The 5.3 is just a mule before the real motor goes in(max effort LQ). Basically I'm going to kill the 5.3 within 6 months. Before I do kill it, I want to see what can be pulled off without boost and cheap/free parts and some spray. Yes I would like to get a couple of months with it torturing the little guy.

Here's the build. Keep in mind this in a sub 3K# car with driver in street trim. Also Z06 parts were free.

2003 LM7
243 heads
02+ ls6 cam
7.425 rods
FAST 90 intake/ls6 rail/injectors
90mm TB
custom(for the vehicle) LT headers into dual 3 in.
EFI Live tune (not mail order)
progressive 150 shot

my guess without the shot is 340ish hp/475+/- with? Sound pretty close or am I waaaaay off here?

I'm thinking 10.99/low 11.xx in the 1/4 on the bottle. I'm keeping the long legs on this girly so please no gear swap stuff. Gear selection is VERY limited and I like having my top end.

 

I think it may be tougher than you think?

 

Yeah if you don't screw up the tune it will most likely take a lot more than that.

When i read the title i was thinking something like like a 200 dry shot!

 

off/on topic, whats the biggest shot known someone's put on a stock 5.3 short block..? total..

 

IMO, put some rod bolts in it and spray more.... like a 200 shot... you wont kill that 5.3 very fast with a 150 shot with good tuning

 

If you plan to break it I would start with that 150 and make a few passes to make sure the car doesnt do anything wild on you then bump it up to 200 or more.

 

I know of a few poeple who have put a 250 shot on stock bottom end 6.0s but 5.3 I think only a 200 shot.

 

Give me the 5.3, then torture my 4.8.

 

i run 150 shot on my setup all the time, if i only had bigger injectors and a better fuel pump then stock i would try 200 thats for sure...

 

Do you guys Think the hp estimate is pretty fair or am I underestimating this little guy?