Hey guys,

I need some help in choosing a strong head for my 5.3 Sierra. Current mods are listed in my sig. Should I go with the TSP Stage 2.5 5.3L heads or the LS6 heads? What are the differences exactly? To my knowledge, the LS6 heads will also fit and if I will mill them what size pushrods will I need?

Thanks a lot for any input.

 

you already have ls6 heads so dont waste your money. have a good valve job and some milling with short turn work. check the front drivers side head its a #799 which is a ls6 without the fancy vett valves. when i do mine im going to run manley race flow valves in stock 2.00 1.55 size.

 

I had stock 799s on my motor and found that they both had numerous cracks in them so got my PRC 2.5 5.3 heads and wow what a difference. felt like a completely different truck after

 

prc stage 1 243's here
I love them, extremely noticeable difference over my stock ones (799)

the difference between the stage 1's and 2's are about 4HP, the valves are a touch different, for an NA application the stage 1's flow more then enough

 

I would give TSP a call. The main determining factor is your bore size. You dont want an intake valve that is so large that it reduces the flow because it is so close to the cylinder wall.

 

Thanks for your input guys. I am boosted so I'm thinking the 2.5s would suit my application more. But I'm torn between the 5.3L and the LS6 ones, I'm not really sure which ones to go for.

 

Between the two you listed, the LS6 heads will flow a tad better, while the 5.3 heads are a tad cheaper. For boost, I would go with unmilled LS6 head.

 

I was thinking the same thing as well. But why not mill them? Any specific reason?

 

Typically, you don't want to use high compression with boost.

 

Biggest difference (especially after being ported and getting oversized valves) is combustion chamber volume.

5.3 Heads are good for bumping compression and once ported, flow fairly well. A 2.5 5.3 will only flow about 8 cfm less than a 2.5 LS6.

For your application, I would recommend a stage 1 LS6 head with minimal milling to keep compression down. The smaller valves will are more suited to the small bore of the 5.3. Give me a call if you need any more assistance!