Using say a 500hp FE as a baseline for this discussion, I've wondered the same question about what others have experienced, and believe there a few factors that determine longevity, such as,
and depending on...
- How the motor was built, balanced, and clearanced to begin with.
- What new or refurbished parts were used.
- How often the motor is checked, valve adjustments/solid.
- How frequently the
oil/type and filter is checked and changed out.
- What cooling system is used, keeping it cool and within temp
- Not over-heating the motor, or running hot for extended periods of time
- Not over-revving the engine; being careful not to unnecessarily abuse it.
Tom at FE Specialties built my 428 CJ, over five years ago, and other than a Shelby rocker/arm failing in the 1st 200 miles (that I provided and replaced) I've had an excellent experience with no issues.
I've heard some guys say you need to go through them at 10,000 miles, others have said they got 50,000 miles with no problems througout the entire motor.
It would be interesting to hear what other engine owners/builders would have to say. Guessing, with a well built motor, seems to me you should be able to get at least 15k-20k out of them easy with spirited driving before having to pull them apart and check bearings, etc. But, then again, it does come back to many of the factors above, and more... starting with who built the motor...