1969 20' engine choice

[samuelcooper]

I am currently redoing a 69 SF 20 ft. (Will raise transom 5 in and deck 3 or so for tank and bailing). In looking ahead for engine choice I really like the e-tec. My choices would be 115 or 150. In reading old posts, the majority opinion seems to be 150 or more for hp. However, an e-tec dealer says the 115 will be plenty for the boat. So,...I'm wondering if anyone out there is actually running a 115 (e-tec or other) and can give info. on performance. I will rarely be on flat ocean so top speed is not that impt. But ability to plane and plow through rough ocean is. I took a 1977 Johnson off the boat and that was more power than I need.

[eggsuckindog]

Back when they were made we always hung inline 150 Mercs on 20's, I had a 115 on my 18 and it was just fine but could have handled the 150 and I wished I had done that for mid range in swells, the 115 would bog a tad. Keep in mind I think these new DI motors may be a good deal stronger than the old ones too, so a new 115 may be comparable, maybe someone else can add something regarding that.

You might check here for a motor-You will have to email in for a quote on a motor but they are on the biggest buy program this year so nobody can sell them cheaper, it involves dealer incentives for commiting to X amount of motors. You would have to weigh it against how good a relationship you have with a dealer, they can get their feelings hurt if he's a good friend.

www.usavemarine.com

[oldbluesplayer]

Yes, I am running a 115, an old '84 Johnson V-4, although on a 20' Seafari - probably a little heavier and more windage than your CC. The motor is sound and solid, and with 2 on board and a full tank of gas I top out at 31 mph GPS - like you say, on open ocean I rarely can run it there, but it has a nice comfortable cruise point at 25-27 mph, put it in 2 - 3 ft chop and I'm down to 15 - 18 mph, holds a plane down to about 10 mph - which I have had to do when faced with unexpected 5 - 8' slop - would choose not to repeat that, thank you

If I had an open wallet, I would look at a 135, either an Etec or a Merc Opti - but then I have the 20" transom and original floor height, so motor weight would also be a concern to me. With the mods you're doing, 25" tranny, raising the floor, you won't have those concerns. Given that, a Suzy 140 fourstroke might be a real good choice, also.

On the flip side, there are those who think a 150 minimum is needed for these 20's - I just can't see that, given how mine runs with an old 115.

If I might ask, what hp was the old 77 Johnny you took off, that you thought was more than needed ? Some folks have put up to 225's on these boats - older, lighter two strokes, that would be a screamin machine... on a lake!!

All boils down to you, your preferences, need for speed, intended use, etc.

Bill

[oldbluesplayer]

E-S-D - just a follow-up to your train of thought - I don't know when they changed the outboard motor hp ratings from measured at the powerhead, to at the prop, I'm thinking sometime after the 70's ?? but from what I think I know on that, wouldn't an older rating 150 be about equal to a new rating 130 - 135 ?

On the bogging, not uncommon on older, carbureted 2 strokes, mine bogs initially when coming off a prolonged low speed troll, till it clears out - don't have any injection motor experience, but I would suspect that more accurate fuel metering would help that greatly - two stroke carbs are notoriously hard to dial in for both mid range and top end, whether bike or ob, get too lean and you cook the motor, leave it fat for motor life sake, and live with the bog, unless you're racin, in which case you know your pushin the limits and in for constant tear down and rebuild anyways.

just some stray thoughts

Bill

[Michael Vezzosi]

More stray thoughts. Part I's '87 18 originally powered by a V-4 Johnson 112/115, slightly underpowered, in his opinion. Rebuilt V-6 Johnson 150, not sure of GPS WOT. Much happier.

My '79 20 MA originally powered by Merc. 200 BM blew up 1 hour after seatrial. Repowered 1999 V-6 carbed Johnson 175. ($600 for 200 HP carbs. (not necessary!)), not sure of GPS WOT. Much happier

The 20 is only minimally faster. Guestimatation: Both running very close to 50, light load, one occupant and trimmed. Both 15" transoms, and stock floor heights. Neither have T-top, trim tabs, or Porta- Potties. However, both do have fully stocked adult beverage coolers!

NOTE: We share a Jersey Speed Skiff, we guestimate closing in on 70 GPS, but thats unofficial as well. Stop down the LowCountry! Mike.

[Kahuna]

SC,
I have a 20' seafari myself with I/O, but two weeks ago I ran a clean 75 20' CC, with a very new 130 2-stroke yamaha. What a ROCKET!! full fuel, two people + dog, if you weren't holding on, you were going out the back. Based on the transome height, I would not put any more weight on the aft end of that boat even if the transom was 4-5" higher. I can't imagine 15 less hp would be a big production. The difference you will have between a 1977 outboard and a new one is going to be substantial. I do know somebody who is redoing a boat just like mine, raising the transom 5" adn plans on putting 115 2-stoke on it. 6 cylinders is too much weight, in my own opinion of course...

[NoBones]

200 hundred ponies on the back of NoBones is nice to have
when those famous afternoon storms sneak up on us in Florida. The weight is not that big of an issue with a raised transom and deck. Plus the fact that when you are
loaded up with gear and people the fuel consumption is far
less with more HP. You do not have to stuff the throttle
with a load. I have been in 20's with 90HP to 225HP
I'll take the 175-200HP range any day.
See ya, Ken

[Yamtt125]

I have been thinking about this same question for some time now, and this is what I came up with...

Alot of people here have suzuki 140's on their 20's, but the suzuki 140 is closer to a 115 b/c it used the same block.
The evinrude etec 115 i'd say would have about the same power as the suzuki 140. believe the prices of the two would be similar also.
I don't know anything about the merc opti's, but i have heard good things.
My personal engine of choice i think would be a honda 135. The 135 is based on the block of the 150 and is still only a four cylender, so your get the fuel efficiency of a smaller engine, but the power of a bigger one....

Ok..enough rambling. This is just my 2 cents.

[VirginIslander]

Some things to look at when deciding on an engine size that are not usually brought up, are gearcase size and overall weight.

Some smaller block motors share the same gearcase size with their larger cousins, but with a numerically higher ratio. This lets them use the same props, but puts the RPM range significantly higher for an equivalent speed. This can make the predicted fuel savings of the smaller motor dissappear.

Other times, the smaller HP motor is on the same block as it's larger cousins, and so weighs the same, just has less power.

Best overall results usually come with the most power in a given sized block selection. That configuration has everything working in it's most efficient combination.

I have an 18SF with an Eagle series (60 degree V6 block) Ocean Pro 150. It's nice in that it's about 75# lighter than the 90 degree V6 blocks (200 and 225 hp). It runs low 40's (wot) on GPS and has it's sweet spot around 3000rpm.

I can't imagine putting any less power on a boat any bigger.



Darlene

[Bigshrimpin]

If it were me . . . I'd look at a 115/140 suzuki or a 150/175 suzuki.