LS Swap questions

[kbaszak]

I'm debating on either doing an LS swap or turbo'ing my e30 sometime next year and had a question. How come is doesn't seem like people are using the lm4 for any swaps? Especially budget ones. You can pick them up for 500 bucks all day and then even if you get some machine work done, add heads and intake, get the different accessories, you're still cheaper than buying an ls1.

Is there any reason people don't use them as much as an ls1?

[shiboujin]

I think lots of people use truck motors and other stuff. The LS1s generally come with T56s attached to them and a good compact belt/intake system. That way, you need less for the swap. Any truck motor will have a bigger intake manifold that generally won't fit and a big ass water pump that will poke your rad.

But honestly, if it works for you, go for it. you can always swap it out later.

[CLM21]

Because then you cant say you have an LS1 corvette engine in your car. duh.

[kbaszak]

I understand that there would be more work involved but I feel like the cost savings would be well worth the work

[CLM21]

In all seriousness though, I think it would be a good idea. Not sure about the LM4, but other LS engines like the LS2 (which have truck applications) have conversions for car intake manifolds and car accessory drives, which would free up a lot of space for you. I bet you could make those work for an LM4.

[The Dark Side of Will]

My dad's installing a 5.3 into his Datsun.
While there are aluminum 5.3's out there, most are iron block and about 80 lbs heavier than the aluminum block engines.
350 HP is as close as a cam, pushrods and valvesprings.

The truck intake manifolds are inches taller than the car manifolds, the truck exhaust manifolds are bulkier and has already been noted, the truck accessory drive protrudes further forward.

If you're inclined to fabrication, start with an LS4... it's aluminum and has a smaller bellhousing pattern than the longitudinal engines. However, it requires use of a bellhousing mounted starter.

[CLM21]

Isnt the lm4 exclusively aluminum block? Sounds like he thinks he can get his hands on one easily?

LS4 would be cool. Im pretty sure theyre shorter than other LS blocks because they were intended for fwd cars. No idea on the prices of them though.

[kbaszak]

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.

Add in intake/tb/inj/rail, cam, heads from an ls2 or 799 heads from a truck which are the same just minus sodium valves, accessory drive, and starter and it's only around $1k

[shiboujin]

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

[blusylver]

Do as I did and do both. Procharge a ls

[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?

[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.

[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.

[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.

[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