How much extra power potential do you think the iron factory blocks have over an ls2/ls3 block? I've seen guys make some rediculous amount of power with an aluminum block that was prepped right and I haven't seen posts about people breaking the aluminum blocks except when they have another catastrophic failure of a piston or rod.

I don't know. To me, the extra 110lbs is tough to get back and it does make a difference to anyone who drives their car in anything but a straight line.

Yikes! Guess I'm lookin for an aluminum block now. Thanks for the info guys!

thanks for the info I was curious what the weight differences where

Did not get a chance to weigh my new block but I did scrap my old one. Scrap yard weighed it at 87lbs, LS6 block, completely stripped of all non aluminum bits, except for the sleeves of course.

I think the scrap yard just ripped you off 20lb.

Well, the other weights above included the main caps. I'm sure those don't weigh 20lbs, but we're only talking about a few bucks here. I did get the sense their scale was tipped in their favor.

What? Scrappers not being honest, who would have thought, lol.

Completely bare first-gen weighed 160 on my race car scales, checked it today along with some crankshafts we had laying around.

hahaha picking on that poor guy!

the funny thing is they have a state agency to check these things yet so many aren't truly checked.

good example is the local ups store. I bet I could take a 5lb weight and the **** would say it weighed 8lbs. Ive weighed packages and even reshipped items in original packing only to find they gained a couple lbs or more after walking into the store.

I had the same thing happen to me. I shipped back a subwoofer that had a UPS shipping label on it that said 21lbs, and when I took it to the UPS store, they said it weighed 29lbs. Swore up and down to me that the original label was wrong, and I when I asked for the calibration data and certification for their balance, they just got loud with me.

So in round numbers the weight of an aluminum headed 6.0L and an iron headed GenI should be close to the same weight?

if you aint first your last so build it strong!!

Wow! 110lb difference in iron to aluminum is massive!
You guys are to close minded... Yeah, you can ditch the HVAC, bumper support, power steering, and do a tube k member/a arms and coilovers to lose the extra weight.
BUT... If you've already done those weight-saving mods, and want to drop even more weight, you're looking at some SERIOUS cash for brakes/spindles, manual rack, Manual brakes, lightest of the light drag wheels/tires, pin on hood, etc. even those extreme measures won't drop 110 more pounds.

Iron 6.0, $150
Ls2 block, $500
Try dropping 110lbs for $350!

I have a bunch of LS1, LTX EFI, LTX carb and Gen I SBC parts in my garage so I weighed everything and made a spreadsheet.
If anyone has an aftermarket aluminum intake for a carbureted LS engine I'd like to confirm the weight of that.

good info but a 5./4.8 block?

Fwiw my iron block 6.0, ls3 heads, single plane victor jr, 4150 4bbl Holley carb, truck style water pump, alt bracket, alternator, and Hughes sfi flexplate weighed in at 452lbs

I find that very hard to believe that your iron block engine weighs 12 lbs less than my aluminum ls1 in similar dress.

I can tell you the LS3 weighs 403 with intake to oil pan (aluminum block) and rated at 430 horse power.

That sounds a little heavy - by any chance does that include starter, alternator, accessory brackets, etc? Is it installed in your 65 Malibu? I'd like to see pictures if so - fell free to PM me. Thanks.