Ive got a 03 5.3 with 130,xxx miles on it and im beginning to think its time to tear into it. I run through 8 qts of oil in a 5,000 mile oil change, running full synthetic. I would like to know what my best options are to make around 450 at the wheels. Im for sure that I would like to get a cam. Im particularly looking at the Texas Speed 224R cam. I want a rough idle so im thinking a 113 or 112 lsa is what im after. As far as heads go, I have 706 castings now. Is it worth my money to have them milled and ported to flow a little more? Ive done some reading and it seems like a set of 243 heads fall off after about .550 lift. Id like to have the best bang for my buck on heads, so any help there would be appreciated. Also, where is my limitation on fuel? I still have the original fuel pump in the tank. Still has around 47-50 psi, but I can feel the truck surge at WOT in 2nd gear when its running through the RPMs. If I dont need bigger injectors or a larger fuel pump, ill just go ahead and replace with OE. I would like to know before I spend any money here. Any and all comments are appreciated. Thanks in advance for any input.

 

For that kind of power, you'll have to have new injectors, and a new pump. If you're keeping the 5.3, only way I know of to reach that kind of power is to start forcing air into it with a blower or turbo, or start spraying a 150 shot of Nitrous.

Best bang for the buck head is the 243 stock casting at about $350-400 a set. However, a set of stage 2.5 5.3 heads are better, running about $1,300 and can be milled to whatever chamber size you want between 58 and 63cc, on top of being new and not used.

My fuel pump gave up at about 310 RwHP on my 4wd (I'm guessing around 356 crank assuming 15% drivetrain loss).

 

Would running a turbo at around 8 psi be enough to make that kind of power? It is a 4wd truck. Id really like to be able to go to the pump and dump 87 in it to daily it, and 93 or a mix when I want to play. It will be inter-cooled if i start pumping air into it. How much would a stroker crank help here?

 

Na 450 rwhp will be very expensive and would have to be the perfect combo. I did 370 with a t56, hand ported 243s, ls6, 218/226, and full bolt ons.

 

With money, you could make any HP you wanted with a 5.3 lol. IMHO, pick up a lq4, lq9, ls1, etc. I was going to cam my 5.3 but I got a killer deal on an 01 ls1/ls6 short block and I put a set of 243's cut .030 and a cam motion 221/226 114 in it. It feels pretty strong, especially with my yank ss3600.

 

Haha makin power is easy, just takes money. Will my factory harness work with a 6.0 block

 

yes it will

 

your tranny will go boom with that much power sooner or later so don't over look that. i think it was hot rod mag that put a 72 mm turbo on a 5.3 and made 600+ hp IIRC.

 

Bore it and stroke it. Build a 383 unless you really want that 408 from a 6.0.

 

The tranny has been gone through already. Its got a beast sunshell, hardened accumulator piston and pins, .500 boost valve, corvette servo, clutches are all fresh and stacked, has a drilled separator plate thats for HD use, and it has a small TransGo shift kit. Should this be enough to hold the trans? In its stock form now, it will chirp tires hitting 2nd gear on dry pavement, and if its wet, it spins posi at 75 when it hits 3rd gear. I plan on putting a deep aluminum pan and a larger cooler on it. Just haven't had the need for it yet.