My brothers new SeaCraft Tsunami
 

Just repowered with mercruiser 383 stroker.

I/O or true inboard? Couldn't tell from the pics. How much HP? Good looking rig!!

My guess is I/O based on the seating arrangement.
Very clean looking.

If it is like mine it should have 350 ponies.

Ent. I would like to compare numbers when you get a chance...:D

Very very nice Tsunami..I love the teak on the top gunnels....
Fred

I/O here is a pic

I believe 350 at the flywheel.

That is a sweet package,and a nice looking rig.I wish I had the cash at the time of the restoration to put the 383 stroker in my Tsunami.
Does your brother have any performance numbers for it? I'd be interested to hear what they are.

We will have the numbers in a few days we are still breaking in the engine. We tried a 18p 4 blade prop but didn't like it so now we are going back to 17p 3 blade.

I tried several props and ended up with a 15-1/2" x 17 pitch Mirage ss prop.It is about as close as I can get to being the best performer.
My Tsunami has less ponys(350 ci 260-275 hp) than your brothers however,and My outdrive is a Mercruiser Alpha with a 1.65 gear ratio.

Yeah this is 1.5 ratio bravo 1 it had a 260hp with mirage 19p on it which we have not tried yet.

Sits beautifully.

Beautiful boat. You and your family definitely have the South Coast Sceptre market cornered. ;)

Different boat but here are my first set of numbers.

I was able to pick up a Mirage + 3 blade 21 from blue heron...I believe it is a 14 3/4 diameter.

All the numbers are gps smooth water and a mile run through each rpm range. Boat had one person and approx. 40 gals. of fuel. No trim was used (motor and tabs).

Let me say this: instant response and torque on demand. Pulls hard all the way.

Motor is new less than 3 hours in the test. I have a feeling that I may be under propped when the stroker loosens up. Not by much.

rpm- gph- mph- mpg-

1000/ 2.1- 6- 2.8

2500/ 6 - 23.5 - 3.9

3000/ 9 - 29 - 3.2

3500/ 12.5 - 34 - 2.7

4000/ 14.1 - 42 - 3.0

One quick blast up to 50 @ 4900.


I hate to say it, but that was 2 summers ago...hopefully new numbers coming soon.:D

Terry,

FYI, Bob liked to cruise the Unohu at about 20 kts/23 mph and 9"Hg vacuum. Interesting that your optimum cruise speed appears to be about the same as his! However his mpg with a 260 hp Mercruiser was somewhere between 2.5 and 3.0 mpg, with a Bahamas type load.

What's the rated rpm on that stroker? Denny

I believe it is 55-5600 rpm.

383 Stroker:

SPECIFICATIONS:
Horsepower: 350hp @ crankshaft
Torque: 390 lb/ft @ 4,200 rpm
WOT Operating Range: 4800-5200 rpm
Engine Configuration: GM Small Block V-8
Displacement: 383 ci / 6.3L
Compression Ratio: 9.0:1
Idle Speed: 600 rpmThis engine comes with a 3-YEAR MerCruiser factory warranty!