Looking for more speed

[akuczera]

Hello I have a 83 Baja 190 BR with a slightly beefed up 150 black max. I have noticed that trimmed out and at WOT is spinning at 6500 to 7000 RPMs. According to Mercury, my RPM at WOT should be 5000-5500. My current prop is stainless steel 3 blade 14.5"dia 21p. As I understand Mercury's measuring of the motor height, it measures 25" with a jack plate giving it 2.5" to 3" lift to make the 25".
Now by slightly beefy I mean between the reed valves, cylinder boring, head shaving, exhaust and carb tuning, I was told by the shop that it will have about 175 to 180hp. Now it does launch out of the water like a rocket, and that's good when pulling up three skiers or multiple tubers. Which is what I'm doing most of the time. Though every once in a while I would like to go faster than 55 which is where it seems to top out again at 6500+RPM. I'm thinking of getting a trophy plus series 4 blade 14" 23 - 24p. Was wondering how much more speed I could expect to get and whether or not to spend the money. Thanks for any help.

[Superbender]

Welcome to Scream and Fly.
we are all looking for more
Set up set up set up.
try as many props as you can,try a little more set back,your slip seems a little high probably from over trimming,get a water pressure gauge.for starters
Great looking boat btw

[akuczera]

Water pressure gauge? Sorry not to sure what you mean. I do have a trim gauge. Half red lines half white and set to middle produces highest speed.

[south599]

Your motor is water cooled. The holes in the lower unit are the intakes as your jack your motor higher or trim it enough you have the potential to start bringing the holes out of the water allowing them to reduce water intake by sucking in air. This loss of cooling power can burn your motor up. The gauges read how much water pressure is moving through the engine i think on mercs its around 15psi or above is safe. It can also let you get the longest possible use out of your impeller because you can tell when it starts to lose its power

[Dave Strong]

Sounds like your over triming, slip is higher than it should be.

Dave

[albypine]

This thread has Pete writen all over it for him to help he knows his set up on the black maxes

[panther150]

you need your motor up higher to go faster, as stated above, make sure you add a water pressure guage before raising the motor. A hydrallic jack plate will allow you to have the best of both worlds, height for speed and a little deeper for skiing , etc. when you get the motor up a little higher , you will be able to turn a bigger prop and go faster. you will probably end up with a ski prop and a speed prop. motor height is measured between the propshaft centreline with the motor trimmed parrallel to the hull bottom and the bottom of the hull.

hope this helps a little

Steve

[ar300johnson]

I had the same boat with a 2.4 200 Mercury. I ran a 3 blade Turbo Prop and turned it a little over 6000 rpm. This was 25 years ago and I did not have gps but I believe that the boat would run in the low to mid 60's. The boat would start to chine walk as you reached top speed, but it was easily controlled with small corrections. It was a great little boat and I really had a lot of fun with it. This is a safe, fun hull to learn how to Scream and Fly.