LS Swap questions

[kbaszak]

I think lm4 is the route I'm gonna be going. Might upgrade internals to ls1 internals or possibly use 4.8 pistons to up the compression a little bit. I wish there was enough room in the engine bay to possibly go fi sometime down the road but from the pictures I've seen it just doesn't look like it

[garretvs]

Absolutely nothing wrong with the LM4 version of the LSx series of GM engines. Aluminum block, 325 cubes, easy to get hold of. It would make an E30 a rocket!

[rzerob]

"Gertech" did a L33 swap in his E30. Considering the LM4 and L33 are so similar I would ask him some of your questions. He has a build thread.

http://www.r3vlimited.com/board/showthread.php?t=306302

[CLM21]

Yeah ^^ what he said. 5.3s can actually take a lot of boost. The guys in this article experimented with a stock 5.3 and it was able to take 26lbs of boost.... which is ridiculous:

http://www.hotrod.com/techarticles/hrdp_1109_stock_gm_ls_engine_big_bang_theory/

[Tico Frank]

If you get a 5.3 they are good to go low boost later down the line without lot of internal work. Also if you blow a 5.3 vs an ls1 you just go to the yard and grab another $300 engine vs a $1500+ engine.
I am going 5.3 and if you are on a budget so should you.

[CLM21]

You can bore all the 4.8L and 5.3L LS engines to the same max bore as the LS1. They both have very thick cylinder walls.

[The Dark Side of Will]

Stock LS1 bore is 3.897 (99mm) and GM only rates it for a .010-.015 overbore... the book probably mixed the numbers up between the 5.3 and 5.7.

The only way that would work is if GM used all the same cores for the water jackets between the 5.7 and 5.3, then used the liner to make up the difference in bore. It's possible that they did, but I think it's extremely unlikely. Google probably has some photos that would shed light on the matter.

[CLM21]

Well according to an LS book I have.... the gen III 5.3 aluminum block has a stock bore diameter of 3.780" and has a max bore of 3.910". Which is a 3.3mm bore.

[kbaszak]

I think youre gonna struggle to find someone on this forum with lm4 knowledge. Maybe make a post on ls1tech or a truck forum or something.

But as far as I know, lm4s have been bored out to 5.7L very very often. Which would be the 3mm bore that youre talking about. A lot of guys have made big power off bored 5.7 lm4s. So id say youre safe there.

As far as ecu goes... it depends on the generation. GTOs, depending on year, had a gen3 LS1 in it in 2004, and a gen4 LS2 in it in 2005 and 2006. Considering the lm4 is gen3, the 2004 gto ecu will work. 05 or 06 definitely wouldnt. Going from gen3 to gen 4, gm changed knock sensors, cam sensors, etc....

Also I ran across something interesting this morning which I thought would pertain to you. Saw a build thread for an lm4 in a 944 turbo. The guy used a gen3 gto ecu. And he had to swap to an ls1 intake manifold, rails, injectors, and throttle body to get everything to fit under the hood. Just something to think about as an option if you cant get the lm4 to fit.

I've seen people say that it can be bored 3mm over and I've also seen people say that it can't be done but idk if the people saying that ha e actually tried. I'll probably go ask it over on a truck forum, they'll probably know the most.

I knew about the intake and stuff needing to be used to fit. Also the accessories stick out further so I'd have to change those over.

Where did you see the thread on the 944? I saw a thread about that somewhere but it was pretty dead and there wasn't much info in it

[CLM21]

I think youre gonna struggle to find someone on this forum with lm4 knowledge. Maybe make a post on ls1tech or a truck forum or something.

But as far as I know, lm4s have been bored out to 5.7L very very often. Which would be the 3mm bore that youre talking about. A lot of guys have made big power off bored 5.7 lm4s. So id say youre safe there.

As far as ecu goes... it depends on the generation. GTOs, depending on year, had a gen3 LS1 in it in 2004, and a gen4 LS2 in it in 2005 and 2006. Considering the lm4 is gen3, the 2004 gto ecu will work. 05 or 06 definitely wouldnt. Going from gen3 to gen 4, gm changed knock sensors, cam sensors, etc....

Also I ran across something interesting this morning which I thought would pertain to you. Saw a build thread for an lm4 in a 944 turbo. The guy used a gen3 gto ecu. And he had to swap to an ls1 intake manifold, rails, injectors, and throttle body to get everything to fit under the hood. Just something to think about as an option if you cant get the lm4 to fit.

[The Dark Side of Will]

Come someone who has experience with an lm4 help me out?

First off, can it be bored 3mm out or would I need to resleeve it? Secondly, if that can be done, would I be able to use a gto ecu or is there an issue with differing sensors or anything like that?

Pretty sure a 3mm bore would be a sleeve job. It's a pretty rare iron block that will take that much overbore.

Why do you want to do that? 350 HP comes from a cam swap and 400 with not much more work... The extra couple hundred cc's doesn't become necessary unless you're trying to clear 500.

[The Dark Side of Will]

Lm4 is aluminum block and they're really easy to come by. There's 6 within 10 miles of my house for under $600. 5 out of the 6 have less than 120k on them.

I hadn't looked, but I wasn't aware they were that cheap or common yet. Nice.

[kbaszak]

Come someone who has experience with an lm4 help me out?

First off, can it be bored 3mm out or would I need to resleeve it? Secondly, if that can be done, would I be able to use a gto ecu or is there an issue with differing sensors or anything like that?

[blusylver]

Do as I did and do both. Procharge a ls

[shiboujin]

Or get a GM LS3 crate motor that's super charged for like $14k more.