Aluminum or cast block pros/cons?

[joeydurango]

I've got a line on an aluminum-block 5.3 LS33 (new) for a good price (less than cast!). Could also get the cast block as well. Looking to do a swap into my '72 K10 4x4 along with a 4L60e, for daily driver use. Not into hot-rodding or serious off-roading. I understand the aluminum is lighter - beyond that, what advantages/disadvantages are there between the two block materials? In my industry, aluminum is valued for its light weight, but is known to be less durable over the long haul. Does this hold true for an engine block as well, or are there no real disadvantages to the aluminum block besides the normal price premium?

[BR3W CITY]

In a basic swap-for-fun configuration like your talking about, the aluminum block motor will be plenty fine. The biggest advantage to the Iron is to those of us building high-hp motors*. The iron is naturally impressive in strength, and specifically in boost/nitrous configurations, that strength is a big plus. Not only can you throw boost at it, but you can install things like oversized head studs etc, without further worrying about the strength of WHAT you tap into. Also, the iron block is more forgiving to detonation, and issues like block damage from overheating (instead of just damage to the aluminum heads), or block damage from lifting a head/pulling out a stud etc. You can also bore an iron block further because you don't need the extra wall thickness of an iron sleeve like you do in the other block types.

The aluminum block will give you the weight savings, a slight advantage in cooling (iron likes to hold heat), and you'll never have to paint your rusty-gray block lol. Because of heftiness of these trucks, the weight savings is nice (and weight savings is usually VERY expensive after-the-fact).



*someone will now confront me saying that on such-and-such a forum, or such-and-such a person they know says "but the Corvette guys are making big power with aluminum blocks" etc.....ya I know. In many places, guys with MASSIVE budgets are building MASSIVE horsepower on some aluminum blocks. This is true, but not applicable to our scope, or this thread. If you really wanna go down that road, we can start to include Billet blocks and some of the other hybrid type blocks available aftermarket now*

turned into a rant sorry lol.

[joeydurango]

Thanks BC, that's what I was looking for. I could see the high-performance people getting into aluminum for the weight savings, and not caring too much if they needed to replace the block once in a while for the reasons you mentioned. I just wanted to know if for pretty mild use (truly daily driver-style) there were any durability issues. Sounds like not - if anyone else has experience with this, the more opinions the better!

[Wasted Income]

The aluminum block is also cast

I'd go wtih the aluminum L33. It got a power bump and better heads than the earlier iron 5.3. For daily driver use, that bump in compression and power will get that heavy 4x4 moving a little easier.

If you go the cast iron route, send me the contact info on the cheap L33

[joeydurango]

Originally Posted by Wasted Income

The aluminum block is also cast

I realized that as soon as I posted... oh well. Got the point across anyway...

I've gotta pull the trigger soon. If it doesn't happen I'll get you some info!

[BR3W CITY]

haha, if it was a Billet aluminum block, he wouldn't be asking US....we'd be asking HIM lol.