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E-TEC Motor Choices for 1971 21 Outrage
|Author||Topic: E-TEC Motor Choices for 1971 21 Outrage|
posted 08-06-2014 09:25 PM ET (US)
I have been contemplating power choices for my 1971 Boston Whaler Outrage 21 project. For the purpose of this thread I would like to discuss E-TEC motor choices. (I am considering others but want to narrow down my E-TEC list)
At 418 pounds for the 20" shaft I can get the following E-TEC engines.
I know that 150 is more than enough for this hull but why would I not chose a higher HP motor if the weight is the same. What would the trade off be other than initial cost?
The boat will be used for cruising and fishing. I would like to see low-50-MPH top end even though I may rarely take it there, I would still like the ability to do it.
posted 08-06-2014 09:55 PM ET (US)
I was at Torch Lake last week, tied next to a 21 ribbed Outrage with a 225 Yamaha and a hydraulic jack plate. That is a LOT more than 420-lbs and he had no problems with it at all; speeds were in the mid 50's. Get the 200. The hull is rated for it, and the fuel economy will be the same as with a 150.
posted 08-07-2014 06:58 AM ET (US)
I know the hull can handle the weight. I just want to keep it lighter if possible. Is it that true that the fuel burn would be comparable on my boat between the 150 and the 200? That would make my choice a lot easier.
posted 08-07-2014 07:37 AM ET (US)
Yes, the 150 and non-HO 200 have the same displacement. Evinrude turns the 200 into a 150 simply by changing the fuel injection mapping, thus not allowing it to ingest as much fuel and air as the 200 gets.
That means that with the 200, unless you're actually using the last 50 ponies to go faster than the 150 could, your mileage will be pretty much equivalent to the 150. In fact, it will probably be a little better than the 150 at equivalent speeds, since you'll be running a taller prop.
posted 08-07-2014 10:34 AM ET (US)
Probably not. Just because you are turning a "taller" prop does not mean better fuel economy. Probably more likely that its burning fuel at the same rate for the same speed but just turning fewer RPM while doing so. In other words, the fuel consumption rate per RPM gets compressed because the 150 and 200 have the same WOT RPM max.
posted 08-07-2014 12:32 PM ET (US)
Fuel consumption for an engine is measured by its brake specific fuel consumption (BSFC) which varies quite a bit with engine speeds and loads.
Evinrude has published some BSFC data for the E-TEC engine. You can find it figure 29, WOT BSFC, in the technical paper, "Development of a Compact Intake Porting Design fo ra 2-Stroke DI Outboard Engine," by Paul Westhoff and Justin Johnson, BRP US Inc.
The plotted data shows quite clearly the BSFC is higher at lower mid-range RPM. This tends to refute the notion that running the engine at a lower crankshaft speed and turning a higher pitch propeller will result in improved fuel economy from the engine.
The BSFC of the E-TEC G2 improves to 325-g/kW-h at 5000-RPM from 425-g/kW-h at 3500-RPM, with most of the improvement coming once the engine reaches 4000-RPM.
There is also data for the E-TEC (not G2). The E-TEC shows improved BSFC over a rather steady plateau from 4000 to 5000-RPM, improved from the higher BSFC at lower speeds.
In my own experience, I have found that optimum fuel economy for my boat, engine, propeller, and load tends to occur right at 4,000-RPM. This is confirmed by the shape of the BSFC curves for the E-TEC.
There will be other influences on the boat MPG in addition to the engine BSFC. The propeller efficiency may vary with propeller shaft speed. Propellers of different pitch and diameter will, no doubt, also possess different efficiencies
posted 08-07-2014 12:38 PM ET (US)
The physics of internal combustion engine efficiency are complicated. [Changed topic to discuss the thread itself, rather than engine efficiency].
Practically speaking, comparing the 150 to the 200, you'll probably find that with the 200, the cruise speed (the speed at which maximum mileage is acheived while planing) is a little higher, as is the fuel consumption per unit time; the mileage will likely be about the same.
posted 08-07-2014 01:19 PM ET (US)
" Everybody wants some "
" I want some to "
posted 08-07-2014 02:41 PM ET (US)
JayR's boat seen here with 150 e-Tec seems to rum well. [Link did not lead to the intended video; please try that URL again. Thanks---jimh]
posted 08-07-2014 08:45 PM ET (US)
Sorry Jim , here's another try.
posted 08-07-2014 09:09 PM ET (US)
I agree the boat runs great with a 150 E-TEC on it - I just don't see the downside (other than price) to just installing the 200 - I was thinking maybe I was missing something. If cruise fuel economy will be similar then I do not see the downside to 50 extra HP.
posted 08-07-2014 09:46 PM ET (US)
Of course the question will become is the 50hp really worth the $4620 difference in MSRP. Thats a question only I can answer as its my money at the end of the day - For anyone still readings reference here are the MSRP's of the motors in question - ( I have not really considered the 135 H.O. to be honest)
E135HSL 135 H.O. (-$960 under 150 std)
posted 08-08-2014 07:05 AM ET (US)
Which motor to choose depends on what you want out of the Outrage. If you are going for the highest top speed then of course the 200 is the way to go. If you want better hole shot, then the 150 would be the better way to go. Here's why --
Assuming that a 150 and 200 are both propped to achieve 5850 RPM at WOT, then the only way the 200 achieves greater speed is with a higher pitch prop. With a higher pitch prop, the hole shot is going to suffer because at the lower and middle ranges, the differences in the outputs of the 150 and 200 HP motors is not that great. The 150, running a lower pitch propeller, is likely to be less stressed overall.
Thus, for me the choice between 150 and 200 HP would be between the 2.6L 150 and the 3.3L 200 H.O. In that case, with the 200 H.O. you'd get both better hole shot and the higher top speed.
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