In July '09, Gary Castillo, owner of Design Craft Fabrication, began Internet threading on S2Ki.com, discussing the possibilities of converting the S2000's F-series engine from VTEC to iVTEC. Within minutes, his posts were dismissed as nothing more than a pipe dream, as S2K devotees were adamant that iVTEC on an F20C or F22C engine would never work. One visitor was even quoted as saying, "Having played with cam gears quite a bit, I don't think having variable cam timing on the intake would be advantageous, considering the cost to get a system working."
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Honda Cam Tuning - Tech Knowledge
"I posted on the S2K forums to gauge potential interest in converting to iVTEC, and to see if such a feat had been accomplished before," explains Castillo. "I received more positive feedback from owners after discussing my ideas, but what no one knew was that by the time I logged my first post, we already had a prototype unit (dubbed "ECS"-Electronic Control Sprocket) completed. This wasn't some spur of the moment product I decided to whip up last week." Gary had actually been working on the project since early '08, and ran some preliminary testing on the turbocharged BC/C West time-attack S2K to find the new setup delivered more power than he had expected.
"Having wrenched on numerous Honda engines, I noticed striking similarities between the K-series and F-series valvetrains, and wondered how I could combine the benefits of the two," he explains, referring to the F20C's high-flowing head and the dynamic/continuous intake valve timing and overlap control of the K20's iVTEC. Swapping the K20's cylinder head onto an F-series block was prohibitively complex, even before any cylinder-head porting necessary for it to match the F20's flow characteristics. "It seemed logical that adding iVTEC to the F-series engine was the best way to go."
During the initial testing phase, Castillo called upon colleague Mitch Pederson, of MP Tuning, to aid in tuning the BC/C West S2000 equipped with the prototype ECS unit. A former engineer of AEM who collaborated on the development of the company's EMS fuel management system, Pederson confirmed that proper intake cam timing should be able to result in a relatively large increase in low-end torque, with an intake manifold and camshaft profiles that are optimized for use with variable cam timing. "Typical power gains should be in the 20-30 percent range, but improvements of up to 40 percent or more have been seen versus having the intake cam timing completely deactivated (as is the case with regular VTEC)," he explained prior to testing, "Along with the increase in low-end torque, turbocharged applications should see a sizable reduction in spool time and an even greater increase in mid-range torque and power".
On the prototype ECS-equipped BC/C West S2000 test car, Pederson found the optimal intake cam timing to be 20 degrees advanced from full retard from idle to 2,000 rpm, increasing to a peak of 45 degrees advanced at 3,500 rpm, before retarding linearly to 10 degrees advanced at 7,500 rpm. Dyno charts revealed a noticeable increase in mid-range power and torque, due to the variable intake cam timing and improved turbocharger spool-the new iVTEC setup posted a whopping increase of 99.3 hp and 130.4 lb-ft torque at 4,000 rpm, compared to our previous VTEC numbers.
The Design Craft ECS system is currently in late prototype stages, and has gone through numerous revisions to improve its performance and reliability. Design Craft plans to release the final version in January of 2010, for booted and naturally aspirated applications, as a true bolt-on system. According to Castillo, all that will be required to convert to an iVTEC setup, in addition to the production ECS kit, will be a few factory K-series valvetrain components and a compatible engine management system.
Engine: F20c
BC 2.4L stroker kit
CP pistons (9.5:1 compression ratio)
BC connecting rods
ACL main and rod bearings
GReddy turbo kit
GReddy T57 -25G turbine
GReddy 24R-HG intercooler
GReddy Type R wastegate
GReddy Profec B SPEC II boost controller
WPC treated engine components
Valvetrain:
BC prototype iVTEC camshafts
BC stainless steel valves
BC single springs
BC titanium retainers
Fuel:
RC 1,000cc/min injectors
Twin-feed Bosch fuel pumps
Drivetrain:
ACT HD clutch/ flywheel
Engine Management:
AEM EMS (Version 2)
DYNO RESULTS VTEC IVTEC GAINS RPM HP TQ RPM HP TQ HP TQ 2000 51.525 135.308 2000 61.957 162.703 10.432 27.395 3000 75.672 132.479 3000 101.473 177.649 25.801 45.17 4000 128.606 168.863 4000 227.964 299.323 99.358 130.46 5000 288.176 302.706 5000 332.849 349.632 44.673 46.926 6000 415.445 363.66 6000 443.388 388.12 27.943 24.46 7000 467.491 350.759 7000 483.132 362.494 15.641 11.735 7800 447.398 301.254 7800 461 310.413 13.602 9.159