How many hours are these engines running on average before they get tired, with routine mantiance?

200-300hrs for a top end refresh and 400-600hrs for full rebuilds. A lot depends on how hard they are run.

Sounds like someone is shopping... lol

Buying used high performance engines is kind of like playing horseshoes and hand grenades. You can be close but not always on the mark. You can't always apply a general rule as each engine has generally been used differently and cared for differently but the issues with top ends on these engines depending on use seem to be that 200-300hour are for head gaskets and top end freshening on the HP500's and with normal service and moderate use the 400-600 hour area can be close but the HP525efi's with freshwater cooling and good service seem to get closer to 600-700hour area, if they don't have or develop header leaks.
Again the old rule applies, "when in doubt, check it out", compression and leak down tests coupled with oil analysis and an expert eye going over the obvious visuals will get you closer to a good pick.

Best Regards,
Ray @ Raylar

Thanks Griff & Raylor for the input. Keytime it will be a year are so before the next one.Right now I'm having good time just researching what will be next. I'd really like my next one to have some getty up but reliable.

Dan

Along the same lines, what would the cost be for these services? Ive seen alot of people talk about refreshening motors and such. Just wondered what that included and how much it costs. I'm kinda in the market and seen similar boats, one with 525 SCI and the other with 502 Mags. I know the mags are more reliable and less maintenance but have less power. How big of an operating difference would there be?

While on the subject of these motors what does one acutally cost?