johnb

Hi John

Been speaking to Paul A this morning about that very subject, in his opinion it was just one of those things, maybe a faulty shell?

No evidence of oil supply failure, ie didn't find anything blocking the oilways. Althogh the only reason for a bearing shell to fail would of been a poor oil supply i guess.

Who knows, just one of the joys of 21 year old 928 ownership!

John

Fastest928

If you want a crank....I have plenty - cheap!

PM me!

Cheers
Marc

slate blue

As I said to you earlier, nobody grinds one journal of a crank, you have done the right thing in getting another, all options like getting the crank sprayed were going to fail. I hope you are aware and you haven't made a public note atleast that you must balance the new assembly.

You have a late M28/21 or 22 If you sourced the more popular S4 or later crank (except GTS) they will fit but the balance will be way out. That is the balance of the crank, then you will also need to attend to the balance of the rods, they will be out too, there can be enough variance between the rods to worry about it, trust me, I have been there.

Take it to a reputable shop with a good Sunnen machine and have it balanced properly, it is not expensive, I had my pistons, rods, crank, flywheel, pressure plate and balancer done for about $200 USD they balance it to two decimal places, yes 0.00 grams.

Also you will need to at the VERY MIMIMUM have that block lapped, I can garantee that engine will use a lot of oil. It may also suffer complete failure due to this increased oil ingestion through oil driven detonation, I certainly would never put the old rings back in. That thing will be Puffing Billy, my engine which is an M28/22 you can open the oil filler cap when it's hot and rev it and hold a constant say 3,500 rpm and barely any vapours, yours will not be the same I'm afraid. You will have to run a hot plug in that cylinder as a normal plug will oil up very quickly.

I personally would not put that engine back in without over boring to the next size, I was disapointed when you didn't buy Mark K's engine, I think it was a really good deal. I will say it again, you will need to lap the block at minimum, I am not saying this because I like to see my name in posts, just trying to save you some money and aggravation but maybe the point is not to get it running properly but just to get it running? Also if you didn't know there is a tendency for alusil to gall, that is as soon as it gets a hot spot, it will pick itself up and start to roll little pieces off itself and ultimately seize.

I hope whatever way you go it works for you and you don't flog it off to a sucker.

Greg

mark kibort

Greg is right. we put an engine together with the old rings and no other changes, and it siezed up before it even started. everything "looked" good, but obviosly, it wasnt. (this was an effort to save the $1-200 in rings )

the engine is ready to go. again, its the older year, but still same cut outs and 4.7 euro spec.

mk

Fabio421

Did you hone the bores before re-assembly? It's a critical step with the alusil. That is how you get the silicon to stand up to take advantage of the alusil.

BTW. Maybe you missed it. I don't think you ever answered the call to donate that "extra" engine you have to this fellow. Whada' ya' say Mark. Pay it forward. One good turn deserves another. Don't ya' think?

slate blue

By Fabio 421Fabio this is what is refered to as lapping, you are quite right in what you say, the lapping actually eats away the aluminium and leaves the silicon crystals exposed, so to lapp they put the finest stone in the bore and rebore then re-etch the cylinders, so you will lose some material in this process, then it is lapped (honed so to speak) it will give you better ring seating as the bore material will be more aggresive to the rings. It is this process that John needs to do to have any chance.

Well I don't see any need for that, Mark K has been a standout member of the list and 928 community in general, I would have thought that he may well want to hang on to that engine as the day may well come when our beloved 928s are worth big money, an original engine will be important, also I think that Mark does enough, that is putting together other peoples engines for them and offering advice, I say that and can say, that I never made a donation to Mark nor have ever spoken with him. So I hope that is an unbiased view, also who is the most deserving of this donation? I think that would be a very hard question to answer.

Greg

Vilhuer

Lapping will remove 0.002mm material away from cylinder wall. Doesn't sound like much but tolerance between piston and cylinder wall is only 10 times larger. Its not cheap process to do yet I wouldn't even think about leaving it out on rebuild. Local cost is 100e per cylinder.

johnb

Not sure I know of anyone that can carry out the lapping process. I have spoken to a number of local machine shops and they all want to steel sleeve the block, and change the pistons.

Paul Anderson has built quite a few engines without touching the bores at all, several with old rings going back in, and loads with new rings. As far as i know not one problem. No galling and no compression problems.

What would happen if you wiped the bore surface with a very mild acid to etch the aluminium back very slightly? Talking microscopic here, not major etch.

Can't be rocket science, the bores are basically dimensionally correct, all you need to do is expose some more of the silicon in the bore surface, not change its shape at all.

What do you guys think?

John

SwayBar

Mark Anderson has done the same in the past with no problems, and recommended it to one of the Wisconsin guys, Tim, who in turn had no problems with his 570+rwhp 5.0L engine.

I would not do it. IF you elect to do something, then do-so according to the workshop manuals.

mark kibort

lapping the cylinder walls is a 928 block process that needs to be followed. several shops in LA are very familar with it (like Greg Brown PMW ) and Elsworth in nor cal.
as long as the bores are clean and not scratched, a re-ring is a good idea. however, if it is gouged or scratched, this process should be performed by someone knowledgable in doing it.
Mk

mark kibort

Bailey made a good point. my older 4.7 euro may not have the LHjet flywheel sensor port on the bell housing, so maybe it would be better to use a newer block, or do the rebuild, unless this is a minor mod.

mk

mark kibort

you dont need to hone and do the alusil process unless you have scratches. this block was in near perfect shape.

the block that failed. (which was then bored to 5 liter after the failure and went through the alusil process) had good cylinder walls but we think the used rings had too much ring gap, and could have been an issue. they gauled the cylinderwalls even before start up.

anyway, scot's 4.7 euro (mine as well) is for sale, as i have about 40 hours of time in scot's car (donated) and some of my own cash, for the only reason to get another 928 out there racing!!!! mission accomplished!
the used block will pay for some of scots cost overruns durin the 4 engines we have been through!
1. stock 4.5 removed(perfect shape, but low power 220rwhp) pulled and sold
2. mystery 4.7 euro, no examination, grenaded after .75 race weekend. enigine disassembled, full of sludge!
3. RE- assemble grenaded engine, re-use old rings / grenades during start up
4. install stock great looking used 4.7 euro, but completely rebuild it with new rings, seals, etc, and it makes 250rwhp, runs for a few hours but is pulled to put in 5 liter made from grenaded 4.7 siezed block for more power.
5. installed 5liter remanufactured short block. Scot now makes 290rwhp and has run 1:41 at laguna and 2:03 at thunderhill.

my time donated to make this happen over a period of 1.5 years.

Mk