80 mph 24'
 

What's it take to push a 24 foot to 80 mph-ish, hp wise? That's my goal for this winter project. I don't think mines much more than the 330 stock or 350 depending on cam, carb, etc.. Also, can a stock bravo handle the hp required?
Thanks for the help.

Also, hesitate to ask this, cause this is going to show my ignorance... but can the bench seat be removed, extend the engine bay and stagger a pair of small blocks on a 24'??? Thought that would be sick.. with a 3 man race bolster. kind of a mini-old school race boat.

IMO where I am located it takes at least 550hp to run a consistant 80. I'm in freshwater and about 1300' altitude.

In salt water at sea level it would take less. And for some reason Jo always seems to squeek another 1-2mph out of them! :D

I guess with enough $$$ anything is possible! LOL

But I think a bad-azz BBC with a beefed up Bravo will put you faster than most care to go in a 24' boat!

Twins are kinda much for a 24.
You could just sqeeze that config in a 28.
BTW I had 560hp 550tq and best i saw was 75.
I believe ziemer is running it now damn close to 79.
Engine probably has 140-150hrs??? probably just breaking in.
I had the bravo 1 beefed up w/ XR internals.

Absolutely, no question, less cost, less maintenance, easier to do... i.e. no modification to the engine bay. It's just for conversation sake. I was thinking about it the other day and wondering if it was possible. I like the old school race boats, like the 41 Apache's, or 35 Pantera with the 6 man bolsters... and I unfortunately have offshore race boat tastes with a Bayliner budget.... if that even...

I tried to do a search on here to see if anyone else asked the question, but didn't find anything.

BTW didn't mean to bring up 41 Apache on here... seems like that is a sore spot.

Engine is right at 125 hours after this weekend. ;)

I think 80 is possible with the current engine, but it won't be an everyday occurance. 75 is a solid number for how it sits. Earlier in the year it ran 77-78 with the wife, kid and I at around 5800 +/-. Right now in this hot a$$ weather it won't duplicate that number. :p

If it were me, and I were building a motor to take me to the 80 mph mark, I'd round it off to an even 600 HP. :cool:

BTW, mine is an SE model. The sport version is a little lighter and would most likely get there with less HP.

OK good stuff. What are we talkin money-wise for the XR internals? Trying to figure out a budget for this project.

I also plan to buy a new alum trailer too. My EZ loader is a POS.

BTW mine is a 1980 24' Sport

Damn dude, we've got a lot in common - right down to the same year 24 Pantera.
I just picked mine up a few months ago, and already working on freshening the motor. I'm not shooting for 80 though.
I've crawling around in the bilge for the past few weeks since the motors out. Sure, you could pull the back bench, but it's gonna be cutting and glassing - and a big project.

I plan to pull the motor in the next few weeks and give up on rushing to get the boat in the season since we are pretty much shot. Football season takes most of my time, but hopefully soon start digging. I finally completed my house so I have a large garage now to work in. If I new more about glassing I would be more apt to take on the staggered project, my knowledge is pretty limited. Engines I can do, but glass work, I need to learn a lot more. ...I just had visions of staggered small blocks with split engine hatch with scoops... center drive, 3 man bolster set up... but since I've already got a BBC to work with probably set those plans aside for another project.

I just bought the boat a year ago and I'm just now finding time to work on it. It looks like the engine has been pulled in and out several times and the rigging job by whoever is not up to my standards. I'm an engineer with a bit of an OCD problem... I like clean rigging jobs.

If i were you....
I'd buy Dude's 525 he just listed in the swap/shop.
Sell yours for whatever.
I paid 2500 for my internals, but i got hooked up by my builders buddy down at a big factory in NC.
So i have no idea what it'd take... are there any XRs for sale in the swap? or classies?

And dont forget FULL Hydraulic Steering to the helm, or just forget about it.

AND... this wont be cheap, and dont fool yourself thinking it will be.

5500engine + 5000drive + 3000steering

you may be able to get away w/ just an xr upper.
i'm sure plenty here would chime in on that.
you could also not do much to your drive and risk it.

oh yea... and don't forget an exhaust to go w/ that engine... $2500.

Now.. you ready to stay at 63mph?

I think I have full hydraulic steering already. Just not all of it installed. ...but agreed it is needed.

I may have the engine taken care of... unless I decide to buy one complete. Either way it is going to cost some bucks. A buddy of mine's uncle owns a speed shop down in Little Rock. I need to get ahold them sometime to see what it is going to take to push the 550 to 600 hp bubble.

Probably a pretty lofty goal. 13k added to the 10k I have already in my boat. ...and I won't be seeing that again.

careful of who you use to build the engine.
1. if not a marine guy, will not know how to build for marine use.
2. if not well known, could hurt resale.
2a. Gellner is in Ohio, probably just as far as Little Rock.

Good luck and keep us posted.
We've all been in the same boat as you.
never be afraid to post on here... misery loves company. ;)

...you're raining on my parade... or being a realist...

Exhaust = check
Steering = check
Engine = 5500+/-, I've got heads already, thinking of punching it to 468 and with a good port job. hydraulic roller, flat top pistons, 8.75 comp. Balance cast crank for now...
Drive = 5000+/-
Trailer = 3000
---------------------
Total = 13500, 10 was my number. If it wasn't for the damn trailer...

....BTW, really kind of makes you appreciate/respect the 80 mph boats even more. You guys out there running 90+ ...my hats off to you...

You've all been great help to me. I was really looking into the "cough" shogren boat, 80 mph already, but I just can't swing the 49k even though its a great buy. I'd be scrambling to sell my boat and probably couldn't get what I paid for it a year ago. It just didn't make sense.

I like projects more than turn key anyway kind of puts you're own personality into the boat. And realistically, Kansas boating you don't need a 28 footer most of the time, its just the occasional LOTO or Grand lake 2x year, I'd like the extra length and the WOW factor never hurts either.

With 525hp you could get away with your stock Bravo IF you were easy on the holeshot and good with the stick.

...yeah I'd think you're right. but I'll be straight forward with you guys I don't have a lot of experience with offshore boats... I'd like to blame my heritage of being a Kansas native, and about as far away from big water as you can be...but I won't...

I've owned a couple of 20' bowriders in the past, some I've had quite a bit of money wrapped up into them new, but that's like comparing a Ford Taurus to a 69 Firebird to how they ride and drive.

T-Mone on here has a 24 with somewhere around 600 HP and he runs right around 80 I believe. I'm sure he'll chime in son.

I run with T-Mone 3-4 times per year. He has a 600HP 502 hooked to a stock B1 and has not blown it yet. No one runs harder than Anthony, believe me. He ran it for 3 years and I think just had it gone through. A newer stock B1 will hold up fine on these smaller size boats. I suggest you just buy a spare drive rather than spending the $$ for an upgrade if your drive is in good shape. I bought Storm's old upper for my spare.
As for HP to reach 80mph, I agree 550HP should do it. Remember torque matters too. A 550HP/454 is not the same as a 550HP/502. The 502 cube engine is going to get your there quicker and more often...

Yup, 80 any day of the week running a 5 blade prop.
Faster when he runs his 3 blade.
And even faster when he trys the 3 blade that BBlades is working for me right now...:D

...You make a good point about 550 w/454 vs. 550 w/502. maybe the right question is what torque is needed to reach 80...

Regarding drives, can an XR directly replace a B1? Is the X, bolt pattern, etc... the same? I think for me until I get more experience, I'd better do something with the drive. I have no idea on how many hours are on it and what kind of shape its in internally. I'd hate to spend the money and time on the engine and pop the drive on first launch.

Not trying to rain on your parade, even though i might be.
I've just done it already, and i believe i did it right.
The boat is on its second owner since me.
From what i know, neither have had any problems w/ the engine or drive. OK... ernie had a prob w/ the water pump.:rolleyes: just keepin it real.

And yes, if you care for your bravo, you should be fine.
I upgraded cuz if it blew, i'd never hear the end of it from the mrs.. so it was cheap insurance.

Rob, I can do better than $5,500 on my 525 and you'd be able to recoup some of the cost by selling off the motor you have now (thanks for the plug Stormrider!). The thing runs good, but it's not the right motor for me. I have the opportunity to run for extended periods of time at WOT with that motor (based on the mid 60's speed it will push my 28). So I decided to get something with a bit more heat so that I can run 65 further down in the RPM range. The 525 was perfect for the rivers and lakes that Griff ran it on.

As I recall, when Ironman had 500+ hp in my old 24 (now Bouyhunter's boat) and I thought it ran real close to 80 on Lake George. I'm guessing that running a stock bravo with 550 to 600 hp shouldn't be a problem. The boats are so light compared to a 28 and there are guys running near a thousand hp that aren't having any trouble with a bravo.

Just have the drive gone through, and learn how to properly take care of it.
There are a few here i'd listen too.
Like those running 900+hp w/ bravos having luck. ;)

Really?? That makes me feel a little better about my Bravo. But I think its worth checking out the parts on it.

I'm not married yet... but its coming. So at least for the moment I'm my own boss... LOL.

Yah, sorry I definately think you should go through it and make sure everything is in order. I'm doing the same with my Imco.

My advice on the married thing is to use a trick play... Blow $70 or $80k on a race car first that you never use... that way when you drop $10k or $20k on a boat that you both use all the time it will seem totally reasonable to her! :D :D :D

Well, it depends on the hp vs. rpm ;) but yes generally that is correct!

Then that means my gear ratio is going to mean a little on top speed too. Another reason to tear apart. i don't know $hit from apple butter, when it comes to my drive.

...not a bad plan. My strategy was to build a new house to appease, ...but little harder on the pocket book though.

Most Bravos are 1.5 and that really doesn't come into play because you can go up or down in prop pitch to adjust accordingly.

I was just giving Pat a hard time. If two motors have the same hp curve then they have the same torque curve, regardless of cubic inches. But, generally a 502 will have more hp AND torque in the mid-range over a 454 and that is what Pat was saying.

so you're saying... "There's no substitute for cubic inch..."

I prefer hp engines with higher rpm, I would like to see 6000 vs. 5800. But that's my car background coming out.

I know I'm splitting hairs here, and it really doesn't matter, but would a 454 550 hp vs. 502 550 hp, be more efficient? I also want to stay around 8.75 to 9:1 comp so I can us regular unleaded...

It's easier to get more hp/tq out of a bigger motor at lower rpm. I personally would want to stay under 5500rpm for a 550-600hp motor if possible. Once you get over 1hp per cubic inch then USUALLY the smaller motor will have to rev higher to achieve equal hp. Which equals less torque.

A 454 that makes 550hp at 5800 rpm will have less torque than a 502 that makes 550hp at 5200rpm. Regardless of cid higher revving motors of equal hp make less torque. And boat motors need torque.

No disrespect, I'd like to check into rebuilding my engine first. But your proposal here doesn't sound too bad at all. Damn nice looking engine. It'd look pretty good resting under my future hood-scooped hatch...

80 is my goal but I'd be satisfied with 75 too. 75 is nothing to sneeze at.

What's a 454 worth, new heads, intake, cam, somewhere bw. 330 and 375 hp?

RPM kills valvetrains. RPM is expensive. It's about efficency though. Any given motor is going to have an optimal operating range. So the key is to find a motor with a optimal range consistent with the application's parameters.

As OSP mentioned, HP is really a function of RPM and Torque (can't remember the formula, but that's what the internet is for, eh). Seems like, in a boat, the operating parameters dictate more torque in a reasonable range of RPM operation (3,500 - 6,000 I'm guessing). My small block makes peak power between 7,500 - 8,200 rpms. But that's because it doesn't have much torque!

My rule of thumb on pricing used stuff is about 50% of what it would cost to buy it new.

I've heard that with the 24s, 75 is a nice quick ride and 80+ will turn your hair white (unless your last name is Nunez :D ).

Mine only ran low - mid 60s so it was no sweat most of the time. Flat out, trimmed out with a good bump going, you did feel like you were really driving the thing!

...now you're making me look back to my IC engines class books...

I'd say may application would be cruising mostly at 30-45 mph with an occasional WOT blast, to knock off a couple of bow riders and jet boats etc...lol Running 80 mph across a 5 mile wide lake, I'd be across the lake in little over 3 minutes...

Hey me too. :eek:

Damn that sea strainer valve. :p :p

:hitfan:

HP= torque x rpm/5252 :D

I knew that there was an rpm number where the hp and tq were always equal due to the denominator, but I couldn't remember the number!

Oh and Rob, a house isn't near irrational enough to desensitize her!