Look all I was saying is in the Ecotec it is perfectly fine doing this mod without going crazy, Brian my car has 40 k on it several shots of N2O and not a single vibration or otherwise. GM would not even begin to do this if it wasnt mechanically sound, BTW do you know who does all that work for them?
KATECH, read LS7, they would not allow this to go out the door if it wasnt sound, plus they ran the motor up to 7k RPM on a dyno for several pulls and a durability test. But like you say **** it!

He asked I answered you flew off the friggin handle nuff said!

Really, ease off the caffeine man...BTW that engne was then subjected to a N20 hit several times....

he needs to swap pistons, he can do it fine, no marks in the cylinder walls just swap them and reuse the old rings if you use new rings you have to hone the cylinders.

 

I can honestly see both sides of this argument. I was going to swap the pistons when I did my head, but money and the fact I didn't want to reuse the stock rings with aftermarket pistons deterred that.

I agree with Brian, that if I am going to build my engine I am going to do it right, and I will be **** retentive on all aspects of the build. One slip or corner cut, and all the money and effort goes Boom right before your eyes.

On the other hand I think if someone were to use the same rings on new pistons, and ensured that the pistons were all within tight tolerances of each other, they should be fine and have many worry free high boosted miles. I would however still use new rod bolts and ensure they were all in spec as well.

 

Don't be so ******* naďve.

I just don't feel that we have the right to simply say...

"Go for it buddy... All you have to do is swap them pistons out honkey!! Wooo Hoo!!"

That is not all the information that a person needs to make a decision like this. If he has never done it before, he might just start all this in his driveway on a weekend without realizing how important it is that it's done very precisely. Information like what I posted brings home that it is supposed to be done precisely and that information might make the originator of the post decide that he does not have the skill or experience to do this type of job... to seek out and engine shop that can make the decision on weather or not simply swapping the pistons and reusing the rings is all that is required. You say.. just swap the rings... But do you know this person or know their mechanical background? Perhaps they have never even seen a piston ring, never mind know how to remove and replace them without scoring the hell out of the piston walls..

Understand? Gravity of the information presented is PARAMOUNT.

We have to make sure that all that facts aren't discussed so the person can make a proper decision.

 

Now you are getting hypothetical, what if this what if that, he already has the motor apart, thats how he knows he needs a effen piston for christs sake, what his question was and what you are going over and over is can he swap pistons...YES he can.
If he really wants to make an informed judgement, let him weigh the AM pistons and the stockers and see the weight difference.
You are dealing with absolutes, saying GM and Katech is a bunch of lying idiots that would publish a book telling this and that and it is not true.

You are also saying that he has to rip the whole motor apart to make this perfect, if he wants to then he can if he needs to swap pistons and everything else is fine, according to GM he can. if there is a scratch or a nick or a case of bad breth in 1 bore he is NOT fine. Then he has to go another route and do the full moxie.

you are saying you are right and everyone else is wrong....not true.

it has been done and will be done in the future, get over it!

he has enough info and can make an educated guess.
Either trust GM or Trust the almighty Brian.

well, Im going to go drive my swapped piston car and wait for it to explode LOL

GEEZE!

 

You're being impractical.

Name one shop that will balance a rotating assembly within less than .5 gram without charging a massive amount of money. It's a waste of time. Frankly, I'm surprised to see the tolorance that tight. The industry standard is +/- 2 grams total. Why? Because of unknown variables such as oil control. Windage, for instance, the force of oil as it hits the rotating assembly, oil being squirted at the underside of pistons, etc. all contribute to weight on the rotating assembly and unknown variables that can counter balance the assembly.

Regardless, let's not turn this into a pissing contest.

Oh. And to your quote from the page I posted a link to.... read further.

This shows that Witt was correct, to which I proudly acknowledged my mistake.

 

yes but this also acknowledges that balancing IS needed! this is how this whole debate started! i also agree 100000% with brian! how many of you have taken the time to build a performance motor from start to finish? i know i have and it cost me about 6K (would have been about 10K if my friend didn't work at a machine shop and get me **** at cost)! it's not cheak and DEFINATELY no time to GHETTO RIG!!! yes i do call swapping the pistons and not getting the cylinders honed, new piston rings, and balance the rotating assembly at the very least GHETTO RIGGING!!if you sinply switch out the pistong and reuse the same piston ring i will almost GUARANTEE you are getting blow by especially if you are running NOS! i personally think NOS is **** but that's a discussion for a differant day! Bottom line dude balance your ****! be **** retentive about EVERYTHING.

 

Now he does..

 

For all the people saying that Bdwarre can just replace the pistons , he did say his cylinder walls were scratched/scuffed . At that point , imo anyways ...the qwik fix option is eliminated and hes still faced with boring the stock liner or replacing it . As far as boring , what is the safest overbore tolerance on a LSJ liner ? If its as minimal as say a LS1 ....those liners can only be bored .010 over .

What he's gonna do with the cylinder liners needs to be decided before he even orders the pistons . If u overbore you will need a custom size piston and u will need new rings . If you replace the liner , u can order the offshelf LSJ pistons and while its not desireable imo ....u could possibly get away with re-using the stock rings . I would really use new rings anyways though .

 

Awesome Post...

It had brevity and was on the money!

 

i love how soooo many people blindly believe anything GM says! they told us our clutched were good, they told us the stage kits would compete with mopar's stage kits, etc. and they lied about theses things. what makes you think they aren't going to lie about this. when you start doing **** the cheap ghetto rigged way is when your car becomes RICE!!!

 

Yeah putting $700 diamond racing pistons in your car is rice.

 

when you start cutting corners after you spent 700 bucks on pistons is rice! my first question is why would you do this??? why would you skimp after you spent your hard earned $$$ on pistons that expensive? have you ever really built a motor before? i'm sorry this type of carelessness blows my mind!

 

I think the term Rice is a million times overused .....lets just say putting $700 pistons in a cylinder liner that has scuffed/scratched walls is careless and begs for problems if not intially , not to far after the build .

Turboeco- I think he was reffering to the method over the parts used .

 

I'll clear the air right now, since nobody has said it....

You shouldn't use the stock rings on forged pistons. It was mentioned earlier and I'll say it again;

Forged pistons expand and contract at different rates than cast pistons. Because of this, ring gap has to be changed. If you are going to put the used stock rings rings back on, you're going to have to file-fit them. If you do that, you're more than likely going to break one.

Piston rings are brittle enough as is, let alone going through mulitple heat cycles. I've busted a brand new moly faced ring just by squeezing it to much. Pissed me off. I had to go drop another $45 on a set rings, but live and learn.

 

Ever drop one on cement?


Poof...

 

****...well I can say I haved swapped pistons on some of my v8's without tearing the whole motor down and I haven't had any major problems (I used to run a lot of NO2) but I am i the process of building another motor for my car and was thinking of having the whole engine assembly balanced since i"m aiming for a "very" high redline.... I have a few good motor shops by me just having trouble finding a shop that does ecotecs.

 

It's probably cause the pistons you bought are the same weight as stock. I've read specs from just about every LSJ aftermarket piston made and they all weigh within .5 gram of stock, independent of brand and compression ratio.

Edit: and i want to say the weight is 279g iirc. Not including pins and rings of course.

 

Drop what? A ring? No. Too busy busting them with my bare hands even while trying to be as delicate as possible.

A forged piston? No. Never had the need to use any, nor the funds.

A hypereutectic piston? No. But I've heard them doing just that. I guess because of the harder composition of the higher level of silicon, they will literally bust if dropped.

 

Ring..

They do not bounce..

 

I think the issue is are you trying to repair your engine or improve it.

If you are trying to repair it using the stock parks and methods is one thing.

If you are trying to improve it with higher quality parts then perhaps you need to go the extra miles. In all GM's documents they are upgrading a working engine, you are upgrading a busted engine so you need to go the extra steps because it's already a compromised piece.

On another subject related to this topic

I think the real issue is what are you going to change to keep your engine from grenading again, because IMO it didn't grenade from having to much power. A pulley < 2.8 is overdriving the blower, creating lots of extra heat that your cooling system is meant to deal with and all for maybe 20 ft/lbs of extra tq.

several folks have been running 50-75 shots of nitrous ontop of pulley upgrades and we aren't seeing failed pistons, blow head gaskets, yet and we have a lot more HP/TQ than a person running a pulley 2.6 pulley.

The problem is a 2.5 pulley on top of WAY to much timing (12 degree over stock at some points) that might run great on a couple dyno pulls but if your driving it EVERY day not even a forged piston is going to help. Did you also know that the ECU is limited to 8 degree of KR (from the calibrations I have looked at) so the ECU can't even remove the extra timing let alone drop it to below stock levels if there is a problem.

I have a nifty little light on my dash that flashes RED when I have any detonation and I also have a little gauge that tells me how much timing the ECU is pulling (intercepter). You should pick those up along with your pistons.

 

Well I said it before and I'll say it again, if his walls are scratched this is all moot....he has to go whole hog and hone or if really bad overbore them.

And yes I HAVE built many engines in my day from Iron Duke Super Duty 4 cylinders( ever done one of those?) to L98 V-8's and more. So yep been there done that.....

 

**** fixing the 2.0, just get some major fabbing done, move your dash back a few feet, throw an ls7 in that mother, convert it to rwd and drive it from the back seat. can you say rucking fediculous?!

 

LOL!

 

Iron Duke FTW! 90 blazing HP. Never got to see one of the super duty versions though.

 

my comment asking how many people have built performance motors wasn't directed at you BTW. you are saying the exact same thing i'm sayingand i can tell you know what you're doing