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Author Topic:   Repower 18 Outrage
Bobbyers posted 07-25-2003 02:51 AM ET (US)   Profile for Bobbyers   Send Email to Bobbyers  
I need to repower my 1988 18 Outrage and am wondering what motor to buy either 2 stroke or 4. I worry about the weight of the 4 strokes with the batteries, kicker the stern is already heavy with the 150 Johnson I have. What have others done? What HP do you recommend for a replacement?
Thanks Bob
Tom2697 posted 07-25-2003 11:19 AM ET (US)     Profile for Tom2697  Send Email to Tom2697     
It seems like every other week someone asks this question...I myself asked about 3 months ago. Hence, if you do a search on this site, you should find many posts about this topic and everyone's suggestions.

However, I installed a 140 Suzuki 4-stroke (had 150 Evinrude) and am extremely satisfied with it's performance...efficiency, speed, noise, holeshot, etc. are all acceptable or better than I expected.

Tom2697 posted 07-25-2003 03:57 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
I forgot to add:
I have an '89 Outrage 18, no kicker, dual batteries starboard aft, 10 gallon livewell port aft. Also, new motor weighs less than old motor ('03 vs '89).

whalersman posted 07-26-2003 05:39 PM ET (US)     Profile for whalersman  Send Email to whalersman     

I noticed in another thread that you mentioned that your top speed with the 140 is 45 mph....

What is the slowest trolling speed you can obtain consistantly???

My 1985 150 will troll around 1.9 mph and I normally troll between 2.0 and 2.9


Tom2697 posted 08-04-2003 11:35 AM ET (US)     Profile for Tom2697  Send Email to Tom2697     
I went out this weekend and made some speed measurements...

Boat load: Me @ 180lbs, bimini removed, full fuel, two coolers w/ice/drinks/no fish at that point, offshore rods & tackle, etc
Conditions: 1-2 ft chop in bay
Top speed: 40.3 mph via GPS (35 knots)
Minimum troll: 1.5 mph on sounder (leaving channel), 0.7 mph (entering channel), 1.7-2.1 mph on GPS (both directions)

Max speed could have been better...I didn't trim out entirely due to water conditions. RPM's were at 5800-5900. Max with this prop is 6200 rpm at light load (me and 10 gallons of fuel with no other equipment).

Most interesting note: I traveled about 150 nautical miles (170 statute miles) this weekend. About 100 nm were running on plane. The other 50 nm were at trolling speeds (8-10 knots & 2000 rpm) in 3-6 ft conditions. I still have over 1/2 of the fuel left in my tank!!!

whalersman posted 08-04-2003 03:09 PM ET (US)     Profile for whalersman  Send Email to whalersman     

Those speeds and fuel consumption look great... The 140 4 Stroke seems to be the engine to repower an 18 with if a person does indeed want a 4 Stroke...

Thanks for the info....


lhg posted 08-04-2003 03:45 PM ET (US)     Profile for lhg    
The new Yamaha 150 might be worth a look. From everything I have read here so far on it's performance characteristics, I am not convinced the Suzuki 140 is putting out much more than 115 HP, the engine it is upgraded from. I believe they stretched it up to the 140 rating to beat out Honda, with the 130, and to approach the magical 150, where no 4-stroke existed at the time. That's the way they do it in marketing these days. There is no way a Suzuki 140 will outrun a Mercury 135 Optimax either, in speed or fuel economy. You can argue reliability if you want. Who knows.

If Tom's boat will do, say 42 mph, that is about the same as a good 115 2-stroke will do on the 18 Outrage. So where is this 140 HP rating coming from? Most 150 V-6's will do about 50 on an 18, so a true 140 ought do do about 47-48 or so.

If one truly wants the Suzuki, I would think you're better off buying the 115 and saving the money for the HP rating you may not be getting.

Bigshot posted 08-04-2003 03:53 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
The 140 is lighter and is only about $300 more than the 115 and has the controversial cowling. The engine has to be within 10% of stated hp rating so a 125 at least. He also states he has hit 45 which is where 140 2 strokes run. The 135 and 150's are v6's and that is where the performance gain comes from. No inline or V4 2 stroke can match the V6. I ran a 1991 19' with a 150 Merc and she did not hit 50.
Tom2697 posted 08-04-2003 05:52 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
When I had the '89 Evinrude 150 on this boat, with the light load, I only got 47 mph on my sounder. Maybe I was propped wrong but I did 5700 rpm at WOT. I didn't have the GPS with me so I couldn't run true speed. Nor did I have 400+ feet of 1/2" anchor line with 18' of 3/8" diameter chain as rode. Nor did I have a full tank of gas. Nor, did I have the bottom painted. Nor did I have any of the other additions I have since added. Weight will make all the difference. Look at Clark Robert's speed formula based on weight, horsepower, and hull factor in the reference section on this site. Gaining an extra 10 hp will only move the boat about 1.1 mph faster at the same weight. At the lightly loaded condition, my estimated weight is 2200 lbs. With the 140, I should do 45.4 mph. With a 150, I should do 46.5 mph. Remember, the 150's also weigh (on average) 50 lbs more than the 140. At the heavily loaded condition that I was at this weekend, about 2600 lbs, these numbers almost exactly match those I provided via my performance test.

Please, let's debate fact versus fact. Not fact versus "I think it will do this."

lhg posted 08-04-2003 06:33 PM ET (US)     Profile for lhg    
Fact is that several here have reported their Johnson 150HP powered 18 Outrages can do 50. A new (we are comparing new engines here) 60 Degree V-6 150, either Johnson or Mercury EFI, can definitely attain that speed when correctly set up on an 18 Outrage. Both are fast motors. My experience is that a Yamaha 90 degree 150HP won't run with either of these two engines, nor will 130 or 140 HP 4-strokes.
Tom2697 posted 08-05-2003 03:14 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
"Horsepower is the unit of power that has been adopted for engineering work. It is defined as the product of force times distance divided by time. It is equal to 550 foot-pounds per second." Hence, 150 hp = 150 hp = 150 hp. The other factors of the engine are where performance differences come from. These factors include weight, gearing, hydrodynamic drag, wear, marketing, etc. Also, a "new" engine with 1000 hours will probably not produce the same power as an "old" engine with 100 hours. Enough of this...

I never stated that others cannot get their boats up to 50 mph with a 150 hp outboard. I stated that I could not. I could probably get my boat up to 50 mph with the 140 hp if I stripped enough weight off it. My point is, the numbers I got are the numbers I got with how my boat is loaded. If these are acceptable to others with similarly loaded boats, I suggest they look into the Suzuki. If not, look for something else. Suggesting a 115 hp will perform the same as the 140 hp in a similarly loaded boat is pure (and poor) speculation. I have already loaded my boat with the 150 hp to the point where I couldn't get it above 35 mph. Should I have sold the motor at that point and bought a new technology 90 hp?

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