150 hp comparison, a few questions

[whichway]

Hi

The following article is pretty good, but it raises a few questions:

http://www.boatpoint.com.au/portal/alias__boatpointau/tabID__200859/ArticleID__1962437/DesktopDefault.aspx

1. The 150 Suzi pushing a 1500kg package reaches WOT at 58 km/hr, while the 150 Yammy 4st pushing 1900kg reaches WOT at 71 km/hr. How can two motors with the same power result in such a difference in performance

2. Again the 150 Yammy 4st seems to outperform both the Opti 150 pushing 1800kg (66 km/hr), and is not that far behing the HPDI 150 pushing 1500 kg (78 km/hr).

3. And what would be the best for crossing a bar - does top end speed translate to speed throughout the range or would the 2 strokes be better down low, which is just what you need to get out of the way and up the back of the big green waves.

PS I didn't include the etec since it was pushing a much lighter boat in the article, so it is difficult to make a fair comparison with the other motors.


Does anyone know where you can get torque curves for outboards, or acceleration tests.

Whichway

[Spaniard_King]

Whichway,

It's hard to draw direct comparisons from test like that unless they are on the same hull/weight setup.

What you have to realise is that when an outboard is designed it is aimed at a HP group ie 150hp it may fall short or it may be above. There is a 10% margin allowed for an outboard to fall into the category, so an outboard may put out 138hp but can be labelled as 150hp or it may have 165hp and still be labeled 150hp (unlikely tho)

All you can do is read as much as you can and draw your own concluisions.

I havent seen anywhere that publishes HP and torque curves, it sure would be interesting :-X

Garry

[PADDLES]

your dead right on the hull issue garry, you've got to compare "apples for apples" whichway. the other big issue here is that the gear ratio of the two is different, the yam is 2:1 gearing with the sooz at 2.5:1. the power output figures "marketed" by the 2 companies are pretty much identical. looking at the numbers you'd have to think that the sooz would be more responsive down low (holeshot) with it's larger cubic capacity which should give a greater torque and it's shorter gearing. just my guess anyway :D