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6.0 vs 8.1


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OK... I'm definitely a newbie when it comes to GM trucks because I've been driving Toyotas and Fords since the 70's but now I have picked up a 2009 Z71 4wd 2500 mostly because of the cabover slide in Lance camper that it came with.
 
I am falling in love with the truck but I have almost no idea what I've bought.
 
How can I tell whether I have a 6.0 or 8.1 motor?
 
How about what transmission I have?
 
Rear end axle ratio?
 
Sorry for all the newbie questions but I looked around and didn't find an FAQ that would help me.
 
*** EDIT ***  OK... I found a link that told me to check the 8th digit of the VIN code and it's a K which I guess means it a 5.7L small block 350ci engine. Can someone please tell me where to find more information on this motor? Everything I've found so far doesn't even mention it being produced as late as 2009 so the confusion mounts. I'd like to know HP and Torque and other specs as well as information on how reliable it is etc. 
 
*** EDIT #2 ***  The confusion continues... I got on NADA Guides dot com and they say the motor that comes with my pickup is the 6.0L and it has a 6 speed transmission. So now I am once again confused. Is it a 5.7 Liter or a 6.0 Liter? The plot thickens.
 
TIA


It is not a 5.7 350. It’s a 6.0 vortec motor. The trans I am not sure on, I know my 2011 has a 6L90 6 speed. The axle ratios, you will have to check the glove box there’s a sticker inside of it with all the codes for the options for your truck. Google codes for axle and trans and such and you’ll find what code goes to what and what it means. The axle ratio is most likely 3.73 or 4.10. I don’t think they came with any other option for axle.


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4 hours ago, LDHunter said:

OK... I'm definitely a newbie when it comes to GM trucks because I've been driving Toyotas and Fords since the 70's but now I have picked up a 2009 Z71 4wd 2500 mostly because of the cabover slide in Lance camper that it came with.

 

I am falling in love with the truck but I have almost no idea what I've bought.

 

How can I tell whether I have a 6.0 or 8.1 motor?

 

How about what transmission I have?

 

Rear end axle ratio?

 

Sorry for all the newbie questions but I looked around and didn't find an FAQ that would help me.

 

*** EDIT ***  OK... I found a link that told me to check the 8th digit of the VIN code and it's a K which I guess means it a 5.7L small block 350ci engine. Can someone please tell me where to find more information on this motor? Everything I've found so far doesn't even mention it being produced as late as 2009 so the confusion mounts. I'd like to know HP and Torque and other specs as well as information on how reliable it is etc. 

 

*** EDIT #2 ***  The confusion continues... I got on NADA Guides dot com and they say the motor that comes with my pickup is the 6.0L and it has a 6 speed transmission. So now I am once again confused. Is it a 5.7 Liter or a 6.0 Liter? The plot thickens.

 

TIA

Send your VIN to an email here and they will provide your build sheet, may not be "Official" but it comes from GM and is exactly the same as the one I requested through my dealership.

 

[email protected]

Edited by SS502
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18 minutes ago, casey.mikl said:

 


It is not a 5.7 350. It’s a 6.0 vortec motor. The trans I am not sure on, I know my 2011 has a 6L90 6 speed. The axle ratios, you will have to check the glove box there’s a sticker inside of it with all the codes for the options for your truck. Google codes for axle and trans and such and you’ll find what code goes to what and what it means. The axle ratio is most likely 3.73 or 4.10. I don’t think they came with any other option for axle.


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Thanks.... I suspected that the 6.0 was the correct engine and the cover on top of the motor says Vortec. According to NADA Guides the Allison transmission only came with the diesels that year but they say I DO have a 6 speed automatic.

 

I'll check for axle ratios and thanks a bunch for your advice.

 

Do you have any idea what kind of mileage I should expect with my camper off the truck?

 

Also do you recommend any mods to the truck that almost everyone does that are popular? I'm not really looking to boost HP or Torque from the motor but anything else including a gas tank upgrade or addition would be of interest to me.

 

Oh.... One more thing... Do you recommend a particular brand of brush guard that will accommodate a winch?

 

LD

18 minutes ago, casey.mikl said:

 

 

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12 hours ago, LDHunter said:

OK... I'm definitely a newbie when it comes to GM trucks because I've been driving Toyotas and Fords since the 70's but now I have picked up a 2009 Z71 4wd 2500 mostly because of the cabover slide in Lance camper that it came with.

 

I am falling in love with the truck but I have almost no idea what I've bought.

 

How can I tell whether I have a 6.0 or 8.1 motor?

8th code is K if its gas, LY6 6.0 Vortec engine.  360HP, 380TQ, 364 cubic inch.  Bulletproof engine more or less. 

How about what transmission I have?

RPO MYD 6L90 Hydramatic.  All 6.0 HD trucks have had and use this trans since 2007 new body.  A mini Allison if you will.

Rear end axle ratio?

PM sent.

TIA

 

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  • 10 months later...

I have a 2006 chevy crew cab dually with the 8.1. ive also got the exact same truck with the 6.0, except the 8.1 truck is a full LT model and the 6.0 is a work truck. Both trucks are 4x4 and have stock everything. the 6.0 truck has 185k on it and the 8.1 has 125k. both trucks get about the same mileage going around town (around 11) and the 6.0 does better than the 8.1 on the highway, (the 6.0 around 15 while the 8.1 around 12) but when you start towing with the truck, you see a massive difference in everything.

 

The 8.1 not only has MUCH more power, and tows the same exact 10k pound trailer with ease (both trucks have 4.30 gears) but the 8.1 also gets better gas mileage than the 6.0 when it tows. The 8.1 can pull my 30ft enclosed trailer 65mph down the highway getting around 10 mpg and doesn't have to work hard, while the 6.0 works its ass off pulling that same trailer at 65 and gets around 6 mpg. I use the 6.0 truck for work, and its been used and abused quite often by bagging it through fields and pulling around 14k in terms of haybales on gooseneck trailers. the 8.1 gets babied and i drive it when i want a vehicle with way too much power. 

 

What im really looking for at this point is a regular cab 4x4 dually with the work truck package and the 8.1 so that way its super short and it has 4x4 but still is able to pull stuff. i had that exact truck but in a 2x4 and it would get stuck more often doing regular things like driving around a wet cornfield or jacking with a combine trying to fill it up with gas. 

 

I use gas trucks because i get a discount on gasoline with my card for work and i also order gas straight from the company, so i can buy gas for like $1 a gallon and its much cheaper to fix a 6.0 or an 8.1 than it is to fix a 6.6 or a 5.9.

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