Evinrude RX-4 Propeller and TBX Hub Kits

Optimizing the performance of Boston Whaler boats
jimh
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Evinrude RX-4 Propeller and TBX Hub Kits

Postby jimh » Sat Sep 10, 2016 12:22 pm

With the introduction of the Evinrude 74-degree V6 3.441-liter or G2 E-TEC engine, Evinrude also introduced a new line of four-blade stainless steel propellers, called the RX-4. The RX-4 features an adjustable venting system or variable vent port, shown below:

Image

The RX-4 has an exhaust gas outlet with valve regulator at the base of the blades on the propeller hub. The valve allows 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.

Also seen above is the rather complex and swept back shape of the blades. And the exhaust hub snout continues somewhat longer than most propellers, then gently flares at the opening.

The RX-4 is available in pitches of 16, 18, 20, 22, 24, 25, and 26-pitch, and most pitches are available in both right-hand (standard) and left-hand (counter-rotation) orientation. All RX-4 propellers have a 15-inch diameter. The part numbers for them are as follows:

RX-4 RIGHT-HAND or Standard Rotation
Pitch / Part Number
16 = 177340
18 = 177320
20 = 177322
22 = 177324
24 = 177326
25 = 177328
26 = 177330

RX-4 LEFT-HAND or Counter Rotation
Pitch / Part Number
16 = 177341
18 = 177321
20 = 177323
22 = 177325
24 = 177327

The RX-4 propellers use the Evinrude Torsion Bushing eXtreme or TBX hub kit, which uses a plastic field-replaceable torque bushing, as shown below:

Image

Part numbers for the TBX bushing or hub kit are as follows:
767683 = For production-year 2015 and newer E-TEC G2
177283 = For all Evinrude V6 engines through 2015 including G1 E-TEC
177288 = For non-Evinrude V6 engines from competitors

Evinrude has patented their invention of an "Axial Twist Propeller Hub" under United States Patent 6383042, which can be retrieved from

http://pdfpiw.uspto.gov/.piw?Docid=06383042&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D6383042.PN.%2526OS%3DPN%2F6383042%2526RS%3DPN%2F6383042l&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page

The invention shown in the patent linked above appears to be extremely similar to the TBX bushing or hub kit, as can be seen from this drawing from the patent (to which I have added text callouts instead of numbered callouts):

TBX_Fig4_Callouts.png
Adapted from FIG. 4 of patent
TBX_Fig4_Callouts.png (18.58 KiB) Viewed 8232 times


One of the claims made in the patent is that the patented invention provides for a "limp home mode" of coupling between the propeller shaft and the propeller that will continue to allow operation even if the propeller has struck some underwater object and the plastic coupling has yielded as intended. Details of this are given in the text of the patent. The patent was issued in 2002. I believe that the first time the TBX hub kit was available was c.2007.

jimh
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Re: Evinrude RX4 Propeller and TBX Hub Kits

Postby jimh » Sat Sep 10, 2016 12:55 pm

If anyone has any performance information from use of an Evinrude RX-4 propeller with any engine and Boston Whaler boat combination, this thread would be a great place to report the data. The RX-4 was first shown in June 2015, but I don't think it was immediately available then. By now, September 2016, I believe the RX-4 is in full production and readily available, although perhaps a bit expensive.

Peter
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Re: Evinrude RX-4 Propeller and TBX Hub Kits

Postby Peter » Tue Sep 13, 2016 2:50 pm

There has been much praise given to the RX-4 propeller. I wonder how well the RX-4 propeller would work with a G1 E-TEC.

jimh
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Re: Evinrude RX-4 Propeller and TBX Hub Kits

Postby jimh » Tue Sep 13, 2016 4:12 pm

I have the same curiosity. Now that the RX-4 is available in 16-pitch, it is a candidate for a trial run on my boat, to replace a 17-pitch three-blade. My only concern: if it works really well, then I'll have to spend $600 to get one.

I haven't seen any market-prices for the RX-4 propellers, but I anticipate they will be expensive. Since they are designed to fit onto $20,000 to $25,000 engines, I don't think cost is going to be a concern for those engine buyers; but cost is always a concern for me.

Ridge Runner
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Location: Florham Park NJ / Punta Gorda FL

Re: Evinrude RX-4 Propeller and TBX Hub Kits

Postby Ridge Runner » Mon Sep 19, 2016 5:24 pm

Jim your pricing instincts are right on target. List price is $700 with market prices at $567.
http://www.boatpropellerwarehouse.com/category/6205/rx4
Member since 2005
2005 170 Montauk, 2010 E-TEC 115 H.O.
2016 210 Montauk, 2017 E-TEC G2 200 H.O.

"Red sky at night, sailor’s delight - Red sky in the morning, sailor’s warning”

jpar
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Joined: Fri Oct 16, 2015 8:45 am

Re: Evinrude RX-4 Propeller and TBX Hub Kits

Postby jpar » Thu Sep 29, 2016 3:41 pm

Just curious - Does BRP casts their own SS propellers? Or do they have another foundry cast them to their specs?

I think OMC used to cast them in Milwaukee back in the day.

--Jeff

Seahorse
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Re: Evinrude RX-4 Propeller and TBX Hub Kits

Postby Seahorse » Fri Sep 30, 2016 7:35 am

BRP has the propellers cast to their specifications by several companies that specialize in that.

jimh
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Re: Evinrude RX-4 Propeller and TBX Hub Kits

Postby jimh » Mon Oct 17, 2016 10:54 am

In some recent correspondence with BRP, they confirmed that their torsion bushing extreme or TBX hub does incorporate a limp-home mode of operation. If the plastic of the resilient coupling yields under extreme loads, a low-torque coupling between propeller shaft and hub will remain. This will allow the propeller to turn under low-torque conditions and provide a "limp-home" mode of operation following a severe propeller strike.