Bravo derivative to handle 750HP
 

Am looking at the options for 750HP to 800 HP on a 37' stepped hull (Active Thunder).
SSM or other is not an option.

What is the best drive? Bmax? IMCO?

I've heard an XR is no stronger than a X and some ppl get those to live behind this much HP....

imo,the imco scx would be your best bet,the b max would be my 2nd choice.

on a twin application if driven correct the xrs will survive

Scx

The SCX will last a lot longer.. than the XR's, hands down.

To bad you are limiting your options to a Bravo style drive

Yeah I think most would agree that the Arneson Bravo Conversion would be the ideal set up!

The only drive that will gain Strength AND Speed!

I would assume that (like most of us) we all agree that Arnesons are a better choice but without a sponsorship, or a large amount of (Play Money) it becomes a matter of $$$$. Boating is what most of us do with what money is "left over" after paying living expenses. Not Judging Just saying!!

At first a SCX might seem MUCH less expensive but its really not.

$14000 Drive
?+Imco Stainless Gimbal Ring
?+Helmet
?+resovoir
?+Tie bar
$4000+WCM Blueprint lowers
$500+Shipping Lowers
?+drive spacers
Etc.

SCX $20,000 +or- and you probably will LOSE speed

Arneson $22,000 and you probably will GAIN speed

Bmax still has XR lower gears and it slows you down
SCX-4 + the above list + it has not proved itself, especially on a V-Bottom
X-Power to expensive

Nothing is a bolt on perfect option that solves every problem and makes your $XX,XXX boat a Half Million dollar dream offshore.

Out of my financial league, might have to give this thing up. $$$

My advise is to fix what you have and be easy on it!!

I must have missed the press release where everyone else was sponsoring the drives that were breaking and bleeding everyone of their "left over" $$ :D

Thanks for the replies! Obviously with an endless budget I'll be looking at arnesons. Also, I would be looking at a brand new/retail market prices - I'll be looking on the used market, so take 50% off those prices.

I'm on a budget for sure!
Maybe I will try and get Bravos to survive. Despite the power and large boat, this is a fresh water lake boat that I'll mostly cruise with and no big waves to contend with.

I had a BMax that was perfect for 5 years behind 720 hp. Lost about 2mph but worth not being on the trailer.

Is the speed loss due to physically larger gears in the upper?

Yes.

Also, pretty sure the older lowers were not as efficient as the current ones.

i ran xz uppers and imco -3 lowers for 4 years and about 8 poker runs with 750 tq 800hp on my 47 .the key is be easy on the throttles until 70 mph and then give all and no air time . now i run imco sc -3 with #6 hering 17 x 35 six blade so far so good .

What is the length of the 6M kit from hull to tip of prop shaft? If I remember correctly the 6M is a direct bolt on replacement for a Bravo, correct?

The kits are 4" longer than a Bravo on standoff box. The kits are the same as the Bravo Conversions and included all the components needed to convert from the Bravos to the Arnesons.

Just seen your post. Did you end up doing the Arneson conversion yet ?

Also question for Rik, the A/T 37 step hull runs with props turning out and i understand the surface application is typical for a turn in set up. What would you recomend for prop set up ?

Start with them inboard and then try outboard. Just swap drives side to side...

Rik im curious have you done any bravo conversions on 42 Fountain stepped hull and what was the results?


later

The 42' Fountains run very well with Arnesons. What power do you have?

Ok will do. What ride difference would you expect to look for with them running out versus turning in ?

500hp right now the boat run right at 80 what kind of increase would i be looking at. and does the transmission fit in the stand off boxes or the inside?

later

Your best bet is to buy some wet 6's for 35k or go with the arnesons for 45k. Both will be bulletproof for your application,

:lolhit:

there are some used Arneson setups for sell in oso classifieds. I do not know if they are complete kits or condition of them. But never hurts to check into.

Our B-Max on a SVL Big engine was faster. Never broke and even won 1st overall on Saturday in St Pete 2001.

Did you do anything special to the lowers? I thought I heard somewhere they had come out with a poker run version lower which looked more hydrodynamic.

Their new lowers are more hydrodynamic for sure. John spends hours hand shaping each one now. Definitely a work of art.

gears
 

too bad someone just want cut some bravo gears out of a stronger metal. what would happen if a person could buy gears for their imco scx upper and sc lower with gears made from Titanium, inconel or even Tungsten carbide? i know they would be very pricey but strong as heck, the last very$. there are many other very strong metals that would fit the bill. i would pay 3 times (or more) $ for hard gears! if the gears are the major weak point, build them stronger. maybe im just missing something and should buy the scx lower thats shaped like a sperm whales head! someone please set me straight:angry-smiley-038:

Great idea....

What you are missing is that XR gearsets made of titanium, inconnel, unobtanium etc, are like unicorns, atlantis, and girlfriends that actually earn money.

They dont exist.

You can cryo and rem polish but it is what it is.


It takes an unbelievable amount of money to make gear-sets or you'd see them ripped off a lot more.

Uncle Dave

i agree they dont exist but wonder why imco and others dont check it out. maybe its stupid money but ill be damned if i put a scx lower on my boat. i would really like for someone to tell me the actual cost. i also believe you are probably right that someone would have already done it by now if it was cost effective. i work in the aviation industry and know what things have been done in the past to solve problems. the stock bravo gears are sh-t and just wondering with all the technology if someone could come up with something better! btw i did hear some rumors from boost power, but not counting on it.
i have done some research on the net (which is usually BS) about some companys that can copy gears in different metals and will follow up on it. but im not having a good gut feeling on it. we shall see. thx

smitty on here is working on stronger XR gears and hopes to have them out by the end of june at the earliest. I hope so because my Imco Sc's could use stronger upper and lower gears, or its Arneson or SCX for me also.

i cant wait to hear more about this

(not directed at you Johnny)
This is my favorite quote that shows up in all "bravo" threads.

...if you bought a corvette, would you baby it?
...if you bought a ferrari, would you baby it?


Every time I get in my boat I slap the sticks forward and hope for the best. The last time out in 3 footers I never overrevved the engines once, not even a blip in RPM and I still broke a tooth in flat water when I cam back in the intracoastal. There is more to it than babying the throttles, the gears just plain suck. (mine were even cryoed)

There is some great CNC technology that can be used to cut new gears, the problem is we need a good set of data to work from. I checked on using some of the latest surface scanning technology but it doesn't provide a smooth surface, it's stepped. So creating a working model is a lot of work. If someone can get me a set of good gears, I can get them scanned if someone wants to spend hours smoothing all the surfaces of each tooth. I will be glad to help in any way I can I have some money I would be willing to spend on this. I have a number of gear manufacturers in the Southeast Michigan area that might be able to do this reasonably. I've talked to some guys who know their metallurgy and they recommend billet S7 with a Nitride treatment. I am open to any ideas anyone has at this point

I've never chipped a tooth, but have broke a bunch of floors on stock bravos, so any improvement there would be great. I'm the same I drive my boat like its a race boat throttle hard but I pick my moments and keep a spare drive ready at all times just incase I need it

None of those will work well for a gear set. S7 tool steel would be a good place to start. I also don't believe it would be hard to make a set. With the latest CNC mill turns it would be easy the make, however getting a good working 3D model to program from is the hard part.

Cheers,

Waid

i know nothing about metallurgy i was just thinking something else could be used for the gears. no worries guys, just wondering. apperently someone is working on this, thx smitty. im excited about what could comes of this!

If anyone here has the ability to digitize a bravo gear set, I would be interested in speaking with you about machining a set.

Waid