I have a few spare parts and want to help a
friend with a ls build/swap. I have a lm7 that needs to be rebuilt. I also have an ls1, a ls4 , and an ls2 intake , an ls1 cam, a late ls6 cam. I also found a good deal on a L33. I am just wondering.
1- do I always need to replace pistons due to the piston slap issue on higher mileage engines?
2- Will the L33 make more power? A lot? I am trying to figure out if it would be worth the extra $700.
3- I would assume I should use the ls6 cam
over the ls1 or stock cam?
4-what intake should I use. The truck intake is ugly
5- is torque plate honing all that important or is a standard ball hone ( bore if needed) good.
6- what kind of HP can I expect

thanks

 

1. Only if they have piston slap...
2. L33 has flat top pistons, a block that is 100 lbs lighter, better heads/cam from the factory, and depending on the year, better rods/timing chain/lifters.
3. Yes.
4. One that you don't think is ugly.
5. I usually just ball hone, but only if it needs it. My last few engines had great crosshatching.
6. Depends on which engine you decide to go with, what intake, what cam, etc.

 

How much can you get the L33 for?

Thanks.

 

The l33 is apart and in good shape. The heads have just been re done and flow tested. Their is a 600+ receipt for the work and
having the block checked. I can get it for 1000.

 

How is this even a question? The L33 is basically a 5.3 LS6. The LM7 is just an iron slug.

 

With a much smaller (193/193, .482/.482, 116 LSA) cam.
So not even close. Even with 243 heads, the L33 (310HP) puts out about 15 more HP than the latest LM7 (295HP).
Latest LS6 was 405HP

 

I think he was referring to the design itself. An L33 block is extremely similar to an LS6 block other than bore size and uses a lot of the same components.

 

OK. He made a more generalized statement, which I addressed with a general answer.

 

Who cares what cam it has in it? It’s an alloy block with flat top full floating pistons with the same heads as the LS6. With a big cam, it will easily make 405bhp. The alloy block already has all the provisions for F-body accessories and timing chain dampener, no need for drilling nonsense - assuming there’s even enough material in the iron block. The LM7 is not even in the same league as the L33. You’d be a fool to pass up an L33 for an LM7.

 

The L33 is not that special anymore. Many Gen IV 5.3's have aluminum blocks, and all have 243/799 heads and flat top pistons, plus the other attributes of the L33.
You made a very general statement that the L33 is a 5.3L LS6. One of the components that defines what an LS6 is, is the cam
And having to drill ONE hole in an LM7 ?? Big deal...