Guys, thanks for all the time and the input. Tail Gunner- per your request:
No moss, waxed surface, F.A.S.T TAB 2010 Crownline Hull
GPS, into and with wind, 50 MPH
Several Prop, Prop ID and Lower Unit, Lower Unit Model Ratio numbers Closeups attached:
1. We are experiencing a pop- sounds a little like an empty metal paint can being struck with a wooden spoon- loud enough to hear at WOT, WOT by the computer says it is happening consistently at 5000 RPM. Throttle seems to have linear affect on engine up to about 75% throttle, after that it begins to pop- with small hesitation- but seems pretty constant speed. When this whole thing started we investigated and discovered a tuliped valve on one of the cylinders and a burnt plug on another cylinder. There was only one exhaust valve affected- we are concerned it is pre detonation that is the cause?? We want to avoid this issue again obviously- which is why we want to make damn sure the pop is the rev limiter and not due to a lean fuel issue. The low pressure was tested at 8 psi and the high pressure was at 46 psi. SLIP- how can that be improved- I wonder what "spec" might be? Is this really a prop issue? What size/type prop? I want to stick with stainless, decent hole shot, like to maintain a WOT in the high 4k rpm, with a 50+ mph, maintain efficiency and control- whose making the best prop for that?
2. Stainless, 21P 14.75 Volvo Penta OEM- model / ID in attached pic:
3. Attached pic:
4. Per the computer WOT is 5000, helm RPM is 4400- it doesn't sound like 5000 rpm but the computer is probably more accurate? I would bet 4300 lbs with the gear and myself, full tank
5. 2009 volvo penta 5.0 gxi-j pictures attached indicating exact lower unit, engine model, emission kit, EGC, "carter" fuel pump info, fuel tank info, hull info, two pages of specs data, system matrix info- pictures attached
6. 2010 crownline 21ss LPX, dry weight 3800
Thanks for taking a look...