[Natural Light Kid]

Originally Posted by CajunChristian

The tach could be off a bit, you'll know when you hit the rev limiter.

I had a 19' ProCraft, back when they were pad bottom bay boats, very fast hulls. I had a 200hp EFI Mariner/Mercury on it. The recommended rpm range was 5400-5600 rpm. I propped that motor to turn 6200 loaded, ran it for years until I sold it. Only problem I ever had was when it was 11 months old, the engine grenade, not a small problem. It stripped the nylon drive gear for the oil pump and all lubrication stopped. I was crossing Big Lake at 6200 rpm when a rod came through the side of the block. It was replaced under warranty and the complete oil system was removed. That failure had zero to do with rpm, the failure was caused by a lubrication part failure.
That old 2.0L V6 Mercury block is raced as an SST120. I built engines for a guy from Florida. His motors would turn 7200 rpm forever without fail. With good lubrication, proper jetting, sufficient cooling, they will run forever. And by good lubrication, we ran synthetic oils in the race motors simply because of the heat and rpm issue. The SST120 class is carbbed, so we played with jetting and timing, your EFI motor adjusts the air/fuel ratio and the ignition timing automatically. So you only have to worry about cooling and lubrication. That is why I would install a water pressure gauge and HAND mix the oil. I do not trust ANY oil injection systems.
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Thanks. Great info. I do have a water pressure gauge. What kind of psi should I be pumping? Are those gauges pretty accurate/consistant?