Best Drive for high power heavy 27' application??
 

Guys,

This is my first post so I just wanted to say hello and thanks in advance for any advice or guidance you may be able to provide.

Im in the horsepower business (cylinder head designer/engine builder) and I have a Maxum 2700 thats just dying for more power. Currently running all stock engine (300HP mag 350) hooked to a Bravo III drive with 22 pitch dual props. Boat goes 38MPH on the GPS....40 trimmed with a tailwind....LOL

Project this winter is to install a very well built 615 CID BBC engine that will make 800 TQ and probably low 800 HP at the crank (I will be dyno testing this engine to confirm). I could really use some input on a drive that would work the best and give me a reasonable chance of not breaking if I dont abuse the throttle getting up on plane (I believe that where the drive is probably loaded the most). I am looking for much improved planing speeds....would like to cruise at my curent WOT speed or slightly greater (say around 40-45) and it would be really fun to stretch her legs occasionally at WOT hoping to see close to 70 MPH or so (any input on the likelihood of that with the right set-up?).

Considering it does almost 40 now with only 300 ponies (and probably 350 TQ at best), the new 615 will tack 500 or so on both of these figures....some serious gains. The boat is a deep V hull obviously and not meant for any serious speed and while I really need to weigh it to be sure, I believe with the generator, additional audio/video equipment, and big motor, it will likely tip the scales at 8500 pounds or so.

Anyway....even if it went 60 at WOT but got on plane alot faster and cruised at say 3-3500 at 45 ish MPH, I would be pretty stoked. Not looking for a race boat obviously or i would have picked up something different, just a cruiser that can haul the mail and have all the creature comforts at the same time.

Would love yuor opinion on anything drive and prop related....it seems the consensus so far is a dual prop drive potentially bites too much water thereby is more heavily loaded and easier to break (makes sense) and that perhaps getting the right single prop drive is a better way to go (XR seems popular) for increased reliabilty possibly not getting up on plane quite as quickly as the right dual prop set-up.

Im fairly new to marine performance (heavy automotive performance backgraound) but Im learning quick and alot of the same applies....there is always compromises which I understand. Im looking to maximize my performance goals while trying to minimze as many negatives as possible. Reliability is more important to me than an additional 3 MPH top speed for whatever that is worth....

Thanks for your time/consideration and look forward to your input

Cheers,
Tony

heavy cruiser+high horsepower= Arneson
just my .02c though..
:)

I just looked at their website.....looks pretty heavy duty but Im thinking first born just as a deposit.....LOL

Never heard of them (newbie)....looks interesting though.

-Tony

If you think an Arneson is too expensive, you are going to have trouble with all of the other suggestions that are out there. 800tq is really too much for a Bravo unless you don't mind being towed in on a regular basis and spending 3-4000.00 on repairs a couple times a season. Konrad would be a good choice but they're about 20,000.00 when you include everything. Finding a different boat would probably be the easiest and cheapest option.

The B-Max Ht is rated to 950 HP and 14500lbs and is available with up to a two year warranty. Cost is about $15000 and requires no further modification, a birect bolt on.

I am on year three with mine and no problems. I could break a Bravo at will.

It will swap right in place of my BIII that I have now?

Looking quickly at some literature it looks ideal for a high torque application. How is prop availability....same as the XR props or does it take something made specifically for it?

Thanks for the tip.....this is the kind of stuff that makes the message boards invaluable!

-Tony

I went through the same thing. Mine was with a new boat that was already rigged with all new Imco drive stuff. It is really my first NEW boat (still waiting in CA for delivery, hopefully ready in the next week :evilb:) so I did tons and tons of reading.

My boat has more hp and tq but with the levels you want you're in the same situation. Go arneson and fork out the money right away. Otherwise you will bleed it out slowly through rebuilds, replacements, and tows. At best it seems to be a crapshoot even with the best of the two, the B-max and Max Machine. If you truly intend to keep your boat for a long time, which it seems you do, there is only one choice. Shame on Mercury for not producing a viable product:angry-smiley-038:


the potential list of advantages.
-More speed vs bravo
-better efficiency + better gas mileage
-piece of mind by virtue of unbreakable reliability
-cool rooster tail.
-a company and a contact (rik) to help stand behind the
product if there is a problem

Seeing that you're in Valencia, its worth your time to go talk to Teague. They can recommend some various options for you and get you pointed in the right direction.
-Tom

http://www.offshoreonly.com/classifi...o28713-en.html


right here and call it a day!

Konrad should do the trick.

I think thats just an XR Bravo unit isnt it?

Im really liking the B-Max on paper. Spoke to their west coast Rep today and he was sharing with me how much larger all the internals are. Seems like a serious piece thats really built to handle alot of extra torque which is what Im most fearful of with my new combo (not so much the HP).

-Tony

PS....I also like direct bolt on and no additional transmission needed etc.

Konrad Ace will easily handle that power in that sized boat. And not just because I have a one season unit for sale at a great price!

They are warrantied for 800HP and can handle MUCH more. They house the transmission in the extension box and include integral hydraulic steering with nothing attached to the transom.

Email me if you have any questions. [email protected]

http://www.offshoreonly.com/forums/s...-complete.html

You can't go wrong in my opinion. It uses the XR prop hub. I can only speak from my own experiance. No problems. I have never had a problem since. The only thing I would like to see is some more gear ratio options. I went from a 32 Bravo 1.50 to a 28 Bravo 1.30. It does work though.
Bob

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.

Guys,

Thanks for all the opinions etc. Its much appreciated

What are the advantages and disadvantages of having an external transmission (Konrad set-up)?

I like the turn key aspect of the BMax buy I am open to other options which look like the Konrad being next on the list (the third is totally rolling the dice with a Bravo XR and judicious throttle control....LOL)

-Tony

Imco SCX?

x2

Tony, couple of things.

Performance boating is laden with tradeoffs and you may be overlooking a few other things.

Yes, you'll need a drive, but if you dont care about speed and are looking to go 60 why put in a built BBC that makes 800?

How much hook/rocker does the hull of that boat have?

Why not tone it down to 5-600 its still go 60 and you can use an XR or if you need more robustsness an Imco SC or Teague platinum can easily hold that and you dont have to get all special on drive parts.

All the drives the guys are talking about here are great, but do you really need this with the kind of boat you have?

800 HP with what headers?
Not through stock exhaust it wont - you need to budget for this.

Its easy to make 800HP at 7200RPM and a huge roller cam through auto headers through a dyno, but living with that in a boat is far from ideal. More important than the 800 HP is how will it idle, and how many inches of vacuum will it pull at 750 rpm?

An automotive style high HP build may cause reversion issues. Be carefull you must deal with water in the exhaust.

If the drive doesnt include it you need to budget for external steering. No way that things gonna turn at speed without it.

Handling- that boats gonna walk all over the place at speed- youll need to budget some serious tabs - k planes- the big ones will likely be your friend.

Let us know what you do- I'm curious to see picts

Uncle Dave

Great post Uncle Dave....

Let me break it down as best I can....I may sound like a newb and to serious performance boating I certainly am, but engines and cylinder heads are both my hobby and my profession so Im familiar with trade-offs and most of what you mention engine related.

I will break down and handle all your questions....

I shouldn't say I don't care about speed....I should say its not my primary focus because whether it goes 65 or 75....with the type of boat I have that will be plenty. My main objective is to lose the overall "underpowered" feeling for lack of a better word, get up on plane much faster, and cruise at say 45-50 while the engine is still loafing (say 3500 - 3800 RPM's). For that I need alot of low RPM torque to turn a much more aggressive prop than what I currently run. Feed a big inch motor properly and the low RPM torque is never in short supply....a smaller motor (N/A) wont have enough grunt to spin an aggressive prop at that type of RPM (this is how I see it....feel free to correct me if any of what I have stated seems way off base).

I have no clue what you are referring to....thats the newbie factor unfortunately

See reasons above.....really want this boat to cruise at a good clip with little drama and low RPM. I dont think an N/A 600 HP build will have the low RPM torque needed and I want to keep it simple with an N/A combination.

Just looking for something that would have a good chance of living behind this combo (with reasonbable throttle control) and hopefully wont break the bank too badly. I wont invest 20 K but would spend half that if the right situation presented itself. I also dont want a bunch of compromises and would pay a little more for something deemed more durable and more "OEM" like in the way it works.

Im friends with Jan DeJulio at Lightning Headers.....we will probably run a 2.25 wet set-up on this combo.....trying to figure whether we can do a custom silent choice install to keep the neighbors happy and have some peace and quiet when Im in the mood....LOL
.

Thats the beauty of displacement as well....swallows big cams and with a killer set of heads (in the development process right now) it makes big torque and big power early (depending on cam and static CR or course). Im looking for a 47-4800 TQ peak realistically, and a power peak around 5800. I dont need a big cam to do it....just a really good breathing engine (heads, intake, exhaust). The better those components are the less cam you need to make big power.



Yep....also great point....Jan has done a fair amount of testing with that on the dyno and we have a good idea of just how much we can probably get away with....in my case Im going to err on the conservative side because I have more power than I need anyway and Im not trying to compete with some other idiot like me trying to go fast in a big cruiser....LOL



Yes....I had planned on another few thousand for the aftermarket hydraulic steering....I want to boat to be safe as well.

Would love more info on that....are you discussing trim tabs with vertical fins?.....Again, kind of the newb factor but am interested in what you have to say. I am a little concerned of how this boat will behave with all this power and would entertain anything to make it handle better and be safer.

Here is a pic of the boat....not mine but something I quickly grabbed off the net which is an exact copy (my boat is an 03' with the only difference being more of a subdued tan stripe down the side, versus the yellow, which I prefer....I think this pic was actually from the 04' Maxum catalog). Maybe this helps to get a better idea of what I plan on hotrodding. I think its a good looking cruiser and with more power it will be a very fun way to spend alot of time on the water without a whole lot of compromises. Im sure you can buy a fast boat with all the creature comforts but I cant justify dropping that type of coin just yet.

http://www.bateswharf.com/maxum/spor...ic_2700-se.jpg

Really appreciate your post and everyone else who chimed in....Ive got a clue in some areas but could definitely use the right guidance in others....LOL

One thing is for sure....it will be a pretty fun project.

One more thing I would like to add.....right now with 305 OEM HP and a dual prop BIII, at 5100 RPM's my boat achieves a max speed of 37 MPH on my GPS ( 1-2 more with trimming, tail wind, and "ideal" conditions) with a 2.2 ratio outdrive and dual 20P props. How good or bad is that all things considered and what are your guys guesses on what 500 more HP, the right prop, and say 5800 RPM's might bring in terms of speed. Does my current performance data indicate how badly (or how well) the hull is designed and what I could likely expect or is it a total crap shoot what it might do with a bunch more power??

Seems to me considering the weight and hull design its not performing too badly for a heavy single engine I/O

Cheers,
Tony

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

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?

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.

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').

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

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.

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.

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.

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!!

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