Quote Originally Posted by larry_arizona View Post
The only real hard part that would differ is possibly cams and for a engine that you want peak tq at 3500 rpm, I doubt they changed the cams.

Most of the power gains would be from tuning (timing and fuel mapping) to take advantage of higher octane fuel. Also by raising the max rpm (5300 vs 5000) they get some extra HP under the curve.

Going from 89 to 93 octane would easily allow 3-4 degrees advanced timing and that is about 10ft lbs per degree of advance.

I know the 450 will run on 91, but it loses some power as knock sensors would have to pull timing.

Also correct on skiers using a slightly restrictive exhaust and losing some power from the 460.


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For my own knowledge are heads not considered a "hard part" on a motor? (I only ask for my own knowledge so I don't sound like a fool lol) Also in you digging did you find out if the heads are different as well? I don't recall if it was my dealer or Indmar that had told me that, could have been my dealer and they might have meant the intake manifold. I could see the sales people mixing that up especially since I think that was the first year they offered the 450 (MY2019)

Is it possible that they got the power rating for the motor using 93 octane as you said but then say it is "safe " to run or is "approved" to run 89?