Power output is obviously the primary concern, but that has to be tempered by drivability and low-speed torque considerations. One of the most common mistakes people make when selecting a cam is they focus on the "golden ring" of horsepower and never consider they don't have the support necessary to be able to reach up and grab it. It doesn't make any sense to choose a cam that produces "maximum horsepower" yet kills so much low-speed torque that the engine is a dead player at speeds below 5,000 rpm. In addition to making a vehicle unpleasant to drive, camshafts with excessively long duration can actually be a performance liability-by the time an engine reaches the rpm at which the cam starts to deliver significant power, whatever vehicle was in the next lane is long gone.
In the case of our C4orce profile, we kept duration reasonably short, but selected lobe designs with exceptionally fast opening and closing rates. This combination of characteristics delivers an exceptionally broad torque curve and more than enough horsepower to embarrass the same people who snickered at the idea of installing a 5.3-liter "truck" engine in a C4.
Before we could start the engine, the PCM had to be reprogrammed to accommodate a number of the changes we had made. In addition to replacing the original injectors with a set from an LS1 engine, we had also eliminated the mass air sensor and hadn't yet connected the oxygen sensors. The engine was also connected to a manual five-speed transmission (a TKO 600 from Classic Chevy 5-Speeds) instead of the original 4L60E automatic.
Apparently, the Lord of Semiconductor Technology (LOST to those of us who deal with him on a regular basis) wasn't happy with me because the original calibration with which I reflashed the PCM would allow the engine to fire, upon which it immediately died. After checking and rechecking and finding no apparent cause for the problem, I fired up the EFILive tuning program again, built another calibration using a different operating system, and reflashed the computer once again. That must have brought a smile to LOST's face because the first time we hit the key, the engine started and ran perfectly.
One of the many advantages of EFILive software is the vast array of tables to which it provides easy access. When working with an engine conversion, access to those tables is particularly important because so many aspects of engine control are significantly different than they were in the original installation. (EFILive also includes a number of custom operating systems that include features ideally suited to engine conversions.)
If you attempt a C4orce-type conversion, keep in mind that in addition to all the standard considerations, the PCM calibration must be properly configured if alterations (from the configuration for which the PCM was originally programmed) are made in:
>>Air measurement type (from mass air to speed density) >>Injector flow rate (a change in injector size necessitates changes in the injector flow rate table)>>Fuel system type (return to returnless or vice versa)>>Oxygen sensor installation (if the sensors are eliminated, the PCM must be set to operate in open loop) >>Transmission type (changing from manual to automatic or vice versa)>>Rear axle ratio and tire diameter>>Desired idle speed>>Catalytic converter installation