4.8 Swap?

[thirdstreettito]

I did a search, "No search results." Has anyone done it? I dont see why not, you can get the 4.8 on the cheap, its got 270hp+ and with a turbo/supercharger it can do an easy 400hp+. So, has anyone done this? Any comments? Thanks, Bradley

[garys 68]

I'm assuming you're referring to the GM 4.8, 5.3, 6.0 series iron truck motors. I'm doing a 5.3 in a 72 cutlass now. Pretty much anything that applies to the 5.3 and 6.0 swaps will work for the 4.8. The 4.8s are really cheap but the 5.3s are about the same price and are available everywhere.

[thirdstreettito]

Yeah, just wondering if anyone has done a 4.8 swap.

[Nessumsar]

I don't see why; the 5.3 will be the same price (unless you already have the 4.8), and will make more power with the same mods. A T70 turbo, cam/springs, and injectors will put you over 500 hp.

[dontlifttoshift]

400 plus hp is a camshaft and springs away with a late 5.3, way easier than a turbo and definitely cheaper in the long run.

[thirdstreettito]

I like the mileage of a 4.8 though...

[garys 68]

LOL, that's what I say about going with the 5.3 instead of a 6.0 or 6.2. But hey, a 455 would get less than 10mpg, so anything is better than that for a DD.

I like the mileage of a 4.8 though...

[6'9"Witha69]

The milage difference b/w a 4.8 and a 5.3 is laughable. Get a 4.8 and put in a 5.3 crank. This makes a higher compression 5.3. Cam and springs and your done. 400-450 HP easy.

[thirdstreettito]

Darn you tall man. Darn you. What kind of compression we talking? From what to what?

[garys 68]

You got me curious, so I looked up the milage ratings on a 4.8 vs 5.3 in the same vehicles. Best increase with the 4.8 was 1mpg city, and most highway ratings were the same for the two.
The 4.8 and 5.3 share the same bore size. The longer stroke of the 5.3 will have more noticable torque. Go with the 5.3. My 05 with under 50k miles, accessories, harness, ecu, pedal, pump, etc and a 6 month warantee was under $900, shipped to me.

[thirdstreettito]

Thanks. 6'9"Witha69 still waiting for a compressions answer.

[6'9"Witha69]

IIRC it goes up to ~ 10.0-10.2:1. I would have to confirm with the buddy who did it exactly what it was. Reason being that the 4.8 has flat top pistons and the 5.3 uses dished, so OEM they have the same compression ratio despite their disparate displacments.

[thirdstreettito]

Wait, the 4.8 stock has a 10:1 CR? Is the .2 worth it?

[garys 68]

Just a personal note on CR in these motors and some real life experience. The 5.3 and 4.8 have a 9.5:1 and run great on regular gas. My LQ9 with 10.1:1 CR reccomends premium. If I run regular in it, I can feel when the knock sensor trigger timing retard. I've heard from others the same thing and that the spark retard results in worse milage.
If your goal is economy, raising the CR might be counterproductive in addition to the cost of the crank, rods, etc.

[THE TECH]

Just finishing up a 5.3 in a Nova. Should be a fun little ride.

[68Formula]

Just a personal note on CR in these motors and some real life experience. The 5.3 and 4.8 have a 9.5:1 and run great on regular gas. My LQ9 with 10.1:1 CR reccomends premium. If I run regular in it, I can feel when the knock sensor trigger timing retard. I've heard from others the same thing and that the spark retard results in worse milage.
If your goal is economy, raising the CR might be counterproductive in addition to the cost of the crank, rods, etc.

Plus the OP mentioned a turbo/supercharger, so raising it more than stock is pushing beyond pump gas. Sounds like the ideal might be a stock 4.8L or 5.3L with a takeout camshaft from an LS2 and small single turbo would be a good combination fuel economy/power/cost effectiveness.

[Nessumsar]

The easiest way to make big power with a 5.3 is to run an early LS6 Z06 camshaft and springs, a t70 (or equivalent) turbo, intercooler, injectors, and maybe some water/meth for safety. That will put you near 550whp.

[thirdstreettito]

Yeah, but I want to keep good mileage. A T56 will be behind the LS.

[Nessumsar]

Yeah, but I want to keep good mileage. A T56 will be behind the LS.

With a good tune you'll get better than stock mileage, if you can keep your foot out of it.

[thirdstreettito]

Still have the power?