350ci 350hp more hp and io swap

I have a 2005 Crownline LPX 35

I have a 2005 Crownline LPX 350 350hp. I'm interested to know the cam and head spec's. The winter project is to increase the speed to around 70mph. I'm thinking either aluminum heads and cam or just maybe a procharger. My out drive is an Alpha gen 2. Is any of this possible?
Thanks for the help.

"Anything is possible, but jus

"Anything is possible, but just remember, the rate of speed you wish to travel is directly perportional to the amount of tender are willing to separate yourself from. We can get her over 100 if you want. By the way... how big is this boat?

Mr. Crown never intended your hull to withstand the kind of thrashing that comes with 70 mph.

Personally, if you are looking for that kind of performance, I think you bought the wrong boat.
But, that's just my opinion.

Rick"

"I think your setup is already

"I think your setup is already on the edge, putting over 350 HP on a Alpha is asking for trouble. As well I agree with Rick, that hull was not designed for 70 MPH."

Thanks for the response guys!

Thanks for the response guys!
My hull is 20ft. I guess I got hot pants this summer and could have ordered a 22ft with 496 bravo 1 but wanted to use it this summer. What would the difference in the two hulls be besides 2ft and 500lbs.?
I have heard that 350hp is all you want to put on an Alpha but didn't know. What would one be up against installing one of these? I do know high performance does get expensive and being an average guy who want's what he can't have. I'm hoping to have a boat that I can fill with family and food that looks good and every once in a while (having grown up with a BBC Howard Brown flat out of california) fill the wind thru what little hair I have left.
I have put a 5 blade prop on when I got the boat to improve hole shot but it doesn't really impress me. Obviously I have too much weight for the amount of power.
Next question is can the rev limiter be changed. I stop at around 4800.
thanks guys!

"The rev limiter is for the ou

"The rev limiter is for the outdrive not so much for the engine. I have a 24' Liberator with twin tweaked 350's and Ive had the crap scared out of me just touching 67 mph and got out of shape. I believe over 60 there should be bolster seats, deadmans switch and not alot of people on board. Either way lets stop talking horsepower and start on torque, thats what pulls."

"Mark,

Have you been listen

"Mark,

Have you been listening to that salesman again? The Mercruiser 350Mag is rated at 300 hp, not 350. Although the 4800 rev limiter is a bit low in my opinion, you're just about at the top of the power curve anyway, so eliminating it would not gain you much. It runs out of hp at about 5100. If however, you are running up against the limiter, you're not using all of the torque available and should increase prop pitch accordingly. If you can spin a 23" Mirage, you should be in the low/mid 60s. That's respectable for that boat. Take that 5 blade prop off and store it with your water skiis, that's about all it's good for. A good three blade will run faster.

There are compaines who can raise the rev limiter for you but I would not eliminate it. That's what keeps you from scattering your connecting rods when you airmail the boat.

Also, a nose cone wil add 1 mph +or- and TT exhaust will do the same (if you can tolerate the noise). You would also be surprised at what a set of Volvo speed rails will do. Besides increasing lift and therefore speed, they also add to the stability which makes the boat more maneuverable and therefore safer.

As you can see, there are many ways to increase the performance of your boat without ripping into the motor. Get friendly with a performance boat dealer. You'll learn a lot.

Good luck
Rick"

"Great info guys!
I do have c

"Great info guys!
I do have captains call exhaust, not as good as thru transom because of the turn it makes to get out the side I'm sure but better than not at all. LOVE the sound. Not a BBC and dry stacks or even wet headers but still nice sound.
With this being my second i/o bow rider, the first being a Chapparell 305 225hp I didn't even think about improvimg the performance of the boat. Came with a 23" prop and changed it out for a 19" to pull us out of the water. This boat is 100hp stronger (still not much) but it is 1000lbs. heavier thus top end is only about 7mph better. I've never run a Mirage prop but have heard they are very good. I would like to try a 23" but wonder if I have the torque to spin it. Guess I'll have to try it and see. I'm sure a small blower with 5 lbs boost would do the trick.

Volvo speed rails... are they the same thing as cavitation plate on a V drive? Good idea. There is a Baja, Fountain dealer here. Maybe they could help.
Definitely do believe in the rev limiter for protection of equipment and know the cam and head configuration will run out of power...I was guessing around 5500, that's why I was wondering if any one knew what the cam profile and head flow rates are on the 350mpi or where I can go to get them."

""What are you, boy? Some

""What are you, boy? Some kind of speed maniac!" (from a James Bond flick).

How about adding a nitrous system? Cheaper than a blower, easier to install, and you can add as much power as you want (within reason).

Jeff

PS: Don't tell anyone, but I'm a speed freak as well, though tempered somewhat by old age and grandkids!"

"Mark,

Volvo speed rails ar

"Mark,

Volvo speed rails are a system of preformed, annodized aluminum "L" rails approx. 1" x 1" which secure to the edges of the chines on your hull. Usually Volvo grossly overengineers their stuff, but these guys are amazingly simple.

They incorporate a concave bottom surface and a clean sharp edge. When installed, they cover that rolled edge of your chines and replace it with a clean, true, sharp edge. And with the concave bottom they trap water and create lift. More lift means less boat in the water. Less boat in the water means less drag. Less drag means more speed, or the same speed with less effort. Less effort means better economy. Either way, you win.

I have installed these in years past and have been very pleased with the results (especially for the $$$).

Sadly, a quick Google search netted no notable results as far as current articles, retailers, etc. I fear they may have been discontinued. Fortunately, I'll be working the Volvo accessories booth at the NY boat show a couple days next week, so I can get the poop first hand.

I'll let you know what I find out.

Regards
Rick"

"Thanks very much for the time

"Thanks very much for the time you guys are giving me.
The Speed rails sound very interestering. I'm guessing they are glassed in?
Yes I am a speed freak on occasion...usually only when I am awake!
Yes I have Grand kids and they truly love the boating experience pasted on to me.
If I were trying to race the boat I would already have had a NO2 system on it. I just want a boat that sounds like it has muscle, can pull up 2 slalom skiers and have 8 people in the boat while doing it and still have a top end run. ( Don't like the looks of a Nautique!) This to me is a fantastic looking hull and wish it ran as good as it looks."