Choice: OMC 70hp triple vs. Merc 500

[ledgefinder]

I have a choice of a either an OMC 70hp 50 cubic inch triple, or a Merc 500 44 cubic inch four cylinder, to put on a 15 foot ski runabout. <br /><br />I'm wondering if anyone's run both on a hull, and can comment on their relative performance. I'm interested in comments on relative fuel economy and power. Both engines are from the late 1970s, and are in good condition. <br /><br />The 500 pushes the hull fine, and 'feels' like it'll be enough to pop up skiers. Running an 85hp V4 now - too much gas!

 

[dafox99]

Re: Choice: OMC 70hp triple vs. Merc 500

I have had both, and can only offer my opinion. I loved the merc. Silky smooth and whisper quiet (relatively). The OMC tripple (again, in my opinion) was not as smooth and was noticeably thirstier. It certainly did have more power. My two cents.

 

[fishingdan]

Re: Choice: OMC 70hp triple vs. Merc 500

The classic mercury 50 hp 4 cylinder engines will run forever and are generally very smooth. <br /><br />The OMC 70 is also a very good engine that will last a long time. It won't idle as smooth as the merc, but you do get some more power. <br /><br />Assuming both engines are in good shape (good even compression and everything else), I think I would go with the 70 for a lot of skiing/tubing. You will be pushing the 50 to WOT nearly 100% of the time skiing . I have a 1985 merc 50. It is great, but on a 16' boat it needs to run at its upper limit for skiing/tubing. <br /><br />In my opinion the 70 will allow you to ski and cruise at 3/4 throttle and may give you a little better fuel mileage. The downside of the 70 is it probably weighs 25% more than the merc.

 

[Lakebiker1st]

Re: Choice: OMC 70hp triple vs. Merc 500

I've had 65HP-3 cyl Mercs and now own an older (76) 50HP-4 cyl on my pontoon boat, a 93-40HP/4cyl on a 15 Cajun. You can't run fast enough to get me to take another 3 cyl, don't care who makes it. GAS HOG! Rough idle, sorry trolling motor, at least mine was, but that was a few years ago. Things may be better with todays engines. More important, what's the boat rated for? Either one sounds a little small. Whatever that HP rating number is, that's the HP I'd put on it. Just my 2 cents worth.

 

[Chinewalker]

Re: Choice: OMC 70hp triple vs. Merc 500

The OMC triple is MUCH better on gas than the Merc - when comparing apples to apples (.ie running at similar speeds). The OMC is a loop charged motor and as such is inherently more efficient by design. That's how they're able to get nearly 40% more power out of only 10% more cubes.<br /><br />Both motors have very good track records for reliability and longevity, and there are lots of parts and people familiar with them out there to keep them going.<br /><br />The Merc is smoother and quieter, but the OMC definitely has more bite for its bark. I've run both and I think I'd lean towards the OMC triple on this one, particularly for skiing...<br /><br />- Scott

 

[Scali]

Re: Choice: OMC 70hp triple vs. Merc 500

I would lean towards the OMC triple too for that boat for the extra 20 ponies & I've owned both also, {presently I own a 1994 40 Merc 4 cylinder}..<br />I agree with Chinewalkers post except for the point that the OMC triple is MUCH better on gas, yes I know it's a looper & the Mercs a cross flow but I bet they are about equal & least thats the way I remember it

 

[Chinewalker]

Re: Choice: OMC 70hp triple vs. Merc 500

Hi Scali,<br /> I guess my point on the gas was that if the Merc maxed out at 35mph the OMC would use less gas at 35mph. The OMC at max speed, say 45mph would indeed use more gas than the 50 Merc at 35mph... <br />- Scott

 

[NMplayer]

Re: Choice: OMC 70hp triple vs. Merc 500

For skiing I'd probably get the OMC. If you were fishing, that merc is one of the best trolling motors ever made imo

 

[Scali]

Re: Choice: OMC 70hp triple vs. Merc 500

sorry, double post

 

[Scali]

Re: Choice: OMC 70hp triple vs. Merc 500

Good point Scott & that 70 looper is definitely best suited for a 15' runabout, yeah it would do better fuel wise on that boat for sure