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I have question about the Merc Racing ROS 200HP.

There are some of these advertised, and selling with specs that indicate 280HP. On the below link, it shows 200HP.

Was the 280HP ROS an older discontinued model?


http://mercuryracing.com/outboards/optimax200xsros.php

Yes, the 280's are no longer available. Closest thing they have now are the XS version which are direct injected. Good motors but not close in terms of performance.

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also, can I drop a 300XS engine block onto a 200 ROS receiver?

if not, any mods out there that would enable this ?

I 'm almost certain that answer is no. The 260/280's were 2.5 liter based blocks where as the 300XS (badd ass motor though) are 3.0 liter based blocks but w/a stroker crank making the 3.2 liters.
The 3.0 based motors have heavier gear cases and different gear ratios as well.
Think, 260/280 for light weight race hulls where you don't need low end/mid range torque and the 3.0's for real world performance boats.

The new 200 is te new gen 2.5. You can make it into a 280-300 with mods.

compressors and direct injection?

Not reliably. Easier to build the old gen with original parts - if you can find them.

How would this be done?

A website or a modifications list would help greatly...thanks.

Go to screamandfly.com there you will find answers to everything about these motors. The old motor is easier to build due to not being an opti/ direct injected motor.

scream and fly you can find alot of input i have had buit 2 modded 2.5 a 260 and now have a 300 hp 2.5 it is cheaper in the long run buy a 280 or 260 stock you will be better of they do like the gas two