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Outdriveengine mismatch

T

takemetotheriver

New member
"Ok here's one for the exp

"Ok here's one for the experts, I have an 87 bayliner ciera 2155 with a cobra 800 which originally had a 5.0 engine, the guy I bought the boat from replaced the engine with a 5.7, He never finished it but I did when I bought it. The boat seems to need more power to get it on a plane. My suspicion is the outdrive for a 5.0 has a different gear ratio than the 5.7? which makes the boat sluggish and slow to get up on a plane. I currently have a 15x16 prop, I'm thinking about getting a lower pitch one, maybe a 15x13? Has anyone run into this before? does this sound like an acceptable fix for this possible mis-match? or do i have a different problem?"
 
"You've nailed it on the h

"You've nailed it on the head, I had the exact same problem, what are your rpm's at full throttle? You should be close to 4400 +/-200. For every 2" pitch you go down you will go up by about 400 rpm. So you should be able to get back up to where you need to be by changing the pitch."
 
"or try a 14 x 16 prop or a 1

"or try a 14 x 16 prop or a 15 x14, may be you will get the hole shot back and still have a economical cruis with that setup instead of the gear change. the ratios for the v'8 were fairly close, like sea level and high alt gearing, a prop change may be all you need. If your prop shops are like ours you can rent a multitude of props for retainer for damage that is applied to a prop if you buy one. just a thought. as andy stated, judge on your WOT RPM on pitch, your holeshot can be adjusted with diameter and prop fins."
 
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