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Differences in 5.3 block castings

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Old Mar 5, 2017 | 10:48 AM
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Default Differences in 5.3 block castings

If this has been covered please forgive me. I'm curious if there are differences between the BLOCKS from year to year and aluminum vs. iron.

I'm trying to narrow down a selection for a possible build. Things I am considering doing to either an aluminum or iron block is fill and 1/2" studs. I would also like to hear thoughts on Aluminum to aluminum "sealing" vs. iron to aluminum.
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Old Mar 5, 2017 | 11:17 AM
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It depends on the build to me personally. All motor I would go aluminum. Cools off faster and lighter vs iron. Cost more.... also harder to find.
Boost build I would go iron over aluminum. Iron blocks are heavy but can take tons of boost before 💩 hits the fan.

I'm a all motor guy at heart and owns a aluminum 5.3 that can be darton sleeved to go up to 454ci. Can't beat cubes in a all motor application.
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Old Mar 5, 2017 | 02:37 PM
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The aluminum 5.3 blocks seem to be pretty stout. Lots of guys are having luck with them in the 1000hp range so I don't see any benefit of an iron 5.3. It's just added weight for no reason other than they are cheaper.

I just picked up an aluminum 5.3 long block to replace my ly6 6.0 if it blows in my turbo car.
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Old Mar 5, 2017 | 04:45 PM
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There's a lot of meat there for there to be any noticeable difference between an aluminum/iron (5.3) IMO.
The weight difference is a bonus for sure.
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Old Mar 5, 2017 | 05:09 PM
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Originally Posted by MY_2K_Z
The aluminum 5.3 blocks seem to be pretty stout. Lots of guys are having luck with them in the 1000hp range so I don't see any benefit of an iron 5.3. It's just added weight for no reason other than they are cheaper.

I just picked up an aluminum 5.3 long block to replace my ly6 6.0 if it blows in my turbo car.
For me it comes down to price. I have 3 5.3 blocks lying around and the L33 isn't the easiest thing to come by these days.
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Old Mar 5, 2017 | 05:32 PM
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If I go the 5.3 route I'll end up half filling it and throwing 1/2" studs on it and probably Athena gaskets. I'll be looking to see if I can push it past 1300. Sounds like a fun, cheap little experiment.
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Old Mar 5, 2017 | 07:36 PM
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I picked up a aluminum block for 250 dollars. The last numbers of the casting is 048. In the long run I'll forget I paid 250 dollars for a block.
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Old Mar 5, 2017 | 07:51 PM
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if you are really gonna invest in the machining and studs, might as well do it to the motor you really want.

that said, I was under the impression that hardblok was for cast iron motors---that was like 15 years ago I was using the stuff though---maybe things done changed
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Old Mar 5, 2017 | 08:56 PM
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Originally Posted by truckdoug
if you are really gonna invest in the machining and studs, might as well do it to the motor you really want.

that said, I was under the impression that hardblok was for cast iron motors---that was like 15 years ago I was using the stuff though---maybe things done changed
Fair point. They have fill you can use in aluminum blocks.
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Old Mar 5, 2017 | 08:57 PM
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Originally Posted by Tuskyz28
I picked up a aluminum block for 250 dollars. The last numbers of the casting is 048. In the long run I'll forget I paid 250 dollars for a block.
Sell it to me lol
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Old Mar 5, 2017 | 09:05 PM
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Originally Posted by oscs
Sell it to me lol
Right place.... Right time you can get a better deal than I did. I have heard guys buying them for 200 dollars. So I got screwed out of 50 dollars LOL!!

Anyway the plan is to make it a dry sleeved 440ci motor and runs 10s all motor with my T56 in my camaro that's not gutted out.
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Old Mar 5, 2017 | 09:12 PM
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I'd get the aluminum block. Make sure is NOT an LM4 block. The gen 4 5.3 blocks are true siamese bore and are stronger. Go with a gen 4 over a gen 3.

I think the aluminum L33 falls into the Gen 4 block category, since it was an eligible candidate for dry sleeving along with the gen 4 blocks.

Aluminum is fine. A majority of the fastest 5.3s are all L33s. Nate Shaws 7 second Nova is an L33, Brysons X275 car was an L33. The current fastest stock bottom end LS was a stock L33. Barry cook made 1150 WHP with a stock bottom end L33. If you're going to be filling the block, might as well go aluminum.
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Old Mar 5, 2017 | 09:30 PM
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Looked in my photo gallery and got my full block number.

Block # 12571048

This is preferred to use for dry sleeved blocks due to it is a siamesed wall block, no coolant passage between the bores.

Steve at R.E.D told me it's the best aluminum block GM made for sleeving.
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Old Mar 5, 2017 | 09:31 PM
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Originally Posted by JoeNova
I'd get the aluminum block. Make sure is NOT an LM4 block. The gen 4 5.3 blocks are true siamese bore and are stronger. Go with a gen 4 over a gen 3.

I think the aluminum L33 falls into the Gen 4 block category, since it was an eligible candidate for dry sleeving along with the gen 4 blocks.

Aluminum is fine. A majority of the fastest 5.3s are all L33s. Nate Shaws 7 second Nova is an L33, Brysons X275 car was an L33. The current fastest stock bottom end LS was a stock L33. Barry cook made 1150 WHP with a stock bottom end L33. If you're going to be filling the block, might as well go aluminum.
It amazes me how many of them I've seen lately and all Aluminum.. It's insane. L33 is in fact post 04'
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Old Mar 6, 2017 | 09:38 AM
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Does anyone know if there are differences in the *blocks* between L33 and LC9? I don't care at all about the internals they come with or any of that. Bare block to bare block differences only?
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Old Mar 6, 2017 | 11:18 AM
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Originally Posted by gtistile
Does anyone know if there are differences in the *blocks* between L33 and LC9? I don't care at all about the internals they come with or any of that. Bare block to bare block differences only?
This.
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Old Mar 6, 2017 | 12:51 PM
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Originally Posted by Tuskyz28
Boost build I would go iron over aluminum. Iron blocks are heavy but can take tons of boost before �� hits the fan.
Any actual proof to this? As far as I know the alum blocks are stronger than the iron. Due to the Siamese bores as mentioned above.


Originally Posted by gtistile
Does anyone know if there are differences in the *blocks* between L33 and LC9? I don't care at all about the internals they come with or any of that. Bare block to bare block differences only?
They are a completely different casting. So yes, they are different. As far as one being stronger, I was told they are about the same. Main differences being the LC9 is setup with the oil galley towers for the variable timing and DOD. And one is not. THeres always going to be casting/machining differences though and one may be stronger than other. Only to know for sure is to sonic check them.
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Old Mar 6, 2017 | 12:55 PM
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Thank you!
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Old Mar 6, 2017 | 01:18 PM
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Forcefed- I visited the LS fest in 2015. One of the Ohio guys told me that. After all I'd figure they'll know since they cars do runs 7s or faster in the quarter.
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Old Mar 6, 2017 | 01:58 PM
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Originally Posted by Tuskyz28
Forcefed- I visited the LS fest in 2015. One of the Ohio guys told me that. After all I'd figure they'll know since they cars do runs 7s or faster in the quarter.
Not trying to discredit you… Just wondering.

Stock block LC9’s and L33’s have also been in the 7’s... And that’s using the stock rotating assy, unlike the Ohio boys engines. By design Siamese bores are stronger. Whether or not a thick iron cylinder wall is as strong is the question I guess. I know the iron 6.0 block is nowhere near as strong as the L33/LC9
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