Focus Fanatics - View Single Post - VTEC vs SVTF variable valve timing
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Old 07-19-2004, 07:24 PM   #15
Sonic04SVT
Focus Enthusiast
 
Join Date: May 2004
Fan#: 8295
Location: Kansas
What I Drive: 2004 Sonic Blue SVTF

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Best description of the SVT's VCT I have seen is here: http://www.myfordfocus.com/svt/

Summary:

Quote:
The intake camshaft is equipped with an electro-mechanical control mechanism, which allows the camís maximum opening point, relative to crankshaft degrees, to be varied between 85 and 145 degrees after top-dead-center on the intake stroke. The variability is dependent on engine speed and load, and is accomplished by changing oil pressure on either side of a piston in a helix between the cam and its drive pulley. This is the first application of variable intake cam timing at Ford in North America, and is a significant contributor to the engineís remarkable low-end torque.
It's totally different then the VTEC, think of VCT more like adjusting cam gears to retard/advance the cam timing, rather then the VTEC's seperate camshaft lobes for differing RPM ranges.

I have to give it to Honda, the VTEC is actually a great idea because you can have the low RPM cam profile and the high RPM cam profile so you essentially have 2 motors in one. The SVTF's VCT is also a good idea, however your just altering the cam timing more then anything else, benefitual but not as significant.

The REALLY COOL THING though will be when there are e-valves (electronically actuated valvetrain) where you forego a camshaft entirely. You can then have as many different cam profiles as you want, meaning every load, RPM, throttle position, weather condition, air temperature, whatever you can think of..you could have a perfectly matching cam profile for it. Probably will make tuning a pain...but you could have added power, economy, driveability, with lower emissions. Rumor is Ford has worked on such things for some time now show very significant gains, but were having difficulty making it reliable.

Keep in mind camshaft selection only plays part of the role in determining the engine's performance, intake runner length and exhaust style/runner length also determines where an engine makes power, but imagine a e-valve engine with a variable runner length intake...it could be a crazy engine combo.
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2004 Sonic Blue SVTF
"It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*."
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