mark kibort

Do you just make stuff up as you go along? "aluminum worn back to show 14% or more of silicon", " crystalline structure of aluminum and silicon" yes, the block does have a 14% silicon content. The aluminum doesnt have a crystaline structure, the silicon does. Its designed to make a very smooth surface, much more smooth than a hashed iron block honed bore. It also alows more of the mixture of the aluminum and silicon by removing the exposed aluminum . in theory, the rings are not exposed to the aluminum no, just the harder silicon surface. and yes, there are still microscopic voilds to hold oil. Just much smaller than the iron bore hashing. edit: i dont know what it looks like at a molecular level, but i do know that you cant see any hash marks like you can with the iron block boring.

so, you say that the rings "wont break in properly" yet my engines have seated and broken in well! You also said that rings will " probably" glaze and force a full rebuild. what is you probability here, based on what you have "learned" here today? (or before) Hmmmm, just friggen amazing the scare tactics and arrogance here. What credentials do you posess that give you the authority to post such advice? Again, ive only used what engine builders have suggested and what i have read, and the results also speak for themselves. Also, tell us all how many rebuilds of 928 engines you have been involved with.
Do you really think a little assembly lube mixed with oil is going to cause ring glazing and last on that surface long enough to cause an issue. If you were a betting man, what would your probablity be for the next engine i built doing this???? tell you what. Ill build one, do it again, and give you 10:1 odds of there being no issues . $1000???? wanna bet???

IM sure the greg browns and Marc tomas' are laughing over this non-science
Truthfully, I know nothing more than i have learned here on the list, and by those two about engine building (and of course my lawn mower , or motorcycle rebuilding experience). Add that to the few succesful rebuilds and there you have it, my credentials. I do think i am much better beating up on these engines, than i am a resourse for rebuilding

Mk

BC

I am sure someone is laughing Mark, and its not at me.

BC

Its common sense Mark. Why fight common sense? So you look right? So more people will listen to you wax on about gearing?

Everything you argue about, seems to be somehow twisted up and spat back out backwards. There is info there, but its all in the wrong place.

Did you just say the aluminum when mixed with Silicon does not create a crystalline structure? Yep. I think you did.

No one else is out here actually trying to correct you because as I said originally, there never will be a correction in your mind. Nothing will change it, but you have made two more posts about how correct you were in doing it your way, all the while making sure to tell me I am comming off as an expert.

If there is a PHD in knowing to not use some idiotic backyard procedure to make sure you don't "Wear out the rings" on startup by gopping the bores up with assembly lube, then I have it.

I am no expert, and I don't know everything about everything.

But I knew not to do this when I was 14. And mostly everyone else did too.

BC

If I were a betting man I wouldn't even put any money on an issue where you had to do something that required you to learn new concepts.

I'm done. If you want to think that you are right, thats fine, but in no way, in this dimension of time and space, are you.

BC

And referencing the pictures that Mark has posted, just so its discussed - you cannot put USED pistons that have had their entire tin or ferrous coating worn away back into new bores or even used bores with new rings - and expect this never to happen. It won't always happen, but its a sacrificial coating that wears away as everything works together, and is gone on the contact surfaces by about 80k miles (I guess thats a variable, but it makes sense from what I have seen).

For this reason, I did the skirts with a PC-9 skirt coating for my newly lapped bores on my latest engine - so that will wear away as it comes together instead of galling with aluminum on aluminum.

But I am done now unless new info is required or I get stupid and want to engage Mark again.

mark kibort

Talk about twisting things up. Brendan, you are pretty good here!

I found some information about putting assembly lube on the piston skirts. you found some contrary. You dont build engines for a living , nor do i. I took some advice and used it. it seemed to work, and i think i understand why.

well, I dont think you need a PHD to listen to folks that have some knowledge in the area of engine building and apply it either. I didnt make this stuff up, someone suggested it.

It seemed to work Big deal. You chimed in and made a big deal of it. the amount of assembly lube we are talking about is pretty small and im pretty sure its a non issue with our engines.

I think we have beat this one down far enough.

by the way, i did say that the aluminum and silicon is not a crystaline structure. from what i remeber about crystaline structures, they are grown, not mixed. And for sure, someone that has knowlege here can correct me if im wrong. thats why the aluminum is removed with the paste to expose the crystaline structures that are very hard and wear resistant. (alusil bore characteristics)

Pease out!

mk

mark kibort

the tin coating was not as bad as the picture shows after all, these pistons got mixed up with the cylinders in a bad way. no coating wouldnt have saved this piston. the engine never even started! it was the mechanics fault for trying to start a motor for as long as he did. would assembly lube have saved it? dont know. all of the engines i have built have had used pistons that looked as good or worse as far as the coatings on the piston skirts. none of them have done this. (besides this one.) I think many will agree that without oil, starting an engine for as long as this mechanic did, could cause this failure. Or , it could have been the used rings fault. (also, i was not a part of this silly decision)

The final engine we built for scot had some pretty ugly pistons. (pics were shown on the 5 liter build up) new bores, new rings and the used pistons seem to work just fine. after all, it is racing and has raced through a sucessful near full season! maybe the assembly lube save it on start up. I dont know, but it certainly didnt hurt anything.


Mk

mark kibort

As i said Brendan, i learned all of this new from those who do know. Heck, i was even putting assembly lube on the back of the bearings when i first started building the first engine. Marc Tomas laughed and told me why this was a bad idea. When he showed me how do to many of the things i had no idea how to do. And im positive, there are even much more that i dont know either. what I do know how to do is put together a 928 short block out of stock parts.

if i put a little assembly lube on the piston skirts, which some think is a good idea, well that might be an opinion if you think that is bad, but i dont think it is hard fact as you say it is. Thats what this entire last part of the discussion has been about. You made you points. You still think you can grow aluminum into a crystaline structure with sliicon, great! why dont you tell us about your metalurgy PHD too while your at it. Man, can your ego get any larger?

Brendan is right, I am wrong. feel better? Fine, move on.


Mk

Nicholbry

Thanks for the clarification about the piston ring pliers' operation and the link to Harbor Freight. Now I get it.

"atb", you say that your stroker isn't built yet because of piston ring tolerances. Is that to say that the factory rings out of the box are so exact that they can't be used in a stroker, but can be used without grinding in a conventional motor? I realize that I should measure w/ a feeler gauge, nonetheless.

Brendan, that makes sense now that you explain the oval shape of a free sprung ring. When you pinch the rings together they are a perfect circle, but open them up and you invariably angle the leading edge of the end gap out into the piston wall. I see now. Oil that might escape will be captured by the lower ring anyway as their end gaps will be offset.

Now all I need is some pliers and I'm set. Those on Harbor Freight had a max opening of 100mm. Even though the pistons are 100mm, is that adequate for fitting the rings to the piston or should I go up just a little in size to insure enough expansion to go over the piston crown?

Thanks guys.

mark kibort

I didnt know this before, but the pistons are oval too! wider at the piston skirts.

Im wondering if scots first piston sieze was due to a real wide ring gap. kind of like you are saying, if they are too big, then the angle could be such to where the ring opening area digs into the bore. ??????

I think the stroker issue for Adam, is more about finding the right rings, as his pistons are like 968 103mm types. now we get into some variables that i dont understand, but im sure Brendan does.

Mk

blown 87

I think that Hazet has a set of ring pliers that go a bit bigger.

mark kibort

Well, no one suggests assembly lube on the bores? Brendan, here is yet another publication of professionals suggesting assembly lube on the cylinder bores. But of course, with your world of experience, all these folks have to be wrong.

http://www.circletrack.com/tipstrick...ine/index.html

"Rod & Piston Installation"

"Before installing the rod/piston combo in the cylinder bore, wipe the cylinder walls with a lint-free towel. Then, apply a light coating of assembly lube to the cylinder walls. Install the piston rings per manufacturers' recommendations. Phase piston ring gaps opposite from each other to help deter cylinder pressure blow-by. If the pistons have domes or machined- or cast-in valve reliefs, make sure that the piston is installed with proper orientation to prevent piston-to-head or -valve contact."

atb

B.C. wrote
That is correct. Per the Total Seal recommended spec, I added an extra .002" gap to the Remote Mount Turbo motor rings compared to N/A spec.


Nicholbry wrote:

My stroker was overbored to accept 968 pistons. The pistons that I had were used, so I was going to have them coated by HPC in AZ. They have a coating that has been used with success in alusil bores. The coating I believed spec'd out at .00015" thick. My machinest compensated for the coating thickness by taking my bores out an additional .0003". In so doing, the bores were to big for the factory rings, causing too large of an end gap. That's how precise these components are. I looked into using the "overbore" ring at 104.5mm, and then having it cut to size, but assuming that over bore ring was the same width as the standard, I then would have had too much back spacing between the ring and the floor of the ring land on the piston. Pretty wild. We're are talking a few ten thousandths here causing this chain reaction.

So, now I've got different pistons and am nikasiling a block to the correct dimensions. A steep learning curve indeed with these strokers when you're dealing with different components than the norm.

Sorry, the pic really was more for illustrative purposes. I didn't see the spec's on it. If it will only open a ring to a 100mm diameter, you'll need something bigger. Not much, but you definitely want to be able to easily clear the ring lands.

Nicholbry

That's sorta what I was thinking. My search has yielded plenty of ring pliers that expand to 100mm, but haven't yet found one (in the design that supports the ring all the way around) that expands beyond 100mm that is relatively inexpensive for my one time use.

I've found another that simply opens the end gaps up w/ no lateral support around the ring. It seems that this type would be easy to over expand and break the rings; so the search continues. If anyone has a suggestion do chime in.

Additionally, and just so the question doesn't get lost, I wanted to mention it again. Has anyone had success with lightly honing or refreshing the cylinders with the drill, drill attachment, felt pad, and the silicon solution (I think it is called AN-30 or something like that)? I doubt I will attempt it myself, but if there are enough positive testimonials I might consider it. The idea of refreshing the cylinders along with new piston rings is appealing if it can be done without a pricey expense.

Thanks again,

BC

My guy here is about 30 bucks a hole for that process.