buy you a used MP112 and let it eat. I am sure you can find them for cheap now. It won't get you over 400whp though but it will be a beast down low and lots of un.

 

Under 3000RpM, the 4.8L will always underwhelm.
Start with a 6.0L. Cannot stress this enough.

The following sentence has been edited to take into account 33" tall tires.
4.10 if highway MpG is most important. 4.56 if city MpG is most important. 4.30 to split the difference.

Do the above before considering a cam or torque converter.

If you insist on a 4.8L, then supercharge it as suggested. Not worth camming a 4.8L.

 

It's a 4.8L, there is no low end torque. Adding heads and a cam will make what, another 100hp from 4k-7k, and lose what, 10 maybe 20 hp below 4K??


No, not if its the same size chamber. There are several aftermarket options for the small bore, and Texas Speed can be do some nice work to the stock heads.

That's mostly false, and it's completely false if it's a manual transmission.

Headers as in long tubes, which means a complete full exhaust, which won't do anything without a tune.


OP: To really get anything out of the 4.8L you would need to put in heads and a cam, plus full exhaust and a tune, and that's at a minimum. YOU CAN GET THAT POWER GOAL YOU ARE WANTING, but not until over 4k RPM, and you're not going to change that on a 4.8L. If you have a manual transmission, then this is an option. If you don't, then this is silly, and you wouldn't get anything out of it except at the track, and when you're passing someone.
For a daily driver, and about the same cost, you really want a 6.0L. It will drop that 4400ish powerband down to about 1500rpms and actually be usable in a daily driver. You would spend about the same, and you wouldn't get as much up top, but you'd get close, and you'd get a lot more in the first half of the tachometer that you're not getting now or wouldn't get after anything you would do to a 4.8L. If you want to keep going after that, you can go well past your goal easily with a 6.0.

 

A supercharger will make a 4.8 feel like a big block down low.

 

I have a 4.8 in a heavy pig with 35 x 12.50 R20 10 ply tires...
Runs strong with 11PSI BOOST spinning 4.56 gears.
Stock cathedral heads will pass plenty of air for that little mouse motor.
Mine has a "LowLift" Texas Speed cam. 212/218 duration, .550"

 

My heads/cam 4.8 dynoed at around 310whp and 285tq but it has a 4l80. It will take a bit more power to rotate because it’s a bigger unit to but likely not a whole lot and also when it dynoed I forgot to turn the ac off so that also probably contributed a bit. My plan was have fun with this build for a while or until it break. Put a slightly built 4l80 for reliability and rebuild it until I had enough to swap the engine out. At first it was a daily driver and besides chugging gas it drove around town with the a/c on and even could mix in a good amount runs if someone happens to pull next to me while cruising. with no problem. Never got hot on me. But like it was stated before it’s expensive. I spent around 4k on mine plus 5k for the 4l80 swap. But I don’t really count that necessarily towards this build because that transmission is very capable of handling the 408 stroker going in. But that’s your choice. If you’re not looking to add a lot more power later on and just keep it simple. A well built 4l60 will be enough to handle that type of power. But yeah you’re looking at 4k plus. If you’re looking to make it as reliable as possible. With headers, cam kit (cam, lifters, springs,push rods, valve seals etc), ported heads, rear end and transmission. I would also recommend replacing every gasket (head, header, intake, valley cover, oil pan). If you just want the cam and heads you could do it for around $1500 maybe less but probably won’t reach your ho goal and don’t know how long it will last