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Author Topic:   Montauk Re-power

ugasailrboy posted 07-19-2011 09:23 PM ET (US)
[Says he plans] to repower my [1986 Boston Whaler MONTAUK 17] and seriously looking at [Evinrude E-TEC 90] due to weight and familiarity. [The boat is] mainly used for cruising and pulling skiers. [Give the author your thoughts about] other power plants.
Tom W Clark posted 07-19-2011 09:27 PM ET (US)
The Evinrude E-TEC 90 has become the classic 16'-7" Whaler re-power of choice for a lot of reasons, not just its relatively low weight. It is a superb motor.
But all the outboard manufacturers make very good motors these days and a Montauk does well with power from 50-100 HP. Take your pick, but try not to buy anything that weighs much more than 350 pounds.
Sal A posted 07-19-2011 10:18 PM ET (US)
I repowered with an E-TEC 75. I was very happy with that power.
domlynch posted 07-20-2011 03:07 AM ET (US)
I've got an '08 Optimax 90 (375lbs) re-power on my inherited Montauk, wouldn't be my first choice but its ok.
If re-powering again with a DFI 2 stroke I would go with a 90 ETEC. I agree with Tom W. that this motor appears to be a classic for re-powering a classic. If 4 stroke then probably a Yamaha (F70 good for fishing, or bigger hp.for skiing) or a Suzuki (70-90hp) depending on intended useage.
Dom
boatdryver posted 07-20-2011 11:51 AM ET (US)
also, depending on which brand offers good service support near where the boat is.
JimL
Tohsgib posted 07-20-2011 12:44 PM ET (US)
If you want it to be REAL quiet...go with a 4 stroke. If you are a water skier then the E-TEC might be better. I have been on both for many hours and the 90 E-TEC is a perky SOB out of the hole but top end and noise are not much to brag about.
pcrussell50 posted 07-20-2011 01:12 PM ET (US)
While 4-strokes are _amazingly_ quiet at idle, are they really much quieter at, say, 4000 rpm?
-Peter
Tohsgib posted 07-20-2011 01:36 PM ET (US)
My 70 and 115 Suzuki are MUCH quieter all around than Len's 90 E-tec and my 115 is louder than my 70. My 40 you can barely hear. When the alternator kicks in it kinda scares you like "WHAT'S THAT NOISE". At 4k with the wind in yur face you really can't hear it, just a hum like you get from an I/O. Over say 5200 it gets a tad noisier almost like the 4 barrels kicked in.
Blackduck posted 07-20-2011 02:12 PM ET (US)
E-Tec 90 is the engine of choice.
pcrussell50 posted 07-20-2011 02:24 PM ET (US)
Would be for me, too. Quietness is a neat novelty to me, but nothing more. E-TEC 90... baby.
-Peter
jharrell posted 07-20-2011 09:17 PM ET (US)
Etec 90 at 320lbs or Suzuki 90 at 340lbs or Yamaha 70 at 269lbs.
I haven't made up my mind yet for my Montauk, leaning toward the Suzuki based on Fuel burn numbers and performance. E-TEC is so tempting because of the weight and rope start ability, Yamaha because of extreme light weight and economy.
Those are the top three choices in my opinion right now.
stover86montauk posted 07-20-2011 09:49 PM ET (US)
I just put a new Yamaha F90 on my '86 17 montauk. It is noticeably heavier than the old 'rude, but I like that it is quiet, fuel efficient, and doesn't smell like a two stroke or require buying two stroke oil. I have only had it a few weeks, but I feel like it doesn't like to stay on plane at lower speeds due to the weight.
The best advice I can give you is mount whatever engine you purchase up high and get a good prop. Tom W Clark will steer you in the right direction.
WT posted 07-20-2011 09:51 PM ET (US)
Since I boat solo in the ocean and like to travel 35-45 miles one way, I'd get twin Honda 50 fourstrokes which weigh the same as the Honda 40's.:-)
http://i22.photobucket.com/albums/b309/elaelap/KauaiBWs2035.jpg
Warren
weekendwarrior posted 07-21-2011 08:03 AM ET (US)
I have a montauk and get into the ocean when possible. For rough water, especially cruising, lighter weight is good. The ride is much smoother if you can keep the bow down. For this reason alone I would personally go Yamaha, but it sounds like you would do well with any of the choices you listed.
A Little Madness posted 07-21-2011 12:03 PM ET (US)
We went with a Honda BF90D 4 stroke [with] 20-inch shaft, complete [with] binnacle, analog gages, control box, and a Honda Titan Solas 13-1/4 x 15R Stainless Steel Prop in 2007. I have had NO problems [with] the motor, gauges, propeller, etc. to date. It's not that much heavier than the E-TEC 90 and by moving my two gel-cell batteries into the center console it balances very well. Even today I'm still impressed [with] the hole shot, as have been most riders. LOVE IT! Good Luck [with] your decision.
L H G posted 07-22-2011 12:03 AM ET (US)
Classic Montauks are late 70's and 80's boats, not counting the modern looking black and white 90's models. So I recently went with a same generation Mercury 115 6 cylinder Tower.
http://smg.photobucket.com/albums/v429/lgoltz/Montauk%2017/?action=view& current=Scan_Pic0009.jpg
Oversized, heavy, white, black, gray, or gold 90 HP 3-star engines just don't look right on a classic Montauk, or have the power-to-weight ratio and classic appeal of one of these Mercs. As a second choice, I'd go with a same generation OMC V-4.
jharrell posted 07-22-2011 02:02 PM ET (US)
LHG,
Any idea what the fuel burn numbers are with that 115 on the Montauk?
My inline tower 90 looks good on my Montauk but the 80 mile cruise range on 24 gallons is killing me.
KDW posted 07-22-2011 04:15 PM ET (US)
I agree with Tom that there's a lot of good repower choices out there. Back in 2005, I went through the same struggle when trying to decide how to repower my '71 Nauset. Back then, I was looking at the Suzuki DF 70, Yamaha 90 2S, and Etec-90. I was also concerned about too much weight on the transom, so I left the Honda 90 4S and Yamaha 4S off my list of candidates. Cost was a concern, but not the driving factor.
Anyhow, after weeks of second-guessing myself I went to Custom Marine in Statesboro, GA., ready to make a good deal on a Yamaha 90 2S. However, I waffled under salesman pressure and my own jitters and ended up buying the E-tec 90 instead. I don't regret the move as the E-tec worked very well on my Nauset. However, a year or two later I found a '91 Outrage 17 with a Yamaha 90 and then swapped the two motors between my Nauset and Outrage. I still love the E-tec, but would have to say I think the light Yamaha 90 2S is a better motor on the '71 Nauset (she's fast!) and the E-tec 90 better on the Outrage 17'.
I also once owned a 1998 Montauk with a Mercury 100 HP and hated the motor because it dropped out 2 cylinders at low RPM and was always rough between the 2 to 4 cylinder transition. It was a great boat though.
Anyhow, I guess its all about your budget and how you plan to use the boat. I was always a little nevous about buying a 4 stroke because I'm a seasonal boater, and it's probably not really an issue, but I thought all the small carburator parts and other moving stuff could be affected if sitting around for too long. Anyhow, I like the simplicity of a 2 stroke, not to mention the lower weight....but to each his own.
Best of luck in your repower journey!
KW
Tohsgib posted 07-23-2011 01:26 PM ET (US)
Carbs on a 4 stroke? Even the 25 Suzuki and Mercury are EFI. When Suzuki came out with the 4 strokes in late 90's all were EFI from 40up.
pcrussell50 posted 07-23-2011 06:28 PM ET (US)
Yebbut KDW, you're forgetting the overwhelmingly functional upside of all that weight and complexity of a 4-stroke: you can hear the telltale stream hitting the water at idle. Who could live without that?
-Peter
KDW posted 07-23-2011 08:52 PM ET (US)
Thought I remembered the early Yamaha and Honda 4 strokes had carbs....but I'm probably wrong and that was many beers ago.
I'll probably continue to talk smack about the 4 strokes until I own one, then they will be perfect! However, low noise levels won't matter much by then as I'll be deaf anyhow.
Have a good ole biggun or a big ole goodun!
KW
Tohsgib posted 07-24-2011 12:41 PM ET (US)
There were/are 4 strokes with carbs. My point was if you wanted EFI it was just a brand away.
KDW posted 07-24-2011 09:06 PM ET (US)
Understood Tohsgib.
Not meaning to sound argumenative and apologize if it comes across that way. When I was searching for a repower for my old Nauset, I was replacing a tired old Johnson 125 HP that seemed to eat a power pack every year or two.
I was most interested in reliability, low weight, good fuel eff., and a good price. Low engine noise and good warranty were all bonuses. At that time, more than anything the 4 stroke weight was my largest concern, although the Suzuki DF70 looked like a pretty good fit to me on the old Whaler. However, I couldn't find a good Suzuki shop close by, so that kind of killed that option.
Other than a problem with a crack in my oil reservoir requiring replacement, I've not had any issues with my E-tec 90 since 1995. Actually, it has started on the first crank every time and even after winterizing, which is amazing to me coming from so many difficulties with the old 125.
Like all other technology, I'm sure 4 strokes have come a long way in the 5+ years since I've repowered and I'm looking forward to checking them out again if I move up from my '91 Outrage 17 to a newer model whaler or just repower a classic 18/19 Outrage.
Take care,
KW
george nagy posted 07-24-2011 09:53 PM ET (US)
What about those nissan/tohatsu 70/90hp dfi 2 strokes. They remind me alot of the old yamaha 90 2s.
Tohsgib posted 07-24-2011 11:36 PM ET (US)
My Father's 1972 100hp Evinrude DID eat powerpacks ever year or 2.
Peter posted 07-25-2011 07:13 AM ET (US)
4-stroke outboards have come a long way. Just compare one made today to the Bearcat 55 or the 505 lb dry Honda 115/130 which was hardly more than a Civic engine stood on its end and bolted to a drive. But they still don't provide the power to weight to compact size to simplicity ratio of a 2-stroke.
L H G posted 07-26-2011 09:51 PM ET (US)
Jharrell - I am getting somewhere between 4 and 5 MPG on the Montauk with the Mercury 115, at about 25 MPH cruise and about 2800 rpm. Haven't yet taken the time to determine it scientifically. Having too much fun with it! But it is a screamer I can tell you that, with wicked acceleration. Will do over 50 with a 22" Laser II.
The combination of the jackplate and the lift of the Laser II prop give it an exceptional ride, so much better than my old '71 Nauset with similar power that I can't believe it. The smirked hull really was an improvement of major proportions.
Tohsgib posted 07-26-2011 10:58 PM ET (US)
No offense but my Montauk with the DF70 fetched 10mpg at 26mph and 25mpg at roughly 800rpm. Oldies are great but 50% increase in fuel economy is God!!!! Unfortunately my WOT was only 39, not 50. Then again where do we spend 90% of our time?
Slick 50 posted 07-27-2011 12:30 AM ET (US)
Where's the original poster?
Don't need him to have fun.
My Montauk with the 2003 Johnson 115 will do over 50 too. It will consistently get between 5 and 6 MPG between 25 and 40 MPH. Not too shabby for a carbed engine.
The newer 4 strokes and and E-Tec engines sure are nice. Would love to have one.
Rick
jimh posted 07-27-2011 12:59 AM ET (US)
The horsepower needed to push a Montauk that weights roughly 1,800-lbs to 30-MPH can be estimated with Crouch's Calculator if we know the hull constant factor. It seems from some previous data that a hull constant of 200 is about right. We estimate the horsepower as 40-HP. (This fits with L H G's report of 115-HP giving 50-MPH, too.)
With an older two-cycle multi-cylinder engine with carburetors we can expect the brake specific fuel economy to be around 0.6-lbs/HP-hour. With 40-HP this means a fuel burn per hour of 24-lbs or about 3.9-gallons-per-hour.
A boat going 30-MPH and burning 3.9-GPH will have a fuel economy of about 7.7-MPG.
Tohsgib posted 07-27-2011 12:19 PM ET (US)
Jim from owning a few a Montauk with a V4 crossflow will burn closer to 6gph at 30mph which is 5mpg.
jimh posted 07-27-2011 12:35 PM ET (US)
Nick--Yeah, I thought my calculated MPG was optimistic. The horsepower being used is probably too low in my calculation, and the BSFC for an older two-cycle with cross-flow is probably more like 0.7-lbs/HP-hour.
If we use 50-HP and 0.7-lbs/HP-hour, we get 5.6-GPH. If the boat runs 30-MPG that is 5.4-MPG
pcrussell50 posted 07-27-2011 03:31 PM ET (US)
When speccing fuel injectors for a high performance car engine build, we use BSFC assumption of 0.5lbs/hr/hp. Then taking what we learned in the clean engine regulations thread, that carbureted 2-strokes pass a quarter of their fuel unburned, something approaching a BSFC of 0.7 begins to sound reasonable.
-Peter
Tohsgib posted 07-27-2011 03:53 PM ET (US)
Nice to know that when you are burning $24/hour in a Montauk(6gph@$4) you are watching $6/hour go into the water wasted. Any way to put a bucket under the exhaust and recycle that 1.5gals of fuel? No wonder they banned those things on lakes.

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Author	Topic: Montauk Re-power
ugasailrboy	posted 07-19-2011 09:23 PM ET (US) [Says he plans] to repower my [1986 Boston Whaler MONTAUK 17] and seriously looking at [Evinrude E-TEC 90] due to weight and familiarity. [The boat is] mainly used for cruising and pulling skiers. [Give the author your thoughts about] other power plants.
Tom W Clark	posted 07-19-2011 09:27 PM ET (US) The Evinrude E-TEC 90 has become the classic 16'-7" Whaler re-power of choice for a lot of reasons, not just its relatively low weight. It is a superb motor. But all the outboard manufacturers make very good motors these days and a Montauk does well with power from 50-100 HP. Take your pick, but try not to buy anything that weighs much more than 350 pounds.
Sal A	posted 07-19-2011 10:18 PM ET (US) I repowered with an E-TEC 75. I was very happy with that power.
domlynch	posted 07-20-2011 03:07 AM ET (US) I've got an '08 Optimax 90 (375lbs) re-power on my inherited Montauk, wouldn't be my first choice but its ok. If re-powering again with a DFI 2 stroke I would go with a 90 ETEC. I agree with Tom W. that this motor appears to be a classic for re-powering a classic. If 4 stroke then probably a Yamaha (F70 good for fishing, or bigger hp.for skiing) or a Suzuki (70-90hp) depending on intended useage. Dom
boatdryver	posted 07-20-2011 11:51 AM ET (US) also, depending on which brand offers good service support near where the boat is. JimL
Tohsgib	posted 07-20-2011 12:44 PM ET (US) If you want it to be REAL quiet...go with a 4 stroke. If you are a water skier then the E-TEC might be better. I have been on both for many hours and the 90 E-TEC is a perky SOB out of the hole but top end and noise are not much to brag about.
pcrussell50	posted 07-20-2011 01:12 PM ET (US) While 4-strokes are _amazingly_ quiet at idle, are they really much quieter at, say, 4000 rpm? -Peter
Tohsgib	posted 07-20-2011 01:36 PM ET (US) My 70 and 115 Suzuki are MUCH quieter all around than Len's 90 E-tec and my 115 is louder than my 70. My 40 you can barely hear. When the alternator kicks in it kinda scares you like "WHAT'S THAT NOISE". At 4k with the wind in yur face you really can't hear it, just a hum like you get from an I/O. Over say 5200 it gets a tad noisier almost like the 4 barrels kicked in.
Blackduck	posted 07-20-2011 02:12 PM ET (US) E-Tec 90 is the engine of choice.
pcrussell50	posted 07-20-2011 02:24 PM ET (US) Would be for me, too. Quietness is a neat novelty to me, but nothing more. E-TEC 90... baby. -Peter
jharrell	posted 07-20-2011 09:17 PM ET (US) Etec 90 at 320lbs or Suzuki 90 at 340lbs or Yamaha 70 at 269lbs. I haven't made up my mind yet for my Montauk, leaning toward the Suzuki based on Fuel burn numbers and performance. E-TEC is so tempting because of the weight and rope start ability, Yamaha because of extreme light weight and economy. Those are the top three choices in my opinion right now.
stover86montauk	posted 07-20-2011 09:49 PM ET (US) I just put a new Yamaha F90 on my '86 17 montauk. It is noticeably heavier than the old 'rude, but I like that it is quiet, fuel efficient, and doesn't smell like a two stroke or require buying two stroke oil. I have only had it a few weeks, but I feel like it doesn't like to stay on plane at lower speeds due to the weight. The best advice I can give you is mount whatever engine you purchase up high and get a good prop. Tom W Clark will steer you in the right direction.
WT	posted 07-20-2011 09:51 PM ET (US) Since I boat solo in the ocean and like to travel 35-45 miles one way, I'd get twin Honda 50 fourstrokes which weigh the same as the Honda 40's.:-) http://i22.photobucket.com/albums/b309/elaelap/KauaiBWs2035.jpg Warren
weekendwarrior	posted 07-21-2011 08:03 AM ET (US) I have a montauk and get into the ocean when possible. For rough water, especially cruising, lighter weight is good. The ride is much smoother if you can keep the bow down. For this reason alone I would personally go Yamaha, but it sounds like you would do well with any of the choices you listed.
A Little Madness	posted 07-21-2011 12:03 PM ET (US) We went with a Honda BF90D 4 stroke [with] 20-inch shaft, complete [with] binnacle, analog gages, control box, and a Honda Titan Solas 13-1/4 x 15R Stainless Steel Prop in 2007. I have had NO problems [with] the motor, gauges, propeller, etc. to date. It's not that much heavier than the E-TEC 90 and by moving my two gel-cell batteries into the center console it balances very well. Even today I'm still impressed [with] the hole shot, as have been most riders. LOVE IT! Good Luck [with] your decision.
L H G	posted 07-22-2011 12:03 AM ET (US) Classic Montauks are late 70's and 80's boats, not counting the modern looking black and white 90's models. So I recently went with a same generation Mercury 115 6 cylinder Tower. http://smg.photobucket.com/albums/v429/lgoltz/Montauk%2017/?action=view& current=Scan_Pic0009.jpg Oversized, heavy, white, black, gray, or gold 90 HP 3-star engines just don't look right on a classic Montauk, or have the power-to-weight ratio and classic appeal of one of these Mercs. As a second choice, I'd go with a same generation OMC V-4.
jharrell	posted 07-22-2011 02:02 PM ET (US) LHG, Any idea what the fuel burn numbers are with that 115 on the Montauk? My inline tower 90 looks good on my Montauk but the 80 mile cruise range on 24 gallons is killing me.
KDW	posted 07-22-2011 04:15 PM ET (US) I agree with Tom that there's a lot of good repower choices out there. Back in 2005, I went through the same struggle when trying to decide how to repower my '71 Nauset. Back then, I was looking at the Suzuki DF 70, Yamaha 90 2S, and Etec-90. I was also concerned about too much weight on the transom, so I left the Honda 90 4S and Yamaha 4S off my list of candidates. Cost was a concern, but not the driving factor. Anyhow, after weeks of second-guessing myself I went to Custom Marine in Statesboro, GA., ready to make a good deal on a Yamaha 90 2S. However, I waffled under salesman pressure and my own jitters and ended up buying the E-tec 90 instead. I don't regret the move as the E-tec worked very well on my Nauset. However, a year or two later I found a '91 Outrage 17 with a Yamaha 90 and then swapped the two motors between my Nauset and Outrage. I still love the E-tec, but would have to say I think the light Yamaha 90 2S is a better motor on the '71 Nauset (she's fast!) and the E-tec 90 better on the Outrage 17'. I also once owned a 1998 Montauk with a Mercury 100 HP and hated the motor because it dropped out 2 cylinders at low RPM and was always rough between the 2 to 4 cylinder transition. It was a great boat though. Anyhow, I guess its all about your budget and how you plan to use the boat. I was always a little nevous about buying a 4 stroke because I'm a seasonal boater, and it's probably not really an issue, but I thought all the small carburator parts and other moving stuff could be affected if sitting around for too long. Anyhow, I like the simplicity of a 2 stroke, not to mention the lower weight....but to each his own. Best of luck in your repower journey! KW
Tohsgib	posted 07-23-2011 01:26 PM ET (US) Carbs on a 4 stroke? Even the 25 Suzuki and Mercury are EFI. When Suzuki came out with the 4 strokes in late 90's all were EFI from 40up.
pcrussell50	posted 07-23-2011 06:28 PM ET (US) Yebbut KDW, you're forgetting the overwhelmingly functional upside of all that weight and complexity of a 4-stroke: you can hear the telltale stream hitting the water at idle. Who could live without that? -Peter
KDW	posted 07-23-2011 08:52 PM ET (US) Thought I remembered the early Yamaha and Honda 4 strokes had carbs....but I'm probably wrong and that was many beers ago. I'll probably continue to talk smack about the 4 strokes until I own one, then they will be perfect! However, low noise levels won't matter much by then as I'll be deaf anyhow. Have a good ole biggun or a big ole goodun! KW
Tohsgib	posted 07-24-2011 12:41 PM ET (US) There were/are 4 strokes with carbs. My point was if you wanted EFI it was just a brand away.
KDW	posted 07-24-2011 09:06 PM ET (US) Understood Tohsgib. Not meaning to sound argumenative and apologize if it comes across that way. When I was searching for a repower for my old Nauset, I was replacing a tired old Johnson 125 HP that seemed to eat a power pack every year or two. I was most interested in reliability, low weight, good fuel eff., and a good price. Low engine noise and good warranty were all bonuses. At that time, more than anything the 4 stroke weight was my largest concern, although the Suzuki DF70 looked like a pretty good fit to me on the old Whaler. However, I couldn't find a good Suzuki shop close by, so that kind of killed that option. Other than a problem with a crack in my oil reservoir requiring replacement, I've not had any issues with my E-tec 90 since 1995. Actually, it has started on the first crank every time and even after winterizing, which is amazing to me coming from so many difficulties with the old 125. Like all other technology, I'm sure 4 strokes have come a long way in the 5+ years since I've repowered and I'm looking forward to checking them out again if I move up from my '91 Outrage 17 to a newer model whaler or just repower a classic 18/19 Outrage. Take care, KW
george nagy	posted 07-24-2011 09:53 PM ET (US) What about those nissan/tohatsu 70/90hp dfi 2 strokes. They remind me alot of the old yamaha 90 2s.
Tohsgib	posted 07-24-2011 11:36 PM ET (US) My Father's 1972 100hp Evinrude DID eat powerpacks ever year or 2.
Peter	posted 07-25-2011 07:13 AM ET (US) 4-stroke outboards have come a long way. Just compare one made today to the Bearcat 55 or the 505 lb dry Honda 115/130 which was hardly more than a Civic engine stood on its end and bolted to a drive. But they still don't provide the power to weight to compact size to simplicity ratio of a 2-stroke.
L H G	posted 07-26-2011 09:51 PM ET (US) Jharrell - I am getting somewhere between 4 and 5 MPG on the Montauk with the Mercury 115, at about 25 MPH cruise and about 2800 rpm. Haven't yet taken the time to determine it scientifically. Having too much fun with it! But it is a screamer I can tell you that, with wicked acceleration. Will do over 50 with a 22" Laser II. The combination of the jackplate and the lift of the Laser II prop give it an exceptional ride, so much better than my old '71 Nauset with similar power that I can't believe it. The smirked hull really was an improvement of major proportions.
Tohsgib	posted 07-26-2011 10:58 PM ET (US) No offense but my Montauk with the DF70 fetched 10mpg at 26mph and 25mpg at roughly 800rpm. Oldies are great but 50% increase in fuel economy is God!!!! Unfortunately my WOT was only 39, not 50. Then again where do we spend 90% of our time?
Slick 50	posted 07-27-2011 12:30 AM ET (US) Where's the original poster? Don't need him to have fun. My Montauk with the 2003 Johnson 115 will do over 50 too. It will consistently get between 5 and 6 MPG between 25 and 40 MPH. Not too shabby for a carbed engine. The newer 4 strokes and and E-Tec engines sure are nice. Would love to have one. Rick
jimh	posted 07-27-2011 12:59 AM ET (US) The horsepower needed to push a Montauk that weights roughly 1,800-lbs to 30-MPH can be estimated with Crouch's Calculator if we know the hull constant factor. It seems from some previous data that a hull constant of 200 is about right. We estimate the horsepower as 40-HP. (This fits with L H G's report of 115-HP giving 50-MPH, too.) With an older two-cycle multi-cylinder engine with carburetors we can expect the brake specific fuel economy to be around 0.6-lbs/HP-hour. With 40-HP this means a fuel burn per hour of 24-lbs or about 3.9-gallons-per-hour. A boat going 30-MPH and burning 3.9-GPH will have a fuel economy of about 7.7-MPG.
Tohsgib	posted 07-27-2011 12:19 PM ET (US) Jim from owning a few a Montauk with a V4 crossflow will burn closer to 6gph at 30mph which is 5mpg.
jimh	posted 07-27-2011 12:35 PM ET (US) Nick--Yeah, I thought my calculated MPG was optimistic. The horsepower being used is probably too low in my calculation, and the BSFC for an older two-cycle with cross-flow is probably more like 0.7-lbs/HP-hour. If we use 50-HP and 0.7-lbs/HP-hour, we get 5.6-GPH. If the boat runs 30-MPG that is 5.4-MPG
pcrussell50	posted 07-27-2011 03:31 PM ET (US) When speccing fuel injectors for a high performance car engine build, we use BSFC assumption of 0.5lbs/hr/hp. Then taking what we learned in the clean engine regulations thread, that carbureted 2-strokes pass a quarter of their fuel unburned, something approaching a BSFC of 0.7 begins to sound reasonable. -Peter
Tohsgib	posted 07-27-2011 03:53 PM ET (US) Nice to know that when you are burning $24/hour in a Montauk(6gph@$4) you are watching $6/hour go into the water wasted. Any way to put a bucket under the exhaust and recycle that 1.5gals of fuel? No wonder they banned those things on lakes.