Classic AquaSport
Aquasport Mechanicals - things that need a wrench, screwdriver or multimeter => Engines & engine woes => Topic started by: Jimmies on November 01, 2016, 10:42:36 AM
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I've had a 170 for a couple years. I've done a few things to it, but now considering a repower. The hull is currently powered by 70 Nissan outboard, which weighs around 250 pounds. The Suzuki 60 is around 230. It seems to be the best weight engine for the hull. Any other opinions? What else should I be considering for the repower? Is a 60 4-stroke enough power?
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Your on the right track on keeping the weight down. I have a 90 HP Ocean Pro on my 170. Seems like a Perfect power match with great hole shot and 38 mph top end. I believe it weighs 301-315 lbs
Have you looked into a 75 HP Etec?
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Thanks for the feedback. Weight is definitely a concern. The Yamaha 60 weighs 249 with 996 cu in of displacement; the Suzuki 60 is 229 pounds with 941 displacement. My current 2-stroke power is 257 pounds with a displacement of 938. So they all seem fairly similar. With that displacement on the 2-stroke I am getting top end of high 20s. I'm wondering what the top end will be with the 4 strokes 60s. Any thoughts?
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Hi Jimmies,
If your going to light on horsepower, stick with a 2 stroke if you can find one. Much better low end and mid range torque than a 4 stroke version. 4 strokes need to wind up to make the same torque as a 2 stroke. Your Nissan is a great engine which is built by Tohatsu. mid range horsepower 2 stroke outboards are getting harder to find. For torque with a 4 stroke in a 60-70 horsepower range, shop gear ratios of 2.3 to 2.5-1 I really like the Mercury 60 Bigfoot or the F70 Yamaha 4 strokes that may be a good option. Both are in the 250# range. Not sure what Tohatsu offers these days in the 60-70 hp range but consider them as well, they are very good engines but lack strong dealer and distribution networks. On your hull, breaking 30 mph with a 60 horsepower may be an arduous task. If you want good overall performance, shop 75 to 90 hp and stick with 300# max, which is what the typical 90-115 2 stroke weighed back in the day which is what the boat will handle and reasonably self bail at rest.
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Fitz, great info. And great explanation of how a 4 stroke would compare to a 2 stroke. I have not considered mercury but I'll check into them. Tohatsu is a possibility as I do have a dealer nearby. And I definitely am considering the new 70 Yamaha 4 stroke as well. I think the thing I'm really stuck on is weight. How much difference would an extra 50 pounds on the transom make, just seemed like a good idea to go lighter if possible to keep the transom as high as possible.
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The 170 is very sensitive to weight in the aft. In the early years the engines were thin and the clamp to attach to the transom would fit between the scuppers. Around the year of your boat the "standard" changed and the bracket became wider. When I bought my boat it had a 76ish straight 6 merc 90 or 115 (it actually had 150 decals on it but the serial number said different). The boat was a screamer. The engine failed and I put a "newer" 110hp engine on and the bracket covered the scuppers, so now I couldn't get quick evacuation of water and the weight of the engine put the scuppers under water.
I had (and still do have) the need for speed even though I'm in my 60's (can't take the kid out of anyone) but, as stated earlier, a 90 2-stroke is perfect. I repowered my boat with a rebuilt power head that is a v4, 60 degree - 90hp - I'm hoping to break the 40 mph barrier.
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Thanks again for the suggestions. I keep rereading the posts and every time I read I'm learning. Gear ratio is something i never considered. Ill have to read up on that. I want new so not sure 2 stroke would work, although I'll check into the 75 Etec, although I'm hesitant about Etecs based on some things I've heard.
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My neighbor/ fishing buddy has a newer (2005??) 17 angler with the aforementioned 70 Suzuki and I'll attest that it is an EXCELLENT match for that hull plenty of holeshot and tops out at about 38 on the GPS with three 200+ pound adults and I don't see why it wouldn't be a good choice for your 170 being of fairly equal weight and similar hull design.
ALSO as you have noted that the displacement and weight of the three brands of outboard are VERY similar this is because the Suzuki and mercury are also made by Tohatsu with one of the two brands of cowls and emblems all of your 4 stroke engines 70 hp and under are like this EXCEPT Yamaha they do their own thing.
I LOVED my 75hp E-tec but I REALLY wish I'd have bought a 90 instead I'd probably still have it if I did you'll get MANY good years of service out of an E-tec so don't let the Yamaha hype stop you from buying one they are EXCELLENT engines with low maintenance and EXCELLENT warranties and people who stand behind them.
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Thanks again for the feedback. I ordered the Suzuki DF60A and now I'm just waiting for delivery and install. In the end weight was my main concern so I went with the lightest 4-stroke engine, which also ended up being the cheapest. I'll post some performance numbers at some point once I get it out on the water and I'll try to get some photos up too so folks can see where it sits in the water in relation to the scuppers.
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Was there a weight difference in the 70?
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Yes, can't remember what the difference was but I do know the 60 was 229 pounds. For me it was kind of gamble, go bigger HP and worry about too much weight on the transom or choose the 60 and maybe be underpowered but at least I would know the weight was manageable.
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The 60 is a great motor. I have one on my inshore skiff. Different and lighter boat, but you've chosen a great power plant.
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Glad to hear that. The Suzuki dealer near me has been in business for a long time and has a great reputation so that was another reason I chose Suzuki.
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Hey Jimmies, any reports on your 60HP Suzucki? I'm considering doing the same as my '89 175's 75HP Mariner is in extremis. Decent mid range two strokes are impossible to find.
I no longer have "a need for speed" as I am into roaming aimlessly around also the Admiral doesn't like getting bounced or wet.
Has anyone else run a 60 on a 175?
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I know you stated speed isn't priority....but realize when you underpower a vessel you drastically diminish vessel performance as well as keeping the motor under consistent stress. Fully loaded your boat will weigh around 2,000lbs, which is one of the factors contributing to the vessels max hp rating of 130hp.
So to hang a 60hp engine, less than half of its max rating...IMO you're asking for problems.
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Thanks for your input and I see your point. I have a 32 gal fuel tank plus the engine and pax plus gear and we are indeed pushing 2000lbs.
I was hoping that someone had hung a 60 on a 170 or 175 in order to see the results. Decent mid range two strokes are impossible to find and you really don't know what you'r getting. My 89 Mariner 75 runs and I get 23mph at 3800 rpm which is a high as I will push it. However, after every outing I have to repair something and now my lower unit is suspect. I'm in a quandry as I don't use it enough for a major outlay of funds.
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Man I got the motor on my boat and almost forgot about you guys over here. At some point I'll try to get some photos up so you can see how it sits in the water relative to the scuppers. For me, weight was my main concern, not speed. So I did opt for the 60 Suzuki 4 stroke. At 6,000 RPM with a light load I am getting 24 knots. The sweet spot for my rig seems to be around 5,100 rpm / 20 knots. This is about what I expected out of the motor and I'm happy with my choice so far. I should add that fuel consumption is noticeably better than my old 70 Nissan 2-stroke.
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If you're able to turn 6k I might would go up a pitch on the prop and gain a couple mph on the top and have a lower cruising rpm also 5100 is pretty high for a cruise rpm and the Suzuki's gear ratio has the grunt to turn a bigger pitch with less effect on the rpm
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I have a 32 gal fuel tank plus the engine and pax plus gear and we are indeed pushing 2000lbs.
I was hoping that someone had hung a 60 on a 170 or 175 in order to see the results.
I put a 60 on a brand new 170 back around 1984. I would not go ANY smaller. The 60 was just enough to get the boat up on plane with 2 people & minimum gear in semi-friendly sea conditions. An older boat that is a bit water logged & a bit heavier may have trouble getting up with a 60.
You have a 32 gal tank? I thought that the originals were like 27 or 28. I'd love to get an extra 5 gallons into mine. Where did you get that tank?
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I have a 32 gal fuel tank plus the engine and pax plus gear and we are indeed pushing 2000lbs.
I was hoping that someone had hung a 60 on a 170 or 175 in order to see the results.
I put a 60 on a brand new 170 back around 1984. I would not go ANY smaller. The 60 was just enough to get the boat up on plane with 2 people & minimum gear in semi-friendly sea conditions. An older boat that is a bit water logged & a bit heavier may have trouble getting up with a 60.
You have a 32 gal tank? I thought that the originals were like 27 or 28. I'd love to get an extra 5 gallons into mine. Where did you get that tank?
The member who started this thread already bought and installed a 60hp zuki, Fyi. This thread ended a few months ago.
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A 60hp would be to small for my 222. with my 175 i cruise at 3100-3500 and that gives me 22-24 knots which seems to be a good speed for these boats. Since a lot of the original 222 can with twin 70hp I figure I would put a single 140.
To me it sounds like your 60 is working to hard. Your RPMs should be around 4500.
John