Ok, I just bought a block and put my full trust in the guy who I bought it from because he seemed legit and said he did all his research and even gave me the original thread where he bought the block from and the original guys number to call him about it. Well turns out I should of completely disassembled the block before buying something costly even if the guy is reputable. Well it turns out 3 threads were cracked (original builder said he lock-n-stitched all the headbolt threads), 3 trans threads were completely stripped (how did I miss that??), and the pistons have moderate damage to them. I'm going to post some pics up and would like some other opinions on the current quality of these pistons. My buddy already took the block to Kinetics Racing Engines who builds Nascar motors and the guy said the piston to wall clearance was way too much and he wouldn't recommend running them but they would be acceptable. He then removed the piston and said that it had mushroomed a bit and said these are basically scrap metal and the block is too because boost will eventually just tear the threads out no matter what type of fix I used on the head bolt threads. Anyways, the guy is willing to refund me my money as long as he can confirm that the pistons are bad so I'm gonna post some 20 pics up and hopefully some professionals or even commoners can chime in to give me their two cents. I think that the word of a Nascar engine building company that builds for GM, Ford, Chrysler and other car manufacturers should outway most peoples input on here but this guy wants to be fully convinced that the piston are basically useless now. I'll try to explain the pics because the camera isn't proffesional quality but should be good enough.

Cliff Notes:
Bought bad block, was told it was good. Guy willing to refund money only if he feels convinced pistons are really bad. Looking for your input on these pistons to help convince him. I will be showing him this thread

Piston Damage-A little mushroom head, little holes from idk what, top of the piston has ring around it as if it hit the head or a head gasket that was too small, random scoring on the piston walls (some small and some really bad), little knicks on all over piston wall just over combustion ring, looks like something ate away at the top piston ring groove and the actual ring, a piece of metal actually broke off from somewhere and welded itself near to the edge of the piston, etc. (pics will tell all)

 

More pics

 

And lastly, a little bit of mushroom top

 

to ME that looks like a deck height issue or MAJOR detonation, tho i am no expert at reading damage

 

the performance shop told my buddy that the person who originally used the motor most likely ran it super lean at one point (whether intentional or not)

what do you think about the walls being scored up, how the piston is being eaten away at the piston rings


Thx for your input BTW

 

well for the skirts --- that looks like dry starting or lack of oil psi

piston pitting/what not looks like "possible" p2w clearance and detonation or motor sat for a LONG time with being stored properly allowing moisture into engine corroding them.


pics of cyl walls in block? also pics of top of pistons?

 

I should've took pics of them but the guy didn't ask for them at the time so I didn't think of it. The block has RS machine sleeves so i don't know how much damage it could've done to them. I'll take pics right now

 

Here's cylinder #4. I tried taking more pics but my phones shuts off. I'll get more pics using a different camera.

Anybody else have any input? I really want this guy to do the right thing and refund the money

 

That looks Terrible.

 

holy mother of god dude! you have an aweful lot of paperweights on your hands there.

that all looks like: horrible and dirty original engine assembly, improper clearances, poor/no oiling supply, and possibly long term street driving with no air filter.

the pictures you posted have a higher dollar value than all the actual parts.

I build a lot of my own personal engines the wrong way on purpose just to see what type of damage it causes, so I can more easily diagnose failures in other peoples' engines and so I know what works and what definitely doesn't haha.

I see for sure: debris got between the cyl and piston, debris got into the ringlands, no lubrication for the cyl and piston walls, contact with the head and/or gasket, rings not gapped at all (let alone properly sized).

those cylinders are also trashed, and you're correct in saying all the damaged threads are NOT repairable.

there are heavy signs of detonation, but it does not appear to be from a bad tune, it is definitely from the "squish zone" aka "quench zone", which is the area all around the border where the combustion chamber in the head is very shallow. and in the case of this engine, there was no such thing as shallow; it was literally making contact. literally every single combustion stroke it was squishing the mixture in that area so hard and so fast that it was instantly causing detonation all around the borders of the pistons, overheated the living snot out of the pistons causing that pitting you see, and more than likely also bound up the rings, which then damaged the ringlands and cylinders and piston walls. the mushrooming is due to it overheating SO bad that the metal actually became soft, and when it hit the head again it mushroomed out into the cylinder wall, which then pushed back as the piston got dragged back down, causing it to mushroom back upwards again.

90% of that damage is due to absolutely horrible initial engine assembly. its garbage, all of it. you definitely need to get a refund.

p.s. I see no signs of detonation in the center of the pistons, nor excessive carbon buildup or anything. so whatever tune was done on this engine is definitely NOT the cause of any of the damage. it definitely appears as if the tune was perfectly acceptable.

 

Thanks for your input, much appreciated! Yea hopefully I get it all resolved so we can just order new parts and work off the original block. Could this damage be from running lean without any detonation? Because from what I know, motors run way hotter when super lean correct?

and I think debries got between the piston and cylinder wall because there was a lot of play. Way more gap than recommended for P2W

 

highly unlikely. if it were running lean without detonation, it would be constantly burning off any potential carbon buildup on the pistons. but as you can see, there is a very minor amount of carbon on the piston tops as well as some gold coloring (carbon stains), which means it was in fact running cool enough for the carbon to even build up at all. and if it were running rich (which many people may say is a cause because that can wash oil off cyl walls, it is NOT the case in this setup), there would be a much higher amount of carbon buildup.

if it was lean, with or without detonation, the piston tops would be all silver, no carbon buildup, and possibly slightly pitted all throughout the center.

I've actually been experimenting a lot on my car lately with running it lean with ideal timing, lean with retarded timing, and lean with slightly advanced timing, as well as stoich with various timing, and rich with various timing; and looking at the piston tops after doing each of these.

 

Well the carbon build up on the top of the piston looked minimal to me but i don't open motors too often and the block supposedly only has 500 miles on it. I'll double check to see if i have any pitting other than the edges you can see in the pictures

Wow just read the last part of your reply. Looks like your taking everything very seriously....I actually just read in your signature that you do tuning so now it makes sense lol

 

lol, yup. I do tuning, engine builds, and full custom fabrication, and I do take all of it very seriously especially when doing it for customers and not just my own personal use.

I used to do it as an actual job, but when the market for it all got too iffy I went and got a normal job lol. I still do stuff with my own car(s) practically constantly, and recently started picking up side jobs here and there doing it. partially cuz now my main job slowed down a bit, and also because I get way too many people begging me to do work for them and I hated having to tell everyone I couldn't cuz I didn't have enough free time lol.

 

Yea it's not something I'd want to let go either(if i did tune) lol I'm actually having some problems with my other car that I boosted. Could I pm or text you about it?

 

also to note, piston to wall clearance being too big wont really have any effect on debris getting into that area. it would just cause some minor sealing issues, and pistons would wear out a bit quicker, but not get damaged like what you have. at least not unless the clearance was WAAAAAAAAY too big lol.

and just to clarify, the amount of carbon on those piston tops is exactly what you want to see. presence of carbon means its not too lean. and its not completely coated in carbon either, and no thick chunks of carbon, which means its not too rich either.

 

sure, go for it. pm is good

 

you can buff out the scuffing on the skirts. the damage to the dome and surrounding areas of the piston is minimal and you shouldn't have an issue re-using them.

I have a set of Arias pistons where 2 of them contacted the cylinder wall on the pin sides and had scuffing on the section between the dome and first ringland. Took them to the machine shop and measured every possible dimension I could think of and the scuffing did not change the diameter of the pistons at all. I polished down all of the rough spots, I broke all sharp edges with a de-burring tool and hand polished each piston, they look brand new.

The scuffed areas have similar pitting like yours but like I said above, does not affect piston diameter, piston to wall clearance, etc. and were deemed reusable by the shop

clean them up and go for it

 

Problem is my buddy took it to his friend who builds cummins as a hobby and he measured the bottom of the piston and the top of the piston and said they were off one part of the piston and again after a 90degree spin and said it was off...like an oval. I don't really care at this point because I want a refund no matter what. My buddy didn't pay for a block to have to dump a shitload more into it. Thanks for your input though but honestly I would NEVER do what you said you did. I'd make my personal motor to spec and as close to perfection as possible.

 

If I showed you pics of the pistons and how minimal the damage is (roughly 1/4 to 1/2 in length on only 1 side of two pistons) and tell verbatim what the machine shop said, you'd run my pistons as well. They weren't out of round and all of the dimensions where the same as a new piston, no material was lost and nothing deformed

and why are you expecting a refund? the pistons weren't bad out of the box (unless you measured and recorded every dimension prior to install) something happened inside the motor to cause the damage (read: not the pistons fault)

What was your p2w and what power levels were you making when this happened? It looks to me like p2w was too tight and when the piston expanded under thermal load it contacted the cylinder walls

 

i dont know what some of you guys are seeing i CLEARLY see deep pitting in pic 3 (left side) in post#2. it is pitted enough it looks like the aluminum it looks like it is rough to the touch

 

Yes there is some pitting but compared to what happens most of the time when piston and cylinder wall meet, this is very very mild

 

EXACTLY!
I don't know what the heck wantboost is talking about. these pistons are absolutely NOT reusable by any means. there are literally chunks of aluminum missing from them. and he obviously doesn't read either, because he seems think the OP bought the pistons brand new, and ran them in his personal car for a while, and then saw this damage occur.
the OP BOUGHT the engine like this and was told it was an absolutely flawless and well built motor. it did not happen WHILE he owned it.

 

I missed the part where he said the pistons were out of round, they definitely are not reusable. In my case the pistons barely scuffed the walls and came out almost undamaged.

I also missed where he said he bought the motor like this... in that case I would most certainly demand a refund, since that's a huge investment that turns out to be totally worthless. It looks to me like whoever built the motor setup the engine with way too tight p2w clearance

 

there ya go haha.

and for the record, I also have taken scuffed pistons and buffed them out and reused them with perfect results. got an additional 130k miles out of them, til I cracked a ringland due to driver error haha. they were also perfectly within spec like you talk about how you did with yours.