Hi, the most common reasons for low performace for no apparent reason are incorrectly adjusted bypass valve, faulty bypass actuator, air leak on the high boost circuit,faulty T Map sensor, slipping belt. All of which are easy fixes and either carried out or at least checked as part of GTT220 -GTT260 conversions. Graham has a point in that as the cam chain wears (stretchs) the cam timing will retard but this is marginal. We have checked stock and shrick cam timing using degree disc, mag base and drop clock.....all were bang on to manufactures spec. Thats not to say that moving from this figure cannot give gains ,it can,... hence the GTT Adj. sprocket.
Regarding compression the recommended figure is 10% max difference between cylinders. Having said that you can have 20% difference and still have a quicker car than one with all the same comp. readings . These are just my experiences of the situation. |