opinions are like ********, everybodys got one, so heres mine. with the 4.8 the stroke is shorter and it should wind a little quicker, so id try to get my mods aimed more at the torque side, a 116lsa 230s/230s would be the direction id go for cam, take stock heads and do a port/polish and mill should give a balance of good bottom with decent mid and topend, one thing i can definently say from experience is dont put 1.75" LTs on a 4.8 itll gain just a little on top but it KILLs bottom end and take off, id stay with stock manifolds until you go 6.0L. If you want HP id go 112lsa 230s/230s, 6.0L heads with thin gaskets or milled, change over to LS6 intake (takes a little work) and a set of LTs. Or go the budget route get on ebay find a used Z06 or GTO cam for about $50-75, a set of Z06 springs $70, 160 stat $50, ported stock TB $150 and a diablo programer $150-200, mill the heads $30-50, and have an easy 50rwhp with no sacrifice of drivability. might even pick up 1-2mpg, but youll have to run 93oct. Thats if you want to get into the motor, or you can always go the easy way about $300 to get a nitrous kit on ebay and spray it about a 150shot ...... But thats just my 2 cents.

I started with a 4.8, whipple, LTs, NX, now its 5.7 from 2000 SS with arp rod bolts, worked 6.0L heads, TR blower cam, whipple (7psi), NX 125 wet shot, dynatec LTs, tci3000 stall

http://videos.streetfire.net/video/8...c800ef37d4.htm

 

no head work is needed.
a good cam, a set of valve springs, a trail blazer stall,
a serveo trans kit, and some 3.73 or 4.10 gears will
wake your truck up.

after you get use to that and want a little more.
set up for a 50 or 75 shot of nos.

 

if he wants 350hp at the wheels with a 4.8L, it will take more than just a cam. Besides, youll have the heads off to change the springs, might as well spend another $40 to get them milled to take C/R from 9.5 to about a 10.5-11.0 Any time i pull a set of heads (especially aluminum) i always get em surfaced. costs same to get a few more thousandths took off, when you put them back use the MLS gaskets and spend the extra money for ARP head bolts so when you change heads in the future you can reuse the bolts, (if you do heads 2 times youll break even on money, not to mention the extra strength). And i would imagine it should already have 3.73s.

 

Hate to burst your bubble.
You do not have to remove the heads to change the springs.
you can remove the valve from your compression gauge
and fill the cylinder with air or fill the cylinder with rope
and rotate the crank till the rope holds the valves in place.

a 93 oct tune with a good camshaft makes a good jump on hp.
the servo shift kit increases pressure in the trans to grip the clutches
much better and firms up the shifts.
and the trail blazer stall will help a lot more then what he has now.

the 4.10 gears will bring that horse power on much sooner then
the 3.42 gear he has now.

when he builds up some more cash, a good set of headers
and a cold air intake will give him some more hp gains.

with out the aid of nos or some type of forced induction
this is just about the best he will see from a 293 ci 4.8.
if the guys on here running 325ci 5.3 having a hard time reaching
350 to the rear wheels na then please tell him how he can do it
with 32 less cubic inches.

His very best bet to reach his goal is not to spend any money on the 4.8.
But save up his money and build an iron block 5.7 or find a low mileage 6.0.
any thing he does to that 4.8 now is just a waste of money if he is going
to replace it in the future.

 

Guys, you missed the fact that he has a 5spd, so the only way its going to shift faster or harder is to work on the hand, feet coordination...A small cam with the usual bolt-ons can will put you over the 300 mark. I'd recommend getting an underdrive pulley, e-fans, 160 t-stat, cam, tune, muffler.

 

I gotcha, just thought i'd throw mine out there for comparison. Im actually looking for a lq4.

 

thanks guys for all the info. I'm used to the LSx motors and all just not this small of one. I'm on my third f-body now but after seeing what my bro has done i'm very interested in doing it myself. The hand feet coordination is not a problem shifting wise i'm very well qualified in that aspect all my f-bodies have been 6spds and this is my 3rd truck w/ a 5spd. But i was just seeing if i was possible to get that mark n/a in the 4.8. But i guess i will just save and get a 6.0. Again thanks to all of you

 

Basic bolts ons, and stock GM cams are not going to get you 350 rwhp. I think it is a good idea to save your money for the 6.0, especially if you are going to do it anyway. You will be much happier.

 

thats good info on the spring change out, never had tried it like that but i will one of these days, but usually when i do anything on heads i go ahead and pull em to freshen up machine work. As far as the 4.8 making 350 rwhp that comes to 1.2 hp/ci, that would be like a 5.7 making 415 rwhp, i have several friends with f-bodys making more than 415 N/A on stock shortblocks. Heads, cam, pulleys, LS6 or FAST intake, TB, MAF, CAI, headers, and a tune. That seems to be the combination that works. Then when he goes 6.0L everything will transfer over, all he needs is the shortblock. But, the time and work involved in swapping motors, I would agree with Pappy and Sleek, be patient and do it all at once when the cash becomes available. As far as the 5.3s having trouble making 350rwhp N/A, evidently they must not be using the right head/cam combo. I would think a 230ish .600 lift cam with a set of LS6 CNC'd, milled heads with bolt-ons and tune would take a 5.3 over 350hp. I have a friend with a '02 SS Camaro 6spd, the only mods are SLP lid w/K&N and an aggressive 93oct. tune and it made 335/344 in 90deg. heat, of course thats 15hp short of 350 and an extra 21ci., but its also a bone stock motor. I know there are 100s of factors that affect performance, but i guess ive just been lucky with the mods ive done.

 

You are comparing apples to oranges. F-body's have a 6 speed manual in most cases and a 7.5" 10 bolt. Most trucks have a 4L60e and a 8.5" 10 bolt. There is quite a bit of difference there. About 6-8% more drivetrain loss from an F-body to a truck.

Second, you can put a h/c combo on one car and then on another car, and can get significant power differences. So, in fact you might have that freak 4.8 that makes 350, or you might have a turd that makes less than 300. Who knows?

Thirdly, a lot of guys on here have tried countless cams, heads, etc, trying to make good power. To say that the people on here are not trying that right h/c combo is ignorant.

Fourth, big cams don't neccessarily mean big power. Go to big with your cam selection, and you will regret it. Stuffing a 230 duration cam in a 5.3 is dumb, especially if you have an auto. I think you said you had a 5 speed.

Really, this post is to try to help you not waste money. After all you did come here for advise and this is mine. I really hope I helped you out. Happy modding!