It's the classic routine. Small-displacement engines make great power for what they are. When first introduced to our project, the stock LS327 made 327 hp at 5,500 rpm with 347 lb-ft at 4,600 rpm. Compare that to the standard Gen I 350ci deluxe crate engine offered by Chevrolet Performance that makes 290 hp or the next step up 350 HO that makes 330 hp and our LS327 is already a game ahead in the horsepower department. This is mainly due to an efficient production-based cylinder head design, a Chevrolet Performance Parts cam, and Grafal-coated pistons. This is despite the fact that it suffers from small-bore syndrome that tends to detract from good port energy into the cylinder.
Despite these shortcomings, the 5.3L LS327 still has plenty of opportunity to make more power. The best way to accomplish this is to simply introduce more air and fuel into the engine. While we could increase the stroke and bore to give the engine more cubes, that requires more time, money, and resources and really negates the point of buying a crate engine in the first place. Instead, we decided to leave the foundation of the motor—the bulletproof bottom end—intact and concentrate on upgrading the bolt-on components to help the little 5.3L breathe a little easier.
While high-winding, small-displacement engines really sound cool at 7,500 rpm, this combination is not conducive to street-intended engines. Problems stem from a lack of low-speed torque and a distinct lack of part-throttle street manners. That said, we decided a beltdriven supercharger was the most efficient means of getting the air into the engine, aided by a blower-grind cam from Comp Cams and a pair of GenX 205 cylinder heads from Trick Flow, courtesy of Summit Racing.
While any engine will respond to positive manifold pressure pushing air in the cylinders, our cam and head choice pushed the performance of the diminutive 327 that much further by creating a purpose-built set of components designed to work in concert with the supercharger. This is critical because any restriction between the supercharger and the cylinder reduces the ability of the blower to shove more air into the cylinders. With excellent cylinder heads and an efficient cam grind, we will see increased flow, which also means lower boost pressure; that adds up to more power. It's really just as simple as that. And if the blower doesn't have to work as hard to shove that air and fuel into the cylinders, the inlet air temperature into the cylinders is reduced, which improves inlet air density. Combine boosted air with reduced temperature and that's a big part of the equation for good power. The cool thing is even normally aspirated this would still be a great combo.
We have really good cylinder heads and we have a better camshaft than stock to take full advantage of the supercharger that we will be adding, so it's the classic street version of the old one-two.