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....
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Originally Posted by Uncle Dave
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?
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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).
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Originally Posted by Uncle Dave
How much hook/rocker does the hull of that boat have?
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I have no clue what you are referring to....thats the newbie factor unfortunately
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Originally Posted by Uncle Dave
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.
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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.
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Originally Posted by Uncle Dave
All the drives the guys are talking about here are great, but do you really need this with the kind of boat you have?
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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.
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Originally Posted by Uncle Dave
800 HP with what headers?
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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
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Originally Posted by Uncle Dave
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?
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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.
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Originally Posted by Uncle Dave
An automotive style high HP build may cause reversion issues. Be carefull you must deal with water in the exhaust.
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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
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Originally Posted by Uncle Dave
If the drive doesnt include it you need to budget for external steering. No way that things gonna turn at speed without it.
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Yes....I had planned on another few thousand for the aftermarket hydraulic steering....I want to boat to be safe as well.
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Originally Posted by Uncle Dave
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.
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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.
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Originally Posted by Uncle Dave
Let us know what you do- I'm curious to see picts
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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
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