2008. Silverado. New. 4x4. Not yet ordered/purchased.

Not used for towing. Not used for plowing. Mainly driving. Don't want a 6.

What engine has the best reputation?

What engine has the best gas mileage?

 

I would get the 5.3L i just went to michagin and back from oklahoma 2000 15 hourdrive and i got 18 miles per gallon and thats with the bigger tire, TB spacer, dual exhaust and a k&n filter. Before every thing but the k&n filter i was getting 18 on the highway even hit 21.3 one timecoming back from texas with a south wind pushing me. Im not sure what the 4.8l get but thats what mine gets.

 

Go with the 5.3, and the 3.42 rearend. If you plan to tow (which appears you are not), want to race it alot, or plan on bigger tires get the 4.10 rearend. It will affect gas milage, but is better for those applications, otherwise the 3.42 will be fine. I have the 3.42 and it is OK, but I do race and tow and have 33" tires, so I want a 4.10. Also I think the 4.8 gets the same milage.

 

Thank you for responding. The brochure mentions:

Vortec 5.3L Iron Block
Vortec 5.3L Aluminum Block
Vortec 5.3L Flex-Fuel Iron Block
Vortec 5.3L Flex-Fuel Aluminum Block


OK, so which one?

 

That im not for sure i know i dont have the flex-fuel but it seem to be more common on newer trucks and suvs.

 

pretty much all flex...same engine with a fuel identifier on it.

 

Probably the aluminum block will work for you. As far as flex fuel, that is up to you and where you live. You may not have the flex fuel available. Also I believe there is a decrease in power and milage when using the flex fuel so it makes the cost of the fuel a wash. I also would think the flex fuel option would be more expensive.

 

Aluminum or Iron?

What do most get? Which is most common? And why do they offer two that are the same - other then aluminum vs iron?

All I remember is the aluminum engine Vega. Lots of problems that were never fixed.

 

The iron block will of course be heavier and is most certainly a pushrod engine. The aluminum block will save weight and may be an overhead cam engine in which case it isgonna breath better due to the higher number of valves per cylinder typically associated with aluminum engines. Also, aluminum engines are typical in high compression ratio applications.These differences generally all have the impact of increasing engine's output. Unless these greater technologies are employed in GM's alu 5.3, I really do not know why they would offer both iron and alu. Check out the power ratings of each. My guess is that the alu engines have 15% greater output.

The alu engine will conduct heat fasterthan an iron engine.(not sure but most aluminum engines are over head cam)

 

I know zero about the new aluminum engines. Does anyone out there have one? Is this a common choice?

I may be many years older than most posters here, but GM first tried aluminum on the 1970's Vega. And it was a disaster from day one. GM never fixed the problems. The engines wore out way too soon. GM's answer to the problem was to extend the warranty - not fix the problem. Have you seen a Vega lately. I don't think any are left as they were so poorly designed and manufactured. The Vega aluminum engine had a heat problem. The aluminum got too hot. It was not uncommon to replace the engine at 60,000 miles.

Is the new aluminum better? I would like to hear from others.

Or just stick with the iron - and just not give it another thought.

Thanks