How much can a 4.8 and 5.3 be bored over and still be reliable?

 

Have heard .120 over but must be sonic tested first. Was looking into doing the same thing but have pretty much decided against it because of reliability issues.

 

I know of several 5.3l engines that were bored to 3.90". One of them is running 6lbs of boost in a 4X Yukon. Definitely sonic check the block before attempting to bore it. The other benefit of boring .120" over is that now you can run the car heads with the larger 2.00" intake valves.

Good luck,

Richard

 

We have done a bunch @ 3.905 and twin turbo just over 600rwhp.

Sonic test first

 

What is the cost of boring over that much and having sonic tested?

 

Bore/hone w/plates and sonic test about $600

 

Would any performance machine shop be able to do this reliably or will I want ls1 shops?

 

Any competent machine shop can do this, the only prob. may be they don't have a trq plate?

 

I had my block bored to 3.900 with torque plates and sonic checked afterward. Thinnest wall after bore was 0.250", well above the rumored 0.150" minimum. The machine shop was not a LS1 specialty shop ( it was a Bowtie specialty tho ) but the ower/operator definitely answered the right way. Like Richard said this opens up a whole new world of upgrade and performance options with the 5.7 bore, especially since the bottom end crank/rods are the same on LS1, LS6, and LM7-5.3 motors. Be careful, tho, the 4.8 has a different stroke/crank/rod configuration! Else all the GenIII Vortec are standard ubiquitous parts, ie interchangable.

 

4.8 and 5.3 share the same block though so you would just have to upgrade internals which would be pretty easy and cheap with all the ls1 and ls6 take off parts.

 

I can verify that the 4.8 and 5.3 block are the same. When my mechanic had my engine out, it was stamped right there on my 5.3 block, "5.3, 4.8."