Didn't think that out to clearly, eh Charley!
Jeff
Didn't think that out to clearly, eh Charley!
Jeff
"We live at the bottom of an ocean of air." - General Marvage Slatington
The "forked" rod approach won't work with long needels. The angular rotation is different between the two rods and that would cause skidding on the more lightly loaded bearing. To make the forked rod approach work you'd need separate needles for each rod. Not impossible but pretty messy to try to put together unless there was a caged bearing set (you would need 3) one for each of the 'outside" forks and one for the middle rod.
I think the master rod approach is probably the best, but as I said above you've got to get the contact pressure down to somewhere near reality for the bearings to work.
Remember too, that if you make a new rod cap you need to make it out of a high strength steel that can be hardened to RC of more than 58 or so if you want the bearing races to last for more than a few minutes. Not a big deal, but certainly part of the process.
To make this work you need to take the front cover off of a 44 and with the crank in place see how much room there is between the rods and the sides of the bores at their closest position. That sets the size you can have in that area and so long as you stay within that dimension (or plan on modifying the block with the slave rods in it so that what you come up with will fit.
I'm sure way back when that Mercury would have done something like this if it would have been workable. If there was a way to make this work they wouldn't have made "double" 6's with gearing just below the engines....
Oh yea, and if you get it to work why stop with a 8,,, just think about what a flat 12 would sound like making about 300 hp.... Makes my ears perk up just to think about it...
Yellowjacket and others correctly point out the problem with two rods on one set of journal bearings - the differential skidding issue was recognized immediately. As there is insufficient space between the counterweights to allow two sets of needles and divider, the backup plan was to use two bronze rods per journal riding directly on the crank (well oiled). Not an ideal solution, but would have lasted sufficiently long to prove the engine concept.
Given the obvious flaws with the "skinny" rods, and overwhelming interest in the aircraft like master-link rod (my first choice), the concept was re-visited. To make the design more compact, the joint was inverted: The blade will now be integral to the rod cap; a matching fork rod will straddle the blade. Swing tests conducted last night prove the interference zones are rod slots on intake and exhaust side of the aft block (block with the master-link).
Crude dimensions taken from the modeling clay indicate there should be sufficient swing room with some careful grinding. Even better, subsequent layout math suggests there is room for a .312" wide caged needle bearing in the blade section if counterweights are machined for clearance. A hardened steel cross-pin, possibly as large as .500" Dia. would become the link rod bearing surface.
Beginning tonight, a revised rod cap (blade) an link rod (fork) will be machined, and assembled for fitment in the blocks. Cross fingers!
I'm not "HIGH JACKING" this tread, but it reminds of Chad's Yama-Merc. Chad ran P.R.O.P. Tour 1997 and with the death of Jim Hauenstein we quit boating racing at the end of that season.....Funny, I dreamed about Jimmy last night. He and I did our fair share of beer drinking over the years. In my dream, Jimmy WAS supposed to go buy some beers...but he never came back. I think there could be some symbolism here, then again, Jimmy frequently disappeared when it was his turn to buy beers.
It was either 1999 or 2000 that Chad got the idea to build a V-6 Yamaha using a Mercury crankshaft. .055 oversize Mercury pistons fit the Yamaha V-6 bore perfectly. Ted Zahorski, who was Yamaha's National Service Master gave use two blocks. Chad line bored the block and put two powerheads together. He bought the Overton's old Hoffman that Fred Bowden owned. We had ever thing ready and it would not start. I called Randy Pierson, in Avon, Minnesota to ask for help. Randy was leaving the next day to come help us at San Diego.
Randy said, "The gad damn thing is never going to work, as a Yamaha is 90 degree block and a Mercury is a 60 degree."
So, I call Ted at Yamaha. He hangs on the line for a LONG TIME......He finally said, "It won't work as it will go Rum, bum, bum Rum."
I call Randy, he says, "I've got a brand new S-3000, powerhead, I'll bring it with me and I trade you some props...."
We had fun at the race, but that was our last P.R.O.P Tour effort.
Where is this 888 Project going to run? Or is it just a "PROJECT"?
Hi Ron,
Just like my Cosworth Johnson, OMC six-packs, OMC turbos, Merc 444 & 666, the Merc 888 Turbo will be build just for fun.... With any luck at all, it will power a hydro next summer, then be shown at Mark Suter's next fall.
Please keep your ideas and stories coming.
Tim
Eight cylinders is plenty enough to start. If the prototype behaves itself, an opposed 12 would be even more of awesome....
Meanwhile, images show four contact points on the "slave" block. There is less room available than thought available for swing, unless the block is modified - a possibility. I'm attempting to design a 3/8" minimum, possibly a 1/2" pivot pin. The cutaway cap shown required eight round trip assemblies before clear rotation was achieved. Now that maximum dimensions have been determined, engineering can begin.
Tim, this project is quite interesting to say the least. Are you planning to leave the ports stock or are there plans for them later down the road?
Gardner Miller
Lone Star Outboard Racing Association
"Water is for racing. Asphalt is for the parking lot."
Remember....Freedom isn't...."Free".......
Thanks for your interest. The plan is to run stock porting. Raising exhaust ports reduces total volume available for combustion. And though widening is possible, forced induction makes up for lots of porting ills.
Rods and crank will be weak links. Kiekhaefer did a great job of optimizing these engines: Nothing is beefier than needed. Should the rods make it, double duty on the crank journals will likely take them the crank out quickly.
Even so, it's a very cool project.
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