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Old 20-10-2013, 12:22 PM   #1
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Whats the difference Between an Mercury XR2 and an SST120

Im looking at purchasing 2.5L powerhead but getting alot of offers for XR2's
and SST120's

Whats the difference? and are they a better engine to go for than a 2.5L?

Thanks

Niall
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Old 20-10-2013, 01:33 PM   #2
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Yes, no, maybe!

General answer for a general question...Niall, you're gonna get lots of depends how you drive your boat, conditions and set up questions. Your question raises so many others Just go with what your Mechanic recommends, unless he wants to kiss you...don't go with that, and try it.

Re the differences between the SST120 and the XR2 I was told they had slightly different porting and carb set up but that could be all pants. Google it mate.
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Old 20-10-2013, 07:05 PM   #3
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I asked the same recently, and for reference I picked up a complete SST120 power head for £1K that is in reasonably good shape. The SST would be the one I would now go for as they also tend to be newer (at least that was my experience) and I found so many people claiming to have XR2's but didnt really know what they had. I.e. black 150hp versions or unpainted 200hp race versions. Even then people seem to have differing opinions, but the SST120 imho is a better engine.
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Old 20-10-2013, 08:28 PM   #4
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Difference

I thought the sst120 was made for circuit cats,and came with a12" shaft length.where as the xr2 was made for the European 2 ltr offshore class,and came with a 20" shaft.but both had the same power head.
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Old 20-10-2013, 09:08 PM   #5
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Sst

Stands for "super sport tunnel"
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Old 20-10-2013, 10:37 PM   #6
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There are some minor differences, so its not exactly the same power head.
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Old 20-10-2013, 10:49 PM   #7
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There are some minor differences, so its not exactly the same power head.
Which are?
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Old 20-10-2013, 11:46 PM   #8
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See for yourself:

XR2 Parts
http://www.mercruiserparts.com/selec...R+XR2%2FMAGNUM

SST120 Parts:
http://www.mercruiserparts.com/selec...oc_nbr=SST+120

Totally different type of carbs for a start. SST has electronic fuel pump. XR2 is crankcase driven. Reed block assembly is different.

Exhaust tuning is different.

Block/crank/pistons/rods/heads are the same - so there ARE many shared major parts but its not quite the same.
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Old 21-10-2013, 03:27 AM   #9
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Sst is basically an xr2 with locked timing run backwards.
So to run it on an offshore boat you would need to put timing arm on and change starter. Then you'd pretty much have an xr2.
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Old 21-10-2013, 09:53 AM   #10
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Thats interesting. Unless mine was already modded, it turned the same way as the old V6 150 it replaced..
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Old 21-10-2013, 12:11 PM   #11
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Yeah yours was modded, as you say, before you got it
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Old 21-10-2013, 01:27 PM   #12
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Answered

There you go Niall,question 1 answered. As for are they better than a 2.5L? If it's a 2.5 200 your talking about,then I believe the xr2 is quicker,however the 2.5 makes max power at less revs and has more torque at low revs. So for pleasure purposes the 2.5 is proberbly the better choice.Imho.
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Old 21-10-2013, 04:15 PM   #13
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Quote:
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There you go Niall,question 1 answered. As for are they better than a 2.5L? If it's a 2.5 200 your talking about,then I believe the xr2 is quicker,however the 2.5 makes max power at less revs and has more torque at low revs. So for pleasure purposes the 2.5 is proberbly the better choice.Imho.

He knows ya know...I agree wholeheartedly with Mr Andymac.
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Old 21-10-2013, 11:23 PM   #14
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From new a SST 120 Powerhead was a direct replacement for XR2 by simply swapping Starter and Flywheel to make it run right rotation.
Sadly whatever you do to it, it will still be a Mercury and as such will make a really good time consuming hobby !!
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Old 22-10-2013, 11:26 AM   #15
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Hobby

Just out of interest bob,when you set the "National outboard immersed propeller mono" record at a blistering speed of 103mph. What make was the outboard??
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Old 22-10-2013, 11:31 AM   #16
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Quote:
Originally Posted by Niall.Bougourd View Post
Im looking at purchasing 2.5L powerhead but getting alot of offers for XR2's
and SST120's

Whats the difference? and are they a better engine to go for than a 2.5L?

Thanks

Niall
Save some more money and buy a optimax. You will save a large fortune in fuel!!!
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Old 22-10-2013, 11:45 AM   #17
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Quote:
Originally Posted by andymac View Post
Just out of interest bob,when you set the "National outboard immersed propeller mono" record at a blistering speed of 103mph. What make was the outboard??
Aha...Touche.....
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Old 22-10-2013, 01:35 PM   #18
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Quote:
Originally Posted by andymac View Post
Just out of interest bob,when you set the "National outboard immersed propeller mono" record at a blistering speed of 103mph. What make was the outboard??
It only had to last about 3 mins and required a rebuild after 10 !!
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Old 22-10-2013, 02:12 PM   #19
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It still helped set the record tho bob,why didn't you use another make that would do the same or more speed,but not need rebuilding after 10mins.
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Old 22-10-2013, 02:40 PM   #20
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Its all we had !!
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