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SUZUKI Introduces New Engine Models
|Author||Topic: SUZUKI Introduces New Engine Models|
posted 06-23-2012 08:58 AM ET (US)
SUZUKI Announces New Four-cycle Outboard Engines
Recently SUZUKI announced the introduction of five new four-cycle engines. The new models have horsepower ratings of 15, 20, 115, 140, and 250-HP.
The new DF250AP model 250-HP four-cycle outboard engine has a displacement of 4.0-liters, an increase from 3.6-liter displacement in prior models at that horsepower. This is a completely new design from Suzuki, replacing the earlier DF250 model. The DF250AP features Suzuki Precision Control, their name for electronic remote throttle and shift controls. Suzuki also has incorporated an apparent breakthrough in design by providing for a feature called Suzuki Selective Rotation. Suzuki Selective Rotation allows the DF250AP to be electronically programmed to be either a standard rotation (right hand propeller) or a counter rotation (left-hand propeller) engine, apparently without any mechanical changes to the engine. Suzuki also says the DF250AP engine has new lean-burn techonology which will improve fuel economy at mid-range engine speeds.
The new 115-HP DF115A and 140-HP Suzuki DF140A engines are evolutionary revisions of the existing engines. The new DF140A is 14.5-lbs lighter than previous models, continuing a trend for reduced weight in four-cycle outboard engine design. The air intake system has been redesigned, and this engine is also said to have the lean-burn technology for improved fuel economy.
The new DF15A and DF20A are 15-HP and 20-HP new designs. They are four-cycle fuel-injected engines which will be easy to pull start or manually start. Suzuki says this is a first for this horsepower range.
Ethanol Fuel Tolerance
The DF250AP is designed to tolerate alcohol-gasoline fuel blends with as much as 20-percent ethanol (E20 fuel). The new 115-HP and 140-HP engines can tolerate E25 fuel.
The DF15A and DF20A engines are to be available immediately. The three other models will be available in the Fall of 2012.
posted 06-23-2012 08:23 PM ET (US)
The innovative Suzuki Selective Rotation feature first appeared on the more powerful Suzuki DF300AP which was introduced a few months ago. This feature is made possible by the design of the gear case. Suzuki says that in the new gear case both the forward and reverse gears have been strengthened. By electronically programming the engine shift controls, an engine can be converted from standard rotation to counter rotation or vice versa. I believe this means that when a Suzuki engine with Suzuki Selective Rotation is running in forward gear as a counter rotation (left-hand propeller) engine, the gear case will be operating with the gears engaged as if the engine were in reverse for a standard rotation engine (right hand propeller).
Being able to use the same engine as both a standard rotation and a counter rotation model is a significant advantage for Suzuki. In manufacturing it will no longer be necessary to produce different gear cases and different models for standard rotation and counter rotation. Dealers will no longer have to order or keep in stock special counter rotation models. And used engines can be changed to standard or counter rotation as needed for various applications.
In recognition of the innovation of this feature (and other innovations on the DF300AP engine), Suzuki Marine was awarded its seventh National Marine Manufacturers Association (NMMA) and Boating Writers International Innovation Award in February of 2012 at the Miami International Boat Show.
posted 06-24-2012 12:57 AM ET (US)
It's an interesting approach. All the gears must be of equal strength and the unit must be shimmed such that the stresses are equal no matter which way the propshaft is being pulled or pushed.
Back in the 50's Mercury had both left and right hand rotation available with the exact same lower unit.......the change was simply made in the direction that the powerhead was rotated. (this system had no shift system within the lower unit.....it was all down with the direction the powerhead was rotated) Crude perhaps by today's standards...but pretty clever at the time!
posted 06-24-2012 08:09 AM ET (US)
sosmerc--the direct-reversing Mercury was a disaster, known as the dock buster: no neutral and very dangerous. However I couldn't wait to bolt (actually screw clamps) my 1959 Mark78 or 80 on my transom. Evinrudes of the day were only 50hp so 70hp was a great advantage to this teenager. I only knew idle and wide open anyway. Suzuki idea sounds great.
posted 06-24-2012 09:30 AM ET (US)
[Changed topic to discuss a product made by another manufacturer. See a prior discussion on that product if you wish to comment on that product. Let's stick to the new outboard engines from Suzuki for this thread. Thank you.--jimh]
posted 06-24-2012 05:31 PM ET (US)
I have never tried to engineer, design, or manufacture an outboard engine gear case, but I can appreciate that for many decades there has been a standard across the industry of making distinctly different designs for standard rotation and for counter rotation. For Suzuki to achieve a breakthrough with a single design that can be used for both standard rotation and counter rotation says to me that their engineers and designers must have overcome some problems which the other manufacturers have not yet solved.
It will be interesting to see if the Suzuki Selective Rotation gear case design is protected by patents. If so, it might be interesting to find the patent that applies and see what was done to overcome the apparent problems.
Of course, before we get too positive with praise, it will be necessary for the new design to hold up to normal use for a few years. We have seen several cases where outboard engine manufacturers in this horsepower range (250 to 300-HP) have introduced gear case designs that were insufficiently robust. At least two other manufacturers that I can think of had to redesign their gear case to handle the torque and load of high-power outboard engines--and this was with conventional designs, not new designs with one set of gears being used for both standard and counter-rotation models.
posted 06-27-2012 07:43 AM ET (US)
This five-minute video shows details of the new gear case design for the Suzuki Selective Rotation feature.
including details of the gears, shift mechanism, and bearings.
The presentation (about three minutes, twenty seconds in) also seems to show that the new gear case design has been tweaked to reduce water resistance or drag. A side-by-side comparison of a image of the two gear cases designs, new and old, seems to suggest the new design facilitates lower drag. Somewhat counter-intuitive, the new gear case is of larger diameter.
posted 06-27-2012 07:53 AM ET (US)
A nice summary of the technical features of the Suzuki DF300AP, a higher horsepower but very similar engine to the DF250AP, is provided in this video:
Scroll into the presentation to the three-minute mark to find the section on the DF300AP. The technical features are quite interesting and nicely explained in the presentation. More information on the DF300AP is also given about 11:30 into the presentation. The DF300AP is said to use an oxygen sensor in the exhaust to better control combustion. Typically an oxygen sensor in the exhaust provides a closed-loop control system for combustion, and this technique is widely used in automobile four-cycle engines. Its use in four-cycle outboard engines has not been as common as in automobile engines. Suzuki says the oxygen sensor is part of their lean burn system that enhances fuel economy.
posted 06-27-2012 08:36 AM ET (US)
I have a lot of respect for Suzuki engineering and reliability, but for those of us in rural areas, the limited dealer network tends to keep them out of consideration.
posted 06-27-2012 08:45 AM ET (US)
I watched the gearcase video. The mechanical workings of the gearcase do not look like they are new. All they seem to be doing is reversing the servo wiring so that when the operator control is advanced to select forward motion, the signal sent to servo causes the dog clutch to engage the reverse gear rather than the forward gear.
This could be accomplished with a mechanical lever control system by simply attaching the cable end to the lever either above or below the pivot point of the lever depending on which way you wanted to drive the dog clutch with lever actuation in in the same direction.
posted 06-27-2012 10:54 AM ET (US)
The only smoke blowing breakthrough is the interface with the ECU allowing full engine speed in forward or to limit reverse speed when rotation is changed. Gear cases allowing reversible full power rotation are nothing new. All Suzuki did was to ensure their lower unit gearcase was built strong enough without too much drag and simplify the rotation change--a smart move but no great engineering or technological advancement.
|Tom W Clark||
posted 06-27-2012 11:14 AM ET (US)
No, but this is the first time an outboard motor has such a gearcase. Run an outboard motor gearcase in reverse at full power it is will fail within the first hour.
posted 06-27-2012 04:50 PM ET (US)
New for outboards but sterndrives have been doing it for years.
posted 06-27-2012 05:42 PM ET (US)
A schematic diagram of the gear case (at 2:15 into the presentation) shows the arrangement of the gears and bearings. The aft bearing on which the aft gear--the gear that will be used for forward propulsion in a counter-rotation engine--rides is larger than the typical bearing in a standard rotation gear case, where that aft gear is only for reverse thrust.
posted 06-28-2012 08:26 AM ET (US)
Here's two nice pictures of the gearcase:
posted 06-28-2012 09:19 AM ET (US)
I think what is most unique about [Suzuki Selective Rotation] is the decision to do it, made easier by having the electronically actuated shifting. At least visually, there appears to be no significant departure from standard gearcase design here. On the aft portion of the gearcase you have the standard thrust type bearing (the very thin one directly behind the reverse gear) which actually handles the reverse thrust load regardless of the desired forward rotation direction. And then behind that, the rear propshaft support bearing. That bearing may indeed be slightly larger than the one used on the previous non universal gearcase from Suzuki but without a side by side comparison one can't say.
Remember, that regardless of the rotation direction, the load when in forward gear is predominantly on the bearing in the front of the gearcase and the load when in reverse is predominantly on the rear thrust bearing and its washer-type race. The rear bearing [Jim] referred to handles more of the side to side propshaft loads when in forward or reverse.
posted 06-28-2012 10:28 AM ET (US)
Expanding just a bit further with my last comment, while Tom's statement:
"Run an outboard motor gearcase in reverse at full power and it will fail within the first hour."
may in in general prove true, it is apples to oranges with regards to this discussion. Running the Suzuki gearcase in reverse at full throttle for an hour (without changing props to the opposite rotation) may also result in gearcase failure. As I noted before, when in reverse (without changing props) the load is primarily on the reverse thrust bearing (a flat and relatively thin bearing) and it's race. These bearings are not designed to handle long periods of very high loads like the heavier tapered forward bearings used in the front of the propshaft that handles the forward thrust.
I would hazard to guess that if I put a left-hand prop on my right-hand designed 35 year old engines, I could indeed run wide open in "reverse" (effectively forward now because of the prop change) for a long period of time without gearcase failure because the resultant propshaft loads would be more properly placed on the bearings designed for those loads.
|L H G||
posted 06-28-2012 03:42 PM ET (US)
I read that Suzuki will be lowering prices below market pricing of other brands in an effort to recapture lost market because of the earthquake. Who knows what Honda and Yamaha will do. The Japanese auto makers are doing the same thing right now.
So these new Japanese engines will evidently be a great bargain compared to the pricing on the American brands.
posted 06-28-2012 08:25 PM ET (US)
L H G--Please give us the price information for the Suzuki DF250AP. I have not seen any mention of the MSRP or the street price of these engines. This is not surprising as the engine will not be on the market until next winter. It is hard to project that Suzuki will begin selling at less than fair market value before they even bring the engine to market. I wish I could predict stuff like that with that accuracy.
posted 06-28-2012 08:40 PM ET (US)
Tim--That is a very good observation regarding the thrust bearing size for forward propulsion and reverse propulsion.
posted 07-03-2012 12:13 AM ET (US)
I think I could take the time to point out some things about the bearings of the unit in question.
IMPORTANT: To follow what I am referring to here one should open the video presentation that JimH has linked to in his post of 06-27-2012 07:43 AM.
Then please go forward to approx 2:19, where there is this vertical and longitudinal cut presentation of the components inside the gear assembly, with the names of the different components, and red lines pointing to the components them selves. Pause the video to view it as a picture.
Now, with that as a base, here’s my short application guide (for those who are not sure how this gearbox assembly works):
The vertical drive shaft, which transmits the power form the power head above (and outside of the view), is shown in light brown. One can also see the low end roller bearing of the shaft (in green and cyan).
Attached to the drive shaft is the pinion gear wheel (pink), fastened with a nut (cyan) at the end of the shaft. The pinion does not have a bearing of its own.
The pinion drives the two gear wheels (beige) at all time. In normal rotation, the gear wheel on the left is the one that transmits torque when going forward, and the one on the right transmits torque when going in reverse.
The gear wheels have interfaces with the rest of the assembly via four components each.
Second, the hollow shaft extension (also beige) of both gear wheels has a needle roller bearing (pink, salmon red) which sits on the outer diameter and locates the gear wheel in all radial directions versus the housing.
Third, next to the gear wheel on the outer diameter there is an axial thrust roller bearing (green and yellow), which locates the gear wheel in one axial direction versus the housing.
Fourth, inside both of the gear wheels there are taper roller bearings (cyan bearing rings, blue roller elements). The gear wheel on the left houses a taper roller bearing that is a bit larger than the taper roller bearing on the right.
The entire assembly is constructed so that the two tapered roller bearings together with the propeller shaft (blue) and the housing components (hidden) form an axially located package. Taper roller bearing can take axial forces only in one direction, and are therefore mostly used in pares in back-to-back or face-to-face configuration. What we have here is a face-to-face configuration.
This means that even if one of the two tapered roller bearing can take axial loads only in one direction (to the left for the left side bearing, and to the right for the right side bearing), sharing a common shaft and housing stops the two bearing from leaving their axial position apart from a very small axial play or clearance that is allowed without risking the proper function of the bearing when axial load is not present.
When the power head is running and the selected gear position is ‘neutral’ the following components are rotating:
Note that the only torque now transmitted is only the torque needed for the most basic friction load in the rotating components. These loads are mainly generated via gravity forces on the involved components and friction between components or components and lubrication oil (as this whole assembly is submerged in lubrication gear oil).
Also note that the pinion is now, as always, rotating the two gear wheels at equal speed in opposite directions. Both gear wheels have equal amount of teeth, and thus the gear ration is the same.
The propeller shaft is not intentionally rotated. The propeller shaft is meant to be rotating only when the clutch dock (green) on the propeller shaft has been moved - via components like the shift shaft (yellow) and connector pin (pink) - to act as one half of a dog clutch together with one of the gear wheels, thus forming a mechanical rotational interference connection between the gear wheel in question and the propeller shaft.
However, as the two roller bearings are rotating on their outer rings, they try via friction to get the propeller shaft in motion. The two bearings rotate at the same rpm but in opposite directions. The left one is a larger bearing than the right one, and the therefore it’s safe to assume that most other things being equal, it will generate more friction which will try to rotate the propeller shaft – also when the chosen gear position is ‘neutral’.
As stated, the clutch dock is the component which is moved in order to engage one of the two gear wheels to transmit torque from the pinion of the drive shaft to the propeller shaft.
Let’s assume we move the clutch dock to left and engage the left gear wheel and have a propeller with normal rotation (clockwise in forward seen from stern).
The gear wheels both keep turning, but now the propeller shaft is also turning at the same speed as the gear wheels and in the same direction as the engaged gear wheel (i.e. clockwise seen from stern).
The two needle roller bearings of the gear wheels both keep working, inner rings rotating at the same speed as the propeller shaft.
The taper roller bearings both have different situations. The bearing on the left has now stopped, as the outer ring is fitted to the gear wheel, which is turning at the same speed as the propeller shaft, onto which the inner ring of the bearing has been fitted.
The thrust of the propeller, which is on the right, is in the left direction. It goes through the propeller shaft past the very much rotating right side taper bearing to the inner ring of the left side taper bearing (via a thrust washer, purple), to the stationary rollers, to the taper bearing outer ring and to the left side gear wheel. From the gear wheel the thrust goes to the housing via the axial roller thrust bearing (green and yellow), with the gear side ring of that bearing rotating at the same speed as the propeller shaft.
Next, let’s assume we keep the same propeller and move the clutch dock for ‘reverse’.
Now the right hand side gear wheel is engaged to the propeller shaft so that they now share the same direction of rotation. The taper bearing of the engaged gear wheel can stop, and it’s the left hand side taper bearing that has to cope with outer and inner ring interfaces rotating at the same general rpm but in opposite directions. The thrust from the propeller now goes to the housing via the right hand side taper bearing and the axial roller thrust bearing of the right hand side gear wheel.
All understandable? Now, let’s change the propeller to counter rotation (anti-clockwise seen from stern), CR for short, and make the [propeller shaft] turn in the opposite direction compared to earlier.
To have the boat go forward, we now engage the clutch dock to the right gear wheel, just as we previously did to have the boat go in reverse. Again, the right hand side gear wheel is turning at the same rpm as the propeller shaft, and in the same direction, thus the right had side taper bearing is stationary.
The left hand side taper bearing again has the propeller shaft rpm x 2 to work with.
As the thrust is to the left the force is going past the right hand side taper bearing along the propeller shaft to the left hand side taper bearing outer ring, via the now so quickly spinning roller to the outer ring, to the left side gear wheel and via the axial bearing to the housing.
If we want to reverse, the clutch dock goes to the left and the left side taper bearing stops turning (inner ring vs. outer ring), the right hand side taper bearings sees 2 x the propeller shaft rpm and the thrust load from the propeller is now to the right and goes to the housing via the right side taper bearing and the right side axial bearing.
There. Let’s sum up what I think are the main points:
Normal propeller, going forward =
Normal propeller, going in reverse =
CR (as in counter rotating) propeller, going forward =
CR propeller, going in reverse =
And that’s that, hope I wrote it all down correctly! ;-)
PS: So what does it mean? Well, it should mean that if the taper bearings are to last for normal service life in CR mode, then they should last forever in normal, non-CR mode. At least from a fatigue point of view.
posted 07-03-2012 07:26 AM ET (US)
A beautiful explanation! Thank you.
posted 07-03-2012 09:54 AM ET (US)
I'm still a little confused. GSH explains
"All understandable? Now, let’s change the prop to counter rotation (anticlockwise seen from stern), CR for short, and make the power head turn in the opposite direction compared to earlier"
I thought the power head did NOT have to turn in the opposite direction?
The new lower second set of water intakes look interesting kind of like the aftermarket Bobs nose cone.
But it will be interesting to see how that low position works out in real life mud,silt,and sand.
posted 07-03-2012 11:09 AM ET (US)
Yes, Chuck, thanks, that's right!
Momentary lack of logic there...
posted 07-05-2012 08:47 AM ET (US)
GSH, do your eyes see differences between the photographs you linked to first (the top one in particular), and the video at 2:19? In the photograph I see a flat, reverse thrust bearing (thin flat bearing, not a taper) right behind the reverse gear where they are commonly located in outboard gearcases. That's not to say their isn't a taper bearing for the reverse thrust hidden in there as the video indicates, I'm just wondering if something isn't mixed up between these Suzuki presentations.
Regardless, you explained the workings of this gearcase (and most gearcases in general) very well. Bottom line, when trying to move the boat forward, the forward taper bearing transmits the thrust regardless of chosen propshaft rotation and the reverse bearing does the same for reverse operations.
I still don't see any huge engineering breakthroughs with this gearcase. Admittedly, I'm just looking at pictures.
posted 07-11-2012 02:10 PM ET (US)
Adlert, sorry it has taken me this long to reply, I havn't had that much time for the www lately! And thanks for the compliment!
Yes, in the picture taken of the real cut-open gear case they have not opened up the rear taper bearing. I think what you call a flat bearing is the outer ring outer diameter surface of the taper roller bearing.
posted 03-03-2013 10:08 PM ET (US)
It has been eight months (or more) since SUZUKI gave notice of their new model DF250AP, but I can't find any mention of it on their website. I can't even find a thread on any website where someone mentions they bought one. Is this engine on the market? Was SUZUKI exhibiting it at any winter boat shows?
posted 03-04-2013 06:57 AM ET (US)
They have a brochure posted on their website. See www.suzukimarine.com/~/media/Marine/Brochures/ Suzuki%20DF300AP-%20DF250AP.ashx
posted 03-04-2013 08:00 AM ET (US)
Thanks for the link to the information about the DF250AP outboard engine from Suzuki. It is a nice summary of the many innovative features that are used on this model.
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