If you do a search for the word excess in your online dictionary or through Wikepedia, chances are that you'll find a picture of the new RPO Series Camaro from Mr. Norm's Garage. What (you ask) sets these apart from the multitude of '10-and-newer tuner Camaros currently available? In this case, the excess comes in the form of horsepower. Where the stock motor is rated at just a tick over 400 hp, Mr. Norm's felt this just wasn't adequate. What if a ZO6 Corvette owner pulled up along side with 500 hp? How about a Viper with 600 hp or maybe even a Shelby Super Snake Mustang sporting 750 hp?
This irrational escalation eventually led right past doubling the power output of the stock LS3 into the rarified air of stratospheric four-digit power levels. That's right, current (or potential) Camaro owners, Mr. Norm's plans to offer a street-legal Camaro sporting as much as 1,000 hp. Truth be told, their offerings include more modest power levels as well (as we saw in our test of the 650- and 825-horse RPO cars in the December '10 issue), but it was the big number that caught the attention of our editor and, without a moment's notice, we asked them to put their money where their mouth is (or at least their advertising claims).
Truth be told, we could think of no better way to spend an afternoon than strapping someone else's supercharged 7.0L stroker to the dyno and cranking up the boost. The current generation of small-blocks has never failed to impress with its power output, but imagine taking an already stout LS3, adding displacement, bolt-ons, and boost. Now that's a party!
Obviously the right supercharger goes a long way toward adding the necessary power, but excessive boost is not only worthless, but can also be downright destructive on an otherwise stock engine. It takes much more than a ton of boost to coax 1,000 hp from an LS3. Not surprisingly, the stock internals were never designed to withstand such prodigious power outputs. Proper attention to the remainder of the motor was in order before you can add the boost required to eclipse four-digit power levels.
With the new 3.6L Kenne Bell Liquid Cooled supercharger waiting in the wings, the guys from Mr. Norm's decided to team up with the LS experts from Turnkey Engine Supply (www.turnkeyenginesupply.com). Turnkey Engine Supply whipped up an impressive LS stroker designed specifically for the rigors of forced induction. The task was made all the more difficult by the fact that the LS stroker had to not only produce big power number, but also do so on pump gas and in emissions legal trim. The package is in the process of emissions certification as of this writing, but things look good for a honest-to-goodness, emissions-legal, 1,000hp (pump gas) Camaro mill.
To reach the three-tiered goal (emissions legal, 1,000hp, pump gas), Turnkey took a three-tiered approach by combining a drop in static compression ratio with increased displacement and improved airflow. The hope was that the bigger motor would offer not only more displacement and airflow, but simultaneously reduce the chance of harmful detonation.
The more displacement was achieved by replacing the wimpy cast crank with a more suitable forged steel stroker crank. In addition to the increased strength, the forged crank also increased the stroke from 3.622 inches to 4.10 inches. When combined with a set of forged connecting rods and pistons with a 4.070-inch bore, the result was a bulletproof bottom end and a finished (LS7-matching) displacement of 427 inches (7.0 liters). The dished pistons also combined with the ported LS3 heads (from Dr. J's Performance) to produce a static compression ratio near 8.5:1. Though the drop in compression of roughly two points had a negative effect on power, the low-compression motor was much more pump-gas (premium unleaded) friendly.