Question:
What performance gains I would see from keeping my engine standard and only changing the camshafts?
Answer:
It really depends on the engine you have, for example the 1.4L, 1.6L & 2.0L Vauxhall engines have only minimal valve to piston clearance in standard form and if you replace the camshafts, they either have to be so mild that a minimum safe clearance is maintained or that they are retarded so as to avoid valve to piston contact. In both cases, any gains are minimal if at all. When using a larger duration camshaft that is timed in a retarded state normally there will be a reduction in bottom end torque and only a slight gain in peak bhp and the overall result normally makes the car slower. So with these particular engines, it is not worth the money.
Some engines such as the 2.0L Duratec and the Hayabusa engine, have slightly more valve to piston clearance in standard form and therefore allow the use of a mild camshaft and will see reasonable gains, but to see any substantial gains in performance, additional components that give increased compression, clearance and strength will be required.
Your intake system and management system are equally important in any improvement. In any engine using a single throttle body, these are particularly restrictive and have been designed by the manufacturer for a specific purpose. Engines such as the Hayabusa, which have 4 individual throttle bodies allow for a reasonable improvement in performance, but the management system fitted to most engines limits what can be done with your engine.
Category:
Engine Build