JimmyLee

I have dual-mode exhaust on my C6 and frequently leave the exhaust open via an aftermarket switch. I really enjoy the sound, even when stopped at a red light or idling in my garage.

When the new LT1 is idling as a 3.1 V4 instead of a 6.2 V8, will that effect the sound?

rcallen484

Does it go into V4 mode other than at cruising speed on the highway?

RC000E

Of course it will. I imagine though, that the cylinder deactivation scheme will be something that will be able to be tuned out via engine management systems that come out for the platform.

Certainly would take away from the big cam/open exhaust fun at idle if not...

7LitreC5

I have cylinder deactivation on the 5.3 in my 12 Avalanche. It does not activate at idle. It only activates at light throttle or while coasting.

WaxWeekly

Wish they could give me a dial or button or something. Let me pick 4 cyl while sitting in stop and go, the flip it to 8 when I want to play... Letting the computer do it could be transparent to the driver, but may not be as efficient or more efficient than the driver wants.

Brett Hunter

I currently have two trucks with AFM. Active Fuel Management is not active at idle, the only time it comes on is under light loads while driving.

The sound will depend on the exhaust, on my 2008 it is not very noticeable when AFM engages However this truck has a very quiet exhaust. My 2012 has performance exhaust and it is VERY noticeable when AFM engages. It almost sounds like a "jake brake" when running in 4 cyl mode. Because it is a truck (although the MSRP was 7K more than my C6) it doesn't bother my that much. My wife on the other hand cant stand it on the truck. If this was our Corvette it would be unacceptable to both of us.

rcallen484

I would only care about it making an irritating sound (like a drone) under the highlighted conditions. Are you saying that is what it does?

Brett Hunter

Yes, on my 2012 it does have an annoying sound when in 4 cyl mode that is very noticable. This is due to the exhaust. We can only hope that they have considered this when testing and designed an exhaust system that will prevent or at least reduce this effect.

I might try to record the sound today since it is hard to describe.

adamgl

On the AFM L99 auto camaro they had extra resonators before the exhaust that the no AFM manual LS3 didn't. Stock it didn't sound bad when it went to 4 cyl.
But after changing to long tube headers and full exhaust it sounds really bad till you tune out AFM completely.
It probably will have some extra resonators also. Which will add weight over aftermarket exhausts.

rcallen484

A sound that is actually irritating on a stock vehicle is NOT acceptable. On modified exhaust vehicles, a tune sounds like the solution unless the requirements of the federal regulations allow for cylinder deactivation turn-off in "competition" and/or "sport" mode. Performance car enthusiasts have had to be creative ever since the advent of the "air pump" for cleaner emissions back in the late 60's.

BlueOx

@ 1:04...
http://bcove.me/e9bygykn
Sorry about the ad...

JPJR

I agree it sounds good in that clip, ripping out of there.
It's not the WOT sound people are worried about, though.

Will it still pop and gurgle when you lift off the gas, or will it go into 4 cyl mode then, and sound strange?

BlueOx

Nobody has that knowledge yet...

SCM_Crash

I don't plan on changing the exhaust. (No point... Don't want a loud car.)

For the most part, the idea of DoD is great. I would like the option of changing the sensitivity on it, though. Maybe an economy mode and a performance mode...

I wouldn't tune it out, though. I would like to save fuel and the environment when it's convenient. LOL

ottomatic

I also have the 5.3 Avalanche with cylinder deactivation. Last year, I added a Corsa exhaust system to it. It sounds great, but is very noticeable when it changes to 4 cylinder. Of course, instant gas mileage jumps considerably, but the mild droning sound is annoying.

I would prefer not to have it on my Corvette, but we'll see.
!

adamgl

The funny thing is I got better gas mileage on my Camaro after I tuned out AFM. My cruising RPM dropped by about 250.
But if they do a better job on the factory tune maybe that would make the difference though.

SCM_Crash

Well, just keep in mind that when tuners tune your car, they're tuning it for 3 very specific things:

1) They tune it for the fuel you have where you are. The factory tune is good for 91 since some states only have 91. But if you live where there is 93+, a simple tune will yield impressive mileage differences.

2) A dyno tune is specific to your car rather than a tight general tune ment for every build. I'm sure that with today's technology that factory tune is close, but a tuner can usually get more power for that specific motor (which means more efficiency).

3) Often times tuners make your low load AFR a little leaner than the factory. 14.2 is what the factory aims for, but tuners sometimes go a little higher.


All of these things effect your gas mileage, and I'm sure that they squeeze the motor way more than GM would.