Before I order my 2500 HD, a little help?

[Grouperassasin]

Glad I found you guys on here! This is my first post on the site, I hope it helps! I'm looking at ordering a new 2008 GMC 2500 HD. I am in the construction buisness and my Yukon is just not cutting it anymore. I have some questions that when I ask the local dealer, I'm not so sure they really know what they're talking about, hopefully someone on here does. Any help would be greatly appreciated.

Is the 6.0L V8 available in the HD with Active Fuel management? IF so, how do I spec it on my order?

Why does the trailering capacity drop almost 3000lbs when you select 3.73 gears vs 4.10 in the gas motor? I want the better economy of the 3.73 rear end, but don't know if I want to sacrafice what the truck is really meant to do.

what is the difference in fuel economy for the 3.73 vs. the 4.10 if all else is the same?

Is the flex fuel option available on the 6.0L gas motor?

Thank you in advance for anyone who has the time or knowledge to help out, it's a large purchase that I plan on having for a long time, just want to make sure I order the right truck. Thanks again!

Edited November 27, 2007 by Grouperassasin

[Camino LS6]

I'm not sure that AFM is available on HDs, but if it isn't I would stay away from the 6.0.

Don't get me wrong , it is a great engine - but it's a thirsty beast. I had one in my '01 HD and it convinced me to go with the Duramax for my '05. It was that or the 8.1 gas engine (which actually gets better fuel economy than the 6.0).

I don't think you can still get the 8.1, but I would take it over the 6.0 any day. The D-max with the Allison trans easily tops them both (at a premium), but diesel is very high right now so factor that in as well.

As for the rear gearing, you need the 4.10 if you intend to do heavy towing - but you will pay dearly at the pump. Let your usage be the deciding factor. I'm guessing that since you are working out of a Yukon now, you don't really need the extra grunt. Any 2500HD will be far more capable than the Yukon when it comes to contracting.

If you go with the 6.0 with the 4.10, just be sure that the truck is earning money every time you drive it - or the fuel cost will shock you.

I loved my 6.0 4.10 HD, but feeding it was an ordeal. Even with the purchase premium and the recent increase in diesel pricing, I am far happier using the D-max as a work truck.

Hope that helps.

And welcome to C&G.

[Newbiewar]

AFM is not avalible on the HD motors, it may be offered on the VortecMaxx(more power then hd 6.0) motor, but i have forgotten

reguardless... with the 3.73 vs the 4.10...

the 4.10's have almost a 10% more power advantage over the 3.73...

the 3.73's also may be less durable...

but i think the reasoning behind the less gross combinded vehicular weight rating, is the transmission will likely hunt for the right gears when loaded if its got too much weight on it... and eventaully wear out your transmission prematurely

[Camino LS6]

The 3.73s are just as durable (standard with a D-max) . It is just the ratio that changes.

Engine, trans, and gear ratio combined are what really matters. Each configuration has advantages, the key is to match the equiptment to the need.

Oh, and the locking rear is worth the money (just be prepared to change the gear oil fairly often to keep it working smoothly).

[Grouperassasin]

The 3.73s are just as durable (standard with a D-max) . It is just the ratio that changes.

Engine, trans, and gear ratio combined are what really matters. Each configuration has advantages, the key is to match the equiptment to the need.

Oh, and the locking rear is worth the money (just be prepared to change the gear oil fairly often to keep it working smoothly).

Thanks guys! I defintely have the locking rear diff spec'd, along with HD trailering equipment, camper mirrors, etc. The gear thing just threw me off. I run all Amsoil in all the fluids of my vehicles and am pretty religious about changing them at or before the recommended intervals.

I would love to have the diesel, however, the $8300 premium I can't swing at this point. I don't tow incredibly heavy loads, and even the really big ones are only a few times a year. BUt I tow 6-8000 lbs pretty frequently and figure one that is made for heavier loads, should handle those just fine. I just wanted to know that if I did have a 12K lb load back there, the gears aren't going to bust?

All your help is much appreciated. Anyone know why you can't get the AFM on the HD's? I figured it would help GM meet some of the CAFE requirements to get some of those big trucks up there a little more in the fuel economy.

I guess that leads to another question, if the 6.0L is available in the MAX package with the AFM, is it simply a computer program that needs to be downloaded to the truck that makes it have AFM? Hmmmmmmmmmmmm? I wonder if a well placed $100 bill to a friendly tech at my local GM dealer could solve my problem?? any thoughts from you guys?

[thegriffon]

AFM in an HD truck may well be pointless. If you need the HD towing capacity, then you won't benefit much from AFM, as you'll be operating on all eight cylinders more often. To my knowledge the only engine equipped with an inactive AFM system is the L76 fitted to the final-year VZ Holden Commodore for emission compliance (all of Euro3—US engines are typically Euro4 or 5 equivalent).

Note the HD engines come in two versions, low GVWR rating and high GVWR rating (reduced rpm limit and hence less power).

The 8.1 is only available in Class 4 and higher trucks (i.e. Topkicks, Kodiaks and GM-badged Isuzu LCFs).

[Grouperassasin]

Griffon, Thanks for the input. I do trailer heavy loads, hence the need for the HD, but only maybe 5% of the 22-25K miles a year I drive and figured the highway driving with AFM would save some gas. Do we know if there is a different config. for the AFM or is it simply a computer program? The top Kick and Kodiak trucks are too much for what I need. I still need a truck that my wife and soon to be kid can get up in and we can go to the store.

Anyone know about the flex fuel option and if it's available on the 6.0L HD's?

I believe it's the lower GVW that I'm looking at. Just the regular 2500 HD, I believe it's the 9200 lb or under?

[76ChevyTrucker]

AFM isn't really a program per se, its partly mechanical and partly electronic. The electronic part monitors the engine load at kills electrical power to the coils and fuel injectors for a particular cylinder group. You'll also normally have a mechanical side to it that will allow the engine to "float" the valves on those particular cylinders so that they will put a minimum amount of strain on the cylinders that are working.