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

Pt. I: Baseline, Stage I and II Cams, Stage I Heads

Dr Jamie Meyer Apr 1, 2006 0 Comment(s)

Step By Step

0604htp_01_ls2_dyno_test_z 1/20

0604htp_02_dyno_throttle_z 2/20

An engine stuck in a closet with all sorts of wires and tubes running to it is so "Frankenstein." Dan Millen let us run wild in his Livernois Motorsports super shop (Dearborn, Michigan) for a compete dissection of GM's hot, new LS2. Here, Millen mans the throttle stick on his Super Flow engine dynamometer. Our goal was to baseline the LS2, pop in a couple of camshafts, and start studying how bigger heads work on this small-block.

0604htp_04_ls2_basline_graph_z 3/20

In base tune, the LS2 is truly a supercar's engine. The 364 cubes (6.0 liters) are topped with the C5 Z06's cylinder heads and camshaft, while a 4.00-inch bore and 3.622-inch stroke try to suck the Earth of all its atmosphere. Our test engine popped out 402.1 hp at 5,300 rpm and a real stout 437 lb-ft of torque at 4,300 rpm.

0604htp_05_camshaft_and_cylinder_heads_z 4/20

Livernois Motorsports has a complete lineup of LS2-specific camshafts that promote airflow through those potent LS6 cylinder heads. Dan's strategy is to keep streetability and good road manners in mind when designing a camshaft. If that means losing 10 to 15 hp so that your Corvette/GTO will drive like a stocker down low, so be it. On the other hand, Dan has a whole notebook full of evil camshafts for the LS2 if you want to be the first to the finish line--street etiquette be damned. Our testing began with the Stage I and Stage II camshafts from Livernois, both offering more duration and lift than the stock stick.

0604htp_06_ls2_camshaft_z 5/20

Our LS2 modifications began with what we felt would return the biggest gains for the least effort. Both the Stage I and Stage II Livernois LS2 camshafts were installed in the short-block by Dominic Gabriel while the engine sat on the dyno.

0604htp_08_cylinder_heads_power_graph_z 6/20

"Wow" was the first word out of our mouths when the numbers came in from the Stage I camshaft swap. Talk about waking a sleeping giant! The mighty LS2 roared to life with a healthy 494.4 hp at 6,400 rpm and 450 lb-ft at 5,200 rpm. That's a quick 90hp pop with just the cam!

0604htp_10_power_graph_z 7/20

With such a promising start, we couldn't wait to see what just a little bit more cam would do for us. The Stage II Livernois cam tops the .600-inch lift level and offers even more duration. It bumped output to 500.2 hp at 6,400 rpm and 449.8 lb-ft at 5,000 rpm. Check out that power graph--the stock cam starts running out of air at 5,000 rpm, but the Livernois Stage II camshaft keeps the party rockin' well past 6,500 rpm!

0604htp_11_ported_cylinder_heads_z 8/20

Next on our menu of LS2 speed parts was to experiment with a ported version of the stock LS2/LS6 cylinder heads (243 castings). Livernois Motorsports offers up several versions of the LS2 head with substantial port work and completely assembled for around $1,000. Affordable and packed with power, we were really looking forward to what these could offer us with a bigger camshaft.

The LS2 is an outstanding continuation of GM's high-tech, pushrod small-block V-8s. It offers the superior architecture of the LS family of engines, free-breathing heads right off of the LS6 Corvette, the hotter Z06-spec camshaft, and a bump to 364 cubic inches. Delivered from the factory in the base C6 Corvette, SSR, GTO, or as a crate engine from GM Performance Parts, the LS2 delivers an honest 400 hp and 400 lb-ft of torque. What a slice of American pie!

What's more impressive is that even with all of that technology built into a production engine, the aftermarket is already working on ways to make the LS2 an even hotter offering. Borrowing from research and development work performed on the LS1 and LS6, LS2 parts are exploding onto the scene. Almost immediately, performance companies have been playing with porting the stock heads, using aftermarket aluminum heads, designing bigger camshafts, and/or installing stroker kits. With so many parts already available for the LS2, we wanted to find out just how potent these parts could be on an engine that's already making well over 1 hp per cube.

As luck would have it, our good friend, Dan Millen, was wondering the same things. The only difference between Dan and us is that he owns Livernois Motorsports in Dearborn Heights, Michigan, one of the most capable speed shops in the country. Livernois Motorsports consists of a massive 36,000 sq-ft shop with an engine dyno, two chassis dynos, over 30 employees, stocked speed parts from most major speed part companies, a race engine department, and a full installation center that specializes in complete vehicle construction. In addition, Millen's shop is heavily tied into the auto manufacturers as he's done prototype engine work for several different engineering teams located deep within the Big Three. Well-equipped, professionally staffed, and eager to learn--Livernois Motorsports was the place to start our LS2 journey.

So, off to Dearborn Heights, Michigan, we went, ready to help our readers and ourselves understand the true potential of GM's amazing new LS2 engine. Dan presented us with an interesting opportunity--tag along and observe as his army of professionals flog the dog snot out of an LS2 while testing several Livernois Motorsports components as well as other parts from the aftermarket. Our goal for this Part I technical feature was to baseline our test LS2, look at some camshaft options, and then experiment with a set of ported stock LS2 cylinder heads. For Part II, we'll be back at Livernois to size up what a good, aftermarket aluminum cylinder head can do for your LS2 project. We are also going to bring you a feature on the Livernois LS2 stroker kit--but let's stick to the top end components for now.

Baseline
Our test engine was a complete, Corvette-spec LS2 with one exception--an iron 6.0-liter truck block. Livernois had transferred all of the Corvette components into an iron block in an attempt to gain increased consistency with repeated engine pulls. Apparently, the stock aluminum block won't hold heat as well as the older-style iron block. So, for scientific reasons, the iron block got the nod. For those thermal expansion experts in the audience, feel free to calculate in a +/-.5hp difference one way or the other.

With the LS2 bolted into the engine stand and all other systems ready to go, the baseline pulls were made. No surprise--the LS2 is a monster in small-block clothes. A whopping 402.1 hp at 5,300 rpm banged out for peak hp. There was already 330 hp available at 4,000 rpm--or in that transition area where you go from trucking around town to stomping the competition in the next lane. One of the first observations you make when you drive an LS2-equipped musclecar is that it sure doesn't feel like "just a small-block." The GM engineers have packed a ton of torque into this thing, and on our baseline engine dyno runs, the LS2 kicked out over 400 lb-ft from 3,000 rpm on up. It peaked at a ridiculous 437 lb-ft at 4,300 rpm, but the real story is that the torque starts early and just doesn't stop coming on. The torque curve is flat, juicy, and willing to please.One important note--we used the factory GM calibration for this baseline test. Dan points out that that is important because the factory spark tables are based on airflow. As such, the stock computer tends to pull timing (stock GM timing for this engine runs right at 28 to 29 degrees) when it senses an increase in intake air or decreased backpressure with a better exhaust. (This also tells us that bolt-on exhaust and cold-air kits will need a companion tune to maximize horsepower.) Because of this, Dan estimates another 10 to 15 hp could be left on the table with the stock LS2 because there was timing getting pulled during our test runs. Still, you've got all of the factory-advertised horsepower and then some! With that promising start, we got on our way to looking at what simple, basic hotrod modifications will do for the new standard in Corvette horsepower.

Camshaft Time
Livernois actually offers up three different camshafts that they recommend for various applications. Of course, custom-designed cams are readily available from Livernois as well, but Dan has had good luck with his Stage I-III camshafts for the typical LS2 customer. The stock cam and Livernois cam dimensions look like this:

Stock: 204/211 @ .050 .525 lift (116 lobe separation angle)
Stage I: 218/220 @ .050 .570 lift (114 lobe separation angle)
Stage II: 232/236 @ .050 .600 lift (114 lobe separation angle)
Stage III: 242/248 @ .050 .620 lift (114 lobe separation angle)

As delivered (and tested in this story), the cams are based on a 114-degree lobe separation. For most nitrous or forced induction applications, Livernois recommends the same camshaft dimensions but with a 110-degree lobe separation, which will knock down some cylinder pressure due to less overlap. Dan explained the differences for us:

"The overall peak number might be real similar in both cams. From 2,000 to 4,500 rpm, you might see 10 to 15 ft-lbs better on a 110 to 112 lobe separation vs. 114. You'd see that increase in torque for that whole area under the curve until you reach the 5,000-rpm range. Then, the curves might be line for line. After a peak of let's say 6,400 rpm, you might see the 110- to 112-lobe separation camshaft carry the horsepower curve farther before falling off, but not necessarily a bigger number. That's what we see on the engine dyno. The simple way of thinking about it would be if you could take the hp/tq curve at the beginning and at the end, and bend them up--you would effectively provide the result we see."

Starting with the Stage I cam, which is where our modifications began, you get a cam designed for significant power increase with very little sacrifice to the characteristics that make the LS2 such a great street engine. Dan designed the cam to have a very flat torque curve with an increase in top end horsepower while retaining good drivability. Again, the naturally aspirated version of this cam runs a 114-lobe separation angle to complement the airflow of the stock head. "It makes the cam think it's bigger than it is for a naturally aspirated car," Dan told us.

Our numbers for just the Stage I Livernois cam uncovered impressive potential in the LS2. Peak numbers rang out at 494.4 hp at 6,400 rpm and 450 lb-ft of torque at 5,200 rpm. That's a quick, 90hp pop for just a cam change! Torque numbers were up at peak, with only a slight loss down low--369.8 lb-ft at 3,000 rpm, showing that the engine will still offer good grunt with the cam. More interesting is the useable area under the curve and how much more useable rpm the engine picks up. With this cam, you won't need to shift the car until well past 6,500 versus peak numbers of 5,300 rpm for the stocker. Not only will you gain big power, but with an additional 1,000 rpm to use in each gear, the car will feel stupid fast.

As for the tune, Dan used the stock GM computer (no FAST, Accel, etc.) with proprietary GM software to keep the air/fuel ratio right at 12.5 to 12.7:1. The factory tune in our baseline numbers was 12.5:1, so you can see there isn't any "tuning magic" in the reported number set. However, as we alluded to earlier, Dan did tune the engine to correct for the stock computer pulling timing during the run, which would account for the aforementioned 10 to 15hp difference.Next up was the Stage II Livernois Motorsports camshaft that offers up a healthy .600-inch of lift on the valves. Similar to the Stage I cam, the Stage II piece offered a more aggressive profile to help fill the cylinders and make more power. It did a great job, upping the LS2 to 500.2 hp at 6,400 rpm and 449.8 lb-ft at 5,000 rpm. While the hp was up (5.8) and the torque stayed steady, we were starting to realize that we were out of cylinder head. Good thing that Dan had planned for that.

COMMENTS

subscribe to the magazine

get digital get print
TO TOP