Focus Fanatics - View Single Post - VTEC vs SVTF variable valve timing
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Old 07-19-2004, 10:07 AM   #13
SVTF'nGR8
Focus Enthusiast
 
Join Date: Jul 2004
Fan#: 10592
Location: ABQ, NM
What I Drive: 2004 SVTF/EAP Screaming yellow ZX5

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VTEC is actually quite an ingenious thing from what I have learned about it. Indeed it is a sort of trick to get the best of both worlds: a smooth idle with high lift/duration at RPM. It is controlled by the engines speed and throttle position sensors which tell it's computer which of (3) cam lobes (PER VALVE MIND YOU) to initiate. As RPM's climb, the sensor will activate an electronic spool valve which directs oil pressure to a mechanical pin which slides & actuates the valve to the follower on that RPM lobe. (again 1 of 3 intake and exhaust) A crutch, hardly. It is a very real, simple function to almost instantly change the valve timing and thus the engines powerband.
The true VTEC is only found on the DOHC motors, the SOHC civics with VTEC do not have extra 2 exhaust lobes because of the lack of a 2nd cam.
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04 SVT-F|SCT-Xcal3|CFM-65mmTB, STS, Tq Mnt|MSD coil 8mm wires|K&N drop-in|Mintex pads|
04 V70R|2.5L-T5|6MTX|Bell FMIC|Evolve 3.5"DP-3"CATback|IPD tuned|308 AWHP & 363 tq. @21psi(stock turbo)
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