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You're down on revs. Should be closer to 7,600rpm. Those last 600-700 revs will amount to some considerable speed. For reference, with just myself and the dog at 500ft, I can cruise at 30mph around 6,200 rpm or so. 41-42mph comes from being right up around 7,550 rpm with a light load and the bimini stowed. With both boys in the bow, the wife, the coolers, the dog and the bimini deployed, we usually top out at 38-40mph. Slight chop is your friend, glass water is always a mph or two slower. You likely can't get to full revs because of the thinner air up at 4k ft elevation. It's about 5% thinner than it is at 500ft. Less mass going into the motor results in a reduction in power. You need to reduce the load slightly by reducing the pitch on the impeller, to get some more revs. Because fluid dynamics isn't linear in terms of pump flow, it works out that the revs are more important than the pitch in terms of generating pressure. SO, pitch down a bit, get the revs up and you're likely to see some better speeds.
) I would suggest taking ALL of the spacers out of the L13 cone, and seeing what that does for you. Good chance it won't "hook up" quite as well on the initial take off, however you might get some revs back on the top end. I've found that you can overload or "stuff the pump" a bit if you have all of the spacers in. This reduced my revs by ~100-200 on the top end. I pulled one spacer out and got those back. pulled a second spacer and started hitting the limiter, so I put them back in. It was a subtle change, and won't get you to 35, but might help a little along the way.You're down on revs. Should be closer to 7,600rpm. Those last 600-700 revs will amount to some considerable speed. For reference, with just myself and the dog at 500ft, I can cruise at 30mph around 6,200 rpm or so. 41-42mph comes from being right up around 7,550 rpm with a light load and the bimini stowed. With both boys in the bow, the wife, the coolers, the dog and the bimini deployed, we usually top out at 38-40mph. Slight chop is your friend, glass water is always a mph or two slower. You likely can't get to full revs because of the thinner air up at 4k ft elevation. It's about 5% thinner than it is at 500ft. Less mass going into the motor results in a reduction in power. You need to reduce the load slightly by reducing the pitch on the impeller, to get some more revs. Because fluid dynamics isn't linear in terms of pump flow, it works out that the revs are more important than the pitch in terms of generating pressure. SO, pitch down a bit, get the revs up and you're likely to see some better speeds.
Now, to get you the revs you need, you need to go to a "shorter" pitched impeller. What exactly that pitch number is, I'm not sure. I'm a bit out of my depth on the numbers and what changes what for which elevation. You see, I'm going into my 8th season, and I've never had the pump apart on my boat. I'm still running the stock impeller. I've heard it's an easy switch, but I've not personally done it. I do know that I've read nothing but good or great reviews from people that have worked with Impros. I forget the guys name there, but several forum members have had them either repitch the stock impeller, or they've purchased a new one from him, and swapped it out. I would call and talk to them. Tell them the situation, and see if they have some advice on which impeller is best for you.
In the mean time, while you're waiting for a new impeller to come in (We love spending other peoples money around here
I can't stress this enough. ANY weight in the bow will kill performance on this boat. Couple years ago I did an experiment during a group outing. In the morning, it was cool and everyone sat in the back. Had 4 adults, and the worlds largest Yeti cooler on the upper deck of the swim platform. We ran a solid 42mph out to the cove. On the way home that evening. Same 4 adults, but ladies in the bow, and the cooler about 1/2 empty (drained the melted ice out, and most of the beer was gone), and we only got ~38mph. Ladies got cool, so they moved to the back. Almost instantly picked up to 42mph again. They weren't large ladies, but moving ~300lbs from the bow made a significant change in performance.
I can't remember when they changed the hull on the 190's. Mines a '17 and I KNOW it has the previous generation hull. I *think* you have the new hull on the '20 model. There was a marked decrease in top speed when they changed. I'm unsure if it was hull shape, or if the boat just got heavier in general, but I remember there being some discussion about it. SO, you might not ever see 42mph, but you should still see mid 30's or so I would think.
Finally, check out this thread I made a few years ago. This was probably the single best mod I made to the boat to reduce cavitation. This sealant keeps the interface between the intake tunnel (fiberglass), and the ride plate (aluminum) from leaking air into the pump. That area is under a slight negative pressure, and the air leakage in from the interface will contribute to cavitation. Reducing that leakage was a significant increase in holeshot and top end "grip" on the water.
Between the L13, the sealed intake tunnel, and the ribbon delete (spark arrestor removal), my boat isn't really a ton faster, but it's MUCH more consistent. Loading and balancing is less of an issue than before, and it tends to perform just as well in the summer as compared to the cool spring/fall. Fore/Aft loading is still a consideration, however that's more of a trim issue than it is a traction issue.
If there's one thing you'll learn about this particular forum.....it's that we like to talk about our boats
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