1963 Custom 16-footer with SUZUKI 90

Optimizing the performance of Boston Whaler boats
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Phil T
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Engine Mounting Height and Propeller for 1963 Custom 16-footer with SUZUKI 90

Postby Phil T » Thu Apr 30, 2020 10:17 am

[In a thread discussing engine warranty protection for engines not installed by a dealer, the following discussion with advice about engine mounting height for a 1963 16-footer custom hull with a Suzuki DF90 engine has been moved to PERFORMANCE--jimh]

Be warned, dealers and installers who are not experienced with older 16-foot and 17-foot models will typically install the engine in its lowest position on the transom, and often using the "blind" holes in the engine bracket. This is to be avoided.

As posted on this forum, outboard motors on almost all classic models should be mounted much higher than dealers typically do with non-Boston Whaler boats. In most cases, mount the engine two-holes-up as the starting mounting height. Presuming the holes follow the standard BIA measurement template, the engine should be mounted with the top bolts in the hole down that is the third hole down counting from the top. When installed, there should be two empty holes above the bolt. The lower bolts should be in the slots, about three-quarter of the way to the top.

Nick can provide guidance on propeller selection.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

biggiefl
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Re: Engine Mounting Height and Propeller for 1963 Custom 16-footer with SUZUKI 90

Postby biggiefl » Thu Apr 30, 2020 10:44 am

I agree with Phil and most likely I would mount it higher. What gear ratio does the Suzuki 90 have?
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

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Phil T
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Re: Engine Mounting Height and Propeller for 1963 Custom 16-footer with SUZUKI 90

Postby Phil T » Thu Apr 30, 2020 11:19 am

The Suzuki DF90A has the following specifications:

Inline 4 cylinder
Operating Range (RPM) 5300-6300
Gear Ratio 2.59:1
Prop Selection 13-23
Weight: L:343 (dry)

cf: http://www.suzukimarine.com/Product%20Lines/Outboard%20Motors/Products/DF90/2012/DF90A.aspx
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
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Re: Engine Mounting Height and Propeller for 1963 Custom 16-footer with SUZUKI 90

Postby biggiefl » Thu Apr 30, 2020 1:10 pm

I guess a 19-pitch or 20-pitch propeller would get you to a boat speed range of 42 to 45-MPH. At a cruise of 25-MPH the boat should have fuel economy of 9-MPG or better.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

Maverick
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1963 Custom 16-footer with SUZUKI 90

Postby Maverick » Wed May 13, 2020 10:53 pm

[A 1963 custom 16-footer with a SUZUKI 90-HP engine has acceleration from a standing start] like a rocket. Hold on or you’ll be thrown out the stern.

Boat speed over ground is 44-MPG at an engine speed of 6,100-RPM with head seas of light to moderate chop and wind 15 to 20-knots.

[Maximum boat speed over ground is] expected to increase to 46 to 50-MPH in good weather.

[The DF90] burned around 4-gallons of pure gasoline fuel in about 30 miles of travel. The boat speed was kept between 20 to 25-MPH for those results.

The performance is very pleasing. The engine is quiet, smooth, and stingy on fuel. I have no complaints after seven hours of run time.

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Re: 1963 Custom 16-footer with SUZUKI 90

Postby biggiefl » Thu May 14, 2020 10:55 am

If engine redline is 6100, more pitch will be needed to get [more than] 46-MPH boat speed-over-ground. If [engine speed can accelerate to] 6300-RPM, you might make it.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

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Phil T
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Re: 1963 Custom 16-footer with SUZUKI 90

Postby Phil T » Thu May 14, 2020 1:05 pm

Mav--please describe the engine mounting height, and the propeller brand, model, and size.
1992 Outrage 17
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Re: 1963 Custom 16-footer with SUZUKI 90

Postby biggiefl » Thu May 14, 2020 1:33 pm

Suzuki engines like to be mounted high--like all the way up high.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

Maverick
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Re: 1963 Custom 16-footer with SUZUKI 90

Postby Maverick » Thu May 14, 2020 3:10 pm

I’ll have to look at the mounting hole selection, don’t recall right off.

I believe current prop is a Powertech 19-pitch.

[The SUZIKI DF90 engine has] plenty of torque.

I could probably [increase propeller pitch by 1 or 2-inches]

I probably won’t change to a different propeller as this setup adequately checks my boxes.

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Phil T
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Re: 1963 Custom 16-footer with SUZUKI 90

Postby Phil T » Thu May 14, 2020 4:07 pm

Mav-- I would appreciate the specifics on the propeller. I have a mate installing same engine on a Outrage 17.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
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Maverick
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Re: 1963 Custom 16-footer with SUZUKI 90

Postby Maverick » Thu May 14, 2020 5:52 pm

I'll probably pull out the boat from the water soon, and I will look for a propeller number and also at the engine mounting height. To see that stuff at the dock is hard.

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Re: 1963 Custom 16-footer with SUZUKI 90

Postby jimh » Thu May 14, 2020 6:36 pm

I moved this discussion on the performance of the boat to the PERFORMANCE Forum. For pictures of the boat, see the original thread revealing the re-power engine choice. Another thread on this boat discussed the effect on warranty of self-installation of a new engine.