The document describes a Variable Lift and Duration (VLD) system, which is a fully variable mechanical valvetrain capable of controlling valve lift and duration. It can provide up to an 8-12% improvement in fuel economy and a 5-10% increase in peak power output. The VLD system uses two cam profiles to produce a single valve lift profile and allows control of valve lift, duration, and additional valve lift events. It has reached mature development with over 1000 hours of prototype engine running.

1. Variable Lift and Duration Concentric Camshafts Twin Phasers
Variable Lift and Duration System - Gasoline
‘A flexible, modular, fully variable mechanical valvetrain’
VLD is a camshaft actuated mechanical valvetrain capable of providing a range of fully variable
valve lift characteristics via different cam profile designs
• The VLD summing rocker system combines two different cam profiles to produce a single valve lift profile.
• A mature stage of development has been reached with prototype engines currently running at several OEMs and
research institutes. Several fired test engines have now completed well over 1000 hours running.
• The VLD system can be designed into an integrated valvetrain module and is also interchangeable with a
conventional Roller Finger Follower system.
Key Benefits for Gasoline Engines
• Valve head throttling
 Reduction of intake pumping work
Optimisation of volumetric efficiency.
• Trapped mass control
 Increased volumetric efficiency, improving transient
response and increasing downsizing potential.
Lift Control Duration Control Second Event Control
Control of valve lift and opening Valve opening duration control Fully variable additional valve lift
duration. without large changes in valve lift. events.
– Fixed IVO, variable IVC. - EVO, EVC, IVO or IVC available. - Early or late 2nd event timing.
VLD Copyright © Mechadyne International 2011 Page: 1

2. Variable Lift and Duration Concentric Camshafts Twin Phasers
Variable Lift and Duration System - Gasoline
Summary benefits
FUEL CONSUMPTION/ CO2 * ~8-12% improvement in fuel economy
25% for a downsized engine
PERFORMANCE/ AFTER- 5% to 10% increase in peak power output
TREATMENT * 15% to 20% increase in low speed torque
Improved transient turbo response (Additional downsizing
potential)
Optimised expansion work
Improved cylinder scavenging
EMISSIONS * Faster catalyst light-off giving reduced emissions
 60% Nox
 40% CO / HC
DRIVEABILITY Improved transient response
Reduced turbo lag
BASELINE SPECIFICATION 4 valves per cylinder, Intake and Exhaust Phasers
VLD SPECIFICATION Intake VLD (lift control – throttless operation),
• Performance estimates are based upon published data for equivalent VVA systems
Technical Paper
• "VLD a flexible, modular, cam operated VVA system giving variable valve lift and duration and
controlled secondary valve openings". T. Lancefield, N. Lawrence, A. Ahmed, H. Ben Hadj Hamouda
SIA-IFP 2006
If your company is interested in VLD then please contact us for further information:
Dr Tim Lancefield Nick Lawrence Ian Methley
Technical Director Senior Design Engineer Senior Design Engineer
Tim.lancefield@mechadyne-int.com Nick.lawrence@mechadyne-int.com ian.methley@mechadyne-int.com
+44 1 869 350903 +44 1 869 358056 +44 1 869 358051
Website: www.mechadyne-int.com
VLD Copyright © Mechadyne International 2011 Page: 2