Rocker gear - General compendium
Whether you’re building a solid road performer or fire-breathing monster, the main goal is to improve air/fuel flow into the engine.
The more you can get in, the more power you can get out. Cheapest chunk of power improvement comes from sorting the asthmatic manifolding and exhaust by applying a stage one kit. Then what?
Considering the ‘get more in to get more out’ theme, the main restriction - all else being equal - is the valves and their behavior. How big they are, how efficient they are and how long they’re open for determines how much gets in with each gulp each bore/piston makes. Modified cylinder heads are popularly next, although it has to be said that although a well modified cylinder head will improve performance, the gain against cost is nowhere near that given by the ‘stage one’ kit application. A good stage one kit’s improvement verses cost is around £12.50 per 1 hp, a decent modified head typically £30 per 1hp - dependent on application. Hmm.