Are these pistons okay?

[11secondFWD]

I know this is from my dsm but I just wanted to know about the pistons in general.

Here is a pic of my pistons. I traded for a stage 1 longblock. More less stock rebuild. It had treated me great this season. I pulled the head to put in L19 studs and an OEM HG. I then looked at the pistons and found them to be hit in a couple places.

My valves did not hit 100% sure. Engine ran great til day I took it apart, and valves are fine so I am not here to debate that. They were hit previously in another car and put into this engine this way.

I am here to ask if it is okay to reuse these pistons. Pics are below. The guy I bought the engine from, put these in when he did the rebuild. I wish he would have put new but thats what I get for trusting people. SO anyway he put in pistons that were hit by valves and were still okay in his book.

I want to know if these are ok. I plan on 420WHP on E100 this year and dont want any unforseen things to happen. The engine ran strong as hell with the pistons like this but is it okay to run it like this? WHat are the worst possible cases? Should I get forged pistons? I really dont want too since it is new and perfect compression.


Let me know any advice and if they are ok to run or not, Or what I should do. I dont want any spots were I could get detonation on the pistons.


Pics
#4
http://i123.photobucket.com/albums/o293/94atxvr2/SANY0077.jpg

These pistons have been ran all season. Drag raced about 40 times down the track running low 12's/ So they are not "damaged" and have perfect compression and run good. Since they have been running like this for a whole year I know they will be fine at a low power level. But I am definitely worried about detonation and hot spots. I think I have been lucky so far because I only run ethanol. However, I WILL be over 400whp and was going to push it to see if I can get some good runs.

I would love to try and see what it does because it has performed great and has 162 psi compression across the board. But I am scared of this xmas gift I found when I took the head off.

I dont know if this is accurate or not but the 4 piston looks the worst, the 2nd is almost the same and the 3rd and 1st are pretty much un scarred. And when I removed head bolts (stock) I notice the ones all the way toward cyl 4 (the one in the pic) loosened extremely easy and they got harder to toward cyl 1. And the ones on the far right (right of cyl 1) were hard as hell to break loose. And I did loosen according to the manual and in proper order (opposite of tightening order). I didnt go left to right or anything crazy. I just meant that the bolts going passenger to driver were progressively harder to break loose when i did them. And I thought maybe cyl 4 was detonating/knocking and stretched the bolts toward 4 a little bit. Although I was not pushing coolant or overheating.

#1 piston (can see #2 bottom left was hit a little)
http://i123.photobucket.com/albums/o293/94atxvr2/SANY0075.jpg
#3
http://i123.photobucket.com/albums/o293/94atxvr2/SANY0071.jpg

[akotten]

I'm no expert, but it may throw off their weight balance?

[11secondFWD]

Well they should weight the same, they are just dented. At least I think. I am guessing my only problem could be a sharp raised edge that could cause some detonation/ a hot spot to pre ignite the fuel.

[GTOJOE]

I'm no expert but some of those marks look kinda fresh. Are you sure your valves are ok? was the timing right or the belt stretched?

[akotten]

Well they should weight the same, they are just dented. At least I think. I am guessing my only problem could be a sharp raised edge that could cause some detonation/ a hot spot to pre ignite the fuel.

I think I can agree with you here. It might prevent an equal, steady burn.

[green-lantern]

I'd be more worried about what the sides look like. I really don't think the dents would be a problem unless they have weakened the piston and now prone to breaking.

[11secondFWD]

The sides are fine. Everything is perfect compression and straight on sides. It definitely isnt from me. The pistons were just put in since the engine is a brand new rebuild. Everything was perfectly clean before put in. So for only 6 months they are quite dirty. I only run ethanol too and it keeps it pretty clean. The guy reused these pistons straight from another persons engine core, cleaned them and I have been on them all racing season.

100% sure not from my engine thats not in question and I am not worried about that. I am worried about any problems pushing the engine this next season with these ridges/marks on the pistons.

[green-lantern]

Personally I wouldn't worry about it. There could be something I'm not thinking of but since you ran this a full season with no problems I'd say you a fine.

[11secondFWD]

I hope so! I know they would last if I kept it at 32 lbs/min like I had this season. But I am moving to a 47lbs/min turbo and I want to make sure these marks wont cause catastrophic problems.

[Maximal]

Could create hot spots but if you've been running fine all year I doubt they'll be a problem. Reason you don't want to just pick up another used one and throw it in?

[J. Fast]

In the first pictue you posted it looks like the piston is a little higher than the deck which is a moot point since its an interference motor but still was your timing a little wonky there for awhile? You can see valve dimples on there, all 4 of them :confused1: and you never had any knock issues?

[Granny]

Something caused that. This engine has had problems.
I would be more worried about wear on the crank journals or the wrist pins on the pistons.
Was this engine a rebuild? If the block was taken down and no allowences were made then that could caues problems.
What about the heads? The 2 are connecting and shouldn't be.
If I was doing an engine rebuild those babies would be gone but I would also be checking alot of other factors.
If it's running and you are happy then run it until it drops but it will fail at some point.

[Ninja Performance]

I would not use them.

-Chris

[green-lantern]

I would not use them.

-Chris

Why? He has ran this engine hard already?

[GTOJOE]

Why? He has ran this engine hard already?

Why take the risk? It sounds like he plans on pushing it harder than he already is. I don't have even 1% of the experience Chris does but If I was planning a build there is no way I would use something that "could" cause a problem.

[Ninja Performance]

Flame front disruption and possible hot spots. I would not use them.

-Chris

[MaxClass]

It sounds like you really want to keep these.

The weight issue I think is moot here. Although I would feel for any small sharp edges on those dents. If you find any that you don’t like put that piston at TDC, place some masking tape around the piston edges so nothing can get in there and use some sandpaper to gently sand down and smooth the sharp spots. You would be lucky to remove a fraction of a gram of weight that way. Overall probably less than if you cleaned the carbon off of the top of one piston.

Only foreseeable problem from my perspective if left alone is flame front interference [knock] during burn but under the conditions you were running under before it doesn’t look like it would be a problem.

Nice new forged aluminum pistons [Wiseco] could not hurt either but you would have to have the block bored too.

Doesn’t sound like valve clearance is a problem either.

Not familiar with L19 studs. Are they like ARP’s? ARP told me on my build that the factory torque spec’s will not sufficiently stretch the studs so I would consult with the stud manufacture for the correct torque spec’s on them.

Also use ARP Ultra-Torque lubricant on all of their bolts/studs.

[Austin@STM]

L19's are just a stronger head stud made by ARP, and some other companies.

As far as the pistons, i would go ahead and replace them now, DSM pistons a cheap, and since its all apart anyways you might as well.

Otherwise put it together knowing it might go at some point, and look for another short block.

[11secondFWD]

Thanks for all the replies. First of all I want to make it clear.

THESE pistons were used in another engine that had major issues. Then it was used as a core. Then when I bought a "rebuilt" long block from a local shop he used the pistons out of THAT core that bent the valves and put these stock used pistons in mine. My valves NEVER hit, my timing is dead on and my engine has no problems beside having these pistons in it. I know I should have never trusted the shop but I got the engine on a trade for parts I had left from my FWDTT part out and had a talon shell with no engine. So it was too good to be true. But the engine ran great. I ran 12.2 with a small 16g with e85 on a stock auto. I was elated with the results.

I am only tearing into it because I wanted to put new studs and cams into it, along with a fuel setup and turbo from STM. And to my surprise this is what I found.

No the psiton is not taller than the deck. I cleaned off the deck of the block today and the putty knife and razor blade I used to scrape the old gasket off showed me that the piston is even or slightly below the deck since it went smoothly across.

So what does it take to change pistons? I can get stock replacement for a 100 bucks through NPR. But the bottom end performed perfect, is broke in, perfect compresson, 0 knock, ect. I know I will be pushing it more and if I should change them I will. I am hesitant because I dont know whats needed.

Can I take the pistons out the top and put new rings and new pistons on my rods and put it back in and break it in again? Or do I need to send it off to a machine shop and get it decked, and honed? I know I also have to make sure the rings are ground correct and check with a feeler gauge right? Do I need to change rod bearings too?

I mean I have done timing belts, and all bolt on stuff and cams, fuel, tuning ect. But I have never messed with removing pistons and doing the rings and the rod bearings.

Also would I have to have the rotating assembly balanced?

SO Terry, CHris and Austin, along with others, what is needed to change the pistons? Is there an easy way or just send it to the machine shop to get it decked, honed, ect?

What is the easiest I could get away with, whats the best way? I was only wanting to keep these since it ran fine and I dont have to do any major work. But while it is apart I might as well fix it, if it aint too hard.

[11secondFWD]

Yea and L19's are arp head studs that are stronger than originals just like austin said.

ARP "L19" HEAD STUDS | 90-99 DSM | EVO VIII-IX | 4G63 (http://www.streettunedmotorsports.com/parts/arp_l19_head_studs_4g63_evo_dsm.htm)

I was thinking about sanding the marks but I didnt know about the balance of the rotating assembly or making a thin weak spot or something. Some are kinda deep.

[11secondFWD]

Oh and I know if I got over bore I will need it bored decked and honed. But I was asking if I just use stock replacement what I will need to do. like these.

90-92 MITSUBISHI ECLIPSE TURBO PISTONS RINGS SET 4G63 - eBay (item 150522167933 end time Jan-17-11 17:36:45 PST) (http://cgi.ebay.com/ebaymotors/90-92-MITSUBISHI-ECLIPSE-TURBO-PISTONS-RINGS-SET-4G63-_W0QQcmdZViewItemQQfitsZModelQ3aEclipseQQhashZitem 230bd2027dQQitemZ150522167933QQptZMotorsQ5fCarQ5fT ruckQ5fPartsQ5fAccessories)

[akotten]

Well you would need at least a new honing for the new rings to seat properly. Unless I missed it, so the motor is still in the car with just the head off? You would need pull the motor so you can completely strip it down for honing. Again, I'm no expert, but I'm pretty sure new rings require a new honing and when you hone you need to throughly clean the block from the fine metal shavings (its more like wet dust). Unless there is a technique I am unaware of that allows you to hone and not make a mess. Chris would know more, he's a pro at engine building. :)

[11secondFWD]

Thanks. Ya, I assumed if it was honed it would need to be all apart. That is why I was kinda reluctant since it did okay at low power levels.

[11secondFWD]

Oh and chris, what do you think about hylomar blue on composite gasket (OEM). The one I took off had the hylomar on a felpro composite and it held great this season. I can barely get the crap off my block though. Do you recommend a spray on a used block that is not decked? Or on composite or MLS? Or is it not worth it. I feel everyone has different opinions on a copper or hylomar blue spray on head gaskets. I remember you mentioning it to trevor in his build but It is a long thread on 3si.

[Austin@STM]

OEM metal headgasket FTW, its about as good as it gets.
STM: OEM MITSUBISHI METAL HEAD GASKET | 4G63 90-99 DSM (http://www.streettunedmotorsports.com/parts/oem_dsm_metal_hg.htm)

As far as the machine work, since you dont know the history completely, your best bet is find a reputable shop take a look at your block and see what it will need, depending on the fasteners used some things may be replacable, some things are only one time use.

As long as the previous machine work turns out good, you shouldnt have to do much.

If you dont know of any good machine shops, take it to Buschur Racing, the machine shop they use is excellent, and being local to you they see it in person and give you an idea what the its going to require at the machine shop.

-Austin@STM

[mcshooter]

sounds like you are local and if so avoid cable machine in akron, just ask baturbo. also if you hone it just use the bottle brush hone

[green-lantern]

Why take the risk? It sounds like he plans on pushing it harder than he already is. I don't have even 1% of the experience Chris does but If I was planning a build there is no way I would use something that "could" cause a problem.

Because now he is basically looking at a rebuild anyway. He needs to have a machine shop check all clearances or he might be replacing a proven engine with one that could have problems. It's not like this engine has a bunch of expensive internals, it's basically stock. I'm not sure how plentiful these engines are but blowing a stock engine might not be such a big deal if they are plentiful, cheap and he's looking at a complete tear down/rebuild anyway. I would run this engine while building another with stronger rods and pistons, or I'd just go ahead and go all out with this one. I respect Chris's advice also, I've asked for it plenty of times. I just want to know the reasons behind his advice. I'm the type to say if it isn't broke don't fix it but if I'm going to tear it down I'm going all out.

[11secondFWD]

Hey Austin, I know OEM MLS is the best but the surface has to be decked. Both the block and the head. And with certain fini8sh ect. I know alot who have tried to do just the heads and had major head gasket leaks. If I get it all done I will do OEM MLS for SURE. But with this block which is not perfect, I was going to go with OEM composite, if I am going to reuse it, since the surface is not 100% even and composite is flexible. I know you probably know this but I just wanted to explain my why I was going to go composite.

[Ninja Performance]

I respect Chris's advice also, I've asked for it plenty of times. I just want to know the reasons behind his advice. I'm the type to say if it isn't broke don't fix it but if I'm going to tear it down I'm going all out.

Thanks, I gave my reasons in my previous post ;)

-Chris

[neveret]

Wilson automotive cylinder head repair and Fall automotive machine here in toledo can take care of all your machine work (if you get it done). They are very resonable too. You could always take those pictures over to them and get a professional engine builders opinion. I personally would blend that damage and run them.

[KeithMac]

If it were me I`d be tempted to dress the piston damage (very light use of a small die-grinder), but be prepared for a possible engine failure at some point. Removing the sharp edges would significantly reduce the chance of hot-spots and detonation.

You can lightly hone the bores with the engine still in the car if the worst came to it and you went for another set of (none oversized) pistons.

It`s all up to the OP really.

[green-lantern]

Thanks, I gave my reasons in my previous post ;)

-Chris

I know, thanks :) good reasons also, I'd just do what Keith said or go ahead and go all out. Rods, pistons, everything. I'm not sure if OP has the cash so I'd just smooth the top and run it while picking up parts for my new engine.

[11secondFWD]

Yea, I am going to run it. My turbo and fuel system is taking all my cash. If it goes then I will do a full rebuild with rods, pistons, decked surfaces, ect. If I dont run this bottom end I wont be running any car at all this year more than likely. And the ethanol did great with the piston last year, so I am praying the knock resistance and octane of ethanol will save me and keep it from failure for a while at least.

[blindmist]

I am telling you right now, if they are not forged pistons, which they don't appear to be, don't be surprised when one cracks. 4G63T right?

You are going to get a hot spot close to a ring land and there goes that.

Please don't make me post a picture. STM has ross pistons for $450. You wont need a fuel setup with cracked pistons.

[11secondFWD]

Well I dont have a car without the fuel setup, and I have a running engine now. It is a 4g63t. I ran on it all season and with e95 I believe it is helping keep problems at bay. Do I think it is going to fail sometime this season? Hell yes. But I will wait to upgrade when that time comes I guess. LIke I said, if I do pistons and machine work it wont even have a season and it lasted one season without any knock or problems. Is it smart to upgrade now? hell yes but I figured out I cant afford it. I have no fuel tank, and no fuel lines ect. So I need the fuel setup just to have a running car. If I didnt do headstuds I wouldnt even know they were hit at all and I would be in the same boat anyway. So I will keep you updated. And show pics of my cracked pistons probably. But I am pretty good at tuning, and doing it safe, and without pushing it, And ethanol helps, so I hope the best.

Thanks for your input, I would go with that advice 100% if I could.