data (and a larger camshaft) for Part II of this study. Dan reports similar streetability to the Stage I ported heads, but with the typically larger camshaft that comes with more port work and larger runners, you will lose some road manners. Still, you're not talking about a car that you won't want to drive.

Our date with the LS2 on the dyno was an impressive one. First, we learned that the LS2 makes gobs of power in stock form. Its use as a cross-platform power plant assures us that GM is behind this engine family for the foreseeable future. Second, traditional hotrod modifications, namely a more aggressive camshaft, ported stock heads, and a sensible tune, can lead to a very quick and affordable additional 100 horsepower and impressive torque gains. And, lastly, we can't wait to combine the Livernois Stage II camshaft with some aftermarket aluminum heads. We'll be back with Part II of this story to see just how far an LS2 can take us.

So much of the time for this...        read full caption So much of the time for this story was spent watching Dominic work that we thought we should run another photo of him thrashing. With air tools, easy access to the engine, and lots of practice, this guy was "top fuel" fast. Thanks, Dom!	We were slightly surprised...        read full caption We were slightly surprised that Dan's Stage I and Stage II CNC-ported heads don't come with some work to the combustion chamber, but he flatly stated that the LS2 head doesn't need it for the typical customer looking to pick up an extra 100 or so horsepower. However, for those LS2 owners who just have to go that extra mile (or extra couple hundred horsepower in this case), Livernois does offer a larger 71cc combustion chamber. This will effectively knock the static compression ratio down to 9.5 to 9.7:1 depending on the application and other variables such as the thickness of head gaskets used. That's more than a full point off of the stock compression ratio, which is ideal when you are employing a power adder like a supercharger or turbocharger. For you serious LS2 owners out there, you may want to look into this option from Livernois.	We got just what we were looking...        read full caption We got just what we were looking for with the Stage-I CNC-ported Livernois LS2 cylinder heads. They topped out at 520.3 hp at 6,300 rpm and an impressive 467.7 lb-ft at 5,100 rpm. While the peak numbers are impressive--a solid 20 hp and 18 lb-ft gain-the area under the curve is what really stands out. A little cam, some ported heads, and you've got yourself one nasty, small-block GM.
While most LS2/LS6 heads don't...        read full caption While most LS2/LS6 heads don't need combustion chamber port work, once you've gone to a power adder that increases the chance of detonation, this is an excellent modification. It will effectively decrease the compression ratio, keep pre-ignition down, and allow for a ludicrous amount of power from an LS2 that is under boost. Hmmm, sounds like a good dyno story!