Hey yall. I plan to rebuild my 4.8 in my 2002 silverado. I'll be on a budget, but I want to get a little more power. What options do I really have to cheaply try and get around 400hp if I can. Thanks in advance.

 

Welcome to the forums.

Personally, I think the easiest way to get more power out of a 4.8 is to add boost. They handle and respond to boost very well, and the only thing you would have to do is replace the injectors and valve springs.

A single turbo in the 7875, S366 or S475, GT35 range should do about perfectly. A2A intercooler, reuse your truck manifolds for the hot side. Follow Denmah's guide to junkyard excellence and you should be fine.

If you want 400rwhp out of a 4.8 naturally aspirated, then you will need really good heads like Tony Mamo's new MMS205's or TFS GenX205's, good fuel (probably E85), lots of compression, a good cam in the mid to high 220's duration, and a good intake (TBSS or Fast 92/92). Probably looking at a 3600+ stall. Going to need a really good exhaust, headers, X-pipe, true duals.

On a budget, you could have your current heads ported, or at least a good valve job and bowl blend. Switch to the TBSS intake. And have a custom cam spec'ed by Martin Smallwood or one of the other vendors on this site. You may need to change torque converters as per request of whoever specs your cam. And you will still want to get some sort of headers and address your exhaust.

 

You can bore/hone them out to 3.898" and use an LS1 rotating assembly.

 

400 HP at the flywheel can be done on a mild 4.8 build, no need to start replacing everything.

Cam, headers, tune. Add TBSS intake and a couple bolt-ons as the cherry on top.

 

So, I found this while I was (googing). Would this work if I also get my head ported? BTW this will be the first engine I've ever torn into, so as much info about it i can get would be wonderful! Thanks

https://m.summitracing.com/parts/esp-b13405l03068?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-eagle-specialty-products&gclid=CjwKEAiAs_PCBRD5nIun9cyu01kSJAA-WD-rDDqogOK7zps9L-93f0ZfPwdYZC_9irJuHHuztRFF3BoClATw_wcB

 

A forged rotating assembly seems like overkill for 400 HP..
Want 400 HP on a budget? Nitrous. Bone stock engine with a 150 shot.

 

how many miles are on it currently and how does it run? To me, a budget build dictates doing only what is really necessary for your goals. Why do you need 400HP? Have you dynoed the truck so you know where your starting point will be? What kind of performance are you really looking for?

if your engine really needs a full rebuild you might be better off just buying a used low mile junkyard takeout and building that up. That way you can keep driving until you've got everything ready to swap out. I paid $400 at a local scrap yard for a complete 4.8 with about 15,xxx miles on it for my camaro build. If you want to spend a little more than that a good used 5.3 or 6.0 would bolt right in as well.

I personally really like the 4.8 though, especially in a lighter vehicle. You can get pretty close to 400fwhp with a fairly reasonable camshaft and maybe a little bump in compression to retain as much low end performance as possible. That being said a 4.8 really just needs to turn a little higher to make useable power so I would also consider a rear gear/ converter upgrade as well to help take advantage of whatever you decide to do with the engine.