RAGE 15 Jet Re-power

[jbrobinson33]

My 1994 OMC 115 Turbojet in my Rage 15 is blown. I was going to have it rebuilt when I noticed that the X-Flow turbojet motors came in 90, 115 and 140 HP. Has anyone here ever swapped the 115 HP turbojet for a 140 turbojet?

Would be possible to do so in a Rage 15?

The Rage 15 has always been under-powered with the 115 so I'm hoping [changing to a 140-HP jet drive] is possible. Thanks in advance for your help and guidance.

[Pelican]

Hello, I have a 1995 15 Rage 115 Turbojet that I am going to convert to an outboard. I have never run the engine. It is a project boat I bought two years ago. I would consider [the 115 Turbojet] for parts only, but may try to run it yet, as I plan on starting the project this Fall. The engine and jet are coming out soon, make an offer. Thanks

[whalerguy321]

Hello--I have two 15 foot RAGE boats. One I removed the jet drive assembly and glassed in the void. The other I just removed the engine and sealed up the intakes and discharge ports with 5200. One the latter I reinforced the existing transom with a one inch thick fiberglass reinforced wood transom with stringers to the transom and hull. That RAGE has super-sturdy-transom.

The RAGE with the jet drive assembly removed and glassed over has a 10-inch adjustable jack plate and was powered with an Evinrude 115-HP outboard--[the engine] was [too] heavy and [too] much power.

I’m using both RAGE boats for sight seeing, casual fishing, and boating. I’m repowering with a 30 to 50-HP four-stroke-power-cycle outboard engine with a 20 to 25-inch shaft. I’ll enclose a picture of the Whaler with jet drive removed, [transom] glassed over, and set up.

I think a 70-HP four stroke is maximum weight and power for these boats.

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[jimh]

A conversion of the RAGE 15 Jet Drive boats by removing the jet drive, reinforcing the transom, adding a bracket, and mounting an outboard engine has been a popular method to re-power them.

I think you have to repair the hull, too, as there must have been a water inlet for the jet drive that needs to be filled. Perhaps someone can show us their repair of the hull.

[jbrobinson33]

Yeah, I may end up going the conversion route but, call me crazy, I really love the Jet Drives. Replacing the 115 TurboJet with a 140 TurboJet is option 1 (if possible), replacing with another 115 is option 2, and conversion is option 3. But I do appreciate any advice and input you all have - who knows, you could make me change my mind.

[jimh]

The problem I see with re-powering with a jet drive is the availability of repair parts. The OEM jet drive in a c.1995 boat is now 22 or 23 years old. I don't know if repair parts are still available, or if complete new engines and drives are available. The jet drive Boston Whaler RAGE was very popular when first introduced, but I notice that the horsepower options kept increasing every year, and after a few years the whole jet-drive line was abandoned. It seems intrinsic in a jet drive that you would need to replace some wear parts, particularly the main impeller I would think.

I don't know the state of the market for drop-in replacement engines and drives. Jet drives continue to be popular in some areas, but they seem to have moved into larger hulls than these 15-footers. Of course, PWC or Jet-Ski boats have gotten bigger, so perhaps a drive from a larger Jet-Ski boat could be adapted. But I do not recall anyone having written here about a project like that. You could be the first, if you do re-power with a non-OEM non-drop-in replacement jet drive.

[jbrobinson33]

All valid points and worthy of consideration.

Parts are still available but they are becoming harder to find for sure. People that know how to rebuild them are becoming scarce as well. I have found complete rebuilt OMC 115 TurboJets on ebay and some other web sites that specialize in the older stuff, but I've never come across a Mercruiser SportJet 140 any where.

I hadn't really thought about adapting a non-OEM drive because I'm not sure my skills are up to that challenge. And if I have to pay someone to do it, well that's where the real expense comes in - Labor.

Seems like there should be another power plant out there that would drop in "fairly easily" - I just don't know what it is.

[dtmackey]

IMHO - the Rage jet boats were a great idea, but the problem is the motors available at the time were not ideal. The old OMC cross flow 90 - 115 outboards were converted to inboard jet drives and those motors were just OK as outboards (I owned a couple over the years). Bury that motor in a cavity that holds moisture and sees little attention and you are asking for trouble. When you consider a Jet drive they are inherently inefficient for drive units, so that's why they ran such high horsepower ratings. The rule of thumb is about a 30% loss jet compared to prop, so 115 equates to 80hp and the 70hp outboard is the best fit for weight reasons.

Last year in my search for a Supersport 15, I came across a couple of 15' Rage boats with bad motors for short money and was tempted, but opted for the SuperSport since I have fond memories of one back in the 80s as a kid.

D-

[jbrobinson33]

Good info - thanks.

I was thinking that if I did do a conversion to OB that I would use a 90 HP - is the weight difference between the 90 and the 70 really that critical? I can't get past the fact that I think it's under-powered as is and that the 70 would not be much of an improvement - but then again, perhaps the 115 was not performing optimally before it blew up which could make my impression of it skewed. Hard to say since I do not have any experience with a converted Rage.

[whalerguy321]

A 90hp is max that you'll need. Keep in mind the new four strokes are larger and heavier motors. However Yamaha and Tohatsue have lightened up their new motors. Shop around get specs. An late model two stroke could suffice.

[Wweez]

Weight difference depends on the engine. Some 70s are the same wt as 90s. Yamaha 2 cycle for instance.
But the 4 cylinder omc 90s are the same wt as the 4 cylinder omc 115 mentioned above. The post by owner said too heavy and too much power. Those engines are about 350lb. The 4 cycles are heavier.
70hp on the 15ft hull is a lot whether it is a configured as a rage or a 15 whaler.

dtmackey s comments are great and to the point.
My question is how practical would a conversion to pwc engines. They are tough engines, quieter now and of almost any horsepower.

[Pelican]

WHALERGUY'--Do you have any [interference when] tilting engine up?

It looks tight.

Years ago, a friend had a similar 115 on a Forester speedboat, which seemed just fine. I was planning on an E-TEC 90 or 115, which I believe are same powerhead, and should not be weight-prohibitive. But i jump too far ahead.

Lot of work before that. [What] is the best way to attach engin? A Fixed engine mount? OR, adjustable jack-plate?

Thank you all for help, the pictures, and the input.--Pelican

[jimh]

...planning on an E-TEC 90 or 115, which I believe are same powerhead...

The Evinrude E-TEC 90 engine is a three-cylinder in-line engine. The E-TEC 115 is a V4 60-degree. They are different powerheads.

[Pelican]

Appreciate the info. I did notice on Evin wbst that the 90 H.O. seemed to be the same wt and appearance as 115 and 115 HO, yet the reg 90 was much lighter and diff in appearance. Not researching engines much til I get hull ready. I am looking for opinions on best way to mount engine and maintain clearance for tilt. Thanks again for your input. Pelican

[dtmackey]

Appreciate the info. I did notice on Evin wbst that the 90 H.O. seemed to be the same wt and appearance as 115 and 115 HO, yet the reg 90 was much lighter and diff in appearance. Not researching engines much til I get hull ready. I am looking for opinions on best way to mount engine and maintain clearance for tilt. Thanks again for your input. Pelican

Evinrude Etec 75 and 90 are the same block with software tweaks to arrive at the 2 different power ratings and weighs 320#.

Evinrude 90HO is the V4 block and is designed to run about 5 - 8% more power, so you may have something in the 95hp-ish range. IMHO, not worth the additional weight penalty (390 vs 320# of the Etec 75 and 90). These little boats tend to like lighter motors. 90HO is the same engine as the 115, again with software dictating power output.

The Rage 15 comes with a 115 jet drive, once you factor in the inefficiency of jet (30%) that 115hp is more in the 80 range, which makes it an ideal candidate for the Etec 75 and if you feel the need for more, then the standard 90 would sure be the ticket.

Personally the Rage 15 seems similar to the Dauntless 15, maybe there are some small hull differences. The Dauntless 15 is rated for 70hp and does not seem under powered. Can't image hanging a 90HO at 390# and believing you'd have a boat that sits level in the water and has handling problems.

For my project Whaler 15', I have both an Etec 75 and Yamaha 70 2 stroke (320# and 228# respectively) and I'm mounting the Yamaha for weight reasons and selling the Etec 75 because I do not feel the boat will handle and sit in the water the way I'd prefer. The Etec would burn less fuel, less oil, be quieter and cleaner, but I do not feel it ideal for the boat.

Just my $0.02

D-

[Pelican]

Thank you for that wealth of info. A very helpful response. I'm also a Yamaha fan and currently run a 25 hp 2-stroke on my 11' Rib. Great combo, love it. Thanks. Pelican

[whalerguy321]

Pelican,
I have an adjustable jack plate with a ten-inch set back. In the pictures the engine is at its lowest point. When raised to its highest point the engine has plenty of room to tilt. I will be using a 30 to 50-HP four-stroke or maybe a two stroke as both my whalers are for sightseeing and whale watching. I have no desire to bounce my passengers over the side at high speeds. Strictly intercoastal cruising down south and whale and bird watching in the bay up north. The ten-inch set back of the jack plate is sufficient with the right motor and shaft length. I’m not a need-for-speed guy. More like wine, beer, sunset. nature in all its glory person. Again shaft length, tilt-trim, horsepower, weight are all factors. Trailering distance also. A reinforced transom is a must. I picked both my Rage boats up for less than $1000 apiece with the trailers included. Shop around. Think versatility when picking an outboard, that is, can you place the outboard on another boat with ease. Remember the RAGE was designed for an inboard engine. Not an outboard.
Thanks,
Whalerguy