The more you know about direct fuel injection—and the 3.6L V-6 in the new Camaro—the more you’ll like it. It just needs to be super-sized.     

The new V6 engine in the 2010 Camaro marks an important benchmark for hot rodders in a lot of ways. You’ll remember from my blog on March 4 that I rated future powertrain technologies on their hot rodding potential, and I gave Direct Injection/stratified charge technology a “4” on a scale of 0 to 5. At the time, I had no idea the 2010 Camaro would be sporting a 3.6-liter direct injected V-6.

The specs on the Camaro’s base engine are 304 horsepower at 5,900 rpm, and 273 lb-ft of torque at 5,200 rpm. That works out to 1.38 hp per cubic inch, but that’s not even the best part. The 3.6-liter “LLT” does this with an 11.3:1 compression ratio running on 87 octane fuel. That’s right kiddos, it’s not a typo. In the 3,700-plus pound Camaro, it’s even good for 29 mpg on the highway. How’s that for having your cake and eating it?

Some of this blazing efficiency is due to some well recognized technologies; four valves per cylinder are used to increase the curtain area for air and fuel entering into the cylinder. Another trick is variable valve timing and dual overhead cams. By altering the valve event timing, you maximize the ram tuning effect over a broader rpm range. But the big breakthrough this time around is direct injection.

Here’s how DI works. Fuel is injected directly into the combustion chamber instead of the intake port. It’s done at very high pressure; this overcomes high cylinder pressure and improves mixture homogeneity. The injection point is coincident with the spark plug, and you’ll see why in a moment. The important thing to remember is that there are three basic regimes that direct injection gasoline engines operate in: ultra-lean burn mode (for light cruise and idle), Stoichiometric for part throttle, and enrichment mode for full power.

In ultra-lean mode, the fuel is actually injected during the tail end of the compression stroke, not the intake stroke. This allows the fuel to remain in the vicinity of the spark plug, and be ignited in a toroidal pattern. (This is sometimes called a stratified charge, as the fuel is not distributed homogenously throughout the combustion chamber.) The air in the rest of the combustion chamber has little or no fuel, which reduces emissions, and greatly improves fuel economy. Air/fuel ratios can be as high as 65:1.

At part throttle, the air/fuel ratio is increased to 14.7:1 (stoichiometric); fuel is introduced during the normal intake cycle, and the engine behaves more like what we’re accustomed to seeing. At fuel throttle, the fuel mixture is enriched for max power, and to eliminate detonation, and is also a practice we’re used to seeing here in the hot rodding world.

Not impressed with 304 hp from a V6? Well consider this: if the 3.6-liter LLT powerplant were scaled up to, oh, say 6.2 liters—the same size as the LS3 in the big brother SS Camaro—the LLT would make 523 hp. That’s almost 20 hp more than the LS7, and with .8 liters less displacement. For reference sake, the LS3 in the Camaro SS makes “just” 426 hp.

But GM Powertrain hasn’t even maxed out the direct injection bag of tricks, which also includes getting rid of the throttle body. By eliminating pumping losses (sometimes called throttling losses), you can free up a bunch more horsepower. You do this (like BMW has for several years now) by letting the intake valve control the amount of air entering the cylinder.

I’m guessing that in the next two years, we’ll be seeing direct injection V-8s that will be more powerful, smaller in size, and more economical than the current crop of LS3/L99 engines in the current Camaro SS. We may even see mild hybrids with direct-injection V-8s, and if these engines are combined with throttle-less air delivery, we could see Camaros and Corvettes getting 30 mpg while laying down 500 hp!