What are High Engine Hours??

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Pretty much any engine will benefit from at least a little time under moderately heavy load, even if it's in short bursts (such as in a car where you can't keep your foot down for very long). And in applications where it's possible, some time coasting down with the RPM held up in a lower gear is beneficial for keeping the rings moving freely, especially on gas engines where they're throttled and build vacuum in that situation.

Generally with the boat, once we've run a handful of hours at slow cruise (which for us is 1250 - 1300 rpm with the throttles barely cracked open), I pop it up on plane for 5 - 10 minutes to get some good load on the engines. Get some pressure on the rings and get everything good and hot (oil, spark plugs, etc.).

I do similar with boats.

But... with my high performance car and truck engines: I love to occasionally hit passing gear; as well as run em steady for a few minutes in a lower gear to get higher rpm. Also, that we live in rural area with hills it gives good opportunity to go into lower gear while descending downward. One of the hills is taken nearly every time we go to town. It's about 2 miles long and quite steep. Compression in two of my 1 Ton, Standard shift, 4 WD pickup trucks works great in 3rd gear to keep em at 35 mph [the speed on signs]. 67 Buick Wildcat's 430 ci, 400 hp, 500 fpt. 10.5 to1 cr muscle-car engine keeps her at 35 mph in second gear of automatic trany. I watch most in front of me hitting their brakes much of the way down that hill. I seldom ever need to touch my brake pedal!

 

[Art]

I placed the following on post # 55. Can't find much about these engines on the net. Suggestions?? Friend is looking at a boat that has twins.

What's high hours on a 504 cummings diesel?

General comments on 504 cummings... when not too many hours and well cared for.