OK now I know we have allot of different oppions but help out a newbee. I have a 4150 stinger V hull a pair of merc 420s borg warners and 1.5 TRS 23 pitch mirages top speed about 55 . Getting ready to upgrade motors most builders say no blowers on that heavy of boat how much motor can I build into the stock 4 bolt blocks before I must g Would like to cruise around 50 top out in the 80s. thanks

o to a dart or merlin block? what bore? and what stroke? . What heads, cam, intake and carb should I be looking at?
redcorvetteman3

To go from 50 to 80 in that size boat, you will need, to just about double the hp you have now. I'd be looking at blown 502's if it were me. But I don't think the trs's would like it much.




Darrell.

.....Turbines!

are your engine guys car guys? I cant imagine any marine builder steering off blower motors. You will need big power to get to 80mph, my guess is 900 to 1000 per side than you have to consider your drives. TRS wont hold up under that punishment.

That's a lot of boat to get moving that fast. You're talking about picking up 25mph+. Don't know how much marine engine work you've been associated with but that's going to take a significant hp gain. Then, if you get it moving that fast, the extra power is going to be hell on the ole TRS's. How hard is it going to be to find replacement parts for the drives? Do you have exteral hyd steering? If not, you better add that to the equation for speeds over 70mph.

If it's speed you want, you'd be better off looking for something newer/lighter rigged with Bravos (XR's). With the money you're going to spend on motors/props/outdrive upgrades, you'll probably be in the same ball park.

Good luck.

I agree w/ GlassDave. You will need over 800hp a side to get 80mph. There is nothing wrong with high cube well built blower motors. The question is how much do you really want to spend on that boat and is it worth the gains vs. the cost. You will def. have to upgrade the drives to handle that much hp.
I had a friend with an eighties 39' Cigarette that had n/a 700hp motors in it and that boat could barely hit 70. Big heavy wave crusher similar to yours.

700 NTX might get you to 80mph. Cheaper to buy a new boat.

a friend of mine had a flatdeck scarab with a little over 800 a side and he would just nudge over 80 . . . . . at least thats where the TRS's usually let go. Its tought to get those big 'ol straight bottom boats going, and his was several thousand lbs lighter than your Stinger. I would keep the power mild (500 or so) and be happy with that, much more and you will invite headaches.

Looks like me, Tom and Dave were all posting the same sentiment at about the same time! But, be that as it may, I think we are all on to the same thing. If you get that boat to run anywhere near your target speed (which will already be extremely cost prohibitive), the maintenance will finish off the rest of your pocketbook.

Go w/ 750-800hp a side, w/a konrad conversion.
You may not be at 80tops, but 47-50 cruise may be attainable and reliable. Don't know the size of your wallet, but this is not a bad solution.