Hello everyone, just got a 28 foot Sleekcraft Enforcer from 2007, its got a 496HO. The boats been running on 91 octane throughout the years, is that the right octane? As far as rpms go I need to check up where its getting to, I think it was around 4700 to 5000. Its running on a 24Pitch Bravo 1 Propeller 4 Blade, would changing to a prop such as a Mirage Plus 3-blade help? My top speed is barely getting to 60 mph on GPS, 90F Weather. Its a fast boat just want to know what I can do to make it faster on the top end and maybe some small performance modifactions if needed. Also the drive is Bravo X with a 1.5 ratio. Also curious to know anyone with the same or similar hull what their top speed is. THANKS

Ok Thanks, next time I go to the lake I’ll check my max rpm.

In addition to prop slip, you have to consider hp to weigh ratio. Most 28’ single engine west coast boats weigh at least 5000 lbs with driver and 30 gallons of fuel. The 496 HO usually makes around 385 hp at the prop shaft. Those figures indicate that your boat is doing about all it can do without a lot more hp. It will take around 500 hp to run 70. Sorry for the bad news, but this sport takes lots of hp. And hp takes money. You can google bam speed calculator and play what if. They also have a prop slip page that helps with prop and boat set up. Good luck and have fun. Always remember that there will be somebody bigger and faster so have fun with what you have.

OP, you mention you're running in 90F temperatures, I am in the same conditions with humidity usually in the 70-80% mark.
How much does heat and humidity detract from engine performance and even the boat pushing through moist air?

I haven't had much opportunity to run my boat WOT but with a 496ho and 26" Bravo prop, I've only seen about 62 on gps at 5,000 rpm. I've heard a 27zr should be doing around 70 but maybe that's running very light on a downhill lake with a tail wind. Prop slip for me is over 20%!

Not want to hijack the thread from the op but if the revs are there, what will hold a boat back?

Prop condition, mine is a bit ratty from a previous repair.
Heavy load of people, fuel and gear
Incorrect trim settings (boat riding too high/low)
Dirty hull bottom
Fresh water a touch slower
Humidity

Any ideas to help us with our slooow boats?

RR

EDIT: I'm sure there's hundreds of Sleekcraft's all over the states but spooky coincidence, there's one stored in the marina here near my boat. Had a look from outside and it fits your description perfectly! (In a country with very few go fast boats)

Also anyone know how high up a bravo x should trim up, I have no limiter and it was smooth all the way until a rooster tail around 3/4 trim.

Ok thanks I’ll measure it. What about octane? Any specific octane, boats been running on 91 since day one.

Prop slip at 12% is good but your rpm's are down. Others on here know more about props, hopefully they'll have some suggestions.

If you haven't found it already, here is the BBlades slip calculator
BBLADES - Prop Slip Calculator

https://cimg2.ibsrv.net/gimg/www.off...8d74e49b6e.png

Common knowledge?
I would never have known, thank you. :)

Ok thanks

So do you think a 22 pitch bravo 1 with 15.25 is too small? It’s a 28 foot boat.

Ya, see everyone saying you need a bigger pitch to go faster, but if I’m topping out 4500 rpm on a bravo 1 with 24 pitch then mathematically speaking a 22 pitch should get me a better top end. Right ? Thanks

Makes sense thanks.

Each tank is 30 gallons from what we measured, so 60 combined. What is your top speed btw?

^^