Hello,
So Im doing this lm7 build and I read on this forum about switching to flat top pistons. So I found some used LS6 pistons with pins and rods with 70k miles on them. I was just wondering what should i know about swapping in these pistons? Does the rotating assembly have to be balanced or just a good idea? Anything else?

Thank you,
Bryan

Also are the flat tops going to give me enough gains to be worth it all?

 

LS6 pistons are larger than LM7 pistons.
No gains because they don't fit. Wrong bore size

 

Well that is good to know! Thank you!

 

So I am looking for 4.8L pistons on 5.3 rods?

 

Yes, exactly. You might read up more on LS engines after seeing your first question....

 

What do you think I'm doing?

 

Hopefully reading up on LS engines, but that's only a guess... lol!

 

Asking the basics and not reading.

If you read about putting in flat tops then you should have done research into the bore size of a LM7 5.3l and the bore size of the LS6 5.7l Pistons you found to see if they would fit. Simple math there and compare the numbers.

Statement was fair, if you saw the numbers you wouldn't have asked and been told they wont fit.

They wont fit the stock 5.3l bore, you can have the block punched out to the 5.7l bore tho, there are options here. If you read into it you'd see that too.

 

So asking a question on this forum requires extensive reading beforehand? Then what is the purpose of the forum? I've been reading everything I can find...guess what I get more confused all the while. One of you "experts" say YES the other says NO. One says DO IT and the other says DON'T. Now lets talk about all the model numbers, acronyms, technical specifics that everyone assumes you know already. I thought the LS6 was the same bore as my LM7. Yes, I asked to confirm. So sorry for wasting your precious time. I had found a set of LS6 pistons cheap and wanted to move on them with haste. Excuse me for cutting right to the source. I've been on numerous forums and I understand there are a few guys that have already forgotten when they were new and learning. Trying to sort out all the contradicting info. I also understand how there are guys that get there rocks off bashing on guys that are struggling. I have read everything I find and continue to. I'm glad you got your chance to feel superior and I have to rely on guys like you for info. Maybe with another topic like Analysis of Concurrent Coplanar Force Systems I could repay this kindness to another. I apologige for plunging head first into an area of information I am completely ignorant to. It was exactly why I got into it though. To learn about something I knew nothing about. Like I said I've been in multiple forums and at the mercy of guys that love to tell you to go read while wating poptarts in their bedroom while mom is yelling at them. I always thought the forums were for learning and questions were part of that process. You guys think its so easy to digest and keep straight all this info whe the majority is contradicting and mostly false. Doing the best I can dude! Sorry for wasting your time.

 

Nothing real extensive. Just data pertinent to info requested.
Like when asking about pistons, a little preliminary homework concerning bore sizes might seem relatable to the info desired.

 

I see a "troll" tag coming.....

 

Sigh... Can we just be a little nicer to new members? I know there's a ton of info out there to be Googled, but it doesn't hurt to simply answer some queries. Driving new people away from the site isn't conducive to keeping it fresh and up to date.

OP: Yes, you need either 4.8 liter pistons, or pistons from a high output 5.3 liter. The best option would be a set of Gen IV HO 5.3 pistons and rods, as the Gen IV rods are a lot stronger. You also shouldn't need to rebalance your rotating assembly if you're not planning on making a high RPM screamer. You can also bore your block to a 3.898" bore, which would allow you to use LS1 or LS6 pistons, but rebalancing would be in order due to the larger weight difference in those pistons. Hope this helps!

 

Thank you for the helpful response. I will try harder to do my research before having to ask. Have a great day!

 

You are fine... If folks didn't post here and ask questions (rhetorical, noobish, or what not), this forum would be even deader than it already is.

 

Nope, we learned **** from reading, built our cars and drive them over to go play with them moms at their house, and eat them snacks. Single moms have great snacks.

Googling Engine spec's and all that goes a long ways. How I learned but clearly methods differ.

Plenty of info here in this post already, couple of us gave you methods of what to do.

 

Dude ive logged dozens of hours googling info....nope I dont have it committed to.memory like some of you but I ask one simple questions and you guys have to respond with "I know something you don't know" crap. Why I hate these forums. Hoping this one would be different but they are all the same. A half a dozen guys with nothing better to do than jump down someone's throat with their wisdom. All the same. I know there are some good guys on here. I will have to relearn how to ignore the dicks.

 

Why the need to be a smart *** to the newcomers? There's just better ways to come across without sounding like a DH..A simple the 6.0's are 4" bore and will not work with an LM7 and what you need are the flat top pistons from a 4.8 as they share the same bore size.

 

LS6 is not a 6.0l..I even said it was a 5.7l I have one in my garage.

I personally don't care for the whining. G_Atsma had a fair statement and I elaborated on it. We've been polite and even put info in here to help but the whining continues so send time..

I built my first 408ci LS Engine back in early 2007 by READING how that combination went together with a 6.0l Block, 4.030 Bore, 4.00 Stroke Crank, 6.125 Rods. I found builds people did and they were very nice with the details. It's not hard to look up ****. I didn't ask anyone I went and found the recipe and cooked that up. I installed it into a 1995 LT1 Camaro Z28, built the wiring to run the LS Engine in the LT1 car and it ran flawless. Found all them schematics on LT1Swap.com. This was 2007....then again some of us are doers apparently.

Fast forward to 2024 where the internet has who knows multiplied in size on what you could find 17 years ago, and someone doesn't have the intuitive thought to go hmmmm what are the LM7 Specs and what are the LS6 Specs and are they compatible. I should look that up so I might lean more knowledge along the way too.

Nope it's lets cry because people are picking on me. I don't have kids so I'm not spoon feeding people things they can learn on their own. That is basic stuff all over the internet, go find it and save it on your phone or computer it's good info to have if you are in this hobby.

 

Thanks for pointing out that I was wrong for mentioning a 6.0 and not an LS6. I know there's a difference but the point is that it's not going to work and this all could've been handled differently.

 

Two of us in here saying do some research into the basic stuff trying to enable the guy to learn some stuff on his own is not a bad thing. That's enabling someone to be better, pushing them to be better on their own. I'll stand behind that all day because that's how I was brought up and how I trained my troops.

Clearly some can't be pushed.