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Old 16-03-2018, 14:11   #1
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Swapping Perkins 4108 to Beta 50

The rear main crank journal is scored so it keeps leaking oil.
Needs a new crank!
Im planning on changing this 52 year old engine out to a Betamarine 50 hp.
I have a Velvet Drive transmission which has just had the seals and o rings replaced. The clutch packs were in great condition.
Does it make any sense keeping the old transmission to save money or should I get the BM transmission?

26000 lb boat
Walters Vdrive
17 Max prop 3 blade

Many thanks
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Old 16-03-2018, 14:59   #2
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Re: Swapping Perkins 4108 to Beta 50

Keep the velvet drive.
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Old 16-03-2018, 15:14   #3
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Re: Swapping Perkins 4108 to Beta 50

Wainui,
It might not be so much a question of the money, but whether the Beta transmission can be made to work well with the v-drive....

- With a Walters remote v-drive, the final drive ratio of the system will be the product of the regular transmission ratio times the v-drive ratio. Frequently the BW gearbox will have a 1:1 ratio and the rest of the reduction will be taken in the Walters v-drive. If this is your arrangement, then you need to use a 1:1 Beta transmission to maintain the same final ratio. Of course it may be that you don't want to maintain the same ratio because the Beta operates at a different max. RPM than the 4-108. This all needs to be examined.

- The BW gear is probably a co- axial output gearbox, meaning the output shaft is on the same line as the crankshaft, but the Beta gearbox might be a drop center gear, where the output shaft is lower than the crankshaft. This means that the u-joint angles between the engine transmission and the Walters will be different between the Beta transmission and the BW. This may or may not be acceptable and should be discussed with a knowledgeable installer or Walters Machine Co.

- The 4-108 engine turns counterclockwise when viewed from the flywheel and the output of the BW gear is probably the same. It may be that the Beta gearbox will run continuously in either direction, but maybe not. If the rotation isn't the same as what you have now, you might need to be looking at a different rotation propeller.

DougR
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Old 16-03-2018, 15:17   #4
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Re: Swapping Perkins 4108 to Beta 50

I asked Beta about repowering and transmissions. When I told them I had a BW Velvetdrive they said it was a great transmission and recommended I keep it.
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Old 16-03-2018, 16:31   #5
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Re: Swapping Perkins 4108 to Beta 50

Many thanks Doug
You have given me much to think about.
One reason for keeping the BW is that I dont have to change the rear mounts and the shaft to the Vdrive.
I was thinking of going with a Yanmar 56hp but would have to change 22 of exhaust hose from 2 to 3 which would be very difficult.
BW 71c are solid transmissions.
The Beta delivers 50hp at max continues RPM
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Old 17-03-2018, 08:09   #6
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Re: Swapping Perkins 4108 to Beta 50

If beta says it will work, its a good transmission. However, I tend towards all new if you are going through the trouble (not much difference in cost).

The beta 50 is a lot bigger engine ... why the increase in size? I replaced my 4-108 with a 35 and feel it is equivalent. It also revs a lot slower (2800 max).
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Old 17-03-2018, 08:28   #7
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Re: Swapping Perkins 4108 to Beta 50

Keep the velvet drive. When I change from a 4-108 to a Beta I replace the VD with a twin disk and live to regretted it. Had to select reverse in an emergency at Highborne Cay and did not want long enough for the revs to drop and lost the tranny. Had to sail to Nassau for a replacement transmission. The VD is heaver but is much stronger.

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Old 17-03-2018, 08:39   #8
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Re: Swapping Perkins 4108 to Beta 50

I can't speak to your specific question, but we have a Beta 50 and love it. You have made a great choice.
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Old 17-03-2018, 09:21   #9
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Re: Swapping Perkins 4108 to Beta 50

Quote:
Originally Posted by skipmac View Post
I asked Beta about repowering and transmissions. When I told them I had a BW Velvetdrive they said it was a great transmission and recommended I keep it.
Kinda interesting because Beta offer several V drive options. Its like these people are unfailingly honest even if there is a chance to get more money out of you, which is to be endeared.

Both these engines are around similar weights, so that checks out and wont grievously alter the balance of the boat. But I think you will inevitable hit a few snags with the present screw and need to change it. But I guess you cant have everything.

Also the alternator is on the other side of the engine you might find your wiring has to cross over, and you could consider one of their larger alternator options far above the 4108 standard 50 AH. The exhaust on the other hand is on the same side but the other end, some changes needed there too.

IMO Beta are among the best of engines
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Old 17-03-2018, 09:34   #10
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Re: Swapping Perkins 4108 to Beta 50

We also changed to a Beta 50..terrific engine
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Old 17-03-2018, 10:31   #11
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Re: Swapping Perkins 4108 to Beta 50

Due to the co-axial design I kept the Velvet Drive. It made the Beta a drop in with no bed changes. I do not remember the engine rotation being an issue but the BW pump can be set for either CW or CCW rotation.
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Old 17-03-2018, 13:38   #12
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Re: Swapping Perkins 4108 to Beta 50

I tend to think going up in horsepower is a bad idea. Your fuel consumption will go up and what about size of propeller shaft etc. I find sometimes during crossings from say Tonga to New Zealand I need to run the enngine quite a bit to stay in cinc with the frontal systems. My boat had a 42 hp. engine and the previous owner got a deal on a 52 hp. yanmar. I too have a V drive and would never put 16 more horsepower engine in a boat designed for less. 20 to 35% more fuel consumption means less rangeand more wear and tear. Its not a 57 Chevy running the Quarter Mile.....Best of luck
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Old 17-03-2018, 16:03   #13
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Re: Swapping Perkins 4108 to Beta 50

So running a 26000 lb boat with a Beta 50 at 2200 rpm which is 42 hp @ 1 gallon ph is Too much for a Walters Vdrive?
Ive read that ideal size of engine is 1hp per 500lbs.
Many thanks for all your replies.
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Old 17-03-2018, 16:11   #14
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Re: Swapping Perkins 4108 to Beta 50

zactly ...
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Old 17-03-2018, 18:12   #15
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Re: Swapping Perkins 4108 to Beta 50

I also replaced a 4-108 with a Beta 50 (BV2203), in 2003. Also a V drive - Hurth 150V, now ZF marine. Four thousand hours later still happy with the choice.

A few options will make life a lot easier than living with the 4-108.

1) Custom engine brackets. Made the engine swap a DIY breeze.

2) Remote mount of both the oil filter and the on engine fuel filter. Put them right up in front of the engine for easy access.

3) Second alternator. Leave the stock Beta alternator in place and add a second high output alternator. The belt ratio on the second alternator can be customized. Mine was selected to provide full alternator output at idle speed.

Also be aware that the BV2203 is a little narrower, longer and higher that the 4-108. Be sure it fits your space.

As for power. My 24,000 pound 44 ft sloop was underpowered with the 4-108. The added HP was one of the decision points on the rebuild/replace decision.

The BV1803 and BV2203 are the same engine except for the bore - everything else is identical. So in the same space you get more horsepower.

BTW, the BV2203 is quite a bit lighter than the 4-108. 100 to 200 lbs if I recall correctly. I now carry 150 feet of anchor chain in the lazarette to trim out the boat.
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