Are There Any Noticeable Differences Between 5.3 Aluminum Block And Th

flatlander · January 12, 2011

I guess, other than weight, I was wondering whether the Aluminum block engine has any advantages over the Cast Iron version of the 5.3, or vice versa. Have had three pickups with the Cast Iron blocks but none yet with the Aluminum block. Have had absolutely no problems with any of the engines except for a water pump replacement on the 2003 Silverado.

Diesail · January 12, 2011

Nope, pretty much the same engine other than the material from what I understand.

mhenshaw · January 12, 2011

Has anyone noticed the aluminum blocks seem to run higher trans temps in the summer?

Mossyoakglock · January 12, 2011

Has anyone noticed the aluminum blocks seem to run higher trans temps in the summer?

I have yet to see over 180* in mine. What are temps with the iron block?

Where in TN are you?

dlstewart01 · January 12, 2011

When the 5.3 aluminum block was first put in the trucks in 2005 there was a bit of a difference. Don't really know about the ones produced now..

Re: Iron block vs. Aluminum block 5.3

If you are talking about the L33 aluminum blocked 5.3 you are talking a little bit special.

More cam, compression and LS6 heads. And it is 310 HP. Floating wrist pins and skirt coatings rid the slap noise. Flat top pistons got the compression up. The motor is 100 pounds lighter than the LM7 in full trim.

Below is a cam and compression comparison chart and GM's news release. The weight savings, compression and heads are a decent reason to choose one over the other.

FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES

RPO L33 FOR CHEVROLET SILVERADO AND GMC SIERRA

The Gen III Vortec 5300 is available in a new lighter, higher output variant optional on some 2005 Silverados and Sierras. RPO L33 will be introduced in short bed, extended cab versions of these pickups. The L33 features an aluminum engine block, new cylinder heads and a high-lift cam. Torque will increase, and horsepower is expected to exceed 300 in final production trim.

One of the L33s distinguishing features is its engine block. As with the 2004 LM4 Vortec 5300, the L33s foundation is a cast-aluminum block with pressed-in iron cylinder liners, similar to the block used for GM Powertrains LS1 and LS6 car V-8s. The L33 block is exceptionally light; as a result, a fully dressed L33 is 100 pounds lighter than cast iron-block Vortec 5300s (RPOs LM7 and L59).

The L33 takes its cylinder heads from the LS6. Originally developed for the Z06 Corvette, these heads improve airflow in and out of the engine. With their pent-roof combustion chambers and new flat top pistons (the pistons in other Gen III Vortec 5300s have a slight sump in the piston deck), the L33s compression ratio increases from 9.5:1 to 9.9:1. This increase improves the engines volumetric efficiency yet still allows it to achieve full power with regular grade gasoline.

Finally, the L33 is equipped with a higher-lift camshaft. Maximum valve lift increases from 11.6 mm on the LM7 and L59 to 12.5 mm. The new cam and compression ratio are the primary sources of the L33s increased horsepower.

The L33 camshaft and cylinder heads were developed in conjunction with the new Gen IV Vortec 5300 (RPO LH6). The design objective was more horsepower for customers who need it, without requiring a step up to the Vortec 6000 (and an increase in operational costs). RPO L33 expands GM Powertrains lineup of Vortec V8s and gives GMs truck customers even more flexibility and choice.

The L33 Vortec 5300 will be built at Powertrains Romulus, Mich., engine plant. With its introduction, Powertrain will cease production of Vortec 5300 RPO LM4. The Buick Rainier, Chevrolet Trailblazer EXT and GMC Envoy XL, previously equipped with the LM4, will now be powered by the Gen IV Vortec 5300 with Displacement on Demand. The 2005 Chevrolet SSR will be powered by the new LS2 truck V-8.

mhenshaw · January 12, 2011

Has anyone noticed the aluminum blocks seem to run higher trans temps in the summer?

I have yet to see over 180* in mine. What are temps with the iron block?

Where in TN are you?

I see around 180 in mine on hot days, but my friend with a 4.8 said his trans will barely reach that high towing a car. Not the best example but I have always heard the trans gets its tempature from the motor.

Im in Memphis

nickvrebel · January 12, 2011

in there current production trucks there is no differences besides the obvious.

they are spec'd the same power ratings. I'm not even sure why they make the two different versions.

gnet158 · January 12, 2011

Has anyone noticed the aluminum blocks seem to run higher trans temps in the summer?

I have an iron block, and mine dose too. I haven't heard Iron block engines having the oil consumption issues either, or lifter noise. But I could be wrong.

MaverickZ71 · January 13, 2011

From the GM Powertrain website, here is what it says as far as the new 1500 series 5.3L engines are concerned (HP and TQ ratings and other listed specs are the same for iron block or aluminum block):

The Vortec 5.3L is offered with either a conventional cast-iron ( LMF, LMG ), or an aluminum engine block ( LC9, ), giving customers a choice and allowing technology appropriate to the application. The lighter aluminum block allows vehicle engineers more latitude in tailoring weight distribution, and can mean a slight improvement in fuel economy. The Gen IV aluminum block is cast from A356-T6 alloy, with cast-in iron cylinder liners.

It weighs roughly 100 lbs. less than a comparable cast-iron engine block.