Independent cam tuner Ed Curtis...
Independent cam tuner Ed Curtis of Flowtech Induction has been doing some interesting work with GM's displacement on demand (DOD) system, "active fuel management" in GM parlance. The internals of this switching roller follower hint at the possible difficulties of creating a cam to work well with it. The key, according to Curtis, was to find a base circle that worked within the constraints of the system yet produced more power. At this he's been pretty successful.
We made sure to talk to most of the big names in the cam industry, but we also wanted to get some input from a free agent, Ed Curtis of Flowtech Induction. The bulk of Curtis' business is working in conjunction with select dealers and installation shops who want tailor-made valvetrain and cylinder head packages. If you wanted to oversimplify the whole deal, you could just call him a custom camshaft and valvetrain designer. Since Curtis works with a variety of camshaft manufacturers, he has access to cam lobes across the board and can use whatever works best to obtain his goal of a successful combination for the enthusiast.
During this conversation however, Curtis had one really hot topic in mind and wasn't shy about sharing his enthusiasm. "The most recent project I've been working on is our latest camshaft profiles and valvetrain packages for GM's displacement-on-demand (DOD) engines, such as the rectangular-port, L92-based, 6.0L engines. Relate that to current L92 and even the LS3 powerplants and what we'll soon see in the new Camaro." Although Curtis has been using the new Pontiac G8GT variant as the guinea pig, the technology will transfer.
He's been working very hard with one of his valvetrain dealers (New Era Performance Parts in Rochester, New York), and the guys have been doing a ton of dyno testing of various DOD-specific cam profiles. "We've learned a lot and gained a bunch of 'usable' power with these FTI DOD-specific valvetrain packages and New Era's software programming with the DOD electronic control system." Though some enthusiasts might think this kind of setup a nuisance, Curtis assures us: "Many people who contact us want to keep the DOD feature functioning."
Curtis' formula includes proprietary camshaft profiles, a heavy-duty timing set, heavy-wall pushrods, and PAC Racing beehive valve springs. These mechanical items, coupled with the New Era Performance software mods, have resulted in more than 400 rwhp (even with a 3,200-stall converter) from FTI's mule, the Project G8GT. (Remember, think new Camaro when we mention the Poncho.)
The car in question managed 12.39 at the recent NMCA LSX shootout, and that was after averaging 23 mpg on the drive from Rochester to Memphis. Curtis figures it for 11.90 at sea level, especially since the 4,200-pound G8GT was also deep staging to meet the 12.50 index class-no wonder they call these new Pontiacs "Charger Hunters," he says.
So how did Curtis go about extracting all that power from the DOD system? "In the beginning we were a bit worried, but by simply taking the time to measure everything-lifters and their bores, camshaft base circles, rocker arm geometry-we came up with the right valvetrain and lobe design to make it all work perfectly. The result was using the correct base circle and setting the preload properly, so the package was able to work with the stock GM DOD lifter along with the correct pushrod and valve spring kit we supply." Per usual, these camshaft kits include heavy-wall pushrods, aluminum roller rocker arms, and the proper valve spring. The whole thing sounds surprisingly simple, but many a long day was spent getting all this OEM-reliable, Curtis says. In fact, he says customers tell him the DOD is actually a bit quieter that the stock cam and, when using the stock mufflers, very stealthy.
The end result of this development by FTI and NEP is that currently three camshaft packages are "all very streetable," Curtis says, though he admits it will take "a certain temperament" for the aggressive one of the trio. "We also have cam kits that eliminate DOD function, but that's only in about 10 percent of applications," he confided. "90 percent of the interest is in DOD-specific applications and tend to use one of the two small cams."