I'm buying a new Silverado and can't decide on whether to buy a left over Classic 07 or one of the new 07s w/AFM & VVT. I have cam,stageII heads,hardened pushrods,R lifters,double row adjustable timing set which were removed from my wrecked 04 to install on the new truck. I know some of these parts can't be installed on the AFM/VVT motor. These features aren't very mod friendly when it comes to top end stuff. Are AFM & VVT worthwhile tradeoffs if you can do the mods you could otherwise do if you stuck with a Classic 07?

 

i know VVT is variable valve timing but what is AFM?

personally i would get the classic for looks ( i dont care for the new 07s) and the fact that you know the parts will fit

 

AFM- Active Fuel Management

 

AFM is Active Fuel Management. It's the new name for DOD(Displacement on Demand) **edit** 03sierraslt beat me to it.

I thought the only new engine with the VVT so far was the 6.2L in the Denali and Esky?

 

thanks

 

What parts couldn't you install if it was a AFM engine only? The lifters would be my guess.

 

The L92 6.2 and the Vortec Max L76 6.0 are the only to use VVT I think. The L76 is the only to have AFM and VVT

 

I would get the new one unless you are strapped for cash. Either way, they are both nice looking trucks. The new 07 one might have bugs in it. The classic has had a while to get refined.

 

AFM(DOD) uses special lifters on the 4 cylinders that get shut off during AFM mode. There are also special lobes on the cam for those cylinders. That means the days of changing a cam or lifters on a 5.3 or 6.0 are over. The VVT means no double row adjustable timing set because the cam phaser takes up the space needed for the double sprocket. They say the VVT motor comes with a more heavy duty timing chain. I also noticed in the exploded pictorial I saw of the motor that the VVT uses a cam chain tensioner. It's not the block type I've seen in the past that resides in the area between the crank and cam sprockets. This is one of the windshield wiper type looking things, but it appears to be fixed instead of spring loaded as is the case in most applications. Since aftermarket cams are out I guess higher ratio rocker will become more popular since that's the only other way to achieve more lift and duration with this motor. The CNCed heads are one of the few things you can still use. I've read the 6 spd auto trans which is already being used in the 6.2L Escalade will be offered on the 2008 trucks that have the 5.3 or 6.0L engines. It has 2 overdrive gears. I don't know what the ratio of the 2nd overdrive gear is, but with a 2nd overdrive and AFM you should be able to get pretty good highway gas mileage even with the bigger 6.0L engine.

 

Is there anyway to tell if your truck came with AFM/VVT? The truck in question is an '07 Silverado. Any factory codes that would let me know?

As long as the truck isn't equipped with AFM, I can still perform a camswap on it like any other LSx based engine, right?