I posted this over at scream and fly, but I just wanted to get the general consensus here<br /><br />I have an '82 Mariner 90 hp I6.....the owners manual states that the rpm operating range is 4500-5000 rpm. Talking to the local merc guy here he recomended running it in the mid 5's range ideally 5300-5400. I had to show him in his own shop manual what the recommended range for the 90 was, I guess he is used to the 115 - 155's.......anyways, would it hurt this engine to prop it above 5000...would I gain anything? I know the info on these 90's, supposedly equal holeshot as the 115's just not the same topend.....small ports, blah blah blah.......I run premium gas with 50:1 mix of Quicksilver P+, with max timing of 21 deg on the starter. I just dont want this thing to lean out if I push the rpms...The motor is on a fairly heavy 17 ft Aquastar, the prop is a 15 " pitch which is about 4900 WOT. I vented the prop to get a better holeshot, helped out a fair bit, but I wanted to try and run a nonvented 13" pitch prop and see how it was, but there in lies my dilemna, better and stronger holeshot, but the higher rpm...could always trim back I guess, but what fun is that?<br />Anyways<br /><br />Thanks for your help
