We know what you're thinking. It seems almost impossible to pick up so much horsepower (142.6 rear-wheel horsepower) from just a cam swap. There must be some sort of trickery or magazine inflation going on.
We assure you that there are no tricks here, just well thought out parts, a pair of turbochargers, and a solid GM-built G8 GT. Unlike other cars (Mustangs, mainly) where it seems like you have to fight tooth and nail for just a couple of horsepower, the new generation of LS motors seem to amaze us with every new modification.
New Era Performance sent us...
New Era Performance sent us its newest G8 turbo camshaft package and the quality and quantity of components was very impressive. The kit includes everything needed to convert from Displacement-On-Demand including the custom turbo camshaft, GM head gaskets, GM LS7 lifters, GM lifter buckets, PAC valvesprings, TrickFlow pushrods, ARP head bolts, GM timing chain dampener, GM valley cover, and three-bolt timing gear. Total cost is $1,249.95 for the whole kit.
Our test subject is an extremely low-mile Pontiac G8, which has had a set of APS turbochargers installed since day one, courtesy of the boost fanatics at Carter Racing in Savannah, GA. Always looking for more power, we made a call to New Era Performance to put its new Twin Turbo camshaft to the test. One of the issues with the current G8 L76 engine is the Active Fuel Management, otherwise known as Displacement-On-Demand, or DOD for short. While a great idea for people looking for maximum fuel economy, the DOD is somewhat problematic on high-performance, forced induction motors.
These issues are two-fold. The first problem, which is especially prevalent on a turbo car, occurs during transient boost situations. Since a turbo is driven mainly by load, instead of RPM, it can lead to some very strange situations, where the DOD is trying to cut back to four cylinders, while the turbo is coming into, or out of, boost. During initial street tuning, this caused the car to buck and surge, which made driving very uncomfortable. The other, more serious problem is the potential failure of the DOD-specific lifters. If you have been following Mike Ficacci's ProCharged G8, you may recall that we replaced the lifters with LS7 units, after collapsing several of the stockers during a dyno session.
In keeping with the K.I.S.S. theory (Keep It Simple, Stupid) we decided it was best to remove all of the DOD parts, install a traditional camshaft and lifter package, and make some big horsepower along the way. Follow along as Carter Racing takes this G8 from a stout 469 rwhp to an amazing 612 rwhp, with a fairly straightforward camshaft installation.
After pulling our G8 tester...
After pulling our G8 tester into the bay at late-model specialist Carter Racing, the oil and coolant are drained. This is a good time to remove the headlights, radiator support, belts, APS intercooler, and related piping. After the coolant was drained the radiator was removed to make room for the cam to slide out.
In the engine bay, the first...
In the engine bay, the first step is to remove the fuel rails. Proceed with caution; no one likes a fuel-fed fire, especially under the hood of your new car.
After removing the fuel rails...
After removing the fuel rails and "intake manifold silencer," the throttle body is unbolted and the intake manifold bolts are loosened.
Getting the intake off was...
Getting the intake off was a little tricky. It is necessary to reach back and pull both the brake booster hose and APS boost-reference hose off. It is important to take your time, and be careful not to crack the manifold, while doing this.
This connector, which plugs...
This connector, which plugs into the stock G8 valley cover, will not be re-used, so it is taped over and moved out of the way.
With the valley cover removed,...
With the valley cover removed, you can really see the difference between a DOD and non-DOD motor. The stock unit (on the right) contains a bunch of wiring and solenoids to control the oil flow to the stock lifters. On the left is our replacement, which is void of such items.