Maximizing Thrust and Traction in the Water
Jet ski racing update: Now, that we’ve found a little bit of horsepower, we need to start getting El Paso Jet Ski Racer Ricky Trevizo from Point A to Point B faster. Since Ricky races his Sea Doo RXP in an unlimited class, the race comes not down to not only who makes the most power, but who can maintain traction.
Not unlike our experiences with drag racing, if you apply too much power too fast during jet ski racing, you lose traction. In water, the flow off the impeller of the jet ski “cavitates.” Small voids form in extremely low pressure areas behind the impeller before the water can re-coalesce as an uninterrupted liquid flow, resulting in turbulence and loss of power — with a coincident loss of speed.
Cavitation is the Enemy of Speed
(In submarines, cavitation creates underwater noise — the crashing of the water globules together as they re-coalesce — which lets subs be tracked by sonar. In both high-speed industrial liquid-handling equipment and in racing, cavitation causes metal fatigue around the moving parts exposed to cavitation.)
One of our goals for the test session was to establish baselines for the data so that we could begin to identify what is “normal” and begin adjusting the MoTec ECM to identify when data is outside the normal parameter and eventually take some kind of action.
Our other objectives were: Add electronic boost controller; hard wire fuel pressure/fuel pressure gauge; install new fuel pressure regulator, only if necessary; collect data on new twin impeller design; accurately measure rate of acceleration; implement ambient pressure, spark and fuel correction (this will automatically adjust the tune based on altitude for the lake being raced).
Ricky heads to Lake Dallas to compete in the unlimited runabout class July 2-4.
This Motiva Performance Engineering white paper lays out the results of our testing at Elephant Butte Lake, N.M.
Motiva Picture of the Day
Here’s
the Motiva picture of the day, a shot of a section of 4-inch diameter aluminum tubing fabricated by Motiva’s fabricator, Brandon 
Reed, to ensure that this 900-plus-hp zoo doesn’t blow its boost anywhere but into the engine. That’s part of what makes Motiva special. When we need a part, we can make it. Not just make it but make it as well as it could be made, which is why we say we make the best better.