65ChevyIINova

So I was sold an engine being told that it is a 5.3. On the back of the block neither the 5.3 or 4.8 were highlighted. So I get it home and break it down to find out it is a 4.8. It has the 4.8 pistons (flat) and crank with casting number verified as 4.8.

Obviously the guy who sold it told me to get lost so now I am trying to figure out what to do with it...

Is it worth my time to replace the crank/pistons to turn it into a 5.3 or should I just sell it for what it is and find a new engine? I have the entire accessory drive/harness/ecm that I paid $800 for.

Thoughts?

427zm

iTrader: (9)

Depends on your goals for it. It could be bored and stroked to 5.7. If your going for a JY build, I'd go for another bock.

65ChevyIINova

Not sure what JY build is (Junk yard??) but my goal is to have a fairly strong but very driveable engine for my 65 Nova. My original plan was just to change the cam/seals/intake and just drive it.

Any ideas on how much it would cost to bore it out to a 5.7 and get the needed crank/pistons/piston rods? How well would the stock vortec heads work with this. The 4.8 and 5.3 use the same heads correct?

PS this is a 2002 gen III engine.

Daz

iTrader: (18)

Why not turbo ? That's what I'm doing to my 4.8 !

65ChevyIINova

Is their enough meat on the block to bore to a 5.7 and still have it being durable? And do the stock heads breath well enough with a cam upgrade to work?

knuts82

I have one bored to 3.905 running 20lbs of boost at 7500rpm.. Id say thats a good test.

wildcamaro

iTrader: (15)

Look up the magazine article either hot rod or car craft where they buy a junkyard 4.8 and 5.3 and put the same parts on both and there was only like a 10-15 hp and 15 TA difference between the two engines...it's not that big of a difference so to me it wouldn't be worth losing money on the 4.8 to get 5.3...just put good heads and a cam and you won't know the difference...

65ChevyIINova

What about the stock heads? How well will they breath with a high lift cam?

Would a cam with around 220 duration at .050" on the intake/exhaust and around .550 lift on intake/exhaust be a good combo?

http://www.summitracing.com/parts/cca-54-424-11

fox12303

iTrader: (7)

Buy a 5.3 crank, LS1 heads and Z06 camshaft. Makes a great 5.3HO. The parts are cheap and you end up with 350+ hp. Have one in my 72 Chevelle and its a great running and performing motor. May have to balance the crank though but you would do that with an overbore anyway. Yes you can bore the block to 5.7L.

The Z06 camshaft has .550/,550 lift but less duration. You can buy them on eBay for less than $100. Used crank are around $100 shipped and a used set of LS1 heads are around $200. I actually have a nice used pair if interested.

Here's a link to my motor build.
https://ls1tech.com/forums/16235381-post7.html

i r teh noobz

iTrader: (4)

I'd just keep it. Its not worth the few extra cubes to lose money.

See what they guys on performance trucks are running in their cam-only 4.8s. Maybe see what works in a 5.3 and go a little smaller.

The heads are the same as the 5.3 heads. Maybe get them polished up and milled (if you want to stay NA) while you have them off.

4.8s seem to love boost. If there's room, I'd do an LS6 cam/springs and budget turbo build.

65ChevyIINova

Any idea on how the extra compression from only changing the internals will effect the engine? It would take it from around 9.5:1 to around 11:1 based on some quick online calculations.

sweetk30

http://www.hotrod.com/techarticles/h...g_bang_theory/

read this one

Tig

I'd keep it, why not.
That story goes to show yah, they are capable little bastards.

65ChevyIINova

Is a 5.3 crank the same as a 5.7? I know the stroke is the same but is everything else the same.

Ls1.63cad

seems to me the 4.8 would do what your asking sounds like you should just do the few mods to it and roll with it you have the option to get into the engine after you get it running and put some miles on it

fox12303

iTrader: (7)

5.3 and 5.7 cranks are dimensionally the same but the 5.7 LS1 crank is gun drilled to lighten it a bit. Be sure to balance the rotating assembly if you do some mix and matching. 11:1 is high but can be done if built properly running premium gas. Piston to head clearance(quench distance) should be .035-.045" to prevent detonation. This means more machine work possibly or more expensive heads gaskets.

Rather than doing that, get a pair of LS1 heads. They have larger combustion chambers and will lower the compression ratio to a safer 10:1 level. Upgrade the springs and trunnions in the rocker arms. Spend your money wisely and you will have a very nice 327.

65ChevyIINova

So a cheap route I have found is a new crank/rods for about $80. This does not include the pistons but basically this combination is what is used for the L33 (minus the heads).

This would give a compression ratio of 10.4:1 (with the 61cc heads vs the L33's 64 cc heads).

Thoughts?

christiandoy

iTrader: (1)

You went from a 4.8 to a 6.2 ? 3905 would make that a 383.

427zm

iTrader: (9)

Are you milling the heads to get them to 61cc? The stock 5.3/4.8 heads are pretty potent when ported and polished. They put down good power for the buck for sure. Chamber size all depends on what direction you want to take it. If you want to stay NA, I'd bump the CR by milling.

knuts82

Nope im still running a 3.27 stroke. 313CI