MEAN GTO

iTrader: (1)

Hi everyone, I have a 2005 GTO with a built 4L60E a 2 Precision 6265 (62mm) turbos. I did a lot of drag racing with the car back when it still had a Maggie on it, but the car has been garaged for quite some time after a local shop did a hack tune and caused me to blow 2 motors. I'd lost interest in the car, but I want to get it back on the road again now. I just scored a good deal on a recently-rebuilt 5.3 LM7 engine. Very clean engine with fresh-looking cross-hatching and a .020" overbore.

I last made 639 RWHP @ 8 PSI on my LS2 engine (higher compression engine, with more timing advance than it should have had) and plan on making more power with the 5.3 when I get it in and get the PCM re-tuned. Going to all depend on what my current fuel system (Walbro 255 in-tank pump with 60 lbs/hr injectors) will support. I plan on using this 5.3L temporarily to get the car back on the road and have fun with it until I can get enough funds together for a fully-forged 364 or 402 engine. I plan on swapping in my custom blower cam from my LS2 for now, 317 heads with upgraded valve-train, and everything else from my LS2 (intake, oil pan, sensors, etc.) on this 5.3.

Is there anything on the 5.3 I should look at upgrading for now? I'm not looking to do anything that isn't really necessary to this engine since I plan on putting all of my money into the permanent engine for this car, but should I be considering a ported oil pump or anything? It looks like the 5.3 I just ordered already has a new timing chain and sprockets.

GTO Eric

iTrader: (6)

My setup consists of a 5.3 stock bottom and stock 706 heads to keep the 9.5:1 compression ratio.
I run a Borg Warner s475 turbo
With 317s it may feel a bit doggy out of boost but I've seen people with experience both ways on that.

I'd do ARP head studs and LS9 gaskets with whatever heads(recommend 706/862 or 243s) and valve train you like. Also if you keep your 317s around for your 364/402 build you don't have to worry about them being damaged if the 5.3 does blow.

I will say that my custom tick cam performs much better then the brute speed blower cam I had in it previously.
The car made 792/796 on 26psi but floated the valves after 5200 rpm. I have since fixed the valve float with shims.
I ran a 10.39@134 last night on 24psi

MEAN GTO

iTrader: (1)

Thanks for the info Eric! Yeah I didn't notice much doggishness after swapping my 243's for the 317's, but I no longer have the 243's. I believe my 317's were lightly ported. Out of curiosity, why do you recommend 243 vs 317 heads on a setup like this?

Do you think you should have a faster time in your car with those numbers?? I was last running 10.90's with 508 RWHP while I was running a Maggie 112 with the LS2 and blower cam. Definitely came out of the hole hard with a 1.54 60', but it lacked on the top end. The twins don't have as hard of a launch but the boost does kick in pretty quickly and it has much more top end now than the Maggie setup did. So I would really hope to see a little faster time with a little less boost than you when I get this 5.3 in, but I guess we'll have to see. Are you running 93 octane? Thanks again Eric!

Blown06

iTrader: (32)

This is hardly advanced tech.

Make a post in the forced induction section for more views.

mpatton

I did rod bolts. Just because.

MEAN GTO

iTrader: (1)

Thanks for the response. Yeah I was about to order bolts, and when trying to determine which bolts I needed I saw a lot of people recommended just to run the stock bolts if you don't want to do machine work, because apparently the ARP bolts will but the bottom of the connecting rod out of round. Haven't made a final decision yet but I just might leave the stock ones in place.


Can anyone chime in on the timing assembly? Looks like my engine has a fresh 5.3 timing assembly. Should I upgrade that too? If so, what are some recommendations for a good unit that doesn't require modification to the timing cover?? Thanks!