I wouldnt buy the ebay pistons, IMO its the heart of the motor, not something to ebay with. Wiseco makes standard size bore pistons. I just learned that myself about 2 days ago. Contact them for further details.
http://www.wiseco.com/default.aspx
1-800-321-1364

good luck man.

ok, but the pistons are not the "ebay" pistons, they are HKS being sold by the actual HKS company. So any other ideas, and then I am going to look at the forged wiesco. Also, what would be the best forged piston for me, my final goals for the car are just over 400awhp

"What size are forged pistons" ?
They're whatever size you get em.

if you get 'em in standard size, they'll fit unbored block. If you get 'em .20 over, then block will need to be bored out. Did that shop order .20 over pistons or something?

This whole thing about pistons "not fitting" is just silly. They're blowing smoke up your butt. If they had ordered std. JE set, it would fit fine. Either they want more money from you, or trying to cover up their own screw-up.

Wiseco pistons will be able to support 400awhp with ease. I did realize they were HKS pistons, although I really dont know anything about HKS pistons. I was in the piston market a year ago and never heard of HKS pistons.

As far as easiest install, (if that term can be used with pistons) in your case, I would go with the Wiseco's. Look into some eagle rods while your at it.

I also agree something is fishy with the engine builders.

crazy_skier said:

Hi, I am getting my engine rebuilt by a reptuable engine shop, home run engines and they are having a problem with the pistons. First off, they want to rebuild my engine without boring it out because there is nothing wrong with the cylinders, and right now are doing the rebuild inside of the car. They say that the pistons they ordered are to large (JE i think), and that I would either have to run oem or get custom Diamond forged, unless they pull out the block and bore it. So my question is, does anybody know of factory size forged pistons, or should i just bore it out. Also, i have found a set of pistons, http://cgi.ebay.com/ebaymotors/HKS-...ryZ33623QQssPageNameZWDVWQQrdZ1QQcmdZViewItem and would these work in the 2G 4G63 block??? thanks alot, Ryan

P.S. i just found out today and they would like to order new pistons today so the sooner the help, the more appreciated.

Click to expand...

And about those HKS pistons, first odd thing is they specify 4G63 as being 2021ml, where dsm 4g63 is 1997ml. Second of all, those are Evo 4&up pistons, which means they will need modifications to drop into DSM, and third, it doesn't say anywhere that they're forged, although for the price, I'd assume that.

Go with Wisecos. They're cheaper and proven.

This seems kindof sketchy to me. First off, you havent really given alot of info. Why exactly are you getting a rebuild if "there is nothing wrong with the cylinders"? Typicly, the reason why one would have to do a full engine overhaul is they either had substatial engine damage (ie melted piston, blown off ring lands, ect) or it's just worn out (high mileage, consuming oil due to loss of ring seal ect.). You havent said why exactly you are rebuilding.

Second, what qualifies as "nothing wrong with the cylinders"? The reason why the majority of the time when an engine is overhauled that a machine shop does a cylinder overbore is that over time, when an engine wears, the bores which are supposed to be perfectly round, get out of round, and start to turn to an "oval" shape, which eventualy leads over long period of time to loss of ring seal, thus the need for a rebuild. The overbore makes the bore perfectly straight, and round, like it was when it was brand new from the factory. This brings me back to my first question, if this is not the case, and the bores have been micd and are true and in spec, why has the motor been pulled apart? Also, you say the engine is still in the vehicle. Did they pull the oil pan and push the pistons out of the top of the block when they checked everything to conferm that nothing was wrong? It's not somthing you can just eyeball up, and say "yup, looks good". You say they are reputable, but I'm just wondering why they chose this route for a legit rebuild.

Wiseco, I'm 90% sure makes a standard size bore forged 2.0 piston for your cars, but you might want to double check.

JaxTalonTSi said:

Wiseco, I'm 90% sure makes a standard size bore forged 2.0 piston for your cars, but you might want to double check.

Click to expand...

Yes they do.

And good point about reasons for rebuild.

I would like to clarify everything up. I pruchased my car with a melted #1 piston, and the cylinders are fine (no scorching etc) and so my #1 piston is shot. The #2 piston isnt looking great and so I am doing a full rebuild and the reason the company said the JE pistons would not fit is if they do not bore them out, which there is no reason to. With that said, they are looking to put in forged standard size pistons, and I was wondering what pistons I should run and also if I should bore out the block to .002 just to be safe or not (the shop said it is not needed and all they build are race engines) this is what I meant by what size piston. Also, I am running eagle or scat H beam forged rods (would like your opinion to) and all new bearings on the crank. If anything else is not clear, please ask before saying this sounds sketchy because I do not know everything that you would like to know, so please ask before accusing. I am more than willing to be helpful, and will ask my builder any other questions that you would like to know. Thanks Ryan JaxTalonTSI, I was also wondering at first why they were not going to overbore it, but if everybody says they need to, then I will have them overbore it atleast .20 Sorry about the confusion earlier, I was running late for an appointment and was just hurring my question

So, basicly, #1 piston was trashed, and the bore managed not to be damaged to the point of needing to be bored. So they are telling you that you can just push out the pistons with the block in the vehicle, slap some new ones in and ride out? Dosn't sound right to me. I have done the "rering" job on a DSMs, all with decent results, but usualy the reason why was because of a budget thing. I discussed my results in another thread: http://www.dsmtuners.com/forums/showthread.php?p=1836141#post1836141 .

Basicly, what I was doing is the "ghetto" rebuild, which consists of pulling the cylinder head, oil pan, pushing out the pistons, examining the bores for major visible damage, honing the cylinders, putting in a new standard size ring in the bore and checking ring endgap clearance, to see exactly how much I could get away with, and if all checks out, install pistons with new rings and rod bearings and reassemble. This all done with the block in the car. Alot of people frown on this because it's harder to keep debris ect. off of the crank journals, and because it's not the "right way" of doing a rebuild. My reasoning behind this is that at the time I could not afford a legit engine overhaul, and that would mean the car would be down for months at a time. The "rering" job might not have been a 100% fix, but it would help ringseal substatialy, and keep the car on the road for that much longer while being able to drive it untill I could save for a REAL rebuild.

But it seems to me that money is not the case for you. You can afford forged rods and pistons, and to pay sombody to do this work, but your not going to have the engine removed and have the job completed the right way? It dosn't make sense. If it was me, I'd have the engine pulled, dissasembled, and have the block sent to the machine shop to be checked for cracks or other problem areas, and have them bore it .20 over, and reassembled with some .20 over Wiseco slugs, if you insist on a forged rebuild.

In the meantime, can you get some pictures of what exactly it is they are doing?

Ok not sure if this would help. The stock pistons are 85mm and are 8.5:1 compression and the ones on ebay that you are looking at are 85.5mm and 8.8 compression so they are .02 over, they even state that bore modification is needed (the compression has nothing to do with the overbore).

http://www.dsmtuners.com/sub.php?page=1g2gcomparison This is where I found the stock compression

http://www.wiseco.com/PDFs/Catalogs/SC06_Mitsubishi.pdf This is where I found the size of the piston.

1G's and 2G's had the same size piston, it is the compression and the wrist pin hole that are different. If the shop says that you do not need to overbore the cylinders, and you trust them then don't. If you still have you car there, you have some trust in them, if you have second thoughts now about their work, then have you car towed out of there while you can. Good luck.

I would not recommend getting those pistons, for the reason being that there is not enough known about those pistons. I bought my rods/pistons from EBAY but they were an Eagle/Wiseco setup, and I saved $100 shipped, and when I received them they had an SBR invoice.

Woo Hoo I just noticed I recieved my proven member status.

crazy_skier said:

I would like to clarify everything up. I pruchased my car with a melted #1 piston, and the cylinders are fine (no scorching etc) and so my #1 piston is shot. The #2 piston isnt looking great and so I am doing a full rebuild and the reason the company said the JE pistons would not fit is if they do not bore them out, which there is no reason to. With that said, they are looking to put in forged standard size pistons, and I was wondering what pistons I should run and also if I should bore out the block to .002 just to be safe or not (the shop said it is not needed and all they build are race engines) this is what I meant by what size piston. Also, I am running eagle or scat H beam forged rods (would like your opinion to) and all new bearings on the crank. If anything else is not clear, please ask before saying this sounds sketchy because I do not know everything that you would like to know, so please ask before accusing. I am more than willing to be helpful, and will ask my builder any other questions that you would like to know. Thanks Ryan JaxTalonTSI, I was also wondering at first why they were not going to overbore it, but if everybody says they need to, then I will have them overbore it atleast .20 Sorry about the confusion earlier, I was running late for an appointment and was just hurring my question

Click to expand...

Here's what sounds sketchy to me:
They claim that cylinders don't need to be bored, yet they get you .02 over JE pistons and they say they don't fit. Why wouldn't they get std. bore JE pistons to begin with?

Another thing is that I have never seen a melted piston that didn't damage cylinder walls, and I've ran DSM-specialized shop for 3 years now and torn down a lot of engines.
Even if you melt center of the piston, and edges stay intact (and usually the case is the other way around), thermal expansion at those temperatures will cause piston to rub against cylinder walls. Again, if you've seen those cylinders and they are indeed fine, then by all means, go ahead with the rebuild, however, I would pull the motor out and do a normal rebuild with .020 over-bore.

Ok thanks for the replys. I am going to have them pull the block out and do the .02 over bore. Also, the reason they said they did not order the std JE forged pistons is that they said they contacted JE and it would be awhile before the std size pistons were going to be on the market. Thanks for the responses and sorry about not being clear enough before. Ryan

the first time. I don't know if this thread is still active. But, for the sake of the DSM gods....do the rebuild right. In the long run you save $$$$$.

My balance shaft bearings just went and do to a shortage of good short blocks I'm rebuilding it.

First - bore it out and use wiseco +20 over pistons with eagle rods. Makes it bulletproof.

Second - send it to the machine shop to be hot tanked (cleaned) this will eliminate all contaminates. Then have them magnaflux the block and crank - this basically means they will check for damage the human eye can't see. I also recommend that the machine shop does the short block assembly this should be about $200-$250 more. Also, provide them the pistons before boring this ensures a great match.

I would also give the head to the machine shop for cleaning and mating to the block.