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{{Short description|Automobile variable valve timing technology}}
'''VarioCam''' is an [[Car|automobile]] [[variable valve timing]] technology developed by [[Porsche]]. VarioCam varies the timing of the [[intake]] [[poppet valve|valve]]s by adjusting the tension on the timing chain connecting the intake and [[exhaust system|exhaust]] [[camshaft]]s. VarioCam was first used on the 1992 3.0&nbsp;L engine in the [[Porsche 968]].
Porsche's more recent '''VarioCam Plus''' combines [[variable valve timing]] with two-stage lift on the intake side. The two-stage valve-lift function is performed by electro-hydraulically operated switchable tappets. Each of these 12 tappets consists of concentric lifters which can be locked together by means of a pin. The inner lifter is actuated by a small cam lobe, while the outer ring element is moved by a pair of larger-profile lobes. The timing of each valve is seamlessly adjusted by means of an electro-hydraulically operated rotary vane adjuster at the head of each intake camshaft.
Valve timing and the valve profile are continuously altered according to conditions and engine load. For improved responsiveness on cold starts, VarioCam Plus raises the amount of lift and retards valve timing. At medium revs with minimal loads, the valve lift is lowered and timing advanced to help minimize fuel consumption and emissions. For maximum power and torque, the lift is raised and the timing is advanced.<ref>{{cite web |title=Porsche VarioCam Plus |url=http://www.porsche.com/usa/models/911/911-gt3/indetail/drive/ |work=Drive - 911 GT3 Features |access-date=April 7, 2008}}{{dead link|date=November 2024}}</ref><ref>{{cite web |title=Shalco - VarioCam Plus |url=http://homepage.virgin.net/shalco.com/VarioCamPlus.htm |work=Shalco Motorsport |access-date=April 7, 2008 |archive-url=https://web.archive.org/web/20080410235304/http://homepage.virgin.net/shalco.com/VarioCamPlus.htm |archive-date=April 10, 2008 |url-status=dead |df=mdy-all}}</ref> This system debuted on the 1999 [[Porsche 996]] Turbo.
A system similar to the VarioCam Plus system was developed by [[Subaru]] for the redesigned EZ30R H6 engine, which debuted in 2003 in the [[Subaru Legacy|Legacy]] and [[Subaru Outback|Outback]].<ref>{{Cite web |title=Subaru EZ30R Engine |url=https://www.australiancar.reviews/subaru-ez30r-engine/ |access-date=2021-04-14 |website=australiancar.reviews}}</ref>
==References==
<references/>
{{Porsche vehicles|state=collapsed}}
[[Category:Porsche]]
[[Category:Variable valve timing]]
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