Maxumus

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.

RBeyer

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

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.

Maxumus

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

NWPC

Imco SCX?

GB

x2

Uncle Dave

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

Maxumus

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.



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

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

Maxumus

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