4.8 combo, looking for a little help.
4.8 and 5.3 are the same block, the 5.3 just has a 9mm longer stroke. DON'T FORGET the ARP rod bolts! I have about the same build as you in my garage right now, only I used ls1 intake and cam, ls6 valvesprings, arp rod bolts, and a new timing chain, which is now all ls2.....
Why do you feel you need to change the head gaskets? Lots of people are on completely stock blocks running 15psi, IIRC.
John
Why do you feel you need to change the head gaskets? Lots of people are on completely stock blocks running 15psi, IIRC.
John
Thread Starter
On The Tree
Joined: Jan 2009
Posts: 127
Likes: 0
From: Sebring, FL
The LS9 gaskets are designed for boost and aren't a hugely expensive... There is nothing wrong with a little insurance as far as the bolts go.
As for the cam... I am going to get it and just check the length to be sure... Might as well do it right the first time. If I got some LS6 heads I would not have to worry about the push rod length though.
As for the cam... I am going to get it and just check the length to be sure... Might as well do it right the first time. If I got some LS6 heads I would not have to worry about the push rod length though.
if the motor u get is sealed and in running as is condition. no real need to swap cams or gaskets. if anything get upgraded valve springs and pushrods and timing chain if engine has many miles.
conventional gen3 24x 4.8/5.3 engines are alredy at 9.4:1 scr.
the 243 heads gen4 engines are slightly higfher scr.
ive machined and built many ls engines from the ground up and would never reuse heads without a slight mill before going back on the engine when changing gaskets. especially if using forced induction.
conventional gen3 24x 4.8/5.3 engines are alredy at 9.4:1 scr.
the 243 heads gen4 engines are slightly higfher scr.
ive machined and built many ls engines from the ground up and would never reuse heads without a slight mill before going back on the engine when changing gaskets. especially if using forced induction.
Head gasket question was answered NemeSS, and the killer of rod bolts is RPMs, not hp. The big load for rod bolts is the exhaust stroke, since it has to take the full load of the rod and piston being flung towards the head (the compression stroke is cushioned with the air/fuel mixture). I had stock rod-bolts on my early 2000 LS1 (weakest of the LSx rod bolts that I'm aware of) and spun it regularly to 7000 rpm Daily for over 2 years with zero issues (Trex cam making ~430rwhp N/A). Also, turbo motors are the easiest on rod bolts (by a little bit) since there is pressure in the exhaust to help cushion the piston on the exhaust stroke.
If RPMs are kept under 6500ish RPMs, the rod bolts will live longer than the rest of the motor (with a smallish cam and a turbo, no need to spin it up high anyway).
If you do decide to put a big cam in it and spin it high I would put rod bolts in it, but you would end up spending more in your valvetrain than the whole motor (kinda defeats the purpose of using a 4.8 or 5.3).
If RPMs are kept under 6500ish RPMs, the rod bolts will live longer than the rest of the motor (with a smallish cam and a turbo, no need to spin it up high anyway).
If you do decide to put a big cam in it and spin it high I would put rod bolts in it, but you would end up spending more in your valvetrain than the whole motor (kinda defeats the purpose of using a 4.8 or 5.3).
Thread Starter
On The Tree
Joined: Jan 2009
Posts: 127
Likes: 0
From: Sebring, FL
Well I picked up my motor, $275 for a 100K mile 5.3 with 862 heads. There is one downside, he pressure washed the motor with no intake and no exhaust manifolds on... So I get to pull the plugs tomorrow and try to prevent any rust. Only the intake and exhaust runners were open.
Will the 5.3 cam make the power to 6500 rpms? I was thinking of spinning to about 6k or so. I know I can add boost to make up for it, but I just want this to be a safe deal. No flying parts allowed.
There will soon be a build thread!
Will the 5.3 cam make the power to 6500 rpms? I was thinking of spinning to about 6k or so. I know I can add boost to make up for it, but I just want this to be a safe deal. No flying parts allowed.
There will soon be a build thread!
Last edited by Slowmo_Bird94; Dec 30, 2010 at 09:32 PM.
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