Miles or compression

[RyanT]

When you by a fd is it more important to look at compression rather than miles, or miles first. I\'m looking at a fd and the miles are 40000 but it has a compression of mid 8s all round which I believe is really good. with the 40000 miles you would say the engine is  2/3s the way through it\'s life. But compression would say it\'s got lot left in it ?

Do you get a gradual decline with compression or does it just fall off a cliff at the end of it\'s life ?

And also has anyone had any dealings with dragon performance?

[m1tch]

For NA engines the seals will just wear down (like piston rings) and will normally show a steady decline. With turbo cars its usually a catastrophic failure due to boost, fuel or cooling that take the engine out. My FC engine is on 89k miles, it has compressions of 7.2s on the front, 6.9s on the rear and still pulls strongly. Mid 8s compression is almost a new engine, so if its looked after with proper changes it should last ages, the main key is that its got even compression. The rotors can coke up after the miles meaning that seals stick rather than move freely which can affect compression.