the only difference between the 5.7 and 5.3 is the bore size. therefore use your 5.3 crank and rods and get 5.7 pistons for the larger bore and your good to go....yes you can bore to 3.905, remember this is an iron block so it is not as critical as boring an aluminum block.....

 

5.3 and 4.8 blocks are the same thing same block but different bore and different cranks ? i can bore the 4.8 block to a 3.905 bore also.....

 

No, the bore is the same, the crank is shorter stroke and rods are longer and pistons are flat toped. Yes you can bore a 4.8 block to 3.905

 

i may have to write a sticky on this.

 

No sense in making another thread if this is here then. I asked this similar question over on your sister site LS1tech, they referred me to here.

https://ls1tech.com/forums/showthrea...26#post8708526

Now that the 5.3L to 5.7L question has been answered, which pistons would you guys use to get a relatively high compression ratio requiring mid octane gasoline and a cam meant for idle-5000rpms?


Thanks,

InchUp

 

You can get forged pistons as cheap as stocker LS1 pistons. I think we got my son's from Texas Speed. With a Zo6 cam and LS1 or LQ4 heads, you're ready to be blown, sprayed, or leave it alone and enjoy about 400 hp at the crank. I wouldn't even think of building a 5.7L with cast pistons. You have it apart.....put it back together right.

 

Thanks for the reply. I've been looking on their site for awhile now and I'm liking what I see.

Is there a certain piston you'd recommend using the 99mm bore, stock rods, stock crank and stock 5.3L heads to yield somewhere in the 9.8-10.2:1 compression range? I've been considering this camshaft for awhile now for my engine, the XR259 cam from CompCAMS.

http://store.summitracing.com/partde...1&autoview=sku

All I'm looking for in this motor is decent power, somewhere in the neighborhood of 1hp/cubic inch, and similar torque numbers while still getting respectable gas mileage. This is not intended to be a racing motor of any kind, all low end grunt.

 

If you're going to a bigger bore, the 5.3 heads won't do without mods. If you have to bore the block, get new pistons, get new heads, etc.....I'm thinking you might be better off just changing the 5.3 out for a 6.0. You'll get more cubes and better breathing heads for not much more money than you'll spend modding your 5.3. Whatever cam you choose will make more power in a 6.0 and be more civilized on the street. I found my LQ4 with 8K on the clock for $1600. You'll eat up 500 for pistons, several hundred for heads, several hundred more for machine work, and you';ll still be a 5.7l. Cubes rule the street. The only benefit I can see to boring out a 5.3 is going to forged pistons. If you don't intend to spray or boost over 10psi, you can get by with stock pistons.

 

What would I have to change on the 5.3L heads to make them work with the larger bore? I'd love a 6.0L, and actually planned on putting one in instead of a 5.3/5.7, but I don't have a 6.0L, I have a 5.3L truck motor that needs a rebuild.

I'm trying to make do with what I have.

 

From what I understand, valves are bigger and the combustion chambers are bigger to match the bigger bore.