Ok, I've looked all over the forum on this situation but it seems that some of the answers varied. I'm getting ready for my build and need help from someone who has done this. My ride is an 03' cavy (soon to be manual shift) and I just bought a lsj long block that I truly want to use one way or the other. I need to know a couple of things: 1) Can I use the whole long block and just use a external trigger? What changes would I have to make cause I know a couple of things are different? 2) Can I use my l61 crank in the motor and be able to use forged rods and pistons for a l61 or do they have to be for lsj or are they the same ( ive heard yes & no so i'm puzzled) can I use the lsj head with using the l61 crank? PEASE SOMEONE HELP WHO KNOWS!!!!!!! I would greatly appreciate it. I can't buy parts til I know. Thanks


WHAT DO YOU MEAN I NEED TO TUNE MY CAR?

Well,

you could use a external trigger wheel.... however what you would need depends on the ECU you are going to run.....

I think that the crank can be swapped however this alters a lot of things ....

You cannot mix and match LSJ and L61 internals. The rods are SLIGHTLY different length and have different small end sizes because the LSJ wrist pins are bigger. In addition, the wrist pin offset is different between the two pistons. You can use either block with either complete rotating assembly inside. Should you choose to use the LSJ rotating assembly, you will need to run an external trigger wheel (OR, get in on the impending group buy for the proper bolt-on internal trigger wheel [price yet to be determined]). Beware, with using the LSJ internals you lose some compression and displacement (2.2 to 2.0 and 10:1 to 9.5:1). It doesn't seem like a big deal for the factory forged rods you gain but trust me, it makes a difference. If you're planning to run an m62, regardless of pulley, run it on the l61 bottom end with the LSJ head(if you desire). There's nothing an m62 can push that an L61 bottom end can't take imo.

If you choose to run the LSJ block, you have some options with the water neck/oil cooler. Most choose to delete the cooler as the LSJ waterneck will not fit over the f23 shifter brackets and the L61 waterneck does not have the coolant line provisions for the cooler. It is possible to mod the LSJ waterneck if you have an aluminum welder or want to pay to have someone modify it for you. IMPORTANT: You cannot just plug the oil bosses to the cooler off, you either need to loop a line from one to the other OR pull the sleeve out of the block that forces all engine oil through that cooler boss; then plug both holes.

If you choose to run the LSJ head with either block you will have to address the ICM cover/coil pack setup. You could cut and splice in LSJ coils to run in wasted spark OR modify the L61 coil pack to fit in the LSJ valve cover and modify the LSJ icm cover to accept the L61 ICM on top of the coil pack. You'll also need to plug the LSJ coolant temp sensor on the head by the upper rad hose. Lastly, you'll need to fabricate a block-off plate for the LSJ cam sensor location (off the end of the exhaust cam) as the jbody PCM does not use it and the sensor does not fit in the jbody bay around the brake booster/master cylinder.



"In Oldskool we trust"

I shouldn't say you CAN'T mix and match internals, but they aren't plug and play like I'm assuming you're asking. It would take a lot of research, fitment and measurement, and possibly some custom parts to make it happen.


EDIT: One other thing to add is that if you plan to run the oil cooler on the LSJ block you'll have to grind a little on the f23 transmission to have it clear. It isn't much but it's something you'll have to do to get the block mated the the bell housing properly.


Edited 1 time(s). Last edited Monday, April 06, 2015 1:20 PM


"In Oldskool we trust"

All of this information is out here.



Why run a external trigger wheel if your going to run a L61 crank?



FU Tuning

Heres what I wanted to do: Run the lsj block with l61 crank, aftermarket lsj h-rods and wiseco forged lsj pistons and then the lsj head if possible. The only reason I wanted to do this is im planning on running alot of turbo boost. I'm not supercharging.. If I cant run this then I guess ill just go with lsj block and l61 internals. Everything will be new forged parts from the crank up. I just know the lsj block is alot stouter is the whole reason I want to use it.


WHAT DO YOU MEAN I NEED TO TUNE MY CAR?

Except it's not. Lsj and l61 blocks are all but identical. If you're running forged parts there's absolutely no reason not to run all l61 parts. What's a lot of boost? What's your power goal? Is this a street machine, strictly track, or street/strip?



"In Oldskool we trust"

Block wise. I would look into a Gen 3 block.

Your reasons don't match up with what you say you want to run. Running LSJ rods and pistons have nothing to do with the block strength.



FU Tuning

Addicted to meth wrote:Block wise. I would look into a Gen 3 block.

x2. This would be the only way to benefit from a different block than the stock l61.



"In Oldskool we trust"

With a m62 there is no reason to change from a stock l61, people are running a TVS with stock l61s and have no issues.




On the inside my car looks like a fighter jet.

So the lsj block is not stronger than the l61? I thought it and the lnf were alot stronger because they are alot less poreus than the l61. If its not then i'll just use all aftermarket l61 parts then and be done with it. See, when you go to different sites you hear all kinds of different crap and never know whats true and whats not. Thats why I asked you guys cause I trust your knowledge more than the other places. I'm sorry I confused everyone with my questions, I just needed to know before I start buying a crap load of expensive parts!


WHAT DO YOU MEAN I NEED TO TUNE MY CAR?

it's only the heads that have that difference. L61 head is lostconstruction which is that styrofoam looking aluminum. lsj is sand cast. That being said I can only recall one or 2 cases where there was an issue with the l61 head casting. Stock for stock there isn't much to gain from just swapping to an lsj head, the real benefit is that the lsj head gives you way more room for porting.



"In Oldskool we trust"

Ok, now i understand all of this alot more. When you have other people (sites) telling different things it all gets confusing. This is my first ecotec build so i am extremely wet behind the ears but eager to learn. Its totally different than the carbureted v8 chevys which im accustomed to building.Thanks for all the information and help guys its much appreciated. Well guess ive got a lsj short block for sale now..lol


WHAT DO YOU MEAN I NEED TO TUNE MY CAR?

Yes a LSJ is stronger than a L61 block wise. LNF is a stronger block.

Depending on the actual goals of the motor would really depend on what is needed.

Are you going to 400+ whp?



FU Tuning

The only difference between an l61, lk9, and LSJ block is that the lk9 and LSJ have piston squirters and an oil cooler. They are all gen 1 blocks and are identical. All the stuff the LSJ and lk9 have can be added or swapped to a l61. There is no difference structurally or design wise. The reason why the LSJ has proven to hold more power is the cars they came with have better computers and the engine has a shorter stroke and lower compression and the parts were stronger. If you build a l61 with forged internals or your just adding a blower you will never no the difference and the displacement will help you. This is why I never swapped to a 2.0.




On the inside my car looks like a fighter jet.

Rob Dotterer wrote:The only difference between an l61, lk9, and LSJ block is that the lk9 and LSJ have piston squirters and an oil cooler. They are all gen 1 blocks and are identical. All the stuff the LSJ and lk9 have can be added or swapped to a l61. There is no difference structurally or design wise. The reason why the LSJ has proven to hold more power is the cars they came with have better computers and the engine has a shorter stroke and lower compression and the parts were stronger. If you build a l61 with forged internals or your just adding a blower you will never no the difference and the displacement will help you. This is why I never swapped to a 2.0.

From a guy who DID swap to a 2.0, agreed with all of the above.



"In Oldskool we trust"

The LSJ head also comes with sodium filled inconel valves on the exhaust side.

COOL, i'm gonna keep the lsj head and sell the short block then. Get some of my money back. And to answer addicted to meths question, yes i'm wanting at least 400 to the wheels. I'm trying to buy the best of everything that I can. It will take me longer but should be well worth it. I'm wanting to run 89.5 or 90 mm bore and have my machine shop o-ring the block. I really dont know how much they know about ecotec blocks and heads so I may have to ship them off or take a rode trip to have the proper work done. Heres a pic of my project car. Its super solid from top to bottom. I was suprised how clean the underneath was and to only have 86,000 on it. Only thing I dont like is the trunk with that big ugly reflector that runs across it, so i'm gonna take one off a 01 parts car i got.

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WHAT DO YOU MEAN I NEED TO TUNE MY CAR?

07 start Gen II blocks regardless if it was a L61, LSJ, LE5.



FU Tuning