stumprrp

iTrader: (2)

So my motor bit the dust, not completely sure what went wrong but i really dont care because its got 120,000 miles anyways and its cheapest to just throw in another motor. My friends and I decided that a 5.3 would be the best route instead of the 6.0 because of the cost and other factors.

I can get one local for hopefully 5-600 bucks out of a tahoe with 76,000 miles. They are asking 750 but i'm sure i can haggle down to that.

Questions are...

Should (if i can) reuse the valve springs in my current motor? They have around 12,000 miles on them.

Do you have to replace the pushrods or are just springs only acceptable?

I literally want to keep this thing bone stock with with valvetrain upgrades. No cam, no head gaskets, no head studs. I dont see the need for rod bolts as this motor should only peak at 54-5600. I will put on my ls1 intake from the old motor (given its ok).

Power goals are what ever i can run on purely pump gas. The old ls1 let go at just over 500 RWHP, 9.8 lbs boost, 12-13 deg timing and 12.0 AFR. This was at 4900-5000 rpm. My tuner who is a beast said we can probably go 14lbs on the 5.3 and make it live over 500 whp.

Sound good?

PS - yes, ive read every thread there is on these topics.

o2camaross

iTrader: (2)

Idk why your motor let go at only 500rwhp. And yes a 5.3 with 14psi will be over 500whp. I would definitely cam it and pushrods are a must with dual springs. 12.0 is a little lean with boost and pump gas so that might have been your problem

stumprrp

iTrader: (2)

I dont blame the tuner at all. He knows his **** along with having 25 years experience with GM in detriot. As far as the motor going it had a lot of hard miles under a so-so tune at 12 PSI and upwards of 15 PSI, so it was tired.

I will buy new pushrods as well then. Dont plan on doing the cam i dont see the need.

o2camaross

iTrader: (2)

Not saying there is a "need" to do a cam but a properly specced turbo cam with help it spool better and prolly give you 50-70 rwhp.

gnx7

iTrader: (28)

If they are aftermarket pushrods roll them on a flat surface. If they aren't bent run em.

I would look for an '05+ engine as they have the stronger LS2 rods. LS1 style rods seem to have a limit of around 600-650rwhp for repeated abuse.

TurboMark8

12.0 is lean on pump. Look for ~ 11.5-11.3 with colder plugs. 12.0 is **** for e85, but not 91-93

stumprrp

iTrader: (2)

I will consider the cam. I know the ZR1 cam is like 100 bucks from GM. I'm going to talk to my tuner tonight about the air fuel, but remember this was at only 4900 RPM. He told me that toward the top of the pull he backs it down to 11.8 or so.

Regardless, its broke. Theres a spring/retainer/pushrod kit on ebay from COMP for like 350 bucks. I can probably get that too.

stumprrp

iTrader: (2)

The exact numbers were actually 11.8 AFR 12 deg timing 10 pounds of boost. Sounds perfect in my book, but regardless i cant bring the motor back.

Does anyone think its worth throwing my ls1 heads on there with the spring setup and everything if its all still good? I think that would bring the comp down on a lm7 to around 9:1

o2camaross

iTrader: (2)

If it was what you just posted then thats fine. I wouldnt put the 241 heads on. I doubt they are intact but even though there is no reason to lower compression. 9.5 is perfect

JRENIGAR

iTrader: (37)

Not if its the newer 5.3 with the 799/243 heads already on it, but if 853's then yes. I believe ls1 heads flow better than the 853's due to slightly bigger valves, however, you will probably loose any extra hp the ls1 heads would make unless you mill them to keep same cr as the stock 5.3 already has.

stumprrp

iTrader: (2)

The motor i'm looking at is from a 2005 Tahoe, so it might be the newer one. I'm just going to throw some springs in the heads that are on there then and let it eat. This old motor was approaching 520 RWHP before it blew so i think with a 5.3 on 11-12 pounds pump gas it should do the same.

stumprrp

iTrader: (2)

Another question I cannot find a straight answer to on here or performance trucks... What's the limits of boost on pump only...no meth! It seems that 12 pounds is the limit. I have no plans for a meth kit right now money has to stay low.

Slowhawk

iTrader: (12)

The stock 5.3L motor has a cam that peaks at 5200. That means dcr is pretty high in the low rpm area's. Not good for a turbo running any decent boost.

You can run 16lbs on a dyno. The question/limit is how much it will hold flying down the highway with good boost for a long period of time. The main reason engines blow up are from either tuning or lack of fuel system. Most of the times lack of fuel system.

o2camaross

iTrader: (2)

JRENIGAR, The 5.3's that were built without 799 heads (the same as 243's but with solid valves) came with 862 or 706 heads, which are basically the same. There is absolutely no way I would put a set of stock 241 heads on my 5.3. Waste of time and would lower compression and lower velocity... no thanks. Like Slowhawk said, the stock cam is far from ideal which is why I suggested a cam swap to begin with. And Stumprrp, If you are getting a motor from an 05 it most likely has the ls2 style rods and most likely has 243 or 799 heads. If it doesnt have those heads then no biggie. The stock 862 heads will support 1000rwhp. As far as how much psi a stock 5.3 can take, that all depends on tune, fuel, valvetrain, and IAT. If you can keep those in check you can see 20+ psi with a set of LS9 gaskets and ARP studs.

stumprrp

iTrader: (2)

The motor will have 60 lb injectors and a walbro...the iats when the old motor went were 95...its got a large intercooler. No studs will be used nor rod bolts. The car will only see pump gas so boost will never get to the point where ill need those.

I know the cam will help, but is it needed under 15 psi? I guess I could always slide an ls6 in there.


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o2camaross

iTrader: (2)

At least run a LS6 cam, those have been proven budget cams. With stock gaskets and bolts you will probably start pushing water around 16-17psi but you wont get close to that with a single Walbro. You can probably run 10psi with a good turbo and ls6 cam and be at the limits of that pump which will be roughly 525-550 rwhp

stumprrp

iTrader: (2)

That would be perfect...thanks for the help guys.


Posted from LS1Tech.com App for Android

stumprrp

iTrader: (2)

Another bump on this. Buying an 02+ LS6 cam tonight. Valvetrain comes in this week. Buying the motor Thursday. My concern, or question is i can get OLDER 5.3's for alot cheaper then the 05+ motors, which are supposively stronger. I've looked as far down as 2002 and all of those are in the 300-400 dollar range and super local to my house. Does it really make a difference for me only wanting to go as far as i can on pump gas? Ill never see the amount of boost some of the locals here are seeing.

a4ls2goat

People say the older style rods start to bend after a lot of beating at around 650whp.

stumprrp

iTrader: (2)

I doubt the car will get to 650 because the trans and rear will pop lol. There is also a 2002 6.0 with 100k for 600 bucks near me as well. UGHH.