Best Drive for high power heavy 27' application??

[Maxumus]

Originally Posted by Uncle Dave

Agreed on cubic inches-

More is better and if big enough you can take on a big bumpstick and still have a mellow powerband.

Agreed on quality of parts as the TRUE path to sustainable high horsepower- I'm a brodix/AFR fan.

Hook and rocker are hull shape issues that cause porpoising and bow dive at speed. Your not exactly running a performance hull and its likely its not straight and true. when you have the engine out run a straight edge along the bottom and see how true it is.

Youd be surprised at how much power the imco and teague XR versions can take and what poeple have behind them lots of guys running blown big blocks on these drives. that said the beefier units are better especially with a hull that weighs that much - but lets see how much money you have before we commit 20+K to a drive.

Lightning make a SUPERB product - good choice and they know their They'll help you pick a cam.

Engines- we agree. Good heads and top end combo go a looooong way.

Trim Tabs Kiekhaffer K-planes (or similar) will stop your boat from chine walking at speed. You'll have a short heavy v with a lot of power and these will keep it stable. The longer the better.

Keep us up to date on this project - sounds like a blast - it's my favorite formula.

Boat+ money=fun

UD

Boat plus lots of money equals even more fun right.....LOL

Truth be told, Im actually the head of R&D at AFR cylinder heads (so I guess I would be partial to that brand!), but once again we seem to be on the same page....LOL.

Im putting the finishing touches on a new BBC head we are going to offer that is really going to get the job done. Its around 370 cc's (big but not huge) but flows in the 450 CFM range and does it at a usable lift point (.750 ish.....it clears 430 as early as .650). Killer piece that I plan to showcase on my 615 CID BBC destined for this boat. Still havent decided whether Im going solid or hydraulic roller....I think I could tap close to 800 even with the right hyd. set-up because this engine will be done by 6000....exactly where a hyd. roller starts giving up the ghost.

Anyway....it will be pretty cool and the ramifications of this new head design on other applications is even more ridiculous. I bet Teague picks up 50 HP when he swaps our 357's to this new head on his blower combo. I wouldnt fall over if they were worth even more on the big HP quad rotor set-up he has.

I will google search those tabs you mentioned and keep an eye out for a good deal on a strong drive. I think the fact others get away with the beefed up Bravo's stems from less weight.....boat just accelerates instead of breaking parts first. Now I will have enough grunt to accelerate the boat but we are fighting the laws of physics and the only thing in between the crazy thrust and a good prop biting water is all the components of the outdrive. No different than a heavy car breaking **** that a lighter car scoots down the track without issue with.

Before I drop 20 K though I might look for a good deal on a beefed up XR and try to be easy with my throttle. I would spend 10-12 though before grenading 5K on the XR if I run into the right deal on a Bmax, Konrad, or equivalent. Time is on my side as this project wont start till this winter and likely drag into the spring/summer of next year before its all said and done if I had to guess.

I will be boning up on high perf boat dynamics and components in the meantime....LOL

Regards,
Tony

[HTRDLNCN]

Have you spoken with manufacturer to get an idea of structural problems that might arise?
I looked up your boats specs and found that the biggest engine offered is the 6.2 small block. Most cruisers in your size/weight range offer the 496 as an option.Maybe there is a reason they only offer the small block in your boat. Maybe not but cant hurt to find out?

[Rik]

Originally Posted by Gimbo007

I say Konrad is the best sterndrive for your application.

About the Arneson Drives, I think they aren't a good choice for your boat, but you could try with other surface drives like JollyDrive.

Please explain to me the difference? The Jolly Drive is nothing more than a copy of the Arneson so why would you want one over the other?

Maxumus, I think you actually might run into the law of diminishing returns with a hull that was not designed to go fast. A lot of hp does not always equate to a lot more speed if the hull is not good.

The most important part of your equation is the hull itself.

[Maxumus]

Originally Posted by HTRDLNCN

Have you spoken with manufacturer to get an idea of structural problems that might arise?
I looked up your boats specs and found that the biggest engine offered is the 6.2 small block. Most cruisers in your size/weight range offer the 496 as an option.Maybe there is a reason they only offer the small block in your boat. Maybe not but cant hurt to find out?

I dont think my boat was ever meant to be a powerful cruiser.....just a cruiser but its isnt a lightweight, seems well built, and it was offered with a 7.4 liter in 2000-2002 (same hull essentially). BUT, it was anemic rated at the same HP as my 350 Mag....but obviously had alot more torque. I think the BBC versions of my boat went in the high 30's to low 40's (MPH). My guess is they turned a steeper pitch prop and perhaps had a 2.1 or a 2.0 drive ratio to my 2.2 version.

Not sure....all speculation but I know they they definitely offered the BBC engine up to 2002 because I almost bought an 01' with the BBC factory installed (had waaaaay more hours and wasnt as nice as the original owner 03' I eventually purchased with only 40 hours on it back in late 06').

Originally Posted by Rik

Maxumus, I think you actually might run into the law of diminishing returns with a hull that was not designed to go fast. A lot of hp does not always equate to a lot more speed if the hull is not good.

The most important part of your equation is the hull itself.

Rik....that obviously makes sense and Im sure i will be pushing alot more water than a boat designed for speed but if I had a boat designed for speed (even the same weight) my guess is I would be in the 80 MPH range.....even a little more perhaps? Wouldnt the fact I go close to 40 now with only 300 HP and marginal torque indicate the hull isnt to bad a design? Or do you throw all that away at 60 MPH?

I just cant help but think 800 ft/bs will turn a seriously aggressive prop and at some point even this much weight is going to want to run like a scalded dog of sorts and I would think the hull/prop efficiency would improve with the additional power because more hull will be out of the water Im guessing.

Im sure that manufacturer will warn me Im crazy and going to kill myself.....yadda yadda. Who knows....maybe the boat will be a handling nightmare and the hull design will kill it....or maybe its just the ticket this fat lady needed....LOL We shall see but that makes it more exciting. I have a good hunch (hope!) it will handle the power well.....seems big and stable at speed now and Im not going to be anywhere near triple digit speeds.

If this ever gets off the ground how fast do you guys think it might go with a good aggressive four or five blade single prop on it?

-Tony

[Rik]

For your own benefit and possibly safety, you need to find like minded people with the same boat. Meaning who has the fastest one of these hulls and make a call to see how fast that is and what were the complications if any.

No one know anything but this could be the best boat in the world and the power wakes it up. Then again it might not be and it might become squirlish above 65.

Research, research research.

[waterboy222]

Do you plan on running your generator while at 60+ mph?
How are you going to route your exhaust?
Definately look at the hull and see how straight the bottom is or you could have a VERY dramatic ride ahead of you at 60 mph.

[HTRDLNCN]

I was thinking more along the lines of Transom and stringer integrity.
800+ ft lbs pushing a 7800lb boat has to put a LOT more
stress on the hull than the 450ft lbs the 454 you say was offered made made.

[Pure Energy]

We all understand your desire!!! But that is the wrong boat for that kind of power. With this type of project, it will cost 3 times more than what you plan for, it will take 3 times as long to put it together. The boat is not going to like it. Then what do you do, sell it, put it back to stock? Why don't you build up the current motor, or swap it for a better small block? 100 hp would be night and day in that boat, 500 more will be a disaster!!

[Maxumus]

Appreciate all the opinions....maybe I will put a baby cam in and shoot for 775/750....LOL

To be honest, I have been thinking about going with a slightly smaller cam....as most of you have pointed out the boat will have plenty of power with that much displacement anyway and I wouldn't mind it being a little smoother at lower RPM's either.

The torque output wont really change much and I still anticipate 775+ ft/lbs. and maybe around 750 HP with less cam duration producing a very potent smooth combination. I will probably dyno the package with a semi aggressive solid roller that might be more associated with a performance automotive build (or go fast dry exhaust marine package) and then finish the testing with the smoother wet exhaust marine friendly hyd. roller stick that I will ultimately run.

Im pretty much set on moving forward with this project and while no one can guess the outcome, I have hopes it will end in mostly smiles all around and a good functioning package. All of the water I would be playing on would be smooth but if I sense some uneasiness in the way the boat handles a certain speed I will simply chip the MSD box lower to keep the speed limited to a safer number. That still affords me a much lower RPM cruise speed at figures I currently need WOT to attain....not to mention get up on plane a whole bunch faster and lose the underpowered feeling that is my biggest complaint with the current set-up.

Should be interesting so keep the flow of ideas, suggestions, and concerns flowing!

Thanks guys

Tony