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While Honda achieved their goal of producing an excellent "dual personality" engine with the invention of VTEC, the use of their heavy steel rocker arms in an engine used solely for racing is certainly far less than ideal. It was with this in mind, coupled with the popularity of these engines, that in January, 2000 I decided to design a rocker arm for use in Honda "hard core racing engines". My design criteria were:

1. To eliminate VTEC actuation, as it's sole purpose is compliance with exhaust emission laws.

2. To employ the use of light alloy materials wherever possible, for moment of inertia and mass reduction.

3. To eliminate the high friction "rubbing block", and employ a virtually friction free, pressure lubricated needle bearing roller, of as large a diameter as possible. This results in reduced bearing speed for greater longevity, and the lowest possible friction.

4. To increase the mechanical ratio of the rocker arm, thereby moving the roller closer to the pivot shaft, and reducing the moments of inertia.

5. To produce a solid one piece design, eliminating the possibility of inconsistent valve actuation, and the need for multiple cam lobes. The single cam lobe design also has the advantage of lower production cost for the manufacturer, and more importantly, the engine builder. The use of a roller cam profile also provides faster opening and closing rates, better filled cylinders, and more Horsepower.

6. To produce a "minimum mass rocker arm", providing consistent accurate valve actuation with less spring pressure at higher RPM.

7. To retain the camshaft's original base circle, for ease of camshaft manufacturing, and engine building.

The photographs you see here are of the prototype set I machined out of 7075-T8351 Aluminum. The axle and roller are made of two different Tool Steel alloys. I made the rocker arms as robust as was possible given the available space, and was still able to achieve a weight reduction of 210 grams (7.4 oz.) per cylinder. I've recently become aware of a process whereby Titanium can be used for the roller, giving us another 30 grams less weight. This yields 240 grams (8.47 oz.) less weight per cylinder, and viewed overall it means your engine will be moving 2.12 POUNDS LESS reciprocating valvetrain mass, with virtually friction free valve actuation. Taken as a percentage, the Honda rocker arms weigh 83% more, and are not as strong. All of my initial design criteria were met, and I have other ideas that will achieve even greater weight reductions. Real world testing in several Drag Racing engines will begin very soon, and the results will be published here. Rocker arms will be available for Honda B-series, H-series, K-series, F20C1, and Acura NSX engines. Engines from manufacturers other than Honda may benefit from this design as well.

Joe McCarthy
Prototype Racing Inc.