The 2010 FrankenMerc Project

[Faztbullet]

Re: The 2010 FrankenMerc Project

LMAO

The first thing that fails are the piston skirts and pretty much everthing else follows..

 

[sschefer]

Re: The 2010 FrankenMerc Project

Max safe RPM is difficult to calculate without knowing the closely guarded secret alloy's used during manufacturing. I'll be gathering measurements and other (blueprinting) in order to calculate the fps of the pistons and then make an educated guess after that. I'm hoping to prop this engine for a sustained 6000-6500 RPM and still be within the stonger area of the power curve.

What fails first? If all else is equal, it, as FB states, should be the piston skirts. When the piston gets to TDC and stops dead in it's tracks the opportunity for rings to flutter is greatest. If the rings flutter badly it transmits down to the piston and the skirts can slap the cylinder walls.

Pinacle balancing of the piston is one of the way's you can try to minimize this effect since not only will the piston weight be centered it should also be equal on the wristpins. The most common method is to use a thinner ring or even go to a race piston with a single ring.

Regarding a no load motor and max RPM... a two cycle engine under no load will run away on itself. RPM's will continue to rise until it leans out and melts down. If you could theoretically provide it enough fuel to remain cool, (variable porting would be needed) it would run until the structural integrity of one or more of the internal components fail through reciprocal stress and fatigue. Again, that's probably going to be the piston. Since we'll never know the formulas for the alloy's and the results of the engineers testing we can only hazard a guess at what point structural failure will occur. We can however, calculate when the engine will begin to lean out and using that we can say it would be the point of Max RPM provided that point is not beyond the component failure point.

P.S. I'm not crazy nuts becuase I hang out at S&F, I'm just crazy naturally. I'm insanely meticulous by nature of my German upbringing. My dad always said if you can't do it right do it again until you can or don't even bother.

Never making a mistake is impossible. If you think you've done something perfect. It means you won't realize your mistakes and therefore never have the opportunity to further better yourself. FYI, there is no such thing as perfect so the opportunity to learn is always there if you let it be.

 

[Huron Angler]

Re: The 2010 FrankenMerc Project

P.S. I'm not crazy nuts becuase I hang out at S&F, I'm just crazy naturally. I'm insanely meticulous by nature of my German upbriging. My dad always said if you can't do it right do it again until you can or don't even bother.

LOL You are doing a great job on the monster, I aree that it's almost too much info for me to handle, good thing your thread will be here for reference.

Where to for the fishing trip this year?

 

[sschefer]

Re: The 2010 FrankenMerc Project

LOL You are doing a great job on the monster, I aree that it's almost too much info for me to handle, good thing your thread will be here for reference.

Where to for the fishing trip this year?

Eagle Lake, Ca.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Did some quick calcs on the motor today. Using a standard of 70psi for bmep I came up with 164 hp at the crankshaft @ 6000 rpm for a stock 150 which is consistent with hp's reported by those that have dyno'd a stock motor.

This sets a baseline for the motor and by calculating the changes to the baseline that I've made I can very closely estimate the horsepower that the engine can produce when completed. The math involved would bore the heck out of you so I won't go into all that but I will give some of the baseline numbers as I assemble the engine that you can use in your own builds.

Stay tuned, it's about to get fun..

 

[saumon]

Re: The 2010 FrankenMerc Project

Wow, thanks for the infos, very informative.

If you don't mind, i have another question. Earlier in the post, you show a 1 inch spacer that you put between the intake/reed block and the crankcase. Is it something that came stock from factory or is it an add-on? And what's the purpose of this spacer? I understand that it enlarge the crankcase volume but what are the effects?

 

[sschefer]

Re: The 2010 FrankenMerc Project

Saumon, The concept is not new in the race motor world and you can buy them from some of the race shops. I chose to try a different approach and I made the spacer out of 1" HDPE.

I also took .050 off the front half because I was advised to but I'm not sure how moving the reed blocks closer to the rod ends is going to help. I can always double gasket if that doesn't work out.

I could theorzie reasons why the spacer plate works but I'd just be BS'ng. The best I can tell you is that in testing that others have done, it seems to provide a significant performance improvement.

It doesn't enlarge crankcase volume because the reed block location does not change except for the .050 that I took off the top of the case. That would also cause some decrease in crankcase volume and inversely it would increase BMEP.

I want to be careful about increasing total BMEP becuase it will directly effect the idle and bottom end. I know that by removing the oiler driven gear and stuffing that vacancy up I'll bring # 2's BMEP in line with the other 5 cylinders. If my figures are right I should be at about 80psi when I'm done and close to 175 hp. We'll have to wait until all the numbers are in to know for sure.

Interesting to note is that if I could get this motors BMEP to 115psi I'd could have a potential for 270+ hp. It's not impossible but I would have a hard time getting it started and it would likely only run well at WOT.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Balancing - My scale could not be recalibrated so they sent me a new one but they sent me the wrong one. This is only accurate to 1g and my other is accurate to .1 gram. You might think 1g is o.k. but if you've ever seen how much metal comes off to make 1g you'd understand why. Nonetheless I proceeded.

These pics came out bad so I'll take some more later...

Overall weight -

Little end -

Big end -

The lightest rod was 349 and the heaviest was 355.

On the small end lightest was 127 and heaviest was 128

On the big end lightest was 225 and heaviest 235 but it was unrepeatable after 6 weighs. I think this is due to the small rod length and the random breaks at the rod caps. It was impossible to repeat the resting spot.

Since the small ends were all within a gram I opted to go for total weight balancing rather than big end small end and take the weight off the rod beams as equally as I could. I still have two rods left to do but apparently its working because the small ends on the ones that I've done are staying nearly the same. I suspect that if I do find a way to get a repeatable weigh on the big ends that they will be very close.

Tonight I'll finish the rods and start the pistons. From there we'll move on to shot peening with glass bead useing multiple nozzels and test strips. I make take these over to my buddies shop. He's all setup and I'd have to put the rig together.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Balancing continued --

Took the rods over to my buddies and put them on his 400.00 balancing fixture and the results were the same as on mine. Big end was not repeatable. We couldn't get them to rest in the same spot twice on his either.

Soooo.. we both decided the best way is to overcome the problem would be to throw out the most precise and difficult methods and go with old school overall weight of piston, wrist pin and rod. Faztbullet sent me a PM about going this route and it makes a lot of sense now.

I brought the rods all to 349g taking weight first from the casting flash and then from the beams as needed.

The pistons came in with a low of 413 and a high of 415 with the rest at 414.

The wristpins came in with a low of 78 and a high of 83.

The small amount of weight difference in the washers, bearings and keepers is insignifcant and in the case of bearings, not adjustable so you throw those out of the mix.

The one thing that overall weight balancing does for you is it allows you to make adjustments that rarely involve any changes to piston weight so that makes it easier.

Since my scale is only reading in 1 gram increments I juggled things back and forth until I came up with a consistent weight grouping of 844g with a low set at 843 and a high set at 845.

I removed some material first from the wristpins since this is the denser material then I took the rest off the rod beams trying to do it equally. The final weight of all six sets is 843g.

I then numbered each component of each set so that just incase I jumble them up I can still put the right parts with the right set.

So why didn't I balance the pistons first then bring the rods in? Simple, the density of the materials is such that taking 1 or 2 grams out of the pistons could have weakend them. I was aware of this and Fatzbullet mentioned it in his PM. The pistons take the brunt of the abuse in this train of components. All the components are abused but minor changes in compression, fuels, fuel mix, timing, etc., are going to first effect the piston. If you have the opportunity to leave them as manufactured I believe you stand a better chance of having them live longer.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Rods and such...

Took the rods down to the shop and glass bead peened them. When you do this you use a test strip to set it up and a group of nozzels. You adjust the distance so that the test strip reacts according to the way you want it to for the material you are peening.

If you don't have test strips, you can use a piece of bailing wire. That's acutally pretty amazing because when you start the wire is easily bent and formed into a more or less permanent shape but when you peen, it becomes nealy rigid but won't snap like you think it might. Pretty cool.

Anyway, the idea is to remove surface tension and replace it with compression and that's what peening does.. Here's a rod after it was peened -

You probably liked it better when it was all shiny huh.. That's where you start but this is really what you want. The area is actually very smooth and fuel won't stick to it like it looks like it may. Polishing it off would risk removing the peen so it's best to leave it just like this and opt for a stronger rod.

And here's the rods, pistons and writstpins spotlessly cleaned -

Tomorrow afternoon, I'll scrub the washers and bearings and I'll do it in a clear bucket and make my point clear why.

So I imagine someone is saying why bother with all this cleaning. Well it is a pain in the rear for sure and it is time consuming but the next time you tear an engine down and look at the cylinder walls and see those fine tiny vertical scratches, instead of wondering where they came from you'll just say,, humm somebody got lazy with the cleaning. All it takes is one little piece of grit from working on these to put a nice power robbing gouge in a cylinder wall.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Update, just traded the 200 Crank and SeaCross rods for a complete 200 EFI to Cary's Mobile Marine in New Caney Texas, not the motor, just the EFI.

Option 1 - WH 40 Carbs
Option 2 - WMV-5 Carbs
Option 3 - EFI

Darn, one more thing to ponder over during my 5 am coffee. LOL

Jay Smith Racing in Dayton TX got the heads and the pistons went to another fellow in Pacifica MO.

I broke even!!!! the 200 is now a no cost item if you exclude the labor and just consider that the American Way of earning a honest living!

I feel GOOD !!!

 

[Willyclay]

Re: The 2010 FrankenMerc Project

This is the single, most informative motor thread I have ever read! Thanks for all the time spent sharing the info & pictures. Frank is turning out to be a "work of art". In fact, he is so pretty you probably need to rename him Francis. I hope you make a video so everyone can hear it run. Good luck!

 

[Jacket4life]

Re: The 2010 FrankenMerc Project

Hey sscheffer-Are you in TX? I 'm far N.E. TX. I'd love to come by and visit you sometime when I'm in your area!

 

[sschefer]

Re: The 2010 FrankenMerc Project

Thank you Willyclay.. A video is in the plan for first crank and first run. I couldn't have posted a video of today's events, they wouldn't allow it..

And with that as a segway, Pro Marine Pro pistons are pretty much what they say, economy pistons. The pistons can vary in weight by amounts that are not easily adjusted if the end user wants to build to any type of precision. The wrist pin weights also vary and while they do give you an opportunity to swap and match with other pistons, that same opportunity is also a problem in that they some are too tight and require lapping and others are too loose and useless unless of course you find the piston that they fit in and then your precision balancing goes out the window.

The retainer clips are junk and easily bend when being installed even when a proper installation tool is being used. I was amazed to see them standing proud of the grooves. On one of the pistons a simple test of tapping the wristpin caused the clip ring to pop out. Having one do that when the engine is running would be devistating.

Am I mad? Just at myself. I saw them, read the info on them and chose them over the slightly less expensive Vertex piston. I also blew off the more expensive Wiseco piston because of rumors about swell.

I'm going back to the drawing board.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Went back to the drafting board, did some research and came up with a solution...

I'm going to make these work.

I got out my Dremel and went to work on the wristpins. It's not easy task to take 4 grams out of a wristpin and keep them fairly well balanced on center but it can be done and I did it.

I took a worn Merc wrist pin and chucked it in my drill press. I took a small amount off the outside then used valve lapping compound and lapped the bosses on the pistons. The pins now fit snug but can be pushed through with moderate finger pressure.

I took the rods and equaled them all out again and I'm making a sliding axis for my weighing fixture so I don't need to worry about finding the resting spot and the weights will be repeatable.

I am going to balance these big end/small end because it is the right way. I'm just not willing to overlook the fact that the big end is rotating and the small end is reciprocating. Neither will I overlook that there is no immediate opposing piston or the short stroke block design because there will always be oppositon and there will always be swing (bob) weight.\

I'll take the entire blame for this problem. I figured out the shop time I've spent trying to make this work and the final numbers are just about equal to using Wizard or Wiseco pistons. That's my lesson to myself for the day.

Now,,, back to making this a fun project!!!!

 

[sschefer]

Re: The 2010 FrankenMerc Project

Hey sscheffer-Are you in TX? I 'm far N.E. TX. I'd love to come by and visit you sometime when I'm in your area!

No, I'm in Santa Rosa, California in the Northern red neck pot growing half of the state.. I fall into the red neck category. If you want to see how this is supposed to be done, theres a bunch of builders in Texas. Jay Smith Racing is one I'm familiar with, he's in Dayton.

 

[Jacket4life]

Re: The 2010 FrankenMerc Project

No, I'm in Santa Rosa, California in the Northern red neck pot growing half of the state.. I fall into the red neck category. If you want to see how this is supposed to be done, theres a bunch of builders in Texas. Jay Smith Racing is one I'm familiar with, he's in Dayton.

LOL. My cousin was stationed in that area for 2 yrs in the Navy. He said the ppl in that area reminded him of rural Tx, but hated dealing with the "californication" of things, i.e. taxes, environmental issues, etc.

I'm just trying to build a network of ppl. to ask questions when I finally find the boat that will be my project. I never plan to build a racing engine, but this thread has been SOOOOO informative, I really appreciate you putting it on here! There a lot here that would help the avg person do a LOT better job on just a "normal" rebuild!

 

[sschefer]

Re: The 2010 FrankenMerc Project

Thank you Jacket.. If you're ever in the area you are certainly welcome to stop in and visit.

 

[sschefer]

Re: The 2010 FrankenMerc Project

Balancing Act --- The saga is OVER!!!!

First off, I thought about what was different with my balancing station and my buddies and then what was the same.. Bingo... we both used magnetic bases and my scale. He sent his out for cal when I mentioned that I was going to. The magnetic base was interfering with the scale but only when I tried to weigh the big end. Must have been just the right combination.

I moved my entire station to another location in the shop, unplugged or moved all the chargers, motors, etc. and then screwed the stand down to the bench. I just drilled and tapped a hole in the base and used my pinacle as the new upright.

I then made my sliding axis out of some 1-1/2" aluminum angle and some flat stock then jb welded it together. I cut a knife edge on the top edges so I would have the least possible resitance.

I then taped the axis to the top of the scale so it wouldn't move around and got to the task of weight.. BINGO... totally repeatable. I was so flippin happy

Here's the new setup -

Here's the sliding axis - I tried it without it and went 2 for 5 but close each time. With it I was 5 for 5 and dead on.

What made me even happier was that after I went back through everything and brought the weights all equal on each rod, I only had one rod that was less than a gram out on either end.

Still I went through each one and made them so the tetered between the final number and the next lowest. This should make them within .5 grams or at least close enough to call "Damn Good".

I got the pistons done also and found it wasn't as bad as I thought. I got them to all set level and used the same technique to get them within .5 grams or thereabouts.

All the pin boses are slick now also. Those that I felt might still be a little stiff I hit with a rolled up green Scotch Brite, spinning the piston on it like a wheel on a axel.

These puppies are done!!! Alll I have left to do is clean them and wait for the circlips to get here.

I also talked to a couple of friends about leaving the shot peened surface or polishing and the general concensous was that once the shot peening was done, polishing would be icing on the cake. I went back and polished them all again.

 

[will941s]

Re: The 2010 FrankenMerc Project

I've been keeping up on this post, and you are doing a heck of a job, and mastering a OB of this size like this takes alot of skill and know how. I was reading about rpm's, and one thing that amazes me is the function of a 2-stroke. I've been a automotive mechanic for years, and have always been amazed in the application and reliablity of builds of motors. For instance, a car with a drive train for the motor set up for 1,800 rpm's cruising will last about 300,000 miles. One set up for a cruising rpm range of 2,500 rpm's will last about 150,000 miles. Thats it, if it hits 6,000 rpm's for any lenth of time, the motor will begin wear and self destruct from the inside out. OB's have always grabbed my attention because well, at 6,000 rpm's it's doing it's job, and will maintain that for as long as you pour the gas to it and never skip a beat.....then last for 20+ years. It's crazy how the K.I.S.S. (keep it simple stupid) factor comes into play in a 2-stroke. Less moving parts, simple design, oil/gas flow through the crankcase and roller bearings makes these things bulletproof. And not to mention makes all OB's classify as high performance engines. Heck, i'm just going to build a 2-stroke motor for my truck.....make the liberals crap their pants when I pass their hybribs and blow them off the road with my 2-stroke smoke. Who's with me?