4.8 heads and cam or 6.0?
 

My 4.8 is just over 132k miles now it’s got long tubes and a TVS1900 making 14psi for the last 17k without skipping a beat. I'm about to start collecting parts for the next power phase of the build and not sure which way to go.

Wants/needs: Reliability is the absolute most important but I would also like to be able to push a little more RPM. Right now the limiter is at 6k and I'm not sure if it’s safe to push it higher or if it’s even worth it given the stock cam.

No matter which route I go I will be going to 8 rib with a big ice box and larger HX so IATs shouldn’t be an issue.

Option 1: Keep going with the 4.8. Get a custom cam with new valve springs and push rods.

Option 2: More effort to the 4.8. Custom cam and heads that could be reused on a 6.0 down the road.

Option 3: Leave the 4.8 completely alone and build a healthy 6.0.

Option 4: I'm an idiot and you have a better plan.

Also if you have any other good ideas for reliability upgrades I'm all ears!

Option 2 gets my vote. 132k miles is barely broken in.

That's kinda what I was leaning towards. I figured since it's an 05 I should have the gen 4 rods and my bottom end shouldn't be the weakness. Plus it's fun telling people it's a 4.8 and then suprising them 😎

RMP's mostly a function of the top end - granted my knowledge is limited, but i don't see a lot of life trying to turn stock cam/valvetrain up much above 6k, and if it's on stock heads, too, then they don't flow good enough to really gain much. i'd suggest a better-breathing top end (heads, cam, + supporting stuff) regardless of 4.8 or 6.0 and some 799s/243s would be work & flow good for either motor (with an LQ4 being about 10:1 CR - meaning less boost for the same power & snappier throttle response). that'll both give you reliable parts to turn faster as well as an actual reason to, since it won't fall on its face above 4500.

I knew the stock setup wouldn't be to happy with more RPM but that's kinda what I would like to lean towards. With the NV4500 and 4.10s I run out of gear quick and top end really isn't all that great. I do get some beltslip which the 8 rib should cure but even then I want more.

I looked around at some stock heads 799s/243s but I might just fork out the cash for a set of PRC or TFS heads. That way when I build a 6.0 I can swap the heads over.

I would love to keep the 4.8 alive for another couple years of ripping with just a heads and cam upgrade.

Run your shit until it blows up while saving cash up for a brand new crate motor from TX Speed.

Then the next question is 370 or 408?

for a 1900?
370, if only picking between the two.

and the heads you get now should be something swappable, which some ported 799s would be (or you could spend for some fancier heads, too). the 4.8 would be lower comp, but you're spinning the blower hard anyway, which compensates. with a 6.0 having more cubes & higher compression, you'll have (and want) lower boost at the same blower speed.

as it sits, though, just spinning higher RPM on stock cam/heads won't buy you much more than extra heat & a more finicky tune.

The extra cubes of the 408 are great for ripping off the line when the light turns green. I only drive a very limited number of miles a year since I am in the city. Due to the piston rock and oil ring support issues .... ive been told a 408 isn't great for long term durability. Haven't racked up enough miles to give good enough input. Only got about 15k on mine. 408 would probably work great if you weren't using the factory gen iii block.