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Opinions on power for 27 Magnum


Opinions on power for 27 Magnum

Old 03-08-2002, 09:00 PM
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Glen, if you could find a pair of the Volvo speedmasters it would be worth 10 MPH at least! I did not realize you had Volvos. Both my Mag and my friends Cig had them. He had more money than me and had the speedy's from the factory, then I found a used pair. They were fast as h--l, but could not take the power. I got real good at rebuilding them but the gears were a fortune.

After a few seasons with the Volvo's, I got TRS setups for both boats from a Merc factory rep. We then changed both boats over, my first fiberglass job. Took way too long, and we lost a couple of MPH off the Volvo speedys, but at least we could run the boats hard without blowing a drive.
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Old 03-08-2002, 09:16 PM
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Aggro - HERE'S the deal:

502 cubic inches, 532 hp, BowTie block, GM heads, Arizona Speed and Marine EFI, 1050 cfm throttle body, JE pistons, Crane cam and bits, Manley Inconel/Stainless valves, IMCO manifolds, Corsa cutouts, all assembled by Flagship Marine, and to top it all off, a DPX drive, so there'll be no prop torque. The drive even has built-in hydraulic steering. This engine runs on 89 octane, and pushed my 28 BatBoat into the mid-80's. (It'll be available mid-summer once I get my 600 back... Should have about 60 hours on it then.) E-mail me, and we'll talk.

Miller, Tantrum, DaveP, and Shanghaid Again are all familiar with this engine and can testify to the way it runs.
Retired! Boating full-time now.
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Old 03-08-2002, 09:18 PM
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There is a 27 Magnum running a single BBC called "Vixen" which raced in P-4 (70-80mph) in several APBA races. It is also from your area, Ft. Meyers Florida.
Another single 27 Magnum Raceboat is "Deranged", he ran in P-5 (up to 70 mph) he won several races last year.
I think the 27 is well suited for a single big block. Most Magnum 27 are older hulls, which back in the 70's it was difficult to maintain alot of horsepower. Allmost all the 27's had a pair of small blocks, the drives back then could not handle the horsepower that todays Bravos will handle.
The 27's that are rigged with twins sit dangerously low in the water, when rigged with a single big block, they sit several inches higher.
I bet if Bravos and high horsespower engines were available in the 70's most would be rigged with a single.
I'm currently restoring a 1967 28' Magnum and rigging it with a single.
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Old 03-09-2002, 07:27 PM
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Thanks for the input guys....Robert, I think you hit the nail on the head with your comments about the single big block...cheaper than twins and far easier to work on...and today getting 500 to 600 hp is so easy.
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Old 03-09-2002, 07:40 PM
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Single is a little cheaper, BUT, the lean from the torque is very annoying...always draggin a trim tab is a pain, especially when your running and the wind and waves are constantly changing, you can't EVER get it level.
Old 03-10-2002, 07:11 AM
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Default 27 mag

Hey ag28 good luck, i built a 27 sedan with a single 600 hp and ssp outdrive,made a 6 inch setback on transom. the prop was 46 inches back from the bottom of the v and i incorporated a notch also went 70 and did not lean at all. it weighed 5400 lbs,and there was plenty of room to work on it un like twins tripps
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Old 03-10-2002, 07:26 AM
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I had a 27' Starfire with twin BBC's she ran like hell but was a ***** to work on!!!!
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Old 03-10-2002, 07:44 AM
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Default v6 super charge 300 hp

If weight is a conern .Check these little beauties.
Weigh in at only 500lbs each. Great fuel economy too
I am puttin one of the 300 hp versions in my 22 footer. should run low to mid 70's
Twins for balance and torque 600hp total and light weight
getting ready to order so let me know if interested
Just a suggestion
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Last edited by FlashptA10; 03-10-2002 at 07:57 AM.
Old 03-10-2002, 05:10 PM
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I have a 1976 27' Sport with twin 350 small blocks. I just finished a great deal of work on the engines including new vortec heads and Mercury Racing 700cfm carbs. The engines are pushing a little over 400hp a piece and are coupled to Trs drives with nosecones.
I constantly run betweeen 71-73 mph on GPS. I have thought of putting blowers on to get it up over the 80 mark but I've been told that with my compression at 10to1 this wouldn't be a good idea. I'm not sure if prochargers would alleviate this problem.

Aggravation, all I can tell you that if you start with a project Magnum and are not capable in doing the work yourself, be prepared to spend $$$$$$$$$$$$$$$$.
I love my boat but never in my wildest dreams did I expect to put the type of money that I did into it!
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Old 03-10-2002, 08:22 PM
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Single and big, don't worry about lean just balance the boat naturally by positioning weight to starboard if right rotation, etc....
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