New 6.0L for 2007??

[SoCal_XJ]

I see the all-new Suburban/Yukon has different engines available for the 3/4 models.

The 8.1L is out, and the only option is a 6.0L V8, with 352HP and 383TQ.
3 questions:

1) is this 6.0L the same as prior years (just modified for more power)?
2) will the 6.0L in the Yukon be avail in the 2007 trucks?
3) does anyone know if they are phasing out the 8.1L for the trucks for 2007?

[Quack_Addict]

There are some minor differences with the new 6.0's but I am pretty sure it is the same long block. I know the intake, water pump, MAF sensor and air box are different than before. The PCM is also different; the calibration is probably where the added power is being made.

GM is doing away with the 8.1L, not sure when, but the rumor is the 'replacement' will be a smaller gas engine. Isn't it true there is no replacement for displacement? I've heard the 6.2L tossed around when talking about what will fill the 8.1L slot; that may be as simple as either a bored or stroked 6.0L, or it may be as complicated as a totally new 'series' engine (Gen IV???).

[Kollin Syverson]

They also have a 6.2 liter for the Denali.

[DmaxMaverick]

Too bad if it's true about the 8.1L. GM must be having issues with emmissions. It's an excellent engine, and gets better mileage towing than the 6.0L.

[Quack_Addict]

It's an excellent engine, and gets better mileage towing than the 6.0L.

In a head to head comparison, my brother's 2002 crew cab short box 8.1L / Allison with 3.73 gears gets better gas mileage than my 2002 crew cab long box 6.0L / 4L80E with 4.11 gears, UNLOADED.

According to his fuel economy numbers while towing his 27' 5'th wheel, his fuel economy is still better than what I was getting pulling my 23' boat with the 6.0L truck.

[SoCal_XJ]

Comparing those two trucks is far from head to head.

#1 - the 4.10 gears in the 6.0L will yield about 10% worse fuel economy alone
#2 - The 4L80e, as strong as it is, is a major slush box. It soaks up so much horsepower, it really takes alot away from the rear-wheel output.
#3 - the extra gear in the allison makes all the difference. The 4l80e has to stay in lower gears longer before it gets up to cruising speed. Plus the 4L80e is really old in design and efficieny.

A more accurate comparison would be the 6.0L with the the nv4500 and 3.73 gears (though GM does not allow that from the factory). Obviously the 8.1L would still tow better and may still get better MPG towing with heavy loads. But empty or with conservative loads, I bet the 6.0L would do better.

[ronniejoe]

The 4L80E is a more efficient transmission than the Allison. As for old vs. new, the Allison 1000 is nothing more than an adaptation of and scaling down of their 3000 series. Nothing new there. The hookups and clutch application scheme is all the same.

Both are good transmissions. The Allison is just much bigger...which is one reason its parasitic loss is higher. That's not conjecture either.

[Mark Rinker]

I heard something recently about this motor...sounds like they have updated the ECM and are calling it 'Active Engine Management' or something like that.

Its about time, my 2003 K3500 was a pathetic, puny gas guzzler.

[Quack_Addict]

Comparing those two trucks is far from head to head.

The point I was trying to make is that in their stock configurations as they are offered in the 2500HD platform, the 8.1L / Allison is a more fuel efficient combination than a 6.0L / 4L80E - towing or unloaded. At least that's my .02

[ronniejoe]

And it is fair and you are right.

[SoCal_XJ]

The point I was trying to make is that in their stock configurations as they are offered in the 2500HD platform, the 8.1L / Allison is a more fuel efficient combination than a 6.0L / 4L80E - towing or unloaded. At least that's my .02

Sorry. I misunderstood what you meant by head to head. I see your point now: comparing the trucks as available from GM (since the trucks cannot be configured the same trans, axle, etc) the 8.1L will get better MPG under some circumstances.