Montauk 90 E-TEC musings

Optimizing the performance of Boston Whaler boats
kwik_wurk
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Montauk 90 E-TEC musings

Postby kwik_wurk » Mon Jun 06, 2016 8:00 pm

Musings of a new E-TEC 90 owner [after] logging 12-hours in first fishing outing, in weather that ranged to flat calm to 25-kts wind in 7-foot seas with 8-secoind interval and very yucky stuff:

The good:

--Very quiet for a two stroke engine (especially at idle).

--Fuel consumption at lower RPM very very impressive. Much better than older 90 Mercury, 35% better. Fuel consumption at mid-upper ranges still improved, but not as drastic, 15% better. May be related to prop and speed mentioned below.

--Oil consumption better than expected even through the break in period.

--[acceleration at full throttle from a standing start] was acceptable; mid range "pop" was great as in going from 3400 to 4500 RPM; little-to-no blow out when cornering. I have yet to waterski, so loaded [acceleration at full throttle from a standing start] is [to be determined].

--Nice to have a engine that starts every time without too much feathering; I hope this continues for life of the engine.

-three-year-maintenance free: it’s gonna be hard not to tinker on the engine.

The bad:

--Trim/tilt is rather slow. Past outboard had a two speed trim and tilt and hence faster for full tilt and trim in and out of the water.

--BRP [top mounting remote control] is rather awkward and not ergonomical on a classic console. It is narrow and tall, and slightly (1/4-inch) longer and larger than the flat surface on the console it mounts to, hence a slight bit over overhang. The older Mercury or Qucksilver was smaller and one could rest hand and hold on to throttle lever on whilst driving.

--it shakes the console and one rail whilst at idle. Past engine physically shook more; but did not bother boat, E-TEC has very stiff dampening and shakes the boat more. Tail wagging the dog syndrome. All hardware is bedded, but the one sloppy (egged out) railing standoff is the offender.

-A little slower than expected, or requiring slightly higher RPM (150-200) to achieve same hull speeds; see comments below.

Fine tuning the mounting and propeller: [see drawing below for mounting height] running a Viper 19 pitch, my top speeds 33.8-nautical-miles-per hour or 38.9-MPH at 5,500 RPM. The boat had bottom paint, 15-gallons fuel, anchor and other common gear, battery in console. This top end speed seems off to me; it seems I should crack 40-MPH or 41-MPH, which is only 1 to 2-MPH away. Against the Mercury prop calculator this means 22-percent SLIP with the Viper 19P at 5,500 and 2.00:1 gear.

http://www.mercuryracing.com/prop-slip-calculator/

I can’t tell if I am hitting the rev limiter; is it hard RPM stop at 5,500-RPM? Or, is higher like 5650-RPM? As I hit 5500 and still have a little more travel on the throttle lever, but not sure if there is anything there.

Also my intermediate speeds seem slower too. Specifically, I used to get 19 to 20-nautical-miles-per-hour at 3000-3100 RPM on my old Mercury 90, with a Mercury 19P (but professionally re-cupped so little slip). I have to push the E-TEC up a little higher to 3300 to 3400 to get that speed.

Tried to search the old forum for a like-like comparison, but found Montauks with jack plates, or different props etc. Another member recently talked about a 17 Viper 3 holes up (which seems odd). -- Any one else with a Viper 19P on the forum. Any other notes to compare against.

I hate to “try out” mounting heights, as that’s a lot of 4200 to break up. The dealer had several classic whalers in the lot. So confidence in their work, I am a bit puzzled. -- I have not had an extensive chance to do quality speed runs on reciprocal course, I hope this weekend to have clean water to do so. (My speed test was done with slight wind chop, but I was able to trim out as warranted.)

Mounting height (I'll get a measurement of inches above keel CL to the cavitation plate is, as there are a lot discrepancies on hole position vs resultant height.)

o
o<-This one
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o

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Phil T
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Re: Montauk 90 E-TEC musings

Postby Phil T » Mon Jun 06, 2016 9:06 pm

E-TEC engines like to be mounted HIGH. I would go up at least one or two holes.
Member since 2003
1992 Outrage 17, 1992 Evinrude 115

kwik_wurk
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Re: Montauk 90 E-TEC musings

Postby kwik_wurk » Tue Jun 07, 2016 12:39 am

For the sake of clarity, the mounting position shown in the first post has the engine sitting about 0.8-inch above the top transom (expected 0.75-inch up). This puts the cavitation plate 1.5-inch above keel when trimmed all the way in, and when trimmed to "running condition" the [anti-ventilation plate] is about 1.25-inch above keel.

Marc-B
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Re: Montauk 90 E-TEC musings

Postby Marc-B » Tue Jun 07, 2016 12:04 pm

I am possibly the one that posted that my E-TEC 90 was three-holes-up running a 17 Viper. I made an error. The engine mounting height is [ONE HOLE UP as shown below].

O
O- here
O
O

The standard bolt pattern was not respected, the top bolts are higher than standard by about 0.75 inch, I will probably re drill to the next lower hole as I do find it a bit close to the top of the transom, but that is another problem.

I took a straight board and extended a parallel line from the bottom of the keel and measured the distance to the ventilation plate that is also parallel to the board and measured approximately 2.25-inch above keel, not enough hands to be able to get an very accurate measure.

I have yet to do any kind proper performance analysis. I want to do a proper test in 1,000-RPM increments on a light load,. The initial results are that it will rev past 5,500, (analog system check tach) and did get 43-MPH on GPS.

Yes [the E-TEC engine] does make the boat vibrate at idle, but it seems to be getting better, or I am used to it. It made me find all the loose railings.

So far very pleased with performance, but I can only compare to my old 1979 Mercury 80 HP that could not go over 5,200 RPM on a 17-P aluminum propeller.

Jim, if I am not making sense, let me know and I will re-measure.

Kwik_Wurk, I will send pictures to your email

Marc-B

jimh
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Re: Montauk 90 E-TEC musings

Postby jimh » Wed Jun 08, 2016 5:08 pm

The engine under discussion in this thread appears to me to be described graphically as what we would call mounted "one-hole-up."

Given the conditions described and the sea state, I would not be too worried about speed testing. Test the boat speed in calmer water. Usually a very small wind wave sea state is best for speed testing, even better than dead calm.

Long-term fuel consumption when changing to an E-TEC from a conventional carburetor two-stroke-cycle engine is usually about an INCREASE in MPG by a factor of 1.5 to 1.8.

kwik_wurk
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Re: Montauk 90 E-TEC musings

Postby kwik_wurk » Thu Jun 09, 2016 11:52 am

I have not had a chance to splash the boat, despite being 90 last weekend. --- Ideally, I am going to get some testing done this weekend.

Whal
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Re: Montauk 90 E-TEC musings

Postby Whal » Mon Jun 20, 2016 10:15 pm

If I am remembering right Tom Clark's recommendation for the E-TEC 90 on a Montauk 17 was a Stiletto Advantage 13.25 x 15 stainless steel propeller with the motor mounted two-holes-up. The Stiletto Advantage 13.25 x 15 was said to actually run like a 17-pitch. They no longer make the Stiletto propellers , but maybe you could find one for sale on eBay or some other site. I hope someone else on here can confirm my memory! I once sold a Stiletto Advandage 13.25 x 15 propeller I had to a guy with a Montauk 17 with an E-TEC 90. Maybe just raising your motor one-hole with your 17 Viper would get your desired results; that's what I would do first. I hope this helps.

RogueII
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Re: Montauk 90 E-TEC musings

Postby RogueII » Tue Jun 21, 2016 12:39 pm

You need to mount that motor all the way up:

0
0
0
0 - here

Trust me, you won't regret it. From there, you will be able to go up 2 in pitch to get your RPMs dialed in.

kwik_wurk
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Re: Montauk 90 E-TEC musings

Postby kwik_wurk » Tue Jul 05, 2016 11:59 am

Did not get a chance to raise the motor, but did have a chance to look back aft while someone else was driving. -- One hole up is too low, as there is a lot of water flowing over the anti-cavitation plate. Top speed was ~34.1 kts (~39.2 mph) with 2 adults, 1 child and two 5 gallon buckets of crab and seawater. -- Now it's a question of 1 or 2 holes higher.