Results
Starting with the stock LS2 heads, we quickly reconnected with an earlier test. With over 500 hp, the L92 heads had their work cut out for them. The fact that the LS2 heads, Stage II cam, and stock LS2 bottom end cranked out 502.3 hp and 465.3 lb-ft of torque still warms our hearts. The LS2 is an amazingly efficient small-block V-8 that is a tremendous starting point for making crazy power.
We started our testing with a trip to the flow bench at Livernois. The box stock heads topped 330 cfm on the intake and came close to 200 cfm on the exhaust. Better yet, the low-lift numbers were amazing-225 cfm at .200-inch lift shows how these heads help make big torque in the SUVs that GM is kicking out. The L92 heads were bolted to the awaiting LS2, and we got down to it.
"You've got CNC-ported technology out of the box," Millen exclaimed. "You've got a CNC-ported LS2 head out the box. With some CNC port work, the L92 head is going to crucify everything else on the market. That head is very close to an LS7 head. With some port work-after we get done analyzing the CNC data-we'll be over 350 cfm on the intake. If you've got a 400-inch motor or bigger, the L92 heads will be killer. Those big intake ports on a big-inch LS engine will really make some power. You're talking close to 700 naturally aspirated horsepower from a pump-gas car if the combination is right!"
First up was the L76 intake, which really looks like a stock LS2 plastic intake until you start looking at them side by side. The L76 does have larger runners-they are "hunched" at their peaks on the very top of the intake. And, the ports match the larger, wider L92 heads. The low lift numbers really played out in the torque curve with this combination, as the L92 heads and L76 intake helped the LS2 stomp out 494.9 lb-ft of torque at 5,000 rpm with a very wide torque band. The fact that this combination also produced 546.8 hp at 6,500 rpm seems almost inconsequential. Remember, these are stock parts-with a somewhat warm cam-that can be put together for minimal money. This combination of parts will quickly become the standard by which bolt-on parts will be measured from this point on.
"I think the L76 is a great intake," Dan said. "You can immediately see that GM did some great engineering on it. We saw it when GM went from the LS1 to the LS6. They made an intake that was more efficient-the same thing has happened here. I'm just concerned that there isn't much more GM can do. How much efficiency is left on the table with the LS? Well, if the intake was aluminum, you'd be able to run 30-plus psi of boost on it. But, other than big boost applications, there's no question about it-the L76 intake is clearly better."
Next up was the carbureted intake from GMPP. GM Racing designed this intake specifically for the L92 heads to make it easier for hot rodders to adapt a carburetor onto a more modern small-block V-8. The Livernois technicians saw it as a way to adapt their fuel injection system to an intake with more horsepower potential.
"I wouldn't want to run the carbed L92 intake with anything but a carburetor," said Millen. "We ran it with the fuel injection just to see where it matched up with the L76, but I think the carb would be the way to go. Introduce some nitrous into that combination, and you'd have something really special." Conclusion GM Performance Parts has just released one of the most efficient small-block V-8 cylinder head ever created-the L92 LS Family head. With a 330-cfm intake flow, large intake ports, and massive potential, they are the new standard in the hot rod LS world. We will try to get back to you with a ported version, more cubic inches, and a bigger cam to see just where these things can take a serious LS engine. For now, the L92 head is the most affordable bolt-on head you can buy for the LS engine family. Coupled to the factory-engineered L76 intake or the race-inspired GM Performance Parts L92 carbureted intake, the L92 heads look even better.
Here's a look at the throttle...
Here's a look at the throttle body adapter that Livernois put together for this test. While they pirated the elbow from Dan's 6-second 10.5W-tired Outlaw Mustang, it worked quite well on our 540-horse small-block Chevy. The technicians at Livernois promised us that you will be able to buy this same setup for your car by the time this story runs-elbow, fuel rails, adapter-the whole thing.
This is what we're shooting...
This is what we're shooting for-a stock LS2 carrying the Stage II Livernois Motorsport cam, upgraded valvesprings, and 502.3 hp at 6,300 rpm and 465.3 lb-ft of torque at 5,100 rpm. Bottom line: the stock LS2 with a camshaft is one bad boy. Could we do better with a $1,000 pair of heads and a $500 intake?
The assembled LS2 engine with...
The assembled LS2 engine with the L92 heads and L76 intake looks very stealthy. In this form, the LS2 produced 546.8 hp at 6,500 rpm and 494.9 lb-ft of torque at 5,000 rpm. The short runners of the L76 intake and the good low-lift numbers of the L92 heads created an outstanding torque curve. This would be the hot setup for your typical full-weight street car.
"Top Fuel" Dom minds the store...
"Top Fuel" Dom minds the store at Livernois Motorsports' engine dyno while he puts our LS2 through the paces. Outfitted with 30-plus technicians, an engine assembly area, multiple lifts, two chassis dynos, and over 36,000 square feet of high-performance know-how, Livernois has a lot going for it.
The LS2 crate engine, Stage...
The LS2 crate engine, Stage II Livernois cam, upgraded valvesprings, L92 heads, and L76 intake created these horsepower and torque curves. Impressive for less than $2,000 worth of upgrades.
The carbureted intake for...
The carbureted intake for the L92 heads makes an impressive statement on the high-tech LS2 fuel-injected small-block. Instead of a carburetor, Livernois put their prototype fuel injected pieces to the test. It looks trick!
Here's a close up of the carbureted...
Here's a close up of the carbureted GM Performance Parts L92 intake on the LS2 engine. Along with the very affordable L92 heads, it adds up to affordable combination of parts.
The results are in-the L92...
The results are in-the L92 heads and carbureted intake rock! They produced 545.8 horses at 6,900 rpm and 453.8 lb-ft of torque at 5,200 rpm. The L92 carbed intake gives up some torque down low-no surprise there-but it gains it back on the top end with a peaky power band. This is your race car intake, folks, no questions about it.