vettewreck

iTrader: (1)

Basic question here. I have a perfectly running LS1. However I was going to sell it and build a forged bottom end iron block 5.3 (boring it up back to a 5.7) to use with a TT system and around 18-20lbs of boost for 850rwhp.

Question is, do I keep my LS1 and just buy the forged pistons and rods for that, or… sell it and buy my buddys 105k miles Iron 5.3 motor and bore it out to a 5.7 and install the forged pistons rods in that?

I thought (or I've read) that the aluminum block LS1 didnt like high boost. Opinions on which I should do?

ss performance

iTrader: (17)

Go with the iron block. Its stronger. You could stay at 5.3 and make huge hp. I don't see any gain in boring it to a 5.7. Maybe get a stroker if you want more displacement.

Good luck.

87silverbullet

iTrader: (11)

If you go with the 5.3 I would leave the bore alone. The LS1 can handle 18 psi with no issues. Guys have been doing that since the beginning with prochargers.

If it was me, I'd put the internals in the LS1 block

vettewreck

iTrader: (1)

So 1 for the iron and 1 for the aluminum. Any more opinions guys?

HexenLord

The iron block is going to be stronger. However the aluminum block is still very very strong and should be just fine below 1000 HP.

stock48

iTrader: (17)

I would not be afraid of the aluminum block for below 1000 HP unless it is the really early block with the thin sleeves.

vettewreck

iTrader: (1)

Hmm... Well its a '98 from a Fbody so maybe but im not sure.

omar2guy

It all depends on the tune, honestly. The iron can blow too but not as much damaged as if an aluminum block would.

JustAFooL

iTrader: (45)

My understandings were that the l33 were great for boost. Lightweight and the cylinder walls are much thicker. That's what I got sitting in my corner..

Exidous

iTrader: (11)

The L33 left stock bore is an awesome motor for boost. Thick walls and an aluminim block. I'd run a stock bore L33 boosted anyday.

LS1rob00

iTrader: (9)

+1

I'd go with the iron L33.

Exidous

iTrader: (11)

L33 is Aluminum. LM7 was Iron. Both 5.3L.

3GZJerry

iTrader: (5)

I sell the alumkinum block which can give you some spending cash and get the cheaper 5.3

LS1NOVA

iTrader: (12)

L33 alum at 950whp here, soon to be more.

vettewreck

iTrader: (1)

All good guys. I just posted my LS1 motor for sale in the parts section so to be safe I'm gonna go with the 5.3 iron block!

87silverbullet

iTrader: (11)

If that's the case, then I dunno. Thadd on here has ran 8.70 on nitrous in a 98 block so I would think 18 psi would be still ok

fotoboy

iTrader: (1)

817 whp 98 forged ls1 17 psi

dlandsvZ28

No one has mentioned yet, but the iron block weighs more.

Talk to Bob about the LS1 motors he has built with good results and BIG rwhp. IMO save some money and rebuilt the LS1 with forged internals. Stock crank is plenty strong.

IMO its best to rebuild what you have since know in advance that it is in good condition.

vettewreck

iTrader: (1)

Will the 317 heads on the LS1 lower the compression ratio down to 9.5 ish?

dlandsvZ28

Bob installed Patriot LQ9 low compression heads on my LS1 - an option.