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This paper shows a “manual method” to develop a cam lobe profile, modifying a existing profile, to hit some difference like the lift or event. Employing a micro computer and a worksheet software, we can build a table with cam parameters like acceleration, velocity, lift, area under the positive and negative acceleration curve, curvature radius, etc… all on the degree of the cam lobe. Modifying the acceleration values it is necessary to achieve the equality of the positive and negative areas, hitting a new profile with lift and / or event modified. The modification of the acceleration table must be followed by the visualization of its derivative, or jerk, to assure a smooth curve to both sides of opening and closing cam. This paper does not cover such areas as: limitations on acceleration and decceleration values or jerk factors, cam-tappet stress and cam-tappet pattern run-off.

The better knowledge of a fuel gas methane in an Otto cycle engine, is basic to evaluate its potential on the range of automotive vehicle. The Brazil is favoured to be on hand production alcohol engines with high compression ratio, which bring the possibility to exploit the chemical properties of methane fuel by a hybrid engine running with liquid or gasesous fuel. This paper depicts the major characteristics of a VW engine, 1.6 L, normal aspirated and water cooled, running hybridily with ethilic hydrated alcohol fuel (EHAF) or methane originated from biogas. The major component of biogas is methane (CH4) at 87% per volume of mixture. The behaviour of methane will be evaluated with respect of performance, energetic consumption and pollutants emissions. The methane used on tests were produced in the biodigestors of the SABESP (Company of Sanitation of Sao Paulo State), got by the micro organisms action on the organic matter at the absence of oxigen in the sewerage treatment system.