GTO5.3

So I plan on selling my car that ive had through highschool to buy a GTO. Been a fan of this for a while. Ive rebuilt hondas and wanted to do an lsx build.

-The Plan. Purchase GTO, remove 6.0 to sell and buy 5.3 lm7.

-400-500 hp goal.

-What does a 100k miles 6.0 go for? Is $2,500 too little to ask for (no harness)

-complete 5.3 is $600-800

-Will rebuild the 5.3 for turbo set up

-can get harness made for $350

-I am doing the ls1 intake conversion as well.

- Do i need to fab my own motor mounts? i can weld

------------------------- MY QUESTIONS ----------------------------------

-Do I have to have forged internals for my hp goal?

-What cam specifications are good for turbo setup and my hp goal
(intake lobe, exhaust lob, lob separation, intake center line, comp 918 spring?, what length push rod?)

- What turbo kit? or should i piece my own? If piece, what a good options?

- How much should i expect to spend in exhaust modification for turbo piping?

-T56 will bolt up to 5.3?


I know theres going to be comments on why swap to a smaller motor.. Thats not what im here for.

Thanks for any help. I have till june next year to complete this. i work HVAC and am at community college. So money is semi tight. Ide say 200/week to spend on car.

N20zuki

Why do you want to go backwards from a 6.0 to a 5.3? That's the one thing I am hung up on and don't understand here... 400-500hp is easier to make from a motor that is already 400hp at the crank...

1500-2500$ is right about spot on for a 100k LS2 longblock

Ls1 intake is the worst flowing intake... If anything go with a LS6 or Fast... But then again you're boosting it so who cares...

5.3 will bolt right in place...

No you don't need forged internals for that goal...

T56 will bolt to a 5.3 no problem.

GTO5.3

Your the man! Thanks! It's mainly personal that i want to go 5.3 other than the fact that they handle boost better (so ive heard). I like to be different. Im trying to get more experience in building chevy motors. Therefore, i wanted to sell 6.0 to have a little cash to build and turbo 5.3. Also have never had a turbo car.

N20zuki

The power level you want will be attained easier from the 6.0 without batting an eye...

stock400whp

selling the 6.0 wont get you that much money back. think about it. if your swapping in the 5.3 youll need everything gto specific minus the long block.
so how much money you get from the long block without oil pan is your only saving.

for your goal you wont be touching the engine if your on a budget and dont really need to(if you look around and wait a bit you can pick up great condition low miles 5.3 for cheap). I have a 5.3 in my ws6 (since my ls1 threw a rod) im running 19psi on 100% stock 5.3 longblock. -its also my DD.

and im all about DIY-turbo kit specially.
if you can weld as you say build a kit. all it will cost you is some 2" crossover piping and 3" from turbo back. total cost can be as low as $200 with piping to spare.
turbo can be had for cheap on3 has a 76mm that people are having great success with(me included) for about $300. chinese wastegate are about $50. i had great success with tial replica.
add in some vband clamps and thats basically your hot side done.

since this is your first time building here are a couple of pointers to remember-it will save you a headache later.
1. make sure turbo has a clear line/space for the oil drain with minimal kink.
2. include a turbo support
3. make sure you have enough room for wastegate
3b. dont forget other things that needs to go back. like fans or cables or intercooler piping etc. make sure you have enought room for it.
be extra careful with the hot side, it will melt or boil things that are close pretty fast so make sure to wrap them at least.
4. make sure to leave enough room for turbo intake.
5. measure 3,4,5 times before cutting and try to be as precise as possible if you cant measure it- youll learn some eyeballing skills

sounds simple enough but on the fbody its fairly tight especially since i wanted to keep my a/c system


oh and when planning budget dont forget supporting mods and all the little thing that youll need can easily cost a few hundred.


btw id recomend you build your supporting mods for atleast 600whp just incase you want to turn up the boost(like i did). kinda which i planned for 700 though. soon changes will have to be made

MuhThugga

My questions to you:

- Have you ever driven a car with as much power as the GTO has stock? If not, get used to it before you start adding more. A 400 HP RWD vehicle is not the same as a 200 HP FWD vehicle, and the driving characteristics are completely different.

- What price range are you looking in when shopping for GTOs? These cars are at the decade mark, which means that you are going to encounter ten year-old car issues. The cheaper you buy the car for, the more likely the car hasn't been cared for all too well. Parts for the GTO can get expensive real quick. So, before dumping all of your money into a 5.3 turbo build, I would spend a little extra and get a clean GTO, and still set aside money for general upkeep.

- Have you budgeted for chassis upgrades? Adding power is great for dick swinging contests, but if the chassis can't get the power to the ground, you have nothing more than a burnout queen. As I said before, these are ten year-old cars and parts are starting to wear from age and not miles. The big thing is the carrier bearing on the driveshaft is deteriorating. I would highly suggest spending the $600 and getting a single piece driveshaft over replacing the carrier bearing. You need parts to hold power. The next two things to set money aside for are upgraded halfshafts and inner axle stubs.

Now, onto your questions:

-can get harness made for $350
--Don't bother. You will use the factory harness in the GTO. One thing to consider when buying a 5.3 is that the 05/06 GTO uses a Gen IV block whereas the 04 GTO used a Gen III block. Depending on what year you pick up (and since you plan on doing a turbo 5.3, ANY year will work), you may want to select you engine based upon that for simplicity's sake. Also, if you go with a Gen IV 5.3, make sure it has a 24x crankshaft reluctor. ALL GTOs are 24x; even the LS2 ones. If anyone tries to tell you the GTOs were ever 58x, tell them they are flat-out wrong. Also, if you find a Gen III LM7, I believe you want one that is 2003 or newer. The earlier 5.3s had longer crank snouts that could cause an issue with the GTO accessories.

-I am doing the ls1 intake conversion as well.
--Don't bother. Use the intake from the GTO. It will either be an LS6 or LS2, and either will bolt right onto your 5.3. In fact, depending on what heads come with the 5.3, I would swap to the 04s 241s or 05/06s 243s.

- Do i need to fab my own motor mounts? i can weld
--No. The motor mount brackets bolt to the motor, so just transfer them from the GTO engine to the 5.3.

-Do I have to have forged internals for my hp goal?
--No. You can always do forged rods and pistons, but it isn't necessary. I would upgrade the rod bolts to ARP hardware.

-What cam specifications are good for turbo setup and my hp goal
(intake lobe, exhaust lob, lob separation, intake center line, comp 918 spring?, what length push rod?)
--Cam Motion, Tick Performance, Flowtech Inductions, and other vendors can get you situated with a nice turbo cam. There is a lot that goes into that question, and it is best to speak to a few different vendors and read some of the stickies on the site. Stay away from Comp 918 springs. Lunati and PAC Racing make great springs for these engines. You need to match the spring to your camshaft, and pay attention to seat pressure ratings. It isn't just about lift. You will need to measure for pushrod length. The lifter preload is determined through the pushrod length on these engines. The only way to know what you need is to install the camshaft and measure. I also recommend stepping up to a 11/32 or 3/8 pushrod to fight pushrod deflection.

- What turbo kit? or should i piece my own? If piece, what a good options?
Depends on what you want to spend. APS makes a really nice kit for the GTO, but then you are in the $6,000 range. Your best bet is to piece something together since you said you can weld.

- How much should i expect to spend in exhaust modification for turbo piping?
--Since you can weld, I would price out the tubing.

-T56 will bolt up to 5.3?
--Yes, it will. The 5.3 has the same external dimensions as the 4.8, 5.7, 6.0, and 6.2. So, the bellhousing and trans will bolt up.