Boat speed 24' 454 king cobra 45 mph

[HT32BSX115]

Re: Boat speed 24' 454 king cobra 45 mph

I like where the pump is because it is just so easy to work on...

Just checked it's 1.42 to 1.



It feels fast, my buddy with a 22' 454 bravo III 24p said it was faster than his... That was a seat of the pants feel when we had the rear seating area out with the engine showing for a test drive after we fixed the floor.

I thought that 45 with all that weight and me not knowing how to trim a OD was pertty darn good

Yeah. The engine mounted pumps are great.....easier if on the back of the drive though.... He'll have no problem doing the engine mounted one if required.....

45 may be all you get but you won't know for sure until you have accurate speed and RPM. It sounds about right.

Your buddy with the Bravo III probably has either a 2.00:1or 2.20:1 drive.

trimming is completely experimental........meaning just set your RPM and trim it for best speed. You have to operate the trim in small "bumps" to find the "sweet" spot. It will be different for different speeds and the gage is useless. you do it all by "feel"




Mine is a 1.81:1 and at 4400 with 26p props I get about 55 mph. I did get 57 GPS at 4600 but I'm not turning 4600 now for some reason... (I was pretty light when I tried it)

With the 24p props I did 55mph at 4600+ and it felt like I was up "against" rev limiter so I tried 26p props I bought from ebay.

I know it'll be fine when I put the stroked 502 in it!!!!! I should get 5500 RPM then!!

TOO MUCH IS NOT ENOUGH!!!

 

[sethjon]

Re: Boat speed 24' 454 king cobra 45 mph

All I can say to you is that you probably have never done any racing. Every time you go out you make slight tweaks and see what works best. I said teaking not anything radical and going up or down 1" on a prop is almost like not changing it at all.

 

[bigike]

Re: Boat speed 24' 454 king cobra 45 mph

UPDATE,

Fixed the OD, the issue was worse than i expected. The bellows lip was destroyed so i took a 4" piece of exhaust pipe and expanded one end to fit over the gimbal bearing housing. I heated it up, applied JB Weld to the housing and pipe and hammered it onto the busted area. After that i applied a liberal dosing of Permatex Great Stuff to the outside and inside surfaces.

Because there isn't a lip groove in the pipe i applied a lot of great stuff to where the bellows would connect smoothed it out and let it set up. Great stuff dries into the material they make o-rings out of. I then flared the end of the pipe to keep the bellows from slipping off...

The Gimbal bearing, bellows, and u-joints are all readily available as are many of the parts.

So installed the 19p Balistic prop and with my family of 4 (I'm 300lbs) my Sis inlaw, niece, 2 large friends, the 3 person tube, a full cooler and 50-60 gallons of fuel she did 48MPH on GPS!!! I really need to get her out on the water alone or with my buddy again to bare witness and hold the phone. We were running 5700 RPM now. I've only checked the tach at idle with me snapon timing light and it is spot on.

Rick, she jumps on plane with this 19p, i'm going to run a 23p 4 blade maybe or stay with a 3 if the 3 doesn't hurt my bottom end too much and i think she would give you a run for your money! Big Daddy KC vs Bravo 3 Battle to the death!

Jay

 

[QC]

Re: Boat speed 24' 454 king cobra 45 mph

All I have to add is that the tach is still off. Must verify that. No way you are seeing 5700. Rest of the numbers look great! Thanks for the update.

 

[HT32BSX115]

Re: Boat speed 24' 454 king cobra 45 mph

All I have to add is that the tach is still off. Must verify that. No way you are seeing 5700. Rest of the numbers look great! Thanks for the update.

Yeah. I would get another tach and verify that. You might be turning 5000 (but if you still have the Spitfire ign, I think not. I believe it has rev-limiting built right in)

But I would try a couple of different tachometers to verify. MANY tachs are just not even close at upper RPMs.....

5700, 1.42:1, 19p and 15% slip would yield 61 mph. OTOH, 4600 RPM, yields about 49mph (calculated) That engine is not going to push that boat 61 mph. (unless you stroke it and install a blower!)

If you put a 4-blade 23p prop on it, your hole shot will suffer and you may not even make it to 4000 RPM.......that'll be lugging that 454 "for sure and for certain"!! (as once said by Mathew Quigley!!)

 

[bigike]

Re: Boat speed 24' 454 king cobra 45 mph

Yep i got to check the tach fully, but that boat is weighing around 5500+ lbs with all the gear and people in it. That will bleed a ton of speed.

454 is plenty of cubes for power, no need to stroke and poke, a whipple would be nice, had a 3.3 on my SRT10. She was beast.

 

[QC]

Re: Boat speed 24' 454 king cobra 45 mph

Speed needs to be GPS, and tach has to be right. Without that we are guessing.

 

[bigike]

Re: Boat speed 24' 454 king cobra 45 mph

Speed is GPS, the pickup for speedo is broken. I need a new one of those too. Think i'll get a el cheapo sun tach when i get home, hopefully soon. This rig is less than ideal...

 

[HT32BSX115]

Re: Boat speed 24' 454 king cobra 45 mph

Speed is GPS, the pickup for speedo is broken. I need a new one of those too. Think i'll get a el cheapo sun tach when i get home, hopefully soon. This rig is less than ideal...

If you're doing 48 mph at WOT with a 5500lb boat, I would say you (only) have a tach problem. Your prop is just right and the engine is turning at the "right" RPM.

 

[bruceb58]

Re: Boat speed 24' 454 king cobra 45 mph

Sounds about right to me too since I get similar speed with the boat in my signature.