Re: Engine Shop
 

That one hits home. I didnt tell my wife a thing, when I upgraded my power. However, she did figure out something big was going on when I spent the entire winter in the garage. She never ventures out there, so I was safe from prying eyes. The first time I fired the engine up in the driveway, she thought something was up with the extra noise. I made up some B.S. excuse about it sounding louder because it was echoing off the house and garage. When she came out for her first ride, I had alot of b.s.ing to do. :eek: I got away with it. :D Remember, I am running full dry CMI's with GGB Extreme mufflers. :eek:

Re: Engine Shop
 

Nice save! Mine doesn't say a whole lot about the noise, I think she may even like it. I rarely ever use my captains call. I would rather not have it.

Re: Engine Shop
 

Keep upgrading those motors. Between the motor and the wind noise at high speed, you won't hear a thing she says.


Until it breaks at speed and she is yelling "what was that!" as you coast to a stop dead in the water.
Just be sure the boat is stable at all speeds and she will never know how quick you are, right ?

Re: Engine Shop
 

I agree with the need for stability. Thats more important than running fast. Anything can run fast. Most waverunners are fast. But, running fast, safely in rough water is alot harder to do.

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Well put, running fast safely in rough water is something that takes time to perfect.

Re: Engine Shop
 

Dyno sheet says 461HP at 5100rpms and 514lbs at 3700rpms. The speed of the boat went from 65.0mph (GPS) at 5100rpm spinning a 23 Mirage Plus to 72.3mph (same handhelf GPS) at 5000rpm spinning a 26 labbed. I am very impressed with the speed increase (feels like a different boat at all speeds), but the dyno numbers seem a little soft to produce such an increase in speed. Any thoughts?

Re: Engine Shop
 

I was told 17-20 HP is needed to pull 1 additional MPH @ WOT. Tyler Crockett mentioned most of the stock fuel injected 454MAGs that he has dynoed pull between 370-380 peak HP. Let's say our boat had 370HP to start with and now has 461HP. That's a difference of 91HP. 91HP divided by the 7mph gain equals 13HP. We used the same hand held GPS and driver(me) that we always have on the boat. Don't get me wrong I am extremely happy, but just curious on how the hell that happened.

Re: Engine Shop
 

Rob,

I dont understand those numbers either. More power to you if they are right but the facts are below.

(((pitch x rpm) / ratio)) / 1056= theoretical speed
Then add in slip.

your numbers are as follows, assuming a 1.5 ratio drive..

24.5 x 5000= 122500
122500 / 1.5 = 8166.66666
8166.666 / 1056 = 77.33
So 77.33 is theoretical speed without slip factored in. If you are actually running 72.3 then your slip is only 6.5% . That would be great . Unfortunetly, most likely impossible. Here is a for instance.. I am running a Hydromotive P5-X and am getting 9.5% slip.

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Vinny,
Thank you for the formula. If you plugged in 26 for the prop pitch 72.3mph would equal a 12% slip, maybe more realistic. I hope to do more testing this weekend. Out of the three variables that are plugged into the formula rpm, prop pitch and speed I have the most confidence in the handheld GPS unit. The tach is the orginal unit that came with the boat and the prop was borrowed from a friend who recently picked them up with the purchase of a boat. The prop was given to me in a box that appeared to be a labbed finished prop from Mercury.

Re: Engine Shop
 

Rob, part of that additional speed is realized from the more efficient/larger pitch prop. Don't question the MPH Gods, just enjoy!!! You've already got Wally talking Pro Chargers!