I am about ready to buy a new 05 Z71 chevy and was wondering what you guys thought about the new high output 5.3 V8. It only has an extra 15 horses, torque is the same as the normal 5.3. The main difference is the HO version gets an aluminum block, where the other retains the cast iron block. My thinking is that this aluminum block might lessen the chance of head gasket problems in the future. And, it might help the engine stay cooler when working hard. Any opinions either way?

I am also curious as to what you guys think of the 5.3 V8 in general. Thanks.

 

My dad has the Ho 05 in a Z71 and it does rev faster and run better than my '03 5.3 . As far as perfromance it's hard tot ell how much stronger it is because he has 4.11's to my 3.73's. I think the biggest advantage to the 05's though is the electric fan settup. I think I'm gonna get a 34" rad and get me some factory 05 fans for mine. Oh and those rear drums are absoultely outstanding compared to my discs.

 

5300 HO Engine, RPO L33, Rated @ 310 HP

When I got my truck in 11/1/04 the dealer said GM has put out a memo to dealership inventory ordering personnel stating the L33 option in these trucks has been restricted for the time being. They come and go. He now has 8 units on the lot with L33's. They come in ECSB 4x4's only.

Deep Skirt Aluminum Block with cast in place sleeves. This is basically a 6 bolt main where the block extends below the crankshaft center line allowing for more rigidity and two more main bearing cap bolts to enter from the sides. The old hemi's and American motors used deep skirt blocks.

High-strength cast iron crank shaft is internally balanced and has under cut and rolled fillets to reduce stress loads. The design provides quiet running and reduces maintenance.

Flat Top Coated Pistons (Slap Eliminator?)
Floating Wrist Pins (Slap Eliminator?)
LS6 Heads (YES!)
More Cam
More Compression
More Tuning
Electric Fans (Nice! And they do not kick in above 40 or 45 mph) (Cooler in cab AC temps when idling in a parking lot or city traffic jams.) (No clutch to rob power or mpg in city driving too either)

I have an 05 Z71 ECSB loaded out with 3k miles on it. She is starting to show signs of running MUCH better than my 03 did with OE tuning and getting better. It shifts MUCH more positive and faster than the 03 did also.
The motor was really tight when new.

 

AC, are you really wishing you would hvae went with 4.10's, or do the 3.42's do alright. Also what is your mileage running at a "reasonable" speed on I-75, say at a 75-85 avg speed.

 

I've driven both and I would'nt go with the 3.42's. Personally I think they're offerend for the soccer mom's who are worried about gas mileage more than performance and towing. I talked my dad into the 4.10's and he thanx me eery single time he drives his truck.

 

Heh Heh,

First the answer to the MPG question. Running from Cartersville to the Kennesaw exit @ a deliberate 75 to 80 with only 3k miles and fresh Mobil1 5w30 she averaged 19.1. I reset the average readout after I got on I-75 and up to 75mph. I tried very hard to hold it @ 75 but traffic and lane changes caused me to go to 80 once and a while. This run is not all flat either.

I aren't no soccer mom but I like the 3.42's. I have always had 3.73's and took a chance on the 3.42's and do not miss the 3.73's with this motor. The 4.10's are OK for the stop light launcher types, and the folks whom tow kind of heavy for long and often.
I play up on I-75 and the motor runs real well in the occasional romp in town. I am just waiting on the 05 L33 Nelson 93 tune to get finished and my Corsa to arrive.

 

Sorry dude I did'nt mean that to come out the way it did. What I mean was that Gm was looking for better gas mileage numbers when they nixed the 3.73 rather that satisfying most of the truck market. Personally I think the 3.73's with that motor would be perfect. Not to say that the 3.42's don't work well, but I personally do some towing and like a good launch from a redlight. I'm not sure the 3.42's have any advantage on the highway compared to 3.73's.

 

GM did more than just a lighter block and the 3:42's for mpg for the 05 Silverado.
Efans, an extended lower portion of the front air dam, more gasketing around the head lights, the alternator has a voltage and temperature monitor to shut it down when it is not needed, and the rear brakes going back to drums saves some drag also. A tenth here, a tenth there..... it all adds up.
Before anyone starts in on the drums, they need to experience them. I have tried everything on my other trucks from a full Praise Dyno system, to braided brake lines and high dollar fluids and the improvement was a bare minimum compared to what Bosche did to the Silverado's braking.
And again, as for the 3:42's, for what I do, and I don't go to the track, and my mods to come will be minimal with a Nelson 93 tune and a Corsa catback, they will be complementary to the L33's added power and power band characteristics. It is not just an aluminum blocked 5.3. This motor runs very well compared to my 03 5.3 with a Nelson tune.
Another felt improvement in comparison to my 03 is the transmission shifting. Under normal driving it shifts Buick like. When ran hard the shifts are quick and on the firm side. This was not so on my 03. If I had it set up firm with Nelson or the former Predator I had, it shifted firm all the time. I am thinking of asking Nelson to leave the line pressure alone and just open the motor's full potential up.
Nelson is in the process of dyno tuning an L33 equipped truck. Can't wait.

 

I wish there was someone local with one

 

Hey rock, where did you find this information at?? I have been looking for a while for these things.