I have to agree,,,if u only whant 430-450 ,,,454 are easy beefed up to HP 465 ,,thats basicly what they are.

And a buddy of mine had 465's that made 500 HP !

Nice heads diffrent cam ,better crank ,intake and exhaust and u should be easy in the HP range and your price range.:ernaehrung004:

You can easily build your 454mags to 450hp for under 10k.

I think you are all right and again I want to thank you for the interest in my problem. Its not really a problem, because I love my boat, the engines are running and I am looking forward to go with it. Maybe I do not need more than i have, I will have to see first, before i decide to go for more, (or not.)

Having more is always good:D

But i would take it easy and just go step by step .:ernaehrung004:

Lets assume you are going to shoot for 430HP out of your 365's.

Cam & lifters 200.00
Timing Chain 50.00
Roller Rockers 300.00
Exhaust 2000.00 (although lots of used GIL setups for about half that)
Holley 800 carb 500.00

I would think that for around 2500 per motor, you can upgrade to around 420-440HP if you do the work yourself.

You should see a nice performance increase by just upgrading cams and roller rockers on your motors. The 365's had very conservative cams. Going to a hyd roller cam would be nice, but not necessary for the HP goal. And add alot to the cost and work. If you find a nice set of GIL or Stainless marine manifolds with dry tails, you can go with cams that have 110* centerline and make a little more power than a 114* centerline, providing you have dry exhaust.

You guys really seam to know what you are talking about.

But you said "Dry exhaust". this makes me little nervous. Isn´t this a hot thing and louder too?? I don´t know why but i always think about the 4" dana exhaust with ss risers and silent choice exhaust. Maybe the silent thing costs me a few hp, but without they are going to kill me.
http://www.danamarineproducts.com/Pr...8-99cf0bcd1aec

A dry exhaust is louder,,,but with a sharp cam u will get reversion ( water would go back in the engine ) thats wy a dry exhaust is better.
Also , dry is not with out water,,,it is still water suroundet to cool it, just not mixed with the exhaustfumes !!!!

To kill ya they need to catch ya !!!!! LOL:D

Very interesing, did not know that they are cooled to. i have been searching around a little bit an found out, that some dry systems are just for fresh water use. is this possible?
In my boat I have a closed cooling system and am driving in salt water! How is the dry system cooled - with salt water or by the water around the engine?

I did exactly that to a 454mag. the only other thing I did was mill the heads. I gave the exact specs to somebody else and he also changed his intake. He dynoed at 420hp at 5000rpms.

"Maybe I do not need more than i have"

I think you will find out that you will want more. The easiest upgrade to do is the exhaust, but I wouldn't hesatate to do the other modes that Mild Thunder listed if you have the time and the money. Fairly easy upgrade that will really improve getting on plain and acceleration. Don't forget the price of new props with your changes!