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Author Topic: What the perfect motor for a 170?  (Read 8283 times)

February 09, 2007, 05:37:51 PM
Reply #15

Pat Green

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« Reply #15 on: February 09, 2007, 05:37:51 PM »
Brian, I have a 1970 17 for about 25 years.  For the first 15 it had a 70hp Johnson which was adequate.  When I put a 120hp nissan it screamed(actually scared my wife). The extra weight caused some problems.  It started porposing which a set of trim tabs fixed. I used the fixed type and when adjusted they perform well (about $40).  Also, the new engine style covered both drain holes in transom, so I installed two new drains at floor level with scuppers because with the extra weight the boat was no longer self bailing.  Pat Green
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1971 17 open fisherman
February 09, 2007, 05:38:49 PM
Reply #16

Pat Green

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« Reply #16 on: February 09, 2007, 05:38:49 PM »
Brian, I have a 1970 17 for about 25 years.  For the first 15 it had a 70hp Johnson which was adequate.  When I put a 120hp nissan it screamed(actually scared my wife). The extra weight caused some problems.  It started porposing which a set of trim tabs fixed. I used the fixed type and when adjusted they perform well (about $40).  Also, the new engine style covered both drain holes in transom, so I installed two new drains at floor level with scuppers because with the extra weight the boat was no longer self bailing.  Pat Green
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1971 17 open fisherman
February 09, 2007, 05:40:05 PM
Reply #17

Pat Green

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« Reply #17 on: February 09, 2007, 05:40:05 PM »
Brian, I have a 1970 17 for about 25 years.  For the first 15 it had a 70hp Johnson which was adequate.  When I put a 120hp nissan it screamed(actually scared my wife). The extra weight caused some problems.  It started porposing which a set of trim tabs fixed. I used the fixed type and when adjusted they perform well (about $40).  Also, the new engine style covered both drain holes in transom, so I installed two new drains at floor level with scuppers because with the extra weight the boat was no longer self bailing.  Pat Green
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1971 17 open fisherman
February 09, 2007, 05:48:07 PM
Reply #18

Pat Green

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« Reply #18 on: February 09, 2007, 05:48:07 PM »
Sorry guys, but the forum kept saying message "not sent"  Pat
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1971 17 open fisherman
February 10, 2007, 05:36:16 AM
Reply #19

RickK

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« Reply #19 on: February 10, 2007, 05:36:16 AM »
Quote from: "gw204"
Quote from: "RickK"
On an older boat like mine, that was designed for a 70, the 115 is maxing the acceptable weight limits too.

That's also a good point.  I'm sure if I choose to go with a 115 I'll have to rebuild accordingly (raise the floor a bit, foam core in the floor near the transom, etc.).  Weights on the 115 ETEC, Opti, 2-stroke carbed Yammy seem to be hovering around 360 lbs.

20" ETEC 90 - 320 lbs.
20" ETEC 115 - 369 lbs.
20" Opti 75/90/115 - 375 lbs.
20" Carbed Yammy 115 - 358 lbs.
20" Carbed Yammy 90 - 261 lbs.

261 lbs. on that carbed Yammy could be hard to pass up.

Thanks guys.   :)

The rebuilt '98 115 Johnson 2 stroke I put on the back of mine weighs approx 320 lbs.  I thought the difference in a 2 stroke 90 and 115 was just carb changes - wonder why the ETEC 115 is 49 more lbs?
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Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha
February 10, 2007, 05:42:04 AM
Reply #20

RickK

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« Reply #20 on: February 10, 2007, 05:42:04 AM »
Quote from: "Pat Green"
Brian, I have a 1970 17 for about 25 years.  For the first 15 it had a 70hp Johnson which was adequate.  When I put a 120hp nissan it screamed(actually scared my wife). The extra weight caused some problems.  It started porposing which a set of trim tabs fixed. I used the fixed type and when adjusted they perform well (about $40).  Also, the new engine style covered both drain holes in transom, so I installed two new drains at floor level with scuppers because with the extra weight the boat was no longer self bailing.  Pat Green

Pat, seems the mounting bracket "standard" changed about then and now the ones of us that have old boats, all have covered scuppers (or mostly covered).  The '70 170 you have, does it have the channel that runs from starboard to the motor at the transom for the wiring and cables, etc?  So you drilled new scuppers above that (floor level) and at floor level to port?
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Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha
February 10, 2007, 07:41:21 AM
Reply #21

gw204

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« Reply #21 on: February 10, 2007, 07:41:21 AM »
Rick, I'm pretty sure the ETEC 90 is a 3-cyl where the 115 is a 4-cyl.
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Brian
St. Leonard, MD
1981 Mako 17
1986 Grady White 227
February 10, 2007, 03:10:15 PM
Reply #22

hunter

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« Reply #22 on: February 10, 2007, 03:10:15 PM »
My 170 as a 115 two stroke johnson it will do about 50-55 in calm water, but I think the engine was modified before I bought it. Forinstance the cowl says 90 and the model number on the engine says its a 115.
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February 10, 2007, 09:19:50 PM
Reply #23

Miguel

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« Reply #23 on: February 10, 2007, 09:19:50 PM »
50mph!!!!!!! Is that per GPS? or is it km/h?
I´m almost certain this hull is not able to develop 50mph on 115hp....
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Miguel
1985 Osprey 170 / 1992 115HP Mariner
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February 10, 2007, 11:17:22 PM
Reply #24

John Jones

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« Reply #24 on: February 10, 2007, 11:17:22 PM »
My son has a 18' bay boat, forerunner to the Carolina Skiff Sea Chaser, with a 115 Zuki.  With me driving and my GPS I chickened out at about 52 mph with 3 people and a full tank.  I'll bet it will hit 60.  I'm sure his bay boat is much lighter than your Osprey.
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Politics have no relation to morals.
Niccolo Machiavelli
February 11, 2007, 01:35:59 AM
Reply #25

hunter

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« Reply #25 on: February 11, 2007, 01:35:59 AM »
I hit 53 "mph" according to my gps with two people, a full tank, full baitwell, and full ice chest.  So there's proof an ospree will go over 50!  Also the water was perfectly calm.
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February 11, 2007, 08:58:24 AM
Reply #26

RickK

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« Reply #26 on: February 11, 2007, 08:58:24 AM »
Originally I had a modified straight-6 115 Merc (cowling decals said 150 but Merc said that the serial numbers was NOT a 150) and it felt like the boat did 50+ - no gps back then.  The wind would tighten the skin on your face  :twisted:
Your 115 must be really modified.  Miquel and mine - both 115 and both top out at 40.
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Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha
February 11, 2007, 10:06:58 AM
Reply #27

bamafaninfl

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« Reply #27 on: February 11, 2007, 10:06:58 AM »
Quote from: "RickK"
Quote from: "JimCt"
Only eight MPH faster than my 75???
You must have tested it on a strong tide  :lol:
Seriously, the hull is the key, it'll only do what the engineering will let it do.
Hey Bama, what speed on that 90?
Miquel, what do you get with the 115?
around 31,32
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1977 Aquasport 170
February 11, 2007, 08:33:05 PM
Reply #28

Miguel

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« Reply #28 on: February 11, 2007, 08:33:05 PM »
Hunter, you really have a very special engine.  Mine is propped for running in the  optimum WOT rpms, and I´m lucky if I can hit 40mph going alone.
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Miguel
1985 Osprey 170 / 1992 115HP Mariner
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February 11, 2007, 08:48:49 PM
Reply #29

JimCt

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« Reply #29 on: February 11, 2007, 08:48:49 PM »
Only thing I can think is that you have considerably more static weight in the boat.
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JimCT
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\'74 22-2 inboard
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Chrysler 318
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