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Author Topic:   Evinrude New E-TEC G2 Propellers
jimh posted 07-08-2014 11:59 PM ET (US)   Profile for jimh   Send Email to jimh  
When Evinrude revealed their new E-TEC G2 engines, they also introduced a new line of propellers for them. The new propellers include three-blade and four-blade propellers. The propellers are said to have been developed to match the power-torque curve of the new E-TEC G2 engines.

Here is a closeup of the RX-4 propeller:

Photo: Close up of Evinrude RX-4 propeller.
Photo by Don Jahncke; used with permission

There are several interesting features to note. Most evident is the exhaust gas outlet with valve regulator at the base of the blades on the propeller hub. The valve is adjustable to allow the amount of exhaust gas to escape from the hub and bleed aerated water onto the blades at low speeds. As far as I know, this is the first propeller to have a built-in adjustable valve for this function.

The second notable feature is the rather complex and swept back blade shape shown . There is clearly some complicated geometry going on here, and it is hard to appreciate the shape in only two-dimensions.

Finally, the exhaust hub continues beyond the blade roots rather far aft. The snout on this propeller seems a bit longer than usual.

The four-blade series is the RX-4. I have not seen an official designator for the three blade propellers. These new propellers should begin to be available later in the summer.

Huey01 posted 07-09-2014 02:57 AM ET (US)     Profile for Huey01    
Hi Jim, the new series 3 blade props to suit the G2 are the Raker H.O. with this VVP (Variable Vent Port) system too. The RX4 are available in RH and LH rotating props from 18 inch to 26 inch. [UPDATE: a 16-pitch model was added sometime after this article was written--jimh] The Raker HO are not available as counter rotating and are from 22 inch to 28 inch. As you point out these new props are works of art and are an improvement over the current BRP line-up. Even G1 owners can fit these new props, when they become available, with the hub kit to suit the G1 gearboxes-using prop hub kit P/N 0177283.

From what I was told and felt at the G2 launch on the Raker H.O. the G2 actually accelerated faster with the ports closed, even though the very experience driver at the time said to me it sounded and felt faster with the vents open-the stop watch showed a different results. I am sure with either G1 or G2 a boater can experiment with his/her rig to find the sweet spot which could well be with some open and and some vents shut.



Teak Oil posted 07-09-2014 09:46 AM ET (US)     Profile for Teak Oil  Send Email to Teak Oil     
The highly raked blades are very similar to the Mercury Revolution 4 prop. My 19" Rev 4 has the blades swept farther back then my 21" Tempest Plus and my 21" Viper.

I would like to try one to compare to my Rev 4 but I am sure these will not be cheap props. Perhaps Lockemans will add a few to their testing inventory

Huey01 posted 07-09-2014 07:22 PM ET (US)     Profile for Huey01    
Hi, not many good SST props are what I would call cheap, but the new Raker H.O. is about $100 more than the old Raker. I have not seen any prices for the RX4 but yes 4 blade props tend to be a little dearer than 3 blade props.



jcush87 posted 07-10-2014 09:53 PM ET (US)     Profile for jcush87  Send Email to jcush87     
The VVP is a really cool addition. My first thought when I saw a picture of it is the RX4 is going to be a copy/evoluton of the Rev4 like the Rebel is of the Mirage plus. even RX4 is almost an abbreviation of revolution4. I am looking forward to hearing how the prop performs, the rev4 is a very impressive prop,I wish i could have tried one out on my boat.
jimh posted 07-14-2014 11:50 PM ET (US)     Profile for jimh  Send Email to jimh     
The variable valve on the new Evinrude RX4 propeller is fixed in place by a Torx head fastener. There appear to be small ridges cast into the valve as markers.

Close-up view of variable valve on Evinrude RX4 propeller
Evinrude RX4 propeller variable valve close-up view
Photo by Don Jahncke; used with permission

jimh posted 07-15-2014 08:58 AM ET (US)     Profile for jimh  Send Email to jimh     
I don't have the ability to look at a couple of digital images of the new propellers from Evinrude and then analyze precisely how they were designed. It seems very speculative to conclude that these new propellers from Evinrude are simply copies of propellers made by other manufacturers. And particularly very speculative to base that on just a single image of them. Perhaps if someone has in front of them one of these new propellers and an existing propeller from another maker, they could make some careful measurements of the blade shape, blade rake, blade skew, and so on, and draw some conclusions. To look at one picture and dismiss the propeller as nothing but a copy of some other one seems a bit unreasonable.

The notion of a propeller having raked blades is nothing new. I think the OMC RAKER propeller probably got that ball rolling on that design.

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