Cylinder pictures, input appreciated

[NHerron]

Hey guys I'm here replacing a crap ITM headgasket with the proven Felpro and here's what my cylinders look like after 3K miles.

Not sure if the visible side loading is a-okay but there's really not much I can do about it so I hope it's okay. Piston to wall clearance was set to .0035" and ring end gaps are .020" on top and .025" on bottom. The marks I can't really feel and leakdown results were less then 10% when I tested a month ago.

This similar wear fashion happened on the last block which was from the PO. So I rebuilt it with new pistons and a fresh block. So I'm not really sure what I should do the next time around, but I plan on o-ringing in a year or less and if it's worse then I'll probably do a rebuild.

So is this side loading wear normal or should I have tightened up or loosened the PTW clearances? Thanks

 

[Fehrion_sit]

looks like the rings dragged some crud down the cylinder wall a few times. was the compression in that cylinder bad? could be a problem with one of the rings


that is no way to adjust Piston to Cylinder wall clearance without a honing mandrel and new pistons

 

[WES_393]

It looks like piston slap to me, especially if the opposing cylinder wall has similar scuffs at BDC. Wiseco's are made from low-silicon alloy (2618) which has a higher fatigue strength than high-silicon (4032). The cost of the extra strength is higher thermal expansion. A piston made from 2618 will expand/contract more than a 4032 and therefore calls for a wider PTW clearance. Most companies recommend .0035-.004, but this is a tad wide for frequently driven cars IMO. I'm sure the manufacturer would prefer noisy cold starts over pistons seizing in the bore. So until the pistons warm up, the PTW clearance is wide enough for the piston to "rock" at TDC and BDC, which scuffs the bore.

In a nut shell: It's a typical side affect of using forged pistons. So long as the scratches pass the finger nail inspection and compression is good, I would't worry about it.

 

[My1GLaser]

If those are Wisecos and the PTW clearance was set at .0035" then it is actually .004" now since the coating wore off the skirts.

IIRC, I set mine to .0025" so it would be .003" after the coating wore off. My cyl walls looked great after 18k miles when I did a HG a couple months ago. 35 psi and no piston seizing!

I know nothing about what piston slap looks like, but I agree that it looks like some crud got caught in there.

 

[rastmp]

Looks like oil contamination or bad rings? did you use a sleeve for piston installation or just a ring compressor? ...you got some junk floating around the engine...?

If this was a fresh build maybe something is too tight?

Anyways...Im no expert but i rebuilt a couple of 4g63's that didnt blow up yet..

 

[GSTurbo1]

You should be fine, if you really wanted to get rid of it you could pull the pistons... 1)3 stone hone 2)cross hatch hone 3)coat with break-in oil 4) reinstall with piece of mind. But otherwise you should be fine.

 

[NHerron]

looks like the rings dragged some crud down the cylinder wall a few times. was the compression in that cylinder bad? could be a problem with one of the rings


that is no way to adjust Piston to Cylinder wall clearance without a honing mandrel and new pistons

Well my leakdown tests were pretty consistent with each cylinder, less than 10%

I meant SHOULD I have gone with more or less clearance when I built it.

It looks like piston slap to me, especially if the opposing cylinder wall has similar scuffs at BDC. Wiseco's are made from low-silicon alloy (2618) which has a higher fatigue strength than high-silicon (4032). The cost of the extra strength is higher thermal expansion. A piston made from 2618 will expand/contract more than a 4032 and therefore calls for a wider PTW clearance. Most companies recommend .0035-.004, but this is a tad wide for frequently driven cars IMO. I'm sure the manufacturer would prefer noisy cold starts over pistons seizing in the bore. So until the pistons warm up, the PTW clearance is wide enough for the piston to "rock" at TDC and BDC, which scuffs the bore.

In a nut shell: It's a typical side affect of using forged pistons. So long as the scratches pass the finger nail inspection and compression is good, I would't worry about it.

Wiseco forged stroker pistons. In the box there was a recommended PTW clearance, somewhere in the .002-.003 neighborhood (paper is in the garage, don't feel like digging ) and I did a few days research on the subject. Ended up with .0035". Definitely have piston slap in the morning but quiets up after a few minutes (<10) but figured if I sucked at tuning and ran lean for any amount of time the forged aluminum wouldn't expand too much and seize, basically an error margin with marginal side effects (piston slap when cold).

Now that I think about it I was having cooling problems at one point and the needle was damn near in the red before I shut it down. I suppose the pistons could have swelled up enough at that time and this is the result. Just a guess.

If those are Wisecos and the PTW clearance was set at .0035" then it is actually .004" now since the coating wore off the skirts.

IIRC, I set mine to .0025" so it would be .003" after the coating wore off. My cyl walls looked great after 18k miles when I did a HG a couple months ago. 35 psi and no piston seizing!

I know nothing about what piston slap looks like, but I agree that it looks like some crud got caught in there.

I sure as hell hope not. I don't know where I would get any crud because I boost leak tested the manifold frequently, cleaned the air filter every other month, changed oil with new filter every other month. In fact, the engine bay was my biggest concern and was more often cleaner than the outside of the car. But who knows.

Looks like oil contamination or bad rings? did you use a sleeve for piston installation or just a ring compressor? ...you got some junk floating around the engine...?

If this was a fresh build maybe something is too tight?

Anyways...Im no expert but i rebuilt a couple of 4g63's that didnt blow up yet..

Sleeve vs ring compressor? Hmm, well I used a ring compressor in the form of a sleeve . Just the standard one you could pick up from an auto parts store. But don't worry, I cleaned it very well. It's been surgical procedure fashion for me since I haven't built many engines yet.

You should be fine, if you really wanted to get rid of it you could pull the pistons... 1)3 stone hone 2)cross hatch hone 3)coat with break-in oil 4) reinstall with piece of mind. But otherwise you should be fine.

Well these are my goals evetually:
2G cylinder head swap and
O-ring the block

Now, if I were to pull the pistons and re-ring/hone I might as well o-ring the block in-car since it would be an easy clean up. But then I'd want to do a 2G head swap. Honestly though, I just don't have the time right now and I already miss driving it . I could buy a cheap A-B car since my job is less than 2 miles away but it IS getting to be winter in Montana...

I'm doing an emissions delete while it's apart I think, as well as mounting the battery on the frame rail so it should be even easier next time around pulling the head. The damn turbo bolts always give me hell though, seems it'll never change

 

[rastmp]

Below is the sleeve I talked about...worth the money i think..

EXTREME PSI : Your #1 Source for In Stock Performance Parts

 

[WES_393]

Wiseco forged stroker pistons. In the box there was a recommended PTW clearance, somewhere in the .002-.003 neighborhood (paper is in the garage, don't feel like digging ) and I did a few days research on the subject. Ended up with .0035". Definitely have piston slap in the morning but quiets up after a few minutes (<10) but figured if I sucked at tuning and ran lean for any amount of time the forged aluminum wouldn't expand too much and seize, basically an error margin with marginal side effects (piston slap when cold).

Now that I think about it I was having cooling problems at one point and the needle was damn near in the red before I shut it down. I suppose the pistons could have swelled up enough at that time and this is the result. Just a guess.

Had your pistons overheated to the point of scratching, the damage would be much more severe and spread across the entire bore. Thanks to evaporative cooling and an aluminum head, cooling issues typically pop the head gasket long before causing damage to the engine. Running lean or without oil is a different story, but again you would have much more severe damage.

Dirty assembly or oil contamination doesn't fit either. The contaminants would cause damage to multiple areas of the cylinder. However, the scuffs in your block seem completely isolated to the power stroke side. This is a very typical sign of piston slap. When the PTW clearance is too large, the pistons lack support and will be forced against the cylinder.

Like I said, I don't see any cause for alarm.

 

[NHerron]

Kinda what I was thinking. It's one of the tradeoffs of high PTW clearances. Because the most scratching was on front side of the cylinder (towards the radiator) probably due to the pin offset and clock wise rotation of the engine and when the cylinder fires, the crown of the piston cocks towards the radiator and bottom of skirt towards the firewall. Only thing is, the scratching is only at the top of bore, it doesn't go down lengthwise very far at all.

 

[rastmp]

Piston slap is very noticeable....did You hear any unusual noise?
I agree this may be the issue but Ill stick with ring seating problem...
maybe all the damage was done at first startup....?

did You file the ring gap? the scratch damage came from rings maybe

I would pull the pistons and check the rings...I dont think you should let this issue go and put the head back on...This may bite You down the road...

 

[Colt4G63 also]

The scuff marks seem to extend higher in the bore than the rings reach, so I would agree with it being slight piston slap on cold starts.

 

[BogusSVO]

Was the block bored and honed when the pistons were installed?
Or
Are you still a std bore?

 

[NHerron]

Thanks for dropping by.

The block was bored .020" over and honed. Still can see the crosshatching. The machinist waited until they got the pistons to set the PTW, and I measured to make sure after I got everything back. This was freshly done less than 2k miles ago. I can definitively hear piston slap in the morning but quiets up completly after 10mins of idling. These are forged stroker pistons.

 

[NHerron]

Any comments BogusSVO? Is that pretty predictable wear?

 

[white92talontsi]

Thanks for dropping by.

The block was bored .020" over and honed. Still can see the crosshatching. The machinist waited until they got the pistons to set the PTW, and I measured to make sure after I got everything back. This was freshly done less than 2k miles ago. I can definitively hear piston slap in the morning but quiets up completly after 10mins of idling. These are forged stroker pistons.

If you can hear the piston slap in the morning then it sounds to me like the PTW may be bigger than .004".

 

[NHerron]

I don't know how it would be, because I double and triple checked the cylinder bores/piston skirts. It was dead on at .0035 and the coating is less than .0005

 

[white92talontsi]

I don't know how it would be, because I double and triple checked the cylinder bores/piston skirts. It was dead on at .0035 and the coating is less than .0005

Not sure how but looking at the pictures it looks as if the PTW is pretty big.

 

[BogusSVO]

I want to go against the grain here.

Due to the way the scratches are and the location of them.

You can clearly see where the top ring stops at TDC, and the scratches go above this point.

Now I just measured a coated Manley piston

The skirt measures 3.362 (85.50mm =3.3661) So that has appox .004 clearance built into the piston.

This should hold true for the pistons you are running...

Now when I measured the crown of the piston, I came up with 3.328, so 3.362 - 3.328 = .034

So .034/2 = .017

So the ring lands are set back into the piston .017

Now with .004 PTW clearance or .002 on either side

That gives .019 that the crown of the piston is from the cylinder wall

( I am building a .50mm/.020 7 bolt ATM)

I just slid the piston in the cylinder with out the rings and pressed the piston into the cylinder wall and could still slip a .005 feeler gauge pass the crown, across the ring lands.

With the rings on the piston to help center and stablize the piston in the bore, I just do not see how the crown of the piston would make contact with the top of the bore to cause the scratches above the top ring land.

Also add that there is no alum transfer from the piston to the cylinder wall.

So I would have to say a small amount of grit made it in the engine or the burrs from filing the rings were not smoothed off.

This is not an uncommon thing to happen, Run an engine with out an air fliter, small amount of crud in the IC or pipe, a black inside of a Intake manifold that held some grit, carbon build up from an EGR system that broke loose.

I would almost want to say it was carbon flake from the EGR, that would explain the scratches above the TDC mark of the top ring

 

[JacksonAuto]

Bingo! Chalk it up to carbon build-up above the top ring.

 

[daren_p]

A PTW of .0035 & you have start up slap? That seems strange to me, I'm running the Wiseco HD's @ .0040 (or .0045 after break in coating wears off) & I don't have any issues with slap. Guys are running more then me as well, without any startup slap. I did alot of searching before I picked my tolerances & guys complaining/having start up slap (even with larger PTW) did not seem to be an issue.

 

[NHerron]

Sorry guys, I really appreciate the info. I've been swamped at work.

I've never run without an air filter and I test for boost leaks a lot (mainly looking for ones in the intake manifold that could suck debris in)

The turbo is very recently rebuilt with an oil restrictor installed, so I have no side to side play therefore no compressor to cover contact causing scratching/chipping.

I may not have smoothed out the rings gaps enough, but I remember I did make an effort though.

At one point, I detonated quite a bit to where I could hear it pretty clearly, but I don't see any damage to any of the crowns. Maybe the damage is on the piston side?

I would post a video but the car is torn apart right now for a headgasket / Kiggly crank sensor install

 

[JacksonAuto]

The marks in the photo are not related to PtW or the rings because like Bogus said they are above the highest point of ring travel. The crown of the piston is much smaller in diameter than the skirt. Unless the skirts have collapsed, there is no way that the crown of the piston can be contacting the cylinder walls. This is a possible scenario considering that you report piston slap with only .0035" PtW. I would pull the pistons out and mic the skirts to see if they've collapsed.