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Author Topic:   E-TEC 90 WOT RPM

nordeng posted 06-29-2008 10:44 PM ET (US)
Hello. I just bought a new 90 E-TEC for my Montauk 17. It is only turning 4600 at WOT. [What is] the optimal WOT range for this [motor]? The manuals says 4,500 to 5,500-RPM, but 4,600 just seems too low for this boat. Perhaps it is overpropped. Thanks. Greg.
jimh posted 06-29-2008 11:38 PM ET (US)
The optimum RPM range for a 2008 E-TEC 90 is 5,000 to 5,200-RPM at wide-open throttle. It sounds like you ought to decrease the pitch of the propeller by 2-inches.
beantown posted 06-30-2008 09:26 AM ET (US)
Hey Nordeng,
I had the same problem about 5 months ago. I brought the boat back to the dealer that installed it and told them that it should be turning at a higher RPM. They switched it out for a different one. Now it turns at about 4900, which is still kinda low. But I can't afford buying a 13-1/4" x 15" Stiletto Advantage I which apparently is the best prop for this boat and engine. I hope this helps. Here is the link to my original post.
http://continuouswave.com/ubb/Forum4/HTML/006082.html
nordeng posted 06-30-2008 07:24 PM ET (US)
I went out today and it appears to me that the engine is mounted too low. The anti vent plate is buried about 2 -3 inches below the surface when at cruise. When the guys that put the new motor on mounted it, they drilled the bottom hole at the lower part of the range; therefore, another set of holes will have to be drilled to raise the engine. This will be a hassle as they already had to drill a set of new holes to mount this engine versus my original V4. The prop is a 17" pitch which seems ok, but I'm wondering if I'll do longterm damage to the engine at this height or if I'll just leave some speed and fuel efficiency on the table. I don't run WOT often so I don't really care about top end. Any thoughts? Thanks.
cooper1958nc posted 06-30-2008 08:43 PM ET (US)
I have irritated all the knowlegeable on this forum with my persistant nonbelief in the necessity to operate at the FT operating "range" specified by the manufacturer.
Yet my nonbelief persists, and no, you will not harm your engine going 4900 RPM FT, or 4500 RPM FT, or, of course, less RPM at less than FT.
You might save some fuel, noise, and wear, too.
2manyboats posted 06-30-2008 09:54 PM ET (US)
There are plenty of Montauks with their engines mounted low. I am curious as to your motor could be mounted low and the lower bolts be in the bottom holes and not be below the bottom of the splash well. If you are running a 17 inch pitch and only getting 4600rpms and you can't raise you motor just go to a 15 inch pitch.
Backfire posted 06-30-2008 11:11 PM ET (US)
cooper1958nc , Do you belong to The Flat Earth Society?
Backfire
cooper1958nc posted 07-01-2008 10:55 AM ET (US)
Mr. Backfire, before you continue your nacent personal attack, if you like this sort of thing, why not state your credentials in thermodynamics, metallurgy and tribology, or better yet frame some reasoned analysis, or even verifiable anecdote.
The flat earth analogy is used to describe commonly or widely accepted untruths. Like yours?
jimh posted 07-01-2008 08:46 PM ET (US)
I do not hold with those who believe that cooper' is a Luddite.
kazankota posted 07-01-2008 09:21 PM ET (US)
Mount it on a CMC jack plate or set back brackets and then you don't need to worry about new holes and can raise and lower it to where you want
Tom W Clark posted 07-02-2008 10:51 AM ET (US)
Greg,
I am sorry to report that the installer of your new E-TEC 90 have done you very great disservice by mounting the motor that way. You need to raise the motor on the transom.
It is very common for the 16/17 foot Whalers with OMC motors from the 1960s, 1970s and 1980s to have had those motors mounted using the blind holes in the mounting brackets of the motors. This was usually done to avoid drilling below the bottom of the splashwell and to keep the motor low on the transom.
With today's motors and propellers there is no need for the motor to be so low. The solution for an older boat that has had the transom drilled for the blind holes is to plug (DO NOT DOWEL) the lower holes and drill new lower mounting holes per the NMMA standard layout but raised either 3/4" or 1-1/2" on the transom so they are 7-1/4" or 6-1/2" below the upper holes.
The upper holes are standard and will work with any new outboard sold today.
When mounting the engine use the second or third set of upper mounting holes, and use the upper set of mounting holes on the lower part of the motor's mounting bracket.
This is an FAQ and is described in the Reference Section as well:
http://continuouswave.com/whaler/reference/FAQ/#Q8
Tom W Clark posted 07-02-2008 10:55 AM ET (US)
Greg,
While the recommended WOT range for the E-TEC 90 is a very broad 4500 - 5500 RPM, the optimum WOT range RPM is 5000 - 5200 RPM. 4600 RPM is way too low; your boat's performance will suffer unless you can allow more RPM.
Yes, the 13-1/4" x 15" Stiletto Advantage has proven again and again to a very good fit for the E-TEC 90 powered 16/17 foot Whalers.
nordeng posted 07-02-2008 09:46 PM ET (US)
Thanks Tom - The work was done by a dealer in Jamestown, RI who I had heard was a reputable dealer that had done several Montauk repowers. I still think they are reputable, but probably misinformed. I can now do one of two things: I can keep the engine mounted low and just run a 15" pitch prop which will probably increase the RPM to the recommended range, say 5200 or so. Or I can make a stink and have the dealer start from scratch and try to do it right this time (and fill in holes, reglass, etc.). All this being said, I'm going to run the 15" prop this weekend and see if that at least solves my RPM problem. If it does, I presume I can still run the engine at the current (too low) height and not affect the longevity of the engine. Could you confirm this, i.e., if the engine is turning full RPM, does it really make any difference if it is mounted lower than optimal, other than a few MPH on the top end (which I'll never need anyway)? Your advice is appreciated. Greg.
Tohsgib posted 07-03-2008 10:09 AM ET (US)
Yes you will be fine...you can also install a jackplate and raise her up.
kazankota posted 07-03-2008 10:36 PM ET (US)
Greg
I just had my 90 E-Tec installed ('87 Montauk) by Conanicut Marina in Jamestown, RI who probably installed your motor as well. After doing a ton of research I had my installed on the CMC ML-65 jackplate which worked out perfectly as no holes needed to be drilled. Initially they told me they were going to have to go into the splashwell, open it up, and dig out the foam for the lower mounting holes, but I advised that I didn't want this. The outboard tech said I didn't need the jackplate, etc. But that is what this website is for. I told them exactly what I wanted and they followed it, even though they wanted to do it different.
I would go for the jackplate, it is an easy and solid fix to your problem, also probably the more economical route.
-Torrey
Tom W Clark posted 07-04-2008 09:57 AM ET (US)

quote:
[T]hey were going to have to go into the splashwell, open it up, and dig out the foam for the lower mounting hole...
For Pete's sake, would somebody please contact Conanicut Marina in Jamestown, RI and tell them to stop butchering classic Boston Whalers unnecessarily? It breaks my heart to hear reports of boats twenty, thirty or even forty years old that have survived unscathed until being cut open by ignorant outboard mechanics.
SeaBatical posted 07-16-2008 09:10 PM ET (US)
NordEng,
We just purchased a Montauk 17 and live in North Kingstown. We'll be on the water this weekend and will keep an eye out for fellow Montauks!
I will probably have some performance questions for this forum after the weekend. I road-tested the boat last weekend on the Cape before purchase and it turned 36MPH @ 4900RPM on a prop that was TBD. It has a Yamaha 90 HP 2-stroke and I would have expected 43MPH? I changed the prop to the Yamaha standard; 13-1/4 x 17 aluminum so I can establish a baseline with a known propeller.
For reference it's a 1998 hull with a 1997 engine.
There are five holes underneath the engine with a spring-loaded rod. It was set at the highest (furthest back) position and I moved it the the center hole. Can anybody tell me what this might do?
Thanks,
Chris
Tohsgib posted 07-16-2008 11:13 PM ET (US)
90hp Yamaha with 13x17 prop will fetch 41+, no way doing 43. They are a weak 90hp.
Fishmore posted 07-17-2008 12:59 AM ET (US)
Seabatical, on the five hole issue the hole closest to the transom forces the bow down. The hole farthest from the transom forces the bow up. So by using the middle hole you are at neutral trim. The trim will affect hole shot and/or top speed depending on which hole you use.
When you have power tilt on the engine you start out with the motor tucked in (to reduce bow lift) and then pull it away from the transom as you get up to speed. I normally will get to cruising speed and then move the motor away from the transom until the prop starts to ventilate then I drop the motor back toward the transom slightly in order to achieve my most efficient cruise speed.
With no power trim then you will need to play around manually to see which hole works best for you.
Joninnj posted 07-26-2008 11:29 AM ET (US)
Tohsgib,
I have the same set up, I hit 42MPH @ 5200 RPM on a GPS. I can consistently get to 5200. I have seen 5300 RPM on cooler dry days. And I also have bottom paint on the hull and the Engine is mounted Flush on the transom. If I raise it up a hole or two it is very easy to figure out where the the RPM will go. I Use 19 K series stainless. Set up properly 45MPH is within the capabilites of this engine and set up.
Listed below is performance data for various 90's on the 17 footers directly from this site, missing is the eTec.

Re-Powering
Predicted performance data for Montauk with various engine combinations as computed by Kelly Ewing following the formula suggested by Clark Roberts and explained in the Reference article on propellers:
Fuel=168#
Boat=950#
Gear and Passengers=400#
MAKE/HP/CYCLE MOTOR WT TOTAL WT MPH
---------------------------------------------
Honda 50 4 212 1730 34
Honda 90 4 373 1891 44
Yamaha 50 4 233 1751 34
Yamaha 60 4 244 1762 37
Yamaha 100 4 356 1874 46
Yamaha 50 2 194 1712 34
Yamaha 60 2 228 1746 37
Yamaha 70 2 228 1746 40
Yamaha 90 2 261 1779 45
Merc 50 4 236 1754 34
Merc 60 4 236 1754 37
Merc 90 4 386 1904 43
Merc 50 2 199 1717 34
Merc 60 2 219 1737 37
Merc 75 2 303 1821 41
Merc 90 2 303 1821 44
Suzuki 50 4 243 1761 34
Suzuki 70 4 359 1877 39

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Author	Topic: E-TEC 90 WOT RPM
nordeng	posted 06-29-2008 10:44 PM ET (US) Hello. I just bought a new 90 E-TEC for my Montauk 17. It is only turning 4600 at WOT. [What is] the optimal WOT range for this [motor]? The manuals says 4,500 to 5,500-RPM, but 4,600 just seems too low for this boat. Perhaps it is overpropped. Thanks. Greg.
jimh	posted 06-29-2008 11:38 PM ET (US) The optimum RPM range for a 2008 E-TEC 90 is 5,000 to 5,200-RPM at wide-open throttle. It sounds like you ought to decrease the pitch of the propeller by 2-inches.
beantown	posted 06-30-2008 09:26 AM ET (US) Hey Nordeng, I had the same problem about 5 months ago. I brought the boat back to the dealer that installed it and told them that it should be turning at a higher RPM. They switched it out for a different one. Now it turns at about 4900, which is still kinda low. But I can't afford buying a 13-1/4" x 15" Stiletto Advantage I which apparently is the best prop for this boat and engine. I hope this helps. Here is the link to my original post. http://continuouswave.com/ubb/Forum4/HTML/006082.html
nordeng	posted 06-30-2008 07:24 PM ET (US) I went out today and it appears to me that the engine is mounted too low. The anti vent plate is buried about 2 -3 inches below the surface when at cruise. When the guys that put the new motor on mounted it, they drilled the bottom hole at the lower part of the range; therefore, another set of holes will have to be drilled to raise the engine. This will be a hassle as they already had to drill a set of new holes to mount this engine versus my original V4. The prop is a 17" pitch which seems ok, but I'm wondering if I'll do longterm damage to the engine at this height or if I'll just leave some speed and fuel efficiency on the table. I don't run WOT often so I don't really care about top end. Any thoughts? Thanks.
cooper1958nc	posted 06-30-2008 08:43 PM ET (US) I have irritated all the knowlegeable on this forum with my persistant nonbelief in the necessity to operate at the FT operating "range" specified by the manufacturer. Yet my nonbelief persists, and no, you will not harm your engine going 4900 RPM FT, or 4500 RPM FT, or, of course, less RPM at less than FT. You might save some fuel, noise, and wear, too.
2manyboats	posted 06-30-2008 09:54 PM ET (US) There are plenty of Montauks with their engines mounted low. I am curious as to your motor could be mounted low and the lower bolts be in the bottom holes and not be below the bottom of the splash well. If you are running a 17 inch pitch and only getting 4600rpms and you can't raise you motor just go to a 15 inch pitch.
Backfire	posted 06-30-2008 11:11 PM ET (US) cooper1958nc , Do you belong to The Flat Earth Society? Backfire
cooper1958nc	posted 07-01-2008 10:55 AM ET (US) Mr. Backfire, before you continue your nacent personal attack, if you like this sort of thing, why not state your credentials in thermodynamics, metallurgy and tribology, or better yet frame some reasoned analysis, or even verifiable anecdote. The flat earth analogy is used to describe commonly or widely accepted untruths. Like yours?
jimh	posted 07-01-2008 08:46 PM ET (US) I do not hold with those who believe that cooper' is a Luddite.
kazankota	posted 07-01-2008 09:21 PM ET (US) Mount it on a CMC jack plate or set back brackets and then you don't need to worry about new holes and can raise and lower it to where you want
Tom W Clark	posted 07-02-2008 10:51 AM ET (US) Greg, I am sorry to report that the installer of your new E-TEC 90 have done you very great disservice by mounting the motor that way. You need to raise the motor on the transom. It is very common for the 16/17 foot Whalers with OMC motors from the 1960s, 1970s and 1980s to have had those motors mounted using the blind holes in the mounting brackets of the motors. This was usually done to avoid drilling below the bottom of the splashwell and to keep the motor low on the transom. With today's motors and propellers there is no need for the motor to be so low. The solution for an older boat that has had the transom drilled for the blind holes is to plug (DO NOT DOWEL) the lower holes and drill new lower mounting holes per the NMMA standard layout but raised either 3/4" or 1-1/2" on the transom so they are 7-1/4" or 6-1/2" below the upper holes. The upper holes are standard and will work with any new outboard sold today. When mounting the engine use the second or third set of upper mounting holes, and use the upper set of mounting holes on the lower part of the motor's mounting bracket. This is an FAQ and is described in the Reference Section as well: http://continuouswave.com/whaler/reference/FAQ/#Q8
Tom W Clark	posted 07-02-2008 10:55 AM ET (US) Greg, While the recommended WOT range for the E-TEC 90 is a very broad 4500 - 5500 RPM, the optimum WOT range RPM is 5000 - 5200 RPM. 4600 RPM is way too low; your boat's performance will suffer unless you can allow more RPM. Yes, the 13-1/4" x 15" Stiletto Advantage has proven again and again to a very good fit for the E-TEC 90 powered 16/17 foot Whalers.
nordeng	posted 07-02-2008 09:46 PM ET (US) Thanks Tom - The work was done by a dealer in Jamestown, RI who I had heard was a reputable dealer that had done several Montauk repowers. I still think they are reputable, but probably misinformed. I can now do one of two things: I can keep the engine mounted low and just run a 15" pitch prop which will probably increase the RPM to the recommended range, say 5200 or so. Or I can make a stink and have the dealer start from scratch and try to do it right this time (and fill in holes, reglass, etc.). All this being said, I'm going to run the 15" prop this weekend and see if that at least solves my RPM problem. If it does, I presume I can still run the engine at the current (too low) height and not affect the longevity of the engine. Could you confirm this, i.e., if the engine is turning full RPM, does it really make any difference if it is mounted lower than optimal, other than a few MPH on the top end (which I'll never need anyway)? Your advice is appreciated. Greg.
Tohsgib	posted 07-03-2008 10:09 AM ET (US) Yes you will be fine...you can also install a jackplate and raise her up.
kazankota	posted 07-03-2008 10:36 PM ET (US) Greg I just had my 90 E-Tec installed ('87 Montauk) by Conanicut Marina in Jamestown, RI who probably installed your motor as well. After doing a ton of research I had my installed on the CMC ML-65 jackplate which worked out perfectly as no holes needed to be drilled. Initially they told me they were going to have to go into the splashwell, open it up, and dig out the foam for the lower mounting holes, but I advised that I didn't want this. The outboard tech said I didn't need the jackplate, etc. But that is what this website is for. I told them exactly what I wanted and they followed it, even though they wanted to do it different. I would go for the jackplate, it is an easy and solid fix to your problem, also probably the more economical route. -Torrey
Tom W Clark	posted 07-04-2008 09:57 AM ET (US) quote: [T]hey were going to have to go into the splashwell, open it up, and dig out the foam for the lower mounting hole... For Pete's sake, would somebody please contact Conanicut Marina in Jamestown, RI and tell them to stop butchering classic Boston Whalers unnecessarily? It breaks my heart to hear reports of boats twenty, thirty or even forty years old that have survived unscathed until being cut open by ignorant outboard mechanics.
SeaBatical	posted 07-16-2008 09:10 PM ET (US) NordEng, We just purchased a Montauk 17 and live in North Kingstown. We'll be on the water this weekend and will keep an eye out for fellow Montauks! I will probably have some performance questions for this forum after the weekend. I road-tested the boat last weekend on the Cape before purchase and it turned 36MPH @ 4900RPM on a prop that was TBD. It has a Yamaha 90 HP 2-stroke and I would have expected 43MPH? I changed the prop to the Yamaha standard; 13-1/4 x 17 aluminum so I can establish a baseline with a known propeller. For reference it's a 1998 hull with a 1997 engine. There are five holes underneath the engine with a spring-loaded rod. It was set at the highest (furthest back) position and I moved it the the center hole. Can anybody tell me what this might do? Thanks, Chris
Tohsgib	posted 07-16-2008 11:13 PM ET (US) 90hp Yamaha with 13x17 prop will fetch 41+, no way doing 43. They are a weak 90hp.
Fishmore	posted 07-17-2008 12:59 AM ET (US) Seabatical, on the five hole issue the hole closest to the transom forces the bow down. The hole farthest from the transom forces the bow up. So by using the middle hole you are at neutral trim. The trim will affect hole shot and/or top speed depending on which hole you use. When you have power tilt on the engine you start out with the motor tucked in (to reduce bow lift) and then pull it away from the transom as you get up to speed. I normally will get to cruising speed and then move the motor away from the transom until the prop starts to ventilate then I drop the motor back toward the transom slightly in order to achieve my most efficient cruise speed. With no power trim then you will need to play around manually to see which hole works best for you.
Joninnj	posted 07-26-2008 11:29 AM ET (US) Tohsgib, I have the same set up, I hit 42MPH @ 5200 RPM on a GPS. I can consistently get to 5200. I have seen 5300 RPM on cooler dry days. And I also have bottom paint on the hull and the Engine is mounted Flush on the transom. If I raise it up a hole or two it is very easy to figure out where the the RPM will go. I Use 19 K series stainless. Set up properly 45MPH is within the capabilites of this engine and set up. Listed below is performance data for various 90's on the 17 footers directly from this site, missing is the eTec. Re-Powering Predicted performance data for Montauk with various engine combinations as computed by Kelly Ewing following the formula suggested by Clark Roberts and explained in the Reference article on propellers: Fuel=168# Boat=950# Gear and Passengers=400# MAKE/HP/CYCLE MOTOR WT TOTAL WT MPH --------------------------------------------- Honda 50 4 212 1730 34 Honda 90 4 373 1891 44 Yamaha 50 4 233 1751 34 Yamaha 60 4 244 1762 37 Yamaha 100 4 356 1874 46 Yamaha 50 2 194 1712 34 Yamaha 60 2 228 1746 37 Yamaha 70 2 228 1746 40 Yamaha 90 2 261 1779 45 Merc 50 4 236 1754 34 Merc 60 4 236 1754 37 Merc 90 4 386 1904 43 Merc 50 2 199 1717 34 Merc 60 2 219 1737 37 Merc 75 2 303 1821 41 Merc 90 2 303 1821 44 Suzuki 50 4 243 1761 34 Suzuki 70 4 359 1877 39