king of the wood

I just posted this in another thread also sorry!

Hello everyone!

So here is my dilemma. I have a 5.3L LM7 engine that I am starting to rebuild (first ls rebuild) and I am trying to figure out the set up for myself. I would like to push somewhere between 450-500 hp once im done. But not sure on my heads choices. I would like to keep the stock (to save a lil cash) and p&p them with new valves, new springs etc. Below I have listed what I have thought about so far. *I have not started this project yet*

Here is what I plan to do:
-5.3L LM7 Engine
-New bore 4.030
-Stock Stroke: 3.62
-Eagle I Beam Rods (6.125")
-Mahle Pro Packs
-Texas Speed 224r cam with 112 lsa
-either keep my 862's and port & polish them or upgrade to 243's. I know I may lose compr with the 243's but can I just have them milled to keep a high c/r?
-Patriot dual gold springs (max lift .650)
-Edel VJ Intake (dual plane) with MSD 6010
-Holley 750cfm
-not quite sure on the HEADERS size yet


so my major issue is with the HEADS. I have read mixed reviews on the 862's and the 243's. I would like to just get the best bang for my buck. What suggestions do you all have on worked 862's vs stock 243's? Can I have the 862's worked to match the 243's? will that be more or less $$?

Thanks in advance.

JonCR96Z

iTrader: (33)

I'm no engine builder but 4.03 is a little much to squeeze out of a 5.3 block.

Assuming that you get anywhere near that much bore, the 862s are going to kill the power. And the amount of work that would be needed to get an 862 to flow similar to a stock 243, would cost more than just buying a 243/799. On the flip side though a good set of ported 5.3 heads with bigger valves would flow as good as a set of ported 243s. However that depends on whose porting your heads.

Otherwise a set of 243s and a 224 cam on a 340+ CI motor would easily get you over 450 at the flywheel.