High Lift, Long Duration Camshafts probably change the character of an engine more than any other component. The aggressive High Lift profiles available for road/ hybrid and full race engines by Cat Cams and Kent Cams when matched to other components will lead to significant horsepower and torque increases. By controlling the timing of the inlet and exhaust valve opening this simple component can change an engine from a low revving, economical and docile specification to a high revving race engine. The biggest issue for the driver looking for more speed in todays world is catalysts. If you vehicle will stay road registered and is equipped with a cat it will affect cam choice. All out race cams are designed to operate well at high RPM and often run poorly at low rpm. That said with modern engine management and vernier cam pulleys you can get even very highly tuned engines through an MOT and then optimise for maximum performance on the track.
Honda's VTEC and Toyota's VVTLi range of engines utilise 2 or 3 distinct cam profiles, one of which is akin to a race specification cam. This engages when the revs are above approx 5500 rpm. Anyone who has driven one of these will know what you can expect from the top end of the rev range by fitting an uprated camshaft.
The key to successful cam selection for your engine is matching it to the engines intended use. Many cams suggest the intended application in their name. Race for instance generally means race use only. Bear in mind though that cam choice is influenced by the ratio volume of the cylinder to the valve area. In a nutshell a bigger engine with the same valves will be more flexible at lower revs and probably not rev as high with the same cam as a smaller engine. e.g fit the same cam in a 1.6 and 2.0 engine that have the same head design and the 1.6 engine will be much more inflexible in its power delivery. If you fit a hot cam with a largely standard head the engine will be more tractable than with a big valve head. The big valve head will get into it's stride higher in the rev range and make more power though.
These are all important considerations if you are opting for a capacity increase or if you are fitting a cam into an an engine with 2 valves per cylinder. 2 valve heads usually flow less air but can often stand a hotter cam and remain flexible at low revs.
Cam Selection Checklist
» Assess the published power bands and see which most closely matches your cars intended use - if you plan on road driving err on the side of caution and get vernier pulleys so the cam can be set up to pass the MOT.
» Check the injection system - if you have an airflow meter a hot cam (anything over about 280 deg @0.1mm duration) will be a nightmare at low speeds. If you have a MAP sensor system can you get it remapped? A MAP sensor system can usually cope with a filter or exhaust change but a cam will nearly always require a remap to get the best from it.
» If you order a cam, before we ship we will inform you if there is anything you need to be aware of e.g some hot cams may require certain machining operations. We will always make sure you are happy with the choice before shipping.
Camshaft Bed-In Guide