from a technicians point of view those are excellent numbers for compression. You might ask if that was a wet test or a dry test. Dry test is just as it is described just pull spark plugs and start testing. A wet test is when you add a small amount of oil down the spark plug hole and then check compression. for a short time the oil will hold up in the rings and show higher compression, because the air is not leaking past the rings. the reasoning for a wet test is if a dry test shows low numbers, you then do a wet test. if the wet tests compression is better than you can assume the problem lies in the rings, for the reason mentioned earlier. if it is still the same as a dry test than the valve are bad. oil can leak past a bad valve. I would assume it's a wet test, those are really good numbers for a dry test. A Typical Lexus LS400 with say 50,000 miles will have an average dry compression of 150 psi. If you did a wet test on the same engine if everything was in good shape would be between 170 and 200. Keep in mind when some one else is doing a test you have no idea how much oil they are adding, the more oil the higher the compression. a typical wet test should be about a teaspoon per cylinder max.
I don't know if I agree with "you can calculate engine hours based on compression". I think its a little too convenient the hour meter doesn't work. or work right sound even stranger. There is a guy on here from Tenn. that bought an x22 off ebay a while back with no working hour meter. once he got it working I think it was 200 or 300 hours. soon after he talked about major engine problems and it needs to be rebuilt ( no pun intended). My point being you can have a 100 hours and have a trashed engine or 1000 hours and it be in top shape, it all about what it was used for and how well it was taken care of.
if I remember correctly Tenn. replaced the MDC but, don't quote me on it.
