Horsepower junkies are always looking for that edge to stay ahead of the competition. There are safe ways and risky ways of doing it. Before turning up the boost on any forced induction (supercharger or turbo) motor using pump gas, more octane will be needed to prevent engine-destroying detonation. Lately, many people with a blower on their motor use methanol injection (alias alcohol injection) to suppress detonation rather than use expensive race fuel. Methanol cools the intake charge and combustion while adding 20 to 25 points of octane.
While meth injection is quite popular in supercharged and turbocharged combinations, many people forget that it works equally well at quelling detonation while allowing more aggressive tuning in naturally-aspirated combinations, too, so even if you aren't running a blower or turbo, pay attention to this story.
Back in the August 2008 issue of Super Chevy, we installed MagnaCharger's complete Radix intercooled supercharger system (PN 01-12-60-105-PO) on a stock '06 LS2 Trailblazer SS at Tune Time Performance (Toms River, New Jersey). Once the MagnaCharger was on Dan Smith's AWD '06, his 5,150-pound SUV improved from low 14s in the quarter-mile to the 12.8s. That's really flying for a 2.5-ton box. On the chassis dyno, power increased from 290 hp and 320 lb-ft of torque to an impressive 370 hp and 368 lb-ft with 7-8 psi of boost.
Also stated in that installment was that with additional tuning, boost, aftermarket headers/exhaust, and a better torque converter, we felt that low 12s or even high 11s were possible. We knew that the installation of a meth injection kit from Snow Performance would allow us to extract ever more horsepower without needing expensive race fuel. We returned to Tune Time Performance, where Matt Hauffe and crew installed Snow Performance's Stage 3 Boost Cooler water/methanol injection (PN 20100) and a smaller supercharger pulley, then performed a dyno test and tune.
The methanol injection will protect the engine from possible detonation caused by swapping to the smaller pulley (from 2.9 to 2.7-inch), which will add another 2-3psi more boost. Through "chemical intercooling," the methanol injection will also allow us to advance the timing for even more power and drivability.
It was an easy task for the professionals at Tune Time Performance to install the Snow Performance methanol injection and smaller pulley. But on the first dyno pull, Hauffe (TTP's owner) had to lift. As the rpm and boost increased, the A/F (air/fuel) mixture went dangerously lean at 12.2 to 12.5 (11.5 to 12.0 is ideal). Next, Matt worked magic on his laptop and tuned-in more fuel for the next pull-still the A/F was too lean. We let the LS2 cooldown for 30 minutes and took a risky pull just to see how much power was gained from the smaller supercharger pulley. For that pull we only realized a 10hp gain (now at 380 hp). Normally with 3 psi more boost (now at 10-11 psi) gains should have been in the area of 30-50hp. The culprit is the stock exhaust manifolds-they're now the number one impediment in our combination and are holding the LS2 back in a large way.
Tune Time's ace troubleshooter/technician George Hatizinikitas (aka Huzzy) hooked up a fuel pressure gauge for the next spin of the rollers. On that spin, we noticed the fuel pressure wasn't high enough at high boost (over 7 psi), causing us to lift again. Huzzy adjusted the regulator but to no avail. The fuel pump and injectors weren't up to the task. Next a call was made to MagnaCharger for a Magna Volt (a device that adds voltage to the fuel pump). For added insurance we moved up to a set of Racetronix 60 psi injectors (which TTP had in stock) from the 48-pound injectors. Also, the truck's owner decided to purchase a new fuel pump for insurance since he has racked up over 60,000 miles on his SS.