I don’t know how applicable this is to ski boat performance and the particular engines currently used, but I am researching new trucks as our current F350 diesel dually is more truck than we need, bought when we were trailering horses from FL to PA and MD and back through the mountainous Shenandoah Valley several times a year. It’s overkill for hauling our Prostar back and forth to the lake over flat FL countryside and expensive to run and maintain. I’m looking at the F150 with the 3.5L V6 EcoBoost engine. I came across an article in Car and Driver where they tested this truck and motor with both 87 octane and 93 octane. Here’s a couple excerpts of their results:
“With the fuel tank filled with 93 octane gasoline, the Ford F150 turned in a 0 to 60 run in 5.3 seconds. It is quite an impressive achievement when you consider that the Ford F150 weighs nearly three tons (5,594-pounds). When the C&D crew switched over to 87 octane fuel performance dipped noticeably. The Ford F150 lost 20 horsepower and half-a-second on the track.”
“Here is a list of the results:
87 octane 0 to 60 run: 5.9-seconds
93 octane 0 to 60 run: 5.3-seconds
87 octane quarter-mile time: 14.5 seconds
93 octane quarter-mile time: 14 seconds
Speed trap findings: 4 mph difference
87 octane shows 1.9 psi dip in turbo response
So what do the findings mean? You don't have to be an engineer to see that 93 octane gasoline outperforms 87 gasoline. To show this more clearly C&D performed a real-world test that proved premium gasoline performs better. They took the vehicles used for testing to an interstate where they set the cruise control to 75 mph. Cruising at 75, the testers found that premium (93 octane) gasoline returned 17.6 mpg. When they changed the fuel to regular (87 octane), they found that the Ford F150 with the EcoBoost powerplant achieved 17 mpg, a difference of .6 mpg.”
Again, I have no idea what this means as applied to ski boats and slalom skiing. But in the original thread on the subject of octane, many insisted octane only affects the tendency for an engine to knock, and had no bearing on the engine’s power or performance. But the Car and Driver testers seem to arrive at a different conclusion for what that is worth.