Noko
Jetboaters Captain
- Messages
- 808
- Reaction score
- 508
- Points
- 247
- Location
- Lake Nokomis Wis
- Boat Make
- Yamaha
- Year
- 2013
- Boat Model
- AR
- Boat Length
- 24
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Can I ask what these cost and where you purchased them ?Stock initially but then I replaced them with the R&D antibackfire ones. I used those mainly because they are nonrestrictive and they fit into the stock air filter waterproof boxes.
Increase in Mph is hard to determine, fur th the elements you my mentioned. But increase in rpm isn't effected by water/wind/load, and with increased rpm comesincreased mph.I would have to see some documented and reliable testing to believe 3 MPH increase all else being equal. Water/wind/load would be a bigger factor.
I never paid exact attention to RPM's, but I can promise you at sea level, my wifes ski gained 2-3mph with a ribbon delete. I don't have GPS on hers, but the dreamometer would always top out at 66/67 before, and now hits 69/70. Mine is a carb ski, and always topped out at 62/63 (on the dreamometer for comparisons sake - 58/59ish gps), and I haven't been able to remove the throttle body to delete my flame arrestor as the nutsert in the intake manifold just spins. I've done extensive testing on both (and just broke 50 hours on each), so I'm pretty confident in these results. And it is somewhat surprising, as my opinion beforehand matched yours.My opinion on this is that if you boat at or near sea level removing the stock ribbon and / or installing the throttle body spacers (the r&d versions are called manifold upgrades I think) will not improve top speed or rpms because the engines are already running to their limits as defined and controlled by the ecus. That is these engines are governed / rev limited.
That stated you may be able to reprogram your ecus to improve performance but doing so is not inexpensive. Alternatively if you want to improve acceleration or top speed regardless of the altitude you boat at go with custom pitched impellers but realize that theoretically you cannot improve acceleration without reducing top speed and vice versa.