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Early style head swap for Vortech? Need help please.

Old 01-05-2005, 11:45 PM
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Default Re: Early style head swap for Vortech? Need help please.

Yea, it's heavy. But what a nice ride. That is why i want a few more Hp, to get it up to 50 or so.
How much power can i put through an alpha one? I will check mercs site for the gears. but I'm pretty sure the only came with 1:50-1.
I have most of the parts for a nice 383. But I figured the drive could not handle it.
Thank you so much for all your input, this is a great site with nice people. I'v ben reading the tech board like mad, learning allot.

P.S Nice quote.
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Old 01-06-2005, 08:12 AM
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Default Re: Early style head swap for Vortech? Need help please.

I had a searay 207, 21 foot 1985 bow rider. Not sure how much weight, but a very heavy boat. It came with a 305- ran about 40mph. I put a 260 hp 350 in it and it ran 45. The problem was when I loaded the boat with 8 healthy friends and wanted to ski, it almost wouldn't get on plane. I built a supercharged engine for it, 350, using a 144 b+m blower, way more trouble than it was worth.put 1.34 gears in the top end- bad move, get the heavy duty 1.50 gears from merc.I finally built a 383 stroker and wow, perfection! With this engine, it leaps onto plane even fully loaded with people, accelerates hard, idles great, it completely transformed the boat.My 383 dynoed at 400 hp, 430 ft.# of torque. drive died after 2nd season, thats when I put in the heavy duty gear set. 4 seasons later, still runs fine.I will do the occassional hole shot, but usually roll on the throttle. Stay with naturally aspirated- you can build all the hp an alpha can take without the expense and complexity of a blower set up with a 383 and it will run forever!
 
Old 01-06-2005, 08:34 AM
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Default Re: Early style head swap for Vortech? Need help please.

I forgot to mention, I have a friend who also built a 383 using the vortec heads that were on his 1999 350, and it made more hp and torque than my engine that had canfield aluminum heads, stay with the vortec heads and spend your money on a good steel crank and rods. Also, with the 383, my searay ran 58 mph on gps, lightly loaded.
 
Old 01-06-2005, 11:46 PM
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Default Re: Early style head swap for Vortech? Need help please.

Originally Posted by novaII26
Iput 1.34 gears in the top end- bad move, get the heavy duty 1.50 gears from merc.I finally built a 383 stroker and wow, perfection! With this engine, it leaps onto plane even fully loaded with people, accelerates hard, idles great, it completely transformed the boat.My 383 dynoed at 400 hp, 430 ft.# of torque. drive died after 2nd season, thats when I put in the heavy duty gear set. 4 seasons later, still runs fine.I will do the occassional hole shot, but usually roll on the throttle. Stay with naturally aspirated- you can build all the hp an alpha can take without the expense and complexity of a blower set up with a 383 and it will run forever!

Why do you feel the 1.34 will be a bad move? Is it a RPM isssue or will the motor be under to much load for the torque the engine puts out? I'm all ready to do a 383, It's the drive thats freaking me out. I don't have the cash to do a bravo.

Thanks
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Old 01-06-2005, 11:51 PM
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Default Re: Early style head swap for Vortech? Need help please.

Originally Posted by Iggy
Hmmmm......at 4700/4800 rpm I'm moving at 58-60mph.
You must have a heavy hull. Or does an extra 2 feet of length make that much difference?
The boat is listed as a 24.5 foot but I keep calling it 23 foot. My last boat was a 23'
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Old 01-07-2005, 05:29 PM
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Default Re: Early style head swap for Vortech? Need help please.

Sorry about not getting back to you right away, to use a 1.34 gear set you will need way more hp than the alpha can take, or you will need about a 7 pitch prop! With a 383 and about 400hp, with 1.5 gears, you will probably only need a 21 pitch 4 blade for your size boat. I had great success with the revolution by mercury- it really helped the prop stop blowing out in turns and on hard acceleration. Hope this helps. Rick.
 
Old 01-08-2005, 12:00 AM
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Default Re: Early style head swap for Vortech? Need help please.

Originally Posted by novaII26
Sorry about not getting back to you right away, to use a 1.34 gear set you will need way more hp than the alpha can take, or you will need about a 7 pitch prop! With a 383 and about 400hp, with 1.5 gears, you will probably only need a 21 pitch 4 blade for your size boat. I had great success with the revolution by mercury- it really helped the prop stop blowing out in turns and on hard acceleration. Hope this helps. Rick.
Hi Rick, I think that would be the best set-up. I posted another thread about the gear ratio. Every one made it very clear that this was not a good idea. This is such a great board! You guy have saved me so much time and money. Can't thank you guys enough.

I think the 383 will be the ticket along with the 1.50 HD. I will take it easy on it. If it breaks it breaks. "I have sea tow and a radio" Im going to start putting the pieces together this weekend. I'm new to the make the boat faster and I can't believe the power it takes to gain a few mph. It's so different from the muscle car world I'm use to.

The next question I have is what about fresh water cooling. I have raw water now and I wanted a "full system" if i was to put a fresh motor in it. If I sell the boat I can always pull the motor and drop it in my Tahoe. Can they take the heat of 400-hp? I would like to do this since I could then take advantage of aluminum heads and intakes along with longer engine life and rust free exhaust manifolds. What do ya think?

Thanks
Rob
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Old 01-08-2005, 12:57 AM
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Default Re: Early style head swap for Vortech? Need help please.

I don't know the specs of the second cam that was recommended, but the performer RPM cam you first mentioned is a crappy choice for a boat. You must have a flat torque curve or you'll never get it out of the hole, or if you do, it still won't accelerate worth a darn.

A 383 is a nice choice as it gives a good torque boost.
Combine that with a "normal" performer intake and a cam with around 220 degrees duration @ 050. Your boat is heavy and needs grunt. You'll get it with that combo.

4700rpm 1.5 gears and an 18"pitch prop sound about right. Without doing anything to your motor, I believe a 21" prop will put you at 4200rpm and about the same speed. A 19 pitch prop maybe 4500rpm and a little faster speed.

Be aware that this hull and power combo will never see more than 55 unless you plan to throw a lot of money at it (not recommended).
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Old 01-08-2005, 06:33 AM
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Default Re: Early style head swap for Vortech? Need help please.

I ran raw water cooling, and in the searay, at full throttle the engine temps would start to climb. I chased this problem for a couple of years and finally decided that the alpha drive was not really designed to go 60 mph. At 55 it would run all day, above that, it would start to warm up. I ended up getting rid of the boat and getting a nova, but I think the fix would have been to run a thru- hull water pick up and a bravo sea water pump. As far as closed cooling, I don't have any expierience with it, I ran raw water and had no issues with corrosion, running aluminum heads and intake, but I never ran in salt, and the boat only stayed in the water for a week at a time once a year on vacation. Always pulled the boat out after every use when not on vacation. Mcollinstn is way off on your est. top speed, I would guess it at 54.8. Just kidding, I think he is dead on, I've read a lot of his posts, listen to what he has to say, his info comes from hard work and experience. As far as cams I used a crane cam, I think the number ended in 831 but I'm not sure, would have to look it up. Easy to go too big with cams and carbs in a boat.I used a sea demon 650 and felt it was fine, good throttle response, amazing acceleration over stock.
 
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