Mercury 300x.
 

Hey all, Ive owned a few boats in my life and all were outboards. Motors were all Mercs. 200 EFI, 225 EFI and a 250 Pro XS. You all speak about the 300x motor very highly. Was just wondering why it is head and shoulders above the rest. What is actual horsepower, durability Etc. Why it worked so well for you at the time. Just curious as Ive never owned one or been in a boat with one. It seems like the boats its on run faster than same horsepower different motor. Example Merc 300XS vs 300x or also different manufacturer vs different manufacturer. I know my 250 proxs is actually rated higher than 250 horses. Just wondering the truths from the people who run them. Thanx.

The 300x was more like 320 to 330 hp actually. They turn higher RPM than the 300 promax and XS so that gives them another advantage. Durability seems pretty good with the motor and there is no compressor to worry about failing.

well it's been tested and proven that the 300x put out more like 325hp. not positive but I think that's the most hp Mercury ever offered in a 2 stroke. the later 300xs actually made less power but had a lot better fuel economy. I will tell you that the X is indeed a thirsty motor rated at 30 gph at WOT and remember it needs premium (92 octane minimum). it really doesn't care for cruising or idleing around, it wants to run! it's a pretty rad motor, even ideling it just sounds menacing, which is saying something coming from a guy who loves that sweet music of a healthy big block. true I miss my cammed v8 but the X has really helped me cope with having only an eggbeater in my life. lol.

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http://www.screamandfly.com/showthre...0xs-comparison





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As other have said, its the 2 stroke o/b with most hp to date. They sound amazing. Their only down side was their lower unit have the tendency of not lasting, even though many say they never had issues; but than again all Merc o/b lowers have issues one way or the others. Yes they are much thirstier than efi's or XS but i for one do not care for that now or when prices were $5.00 a gallon. As long as i'm enjoying it and boating.

Hey guys, All your info makes a lot of sense. Im waiting on a 30 Skater outboard. I find it interesting from reading some threads here that the 30 footer with 300XSs runs just over 100mph and with the 300X motors people have seen 112 or there about. With just 25 or so more horsepower a side it could get that much more speed seems pretty good. Is there anything else in play that Im missing. If I remember correct the 300X motors made a lot of noise when running hard going by me when I was out on the water. Is that right or am I mixing them up with some other motor.

Yes 300X are loud and sound great if you ask me. In regards to what you said about the speeds. Just remember one thing. In this sport, MANY people exaggerate there REAL numbers. I'm just saying.

MIke, The guy that owns the 30' Skater with X Motors is no BS. He has a shot of the speedo and is a personal friend of mine. He was the owner of the Mobil One race boat and has owned many OB Skaters in the day.
I am not saying that is an everyday number but I am expecting to see a least an 8mph increase in speed.
The X motor is also lighter than the XS better porting, larger throttle body and better mid section/tuner. Not sure what the actual HP number is but if it runs 8mph faster it is more than 25hp for sure.
50hp increase will not gain 8mph. Maybe 5mph

I believe that 112 was with an extremely light load no fuel headed downstream with good tail wind. 50 HP is not going to yield a gain of 12 MPH IMO. If so your 400 Verados should be good for and additional 48 MPH. If so I'm next in line:evilb:

Maybe those 300xs motors DONT make 300hp???????? Who knows!!!!!! I will soon

Very likely scenario. Dave Bush has done extensive testing on both and has some dyno info on both on his web site. The 300XS compressor requires 30 HP according to him.

I am hoping Jim will run my 300xs DBR boxes while we are in the Keys also so we can put that bs to bed for sure with back to back runs. If his gains are true should see 2-3mph increase.

That would be awesome. Have fun and get May parts and wiring diagrams!

Should have the diagram next week. They are all here at the show and overwhelmed at the moment....

When you say the compressor takes 30 horses to run is that taken after the horsepower is rated or is the 300XS truly rated at the prop at 300 horses. Its not rated at 300hp and net at 270 horses is it or am I totally off base here.

Mercury claims the motor is 300hp with the compressor.

I would be very interested in seeing the results of this test. Please keep us posted!

This link has all the info you need straight off the same dyno:

http://www.davebushracing.com/mercur...0x-update.html

What did you see for results with the DBR parts?

Put the XS crank in the X to make a stroker!

The 672lb beast is unveiled.

http://speedonthewater.com/new-boats...erado-outboard

I heard it says 687 lbs on the ID tag. Either way that's portly!


Okay Dustin, get to work on a Whipple tune for this thing so we can see what it will do! :D