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Mercury #6 Drive Chronology

Old 09-28-2007, 12:32 AM
  #21  
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The level check is just below the split between the upper on the right side of the drive. Look for parts on the magnet (drain plug) most of the junk will collect there and water. The tube inside is a vent line. When the drive was filled to the top the aerated/super heated oil would expand into the reservoir. With the level dropped there was no need for the expensive transom plate and the oil is allowed to expand inside the drive submerging the spur gears and the upper gearset. Let the drive settle for a couple of hours or longer before checking so the water is on the bottom and the air is out of the oil giving you a proper level.

If you notice that is halfway up the side of the drive. 3 shafts and 4 gears are submerged in approx 4 quarts of oil. The upper gearset /spur gearset and inputshaft are out of the oil.

What this has to do with dry-sump I do not know.

The idea behind dry-sump is to get the oil out of the way of the moving parts, remove the air (centrifuge) and inject oil on critical points.

Testing loss is difficult. We did a freewheel test (no load) just to check parasitic loss. The numbers will vary depending on ratio and input speed. We also checked the running temp on the boat.

That is only part of the problem. Bevel sets , Timken bearings ect...

When we were testing the first drives one of the Victory other teams decided to test back to back to check our gain. They did a full speed run from start with the wet-sumps, craned out, drained both drives and tried to run. It got on plane and melted the upper sets.

The easiest way to see how much we gained back is the performance of the teams we worked with after they ran our stuff. The World Championship list is on our web site.

Look at it this way also how much power will you gain if you put 10 g in your motor?

pat W
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Old 10-16-2008, 11:38 AM
  #22  
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I brought this back up to help people understand what is a true dry-sump and what is a marketing ploy.

pat W
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Old 10-16-2008, 11:50 AM
  #23  
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Originally Posted by jeff1000man
Similar in the Dry sump pan set up for High performance BBC I am guessing. I am learning of these and am soon to install a set on my next set of engines. Supposed to be a 30 hp gain at the crank.
30 hp gain at the crank. Try again BIG Daddy
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Old 10-16-2008, 07:04 PM
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Hey Shifter;

Can you tell us about your expierance with skeg shape?
More important to me is 'crabing' issue on a single engine set-up with big HP. Do you know if you can counter prop walk with a narrow but long sleg or is the wider standard length skeg the way to go. On O/Bs running 130mph it is just a matter of fashioning a torque tab and some strategic shaping.
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Old 10-16-2008, 11:45 PM
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We have tried just about everything it depends on bullet height. Where are you going to put it.

Here is one where I cut the cav plate off to clear the prop diameter and stretched the fin a little. it worked with a very high x dim. or Z axis in the macining world.

On the single boats we run below transom for the ski boat guys and reduced skeg for less drag. Mainly they run them aground alot and they do not seem to notice the difference.

I have not put any shape (like outboard) to make the boat go straight. We have run parallel to the leading edge full wedge, #4/5 style, hering, none with rudder ect....

The singles are difficult because whatever you do to react against the power will react when you lift.

Leading edge angle changes quite a bit also and # of blades, prop rake, rpm, cup, dia, ect....

I would not start modifying until you test. Old style used to blow out at around 120. The swept skegs use less input to react because trailing edge is farther from pivot center. Stock swept is not as good as aftermarket. Aftermarket weaker from welding and housing deformation and deheatreating.

I hope this helps.

pat W
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Old 10-17-2008, 07:42 AM
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Thanks Pat;

A couple more if you don't mind.
With light weight boats, the issues of blow-out (on both axis) show up sooner. I am afraid of both. I don't know how much bow lift I need to get the the numbers I want, but right now at lower speeds I need positive trim control and therefore I need the drive a little lower. That exposes the first blow-out issue of the case popping up and trying to ride on the top. I'm told that does not happen with the weight of an I/O.

The one the scares me more is the crab angle blow-out from prop walk. With the heavy hydraulic steering on these drives I can't 'feel' the blow out coming.
At lower speeds I have tested and found that an 'airfoil' shaped skeg works the best, the wedge shape does not make sence on a single. It was suggested that, at 150, the water does not converge once being spead apart in the thickest portion of the skeg, and will not close up behind the skeg if you have the fish shaped skeg. If that is true, what aspect ratio do you need to control the laminar flow over the skeg. Or, is it all crap, am I going to have to test out my own situation myself.

Last one, what about the verticle angle of the leading edge. I don't need any tail lift so I think I would want as straight up and down and rudder like leading edge as possible. Or does that make the steering twichy.

Mark??
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Old 10-17-2008, 01:27 PM
  #27  
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Mark,

baseline the boat and increase the speed gradually each test. Data aquisition will help you can put in parameters and turn on lights to tell you when your slip is climbing.

We looked at putting in a spacer with a additional l shape to hold a rudder inboard with no skeg. The pivot point on a rudder is normally close to the leading edge. We are now talking 30 to 40 from center and offset from centerline. It might be a little strange but arneson runs them offset and so does flexitab.

It is a lot of work.

Shape........ props are a wedge with a kicker.

Good luck,
pat W
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Old 10-17-2008, 03:43 PM
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Thanks again;

Yes the RC stuff are for the most part offset rudders. Makes sense, you don't use accelerated water (and its drag) to turn.

Can we talk shop here?... I like your WMD drive very much. I just did'nt know about the skeg. Questions...
Do you have a spacer system to change drive height?
What is the foot print of the Transom plate (hight from crank to top?)
Maybe you can e-mail me pricing.

The data aquisition thing is a great idea.
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Old 11-07-2014, 02:25 PM
  #29  
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so seeing that some of us like to pose what "they/we" think is a stupid question... here's mine... has anyone ever drysumpped a #5 Speedmaster? and if so what were the gains? I'm curious and I have a pair sitting here waiting if this could be worthy of doing?
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Old 11-08-2014, 10:04 AM
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I would be interested in dry dumping my SSMV's also
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