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Author Topic:   90-HP Low Emission Engines
jimh posted 11-19-2005 09:51 AM ET (US)   Profile for jimh   Send Email to jimh  
The Reference Section has a new article on 90-HP low-emission engines. It summarizes the various models available. Because the 90-HP engine is a popular choice for re-powering many smaller Boston Whaler boats, this information will be of interest to many.

I did not located any particularly good prices for the Tohatsu and Nissan motors. If anyone knows of an on-line source of pricing for those engines, please send me that information via email and I will add it to the listings.

Some of the current prices listed look quite aggressive. This fall may be a good buying opportunity for 2005-model year engines still in stock. Dealers should be taking delivery of 2006-model year engines soon.


Low-Emission 90-HP Outboard Price Comparison

LHG posted 11-19-2005 07:44 PM ET (US)     Profile for LHG    
The question is, when it comes to HP at the prop, in an engine of this HP range, do cubes count, as many here contend? If that is the case, the Suzuki is the clear winner at 2.0 liters. That's amazing since my Merc 150 2-stroke is also 2.0 liters, but with an additional 60 HP, and 15# less weight!
jimh posted 11-19-2005 11:26 PM ET (US)     Profile for jimh  Send Email to jimh     
Suzuki's current advertising campaign uses the theme, "There is no replacement for displacement." It is clear they are making this a selling point. The extra weigh is a concern. A 90-HP motor will be used on a smaller boat, and hauling around an extra 100-pounds bolted on the transom could affect the handling characteristics of some boats.
frontier posted 11-19-2005 11:43 PM ET (US)     Profile for frontier  Send Email to frontier     
Very interesting.
Why is Honda still using carburetors?
jimh posted 11-20-2005 11:04 AM ET (US)     Profile for jimh  Send Email to jimh     
The Honda BF90 uses four carburetors, one for each cylinder. This is a very common technique in outboard motors.
Kelly posted 11-20-2005 12:20 PM ET (US)     Profile for Kelly  Send Email to Kelly     

Try this for the Tohatsu. It says retail is $8,713 and internet pricing is $7,170.


frontier posted 11-20-2005 01:14 PM ET (US)     Profile for frontier  Send Email to frontier     
But why is Honda still using carbs when their cars and most larger (50+ HP) outboards are using EFI? Left over carb stock?
LHG posted 11-20-2005 01:41 PM ET (US)     Profile for LHG    
I think Jim's piece here is a valuable addition to CW, and quite helpful for those using 90 HP engines, particualrly the Classic and 170 Montauks. The only column that could be added is alternator output, also important in selecting an engine depending on what appliances you intend to run.

This chart brings a few things into perspective quickly and easily. My feeling is that the 90 HP range is really suffering from EPA 2006 regs, and that none of these new clean engines are really all that great when compared to their 3 excellent 2-stroke predecessors from OMC, Merc and Yamaha. Only in fuel mileage and idle smoke do they exceed the older engines.

1. The smallest cube engines at 1.3 liters are also the lightest weight, since they are DFI. For those two engines (Tohatsu/Nissan are the same) this forces one to determine whether possible less prop HP is more or less important than weight.

2. Regarding these two smaller engines, it seems strange that the Tohatsu is not more poular. Brand loyalty, which they do not have much of in the US at least, seems to matter here. There is plenty of Evinrude talk here, but no Tohatsu talk at all. Also the general consensus is that the Tohatsu is a workhorse, and not real zippy, so maybe that is factor.

3. I find it surprising that the Honda does not yet have EFI. In spite of their excellent reputation, that should be a deal killer for most. It's interesting that the price also reflects this less sophistication. You get what you pay for.

4. The 90 Optimax also seems not to be too popular here, perhaps since BW only offered it for a short time, and pulled it (reason unknown). But I remember for the performance charts that it did not outperform the Merc/Yam 4-stroke. I have also noticed from test data that it seems to be extremely loud running at higher RPM.

5. The huge cube Suzuki seems to have a weight problem, since the 115 and 140 also run on the same block.

5. This leaves the volume leaders, the Yamaha/Mercury engines, basically one and the same, with the Yamaha powerhead. They are large and heavy, and not great on acceleration under load, with high running noise in the upper cruising ranges. Although highly popular and well liked it seems, and the engine of choice on the Montauk 170, I don't think they're the cat's meow either. For Mercury, at least, this is the last year, which may indicate the lower pricing.

6. The only thing 90 HP fans have to look forward to next summer is the new 1.3 liter Verado 90. Not much seems to be known about it, but I imagine it will be introduced in the 75-115 ranges at the Miami boat show. Hopefully, it will offer a fresh alternative in this not very exciting list of offerings so far, and be quieter at speed.

Peter posted 11-20-2005 04:23 PM ET (US)     Profile for Peter  Send Email to Peter     
Tohatsu dealerships around here are few and far between. I'll bet that is the case in many other places and that is why there isn't much talk about the Tohatsus.

At 375 lbs (20 inch shaft length) and lacking the quietness of a 4-stroke, the 90 Optimax does very little to bridge the gap between 2-strokes and 4-strokes which it really must do to succeed. The 90 Optimax has got to be tough to sell against the 4-strokes.

Where did the 1.3L displacement for the new Mercury 75 to 115 come from? To my knowledge based on a Buckley statement in an investor call early in 2005, the 75 to 115 will be built on the I4 Verado platform but will not have supercharging. The I4 block displaces 1.7L not 1.3L. If they only displaced 1.3L I'm sure that the competition would leave them far behind on performance. One can get away with 1.3L if in 2-stroke format but in 4-stroke configuration, I don't think it will be viable, at least not at the 115 HP level.

A few weights need to be adjusted in the table. (1) The specifications published by Yamaha indicate the F90 (20 inch shaft length) has a dry weight of 369 lbs, not 356 lbs according to the table. (2) The specifications published by Honda show a dry weight of 373 lbs for the BF 90 (20 inch shaft). (3) Mercury's website for the 90 Optimax indicates 375 lbs for the 20 inch shaft version of the 90 Optimax.

I suspect the reason why Honda uses carburetors is that carburetors are lower cost than EFI systems.

LHG posted 11-20-2005 04:55 PM ET (US)     Profile for LHG    
Peter I had heard the Verado 75 and 90's were going to be 3 cylinders. But I don't have any solid reference for this I can point you to. Don't know about the 115. Maybe it will be a four cylinder model?. I wonder if they would supercharge a 3 cylinder version?
Joe Kriz posted 11-20-2005 04:57 PM ET (US)     Profile for Joe Kriz  Send Email to Joe Kriz     
I have a chart I started back in May that included the 90 hp models except the Tohastu and Nissan that has been shown on this site before.

Peter is right, you have to watch out for the length of the shaft size noted on the manufacturers page as the weight varies slightly for the different shaft lengths.

Peter posted 11-20-2005 06:12 PM ET (US)     Profile for Peter  Send Email to Peter     
If I recall correctly, Buckley said no supercharging for 75 to 115 HP engines and that they would be based on the Verado platform. I've always assumed they would just strip off the supercharger of the I4 Verado.

I don't see how Mercury will be able to squeeze 90 HP out of a 1.3L 3 cylinder 4-stroke and be competitive when all of the 4-stroke competition is at 1.6L or more and the 2-stroke competition has as much displacement. It would have to rev higher and would have less torque at the low end. They certainly won't be able to squeeze 115 HP out of that small displacement and be competitive.

For the upcoming Mercury 75 to 115 4-strokes, I think the better bet is a 1.7L 4 cylinder with the same bore/stroke as the I4 Verado 135 to 175. Weight will likely be in the 380 lb range.

Kelly posted 11-20-2005 10:33 PM ET (US)     Profile for Kelly  Send Email to Kelly     
I keep waiting for Honda to introduce a new motor in the 90 hp range. It surprises me that they have waited this long. Has anybody heard anything?


jimh posted 11-21-2005 12:50 AM ET (US)     Profile for jimh  Send Email to jimh     
Kelly--I added the information regarding the Tohatsu on-line pricing. I stumbled across you information here in the thread; I did not get an email.

Larry--you make a good point. Perhaps I should include the fine two-stroke classic motors from Mercury, Johnson, and Yamaha in this list as a point of reference on weight (and perhaps price).

Kelly posted 11-22-2005 01:05 PM ET (US)     Profile for Kelly  Send Email to Kelly     
I was interested in the Tohatsu 90 hp for a Montauk before the TLDI version was introduced. After the TLDI version came out, I thought it would still be a good motor. the more I looked into it though, it seemed a little complicated. It has electronic injectors and a belt driven compressor. It is also my understanding that it will not run if the battery is too low on charge. I guess all of the new motors are more complicated, and it seems that except for the ETEC, they are pretty demanding on the battery. The fact that the ETEC can be rope started is a huge factor to me.

I would be interested in what others think of putting a new 90 hp Yamaha 2 stroke on an older Montauk. It seems that they are still available, and it seems like a perfect motor for the boat.


Sonic posted 11-22-2005 03:23 PM ET (US)     Profile for Sonic  Send Email to Sonic     
The TLDI system on Tohatsus is nearly the exact same thing as Mercury Optimax. Tohatsu seems to have great quality control and their designs undergo significant testing before public release to ensure reliability.

I've been reasonably pleased with the 90 TLDI that went onto the Montauk this spring, replacing an 88 Johnson 90. The fuel consumption is OUTSTANDING, upwards of 7 mpg at times. It always starts right up, but it is still a little rough in the low rpm speeds like most 3 cyl two strokes.

My local dealer's installation was of fairly poor quality and I have had to clean up a lot of his work, but the overall engine seems good. If Honda had EFI on their 90 I may have gone that way, but overall I was unimpressed with the 90's out there.

capedave posted 11-22-2005 08:46 PM ET (US)     Profile for capedave  Send Email to capedave     
As I have just gone through a repower on a older Montauk, Price was the deciding factor. At $6200 out the door price for a Yamaha 90 TLR with controls, tach, prop. The repower is listed back a little bit. It is a treat now to run turn the key no choke, quiet and runs like a charm, it replaced a merc 75, did I say the Yamaha is QUIET!!!!

Have a good one, Dave

swist posted 11-22-2005 10:18 PM ET (US)     Profile for swist  Send Email to swist     
Interesting thread.

Some comments:

1) I have had two Tohatsus and if you look around the working harbors in Maine you will see loads of Tohatsus on work boats of all kinds - people very experienced with boats/motors depend on them for a living, despite the fact that service facilites are few and far between. Tells you something.

2) I have a 90 Merc 4-s on my Montauk and yeah that is one big heavy engine - almost the same size/weight as my old 225 Yamaha 2-stroke. I think this is the next frontier that needs to be crossed in the new technology outboards (weight reduction) - even the DFI 2-strokes are heavier than their old carbed couterparts, and in some case by a lot.

3) Someone commented that the 90 Yamercury was loud at the upper speed ranges? I don't have any comparative knowledge of other 90hp 4-strokes, but it is a hell of a lot quieter than either a Yamaha 90 2-stroke, or a 90 Optimax, both of which I have run. Is this a commonly held opinion?

bigjohn1 posted 11-24-2005 06:50 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
Excellent peice that will be a great reference for folks to do comparison shopping. Yes, those mid-range Yamamerc's are HUGE. When I am walking toward the boat at the dock, I am always silently telling myself how huge that motor looks on a MONTAUK.
jimh posted 11-26-2005 10:52 AM ET (US)     Profile for jimh  Send Email to jimh     
By eye the size of the cowling on the 90-HP or 115-HP Mercury four-stroke motors is the same size as the cowling on their V6 200-HP two-stroke motors.
sosmerc posted 11-27-2005 07:06 PM ET (US)     Profile for sosmerc  Send Email to sosmerc     
I am a big fan of the 3 cylinder Merc 75, 90, and 115 Optimax. Yes, they are a bit heavier than the standard carb 2 strokes they replace. But their running quality is far superior as well as their fuel economy. They share the past benefit of lost foam casting and have a "tight" powerhead assembly with no need for a seperate cylinder head or seperate exhaust or intake covers. Merc has done a nice job of packaging on these engines and they are easy to rig and service. They also have the benefit of being SmartCraft ready. I'd like to see some smaller 3 cylinder versions to cover the 40 to 60hp range.
If Merc is having any problems with these engines, I am not aware of it.
fourdfish posted 11-27-2005 08:19 PM ET (US)     Profile for fourdfish  Send Email to fourdfish     
I'm sorry, I always thought from all the talk that all the Verados were going to be supercharged? I guess it's all in the name. All the E-TECs have the E-TEC fuel injector!
sosmerc-- Nice commercial! I guess it is consistant with the job! I know you and Larry are or will be great buddies! By the way lost foam is used by a lot of manufactures including BRP and many others is many different configurations. Am I wrong or is Smartcraft not compatiable with the NMEA standard.
jimh posted 11-27-2005 08:52 PM ET (US)     Profile for jimh  Send Email to jimh     
Come to think of it, I do not recall if I have actually seen a 90-HP OptiMax in person. (I have seen many of the four-strokers.) I believe the three-cylinder Optimax motors are made from half of the block of the 3.0-liter V6. Is that correct?
fourdfish posted 11-27-2005 09:02 PM ET (US)     Profile for fourdfish  Send Email to fourdfish     
Jim I have never seen a 75 or 90 OptiMax except maybe at the boat show once! However, I have seen the 115hp at the marina and at the boat ramp.
sosmerc posted 11-28-2005 12:25 AM ET (US)     Profile for sosmerc  Send Email to sosmerc     
fourdfish...I don't think Merc was the first to use lost foam casting...OMC may have had that distinction. But at least Merc caught on to that technology and has been applying it successfully to many models. Anytime you can eliminate seperate block components and fasteners, well, that is a good thing.
Regarding NMEA and SmartCraft.....all I know is that the SmartCraft harness has two wires available in their harness to connect to I would assume their system is compatible with other systems out there. Down the road I would think increased compatibility between various aftermarket electronics manufacturers will be commonplace.
Regarding the 3 cylinder Optimax and its relationship to the 3.0 litre Optimax, yes, it shares the same cylinder bore and stroke, pistons and rods, etc. So in some respect, the 3 cylinder Optimax is half of its big brother 3.0 litre Optimax. It shares a similar high output 60 amp belt driven automotive style alternator as well. Nice to know your fuel sip'n 75hp can run the same electrical load as a 250hp Optimax!?
jimh posted 11-28-2005 09:19 PM ET (US)     Profile for jimh  Send Email to jimh     
The interface to a GPS is probably according to the NMEA-0183 standard, which is specific to asynchronous serial port interfaces. The instrumentation communications is via a communications BUS, not a serial port interface. A serial port is fine for a one-to-one connection, but not good for a many-to-many connection. For that you need a communications bus.

There is an NMEA standard for communication buses, NMEA-2000. The SmartCraft standard is proprietary.

cyclops posted 11-28-2005 10:32 PM ET (US)     Profile for cyclops  Send Email to cyclops     
The 2006 Evinrude brochure states the I-Command system is "exclusively for Evinrude V6/V4 E-TEC outboards." I take this to mean the first E-TEC's introduced (90-HP and below) are not compatible with the I-Command system. Is this true? I haven't made it to my dealer yet to ask this question.
cyclops posted 12-01-2005 09:11 PM ET (US)     Profile for cyclops  Send Email to cyclops     
Stopped by my BRP dealer today as I'm trying to decide what direct injection two-stroke to re-power my Eastport with this winter. He confirmed the I-Command gauges are not compatible with the E-TEC 90-HP. I think BRP dropped the ball on this as the Optimax 90-HP and even the 75-HP come SmartCraft ready. As has been stated before on this site, SmartCraft is not built to the NMEA-2000 standard but it is definitely better than what Evinrude is offering in this horsepower range.
jimh posted 12-10-2005 06:21 PM ET (US)     Profile for jimh  Send Email to jimh     
I just noticed that there were corrections submitted in the comments above. One of the reasons I ask people to email corrections to me is to allow me to get notice of them. A long time has gone by between the corrections being submitted and me happening to notice them.

I changed several engine weights, based on information I could find on manufacturer's websites. This also required re-computing the HP/LBS column. I also added hyperlinks to the manufacturer's website for each engine. The links are in the MODEL column.

LHG posted 12-10-2005 07:13 PM ET (US)     Profile for LHG    
In the 7th and 9th photos on this page, you can see a 90 Optimax on a 17' Whaler. loc=chester1#

seahorse posted 12-10-2005 09:54 PM ET (US)     Profile for seahorse  Send Email to seahorse     

The CanBus NEMA 2000 I-Command gauges are not for the in-line E-TECs but you can use the Commander series of guages that show an analog tach and speedo with a digital display screen at the bottom for depth, fuel flow, etc.

cyclops posted 12-11-2005 09:02 AM ET (US)     Profile for cyclops  Send Email to cyclops     
Thanks Seahorse.

The dealer did not elaborate on his answer.

sporttwin posted 12-19-2005 02:56 PM ET (US)     Profile for sporttwin  Send Email to sporttwin     
I'll stick with "American" brands, so to speak. At least Bombi'(John/Rude) is North American----OWNED. The dealer REALLY pushed Yam. I told him I was American and Yamaha is NOT an American name. Does he want my $6K plus-or NOT.

I'll be replacing a Merc. 75, on a 22' toon this spring. Nothing wrong with the 75, other than it was noisy and a bit thirsty. It has close to 1000 hours. Noone can complain about that service. Plus, it's still a great engine, for a second owner.

My choice is, and will be, the John/Rude-75-e-tec.

I've seen them run and I have utmost confidence in the selling dealer and the corp. network.

sosmerc posted 12-19-2005 07:12 PM ET (US)     Profile for sosmerc  Send Email to sosmerc     
Too bad you haven't had an opportunity to run a Merc 75hp is a fine engine, very quiet, smooth and fuel efficient. It would hook up to your old Merc control as well if you wanted to.
But regardless, I'm glad you are going with a DFI motor...I'm sure you will like it.

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