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Discussion Starter · #1 ·
I've got a 04 A4 GTO that I'm trying to save and get her back on the road, the LS1 is too far gone to save and has 250,xxx miles and was abused. I want to make it a fun car to take out and have fun with (hopefully around 550-600whp eventually). I've already acquired/ bought a ARP 1/2 inch Gen III stud kit, MSD coil packs for an LS1 style head, BTR LS1 Stage 2 Truck Cam Kit ( Cam, rods, and seals), Transmission Specialties 2400-2700 stall converter, and a 4L60E PerformaBuilt transmission rated to take the HP I want. The car had 706 heads on it w/ the LS1 so it want to reuse them. Should I get new rockers, rollers, flex plate, etc... I'm younger and just unknowing. Also what are your engine recommendations for the GTO with the high compression heads in 6.0 or a stroked 6.0 that won't kill the build and stand up too a blower in the future. I would like to not touch the fuel system yet too. Thanks in advance for the advice and help.
 

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706 heads on an ls1? Yikes. Sure some jerk didn't slap in a 5.3l?

If you are going 4" bore i would get rectangle port heads if you are on a budget. You can also send the 706 heads off for a CnC job with bigger intake valves and they flow pretty decent. If they are castec heads, throw in garbage.
 

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Discussion Starter · #3 ·
It’s an aluminum block so it’s probably an LS1 and it’s the same car that had the grade 8 1/2in bolts in heads, if you remember that. Tried to save the block with some 1/2in studs but the whole right side was time serted. Don’t feel like pushing it and I just don’t think I’d be happy until it’s got at least a 6.0 in it.
 

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They made aluminim gen iii 5.3l, engines, but i think they came with better heads. but, sae headbolts? Seriously, what the heck?

Throw engine in garbage and start over, lol.
 

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Discussion Starter · #5 ·
Yeah at this point I’m basically going to be replacing the whole drive train. I want to feel safe about pushing the car and engine and not worrying about what else is messed up. I don’t think their castec heads but I’m not anywhere near the car so idk.
 

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Non castec 862/706 heads are a decent basis to work with. Lots of places offer good CnC programs and valve upgrades for those heads. PRC, Advanced inductions (if you can ever get a hold of them!), TEA, list goes on.
 

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Discussion Starter · #7 ·
This car has definitely been a headache for me. Previous owners did some very interesting things to it. What all should i look into replacing if I just buy something like a Blueprint Forged internals 6.0 short block and reused the heads just so I can start looking for some parts.
 

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Discussion Starter · #8 ·
I would also like to keep all the parts above the heads as well, which is why I'm looking to reuse the heads or get a set of cathedral heads but plans definitely change
 

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If you're just just shooting for 600, find a 6.0 or a 5.3 that's in reasonable shape. Put some ring gap in it, decent head gasket, studs, your cam/springs, etc... Then spray or boost it to 600. There's no need for head work other than making sure they're right. A 6.0 with a mild cam and a 200 shot will scare you for a little bit. You're going to need to do some work on the fuel system to make it safe.
 

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Depends on how much work you wonna do overall. Getting a different gen that needs the cam and knock sensors moved and adapted, holes drilled for an alt and oil dipstick plugged. My ls6 is past saving unless I bore it out. But with machine shops being months behind and I dont wonna do alot of foot work im just getting built shot block. Bored and stroked 5.3 iron block. Gen 3 to keep my arp bolts now as they are more than enough for 700/800hp. Swapping my milled 706's over as well, gonna sell the 243's.

Id try to build a spare 5.7 my self. but if you dont mind going iron and getting one that simply drops in, wont be a bad option. Building it to last is on you, forging and balancing the internals I mean. Wont need to touch the fuel system while n/a anyway, just the injectors.
 

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Discussion Starter · #11 ·
So I had a person whose with the car send me a picture of my heads and they’ve got the Castech battery on them. How prone are the heads to cracking. Should I to try to find a low mileage junkyard 6.0 and upgrade it in the future or is buying a pre-built 6.0 off Summit worth it in your opinions
 
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