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Old 22 July 2006, 08:14   #11
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Country: UK - England
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as i said I wasn't trying to start another 2/4 stroke debate and which was the best . Just that these days nobody makes a crap engine or machine , be it car bike or boat engine , so the riliability issue isn't really a reason for choice .

Fred if you look closer at the workings of a 2 stroke your reasons for a 2 stroke lasting longer will no longer make sense , its proven in practice that 2 strokes have a much shorter life , but that is a different debate to the one here

Mollers you had better hope us 15 stone plus ribbers don't sit on you , anyway did you ever see a thin seal , iam fat for a reason
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Old 22 July 2006, 08:31   #12
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Country: USA
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Boat name: Miss bad 61
Make: Crapko, AKA Mako
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well, i guess I'm a YANK,we came form over thare at one time.
anywho, you would need to make your prioritis known, if fuel is important, relieability, speed ect.

the gas for my wee hull is 10bucks a gal, you can't buy it at a pump, it's shipped by drum to my shop, a 1/2 lt would not be enuff to fire it, it's 820cc's.
she'll rip through 12-14 gals an hr at WOT.

if she didn't pull so much fuel i would for sure take it out more, could reset it up to pull less fuel, but then i would be crapin on my prioritys and she would be far less fun..... for me.
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Old 22 July 2006, 08:44   #13
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"Fred if you look closer at the workings of a 2 stroke your reasons for a 2 stroke lasting longer will no longer make sense"

be buildin 2stroke for over 20yrs now, got some out thare ( all over the planet) that have been runnin longer than four strokes have been on the market, and still run like a top. thinkin i got the 2 stroke stuff down.
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Old 23 July 2006, 09:33   #14
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Country: Belgium
Town: NIVELLES BELGIUM
Boat name: INDEPENDENT
Make: BWM RAPIER
Length: 9m +
Engine: Ob 2*250/2t yams hpd
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go with Fast Fred on this one ( what a fantasic, original, sexy username??)

The resaon is very siimle- there are much, much fewer moving parts on a 2t than a 4t. And nowdays a sophisticated 2t HPDI will turn out lower fuel consumption than the equivalent 4t.

Fred 10 bucks a US gal... that's robbery . whether is drummed or not.

Jonathan
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Old 23 July 2006, 09:47   #15
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Country: Belgium
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she'll rip through 12-14 gals an hr at WOT.

That's outragious!!!!!!!!!!!!

being doing some serious testing recently on my yams:: here goes- will use the same units as you.

-- two x 250 3470 c.c yams HPDI

cruising at 4000 rpm - 39 kts 17 usgals/hr -( measured floscan 550)
WOT 5300 rpm 50 kts 21 us gals/hr
comfortable 3200 rpm 29 kts 10 us gals/hr

Same parmeters for all figures. with 23" props Michigan wheel , rapture SS
Boat weighs in at 2200 kgs dry.

FIGURES ARE FOR TOTAL CONSUMPTION ( i, both engines)

1 us gal= 3.87 litters

jonathan
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Old 24 July 2006, 09:09   #16
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the paramiter of the outboard i run are differant than the outboards in your test, set up so to meet the prioritys of it's owner.

if your 250's were set up the same you would see similler fuel consumption,
thay would also be twin 350+hp @ 8250rpm.

can't beat how quiet them 4strokers are.
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Old 24 July 2006, 11:11   #17
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"That's outragious!!!!!!!!!!!!"

just wanted to say, thare are guys that got two ,three,even four SC1400hp
inboards in thare hull, thay eat more $$ in cheapper fuel than i can carry,
just gettin on plain.
my hull is a small fish, speedy fish.
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Old 25 July 2006, 15:30   #18
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Country: USA
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Cinman, just thought I'd add my $0.02.

When selecting your engine, see what other engines the Manufacturer makes that use the same lower unit and similar powerhead. For example, my Nissan 40hp is basically identical to the Nissan 50hp, which means that I can have an extra 10hp with NO weight penalty (they both weight 147lbs). You can bet that when it comes time to rebuild my 40hp, I'll be looking to install a 50hp powerhead.
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Old 25 July 2006, 15:42   #19
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Quote:
Originally Posted by kowached
Cinman, just thought I'd add my $0.02.

When selecting your engine, see what other engines the Manufacturer makes that use the same lower unit and similar powerhead. For example, my Nissan 40hp is basically identical to the Nissan 50hp, which means that I can have an extra 10hp with NO weight penalty (they both weight 147lbs). You can bet that when it comes time to rebuild my 40hp, I'll be looking to install a 50hp powerhead.
I don't understand why all the manufacturers do this .
I know the Honda 20 I had was identical to the 15 exept it revved a bit higher . The bit i can't undrestand is how much more the higher power option often costs .
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Old 25 July 2006, 16:09   #20
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Going back a few years when I was in to motorbikes all my mates used to get their cylinder bores skimmed and put oversize piston rings on. This used to give them more HP. Doesn't anyone do that in the boat world ?
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