Honda Cam Tuning - Tech Knowledge

In comparing the modified cover vs. factory cover, we can visually reference how much was added to the factory piece.

Gary devised a clever way to retrieve a more consistent oil supply to feed the turbo, by drilling and tapping the front cover rather than pulling oil from the oil pressure unit.

The remote VTC oil pressure solenoid valve might look like a pissed-off octopus, but it's considered the most essential part of the iVTEC conversion. The unit basically works like the factory RSX module, but remote.

The VTC solenoid adapter requires an oil-in line, two oil-out lines, and one drain line to function properly. Don't worry-the production system will be a lot easier on the eyes!

Revisions were made to the AEM EMS before tuning the new iVTEC setup, which included changing some jumper settings within the ECU and moving some pins around at the ECU connector. Total time took about 5-10 minutes, with no cutting or soldering required. There were also some changes made to the calibration settings within the ECU to recognize the intake cam position, and to set up the closed-loop cam angle control. The only other major wiring task was connecting the intake cam oil control solenoid to the ECU, which meant running one wire of the solenoid to the ECU and the other to a 12-volt power source.

Pederson made the necessary modifications to our AEM unit to work with the newly installed iVTEC. As of print, the ECS is designed to work with the AEM 30-1052 model EMS. By early next year, the system is slated to work in conjunction with the GReddy V-Manage piggyback cam control, and the Hondata K-Pro.

During the '08 season, the BC/C West S2000 ran a small 20g turbine to help minimize lag, but ended up sacrificing horsepower. "We couldn't make a lot of top-end power with the car maxing out at 430 hp," Gary explains, "By going with a larger, drag-style GReddy T67 25g, we were able to make plenty of top-end power and use the iVTEC to compensate spool-up time in the low- to mid-range." Using the iVTEC setup at their last track event, the S2000 was able to produce excellent mid-range power when exiting out of turns.

With the ECS system installed, we were expecting power to develop at low to mid engine speeds, but as we gave it more cam advance, we were also able to make more power as high as 7,500 rpm. The dyno graph shows our engine continuing to make power at the top end with additional cam timing.

The S2K showed a considerable increase in horsepower and torque when activating and tuning the iVTEC, as this dyno graph shows a gain of 91.5 hp at 3,800 rpm and 122.1 lb-ft of torque at 4,500 rpm.

This screen shot compares dyno pulls with the cam timing turned off (red traces) versus with the cam timing optimized at all engine speeds (blue traces). We can see the turbo spools to 15 psi at only 4,000 rpm with the intake cam timing optimized, whereas we don't get 15 psi until 4,700 rpm with the intake cam timing off-a huge advantage when using iVTEC. Additionally, one can see that the injector duty goes from 20 to 35 percent with the same recorded air/fuel ratio, which indicates that the airflow through the engine has increased 57 percent at 4,000 rpm. More airflow means more power and this is a case where the increased volumetric efficiency of the engine, combined with higher boost pressure at lower engine speeds, results in a large increase in power and torque.

Comparisons between VTEC vs. iVTEC manifold pressure show boost entering 1,000 rpm sooner with the cam timing turned on vs. off. Pederson states the results found on the BC/C West S2000 are fairly typical for engines with variable intake cam timing, but there are many factors that may effect the results on an individual basis. Even on applications that do not see phenomenal gain like these, small gains of 10-15 percent are still valuable enough to warrant the time required to make adjustments to the iVTEC's intake cam timing.