07-12-2007, 10:12 PM | #15 | ||
I used to be Dragoneye...
|
Quote:
But I like to consider myself very knoledgeable about this particular topic...I don't build them...like some of us ...but I read a lot MOST OF THIS IS REPEATED, I just love to type, right?:p It's called AFM, active fuel management. It DID used to be called Displacement on Demand (I like this name better). I seem to have noticed that it's a mostly concentrated feature in Chevrolet engines, other branches have it, I do know that (just not which ones). It shuts off 4 of your cyllinders, either from a V6, or a V8. Got this from chevy.com: Quote:
This technology is really neat, it works like this, so I understand: when activated, half the engine's valves (those of the AFM cyllinders) are "separated" from the camshaft. There are pressurized "connectors", that allow the pushrods to move without effecting the valves. Stopping intake, and exaust valves from moving, thereby taking a load off the engine (allbeit a small one). The injectors are also shut off (hence the fuel savings). Since the computer controls it, it's activation in measured in 100ths of seconds, seamless - and virtually undectable (except for the instant power thing). The activation is triggered under "light-engine load" though what that is defined as.... I wonder, form those with experince behind the wheel of one of these, does it activate under idle conditions? The Camaro has been reported by GM as expecting 30 mpg highway, and I've heard 33, too in other reports - so I'm sticking to GM's 30. Though, expect a little more with extensive highway driving. Silverado's have it, and still make MASSIVE power numbers! so I Like it! |
||
07-13-2007, 07:25 AM | #16 | |
GM Powertrain Retired
Drives: 67SS350, 87 IROC L98, 96SS ver Join Date: Jan 2007
Location: Niagara, Canada
Posts: 352
|
Quote:
|
|
07-13-2007, 09:42 PM | #17 |
www.Camaro5store.com
|
That's what I was saying! And from a powertrain man himself! Kudos to you, Dragon.
Yes, I drove a Malibu, no it wasn't a V8... Since we talk so much about the V8, it just came out that way. But, I didn't even realize the engine was shutting off 3 of the 6 valves while driving. It was a while after driving that I was messing around with the odo contols to see what all the Malibu had. We were on the 101 doing about 80 or so and it said something like "3 cyl _____" Don't remember what else it was...maybe "off?" But, I'd hit the gas....NO LAG AT ALL....and bam, we were moving again w/out any hesitation. Really, like GM said, it was seamless. You couldn't tell at all. As for the idling, I couldn't tell you for sure, but I'm 99% positive it will not deactivate the cylinders while idling. Again, I really liked that write up. It was informative! |
07-13-2007, 09:44 PM | #18 |
www.Camaro5store.com
|
Oh, and it constantly went from 3 to 6 on the hwy. Press the gas and it's 6. Let off the gas and it's back to 3. Tap the gas just a tad harder than you should and it's off again. But, it does work...and it does save gas.
|
07-13-2007, 11:03 PM | #19 | |
I used to be Dragoneye...
|
Quote:
btw, did I cover it all whiterag? |
|
09-23-2007, 11:17 AM | #20 |
GM give me my fix please!
Drives: 95 Toyota GT4 Join Date: Sep 2007
Location: England.. aka the EU's whipping boy!!! (but not for much longer, hopefully)
Posts: 173
|
Umm... now i like the idea of saving fuel, but what about the exhaust note, obviously with all the V8's cylinders pumping away we should get a nice sound but what will happen when 4 shut off??
Will it quieten down or will it keep it's muscle tone?? |
09-23-2007, 07:08 PM | #21 | |||
Truth Enforcer
Drives: anything I can get my hands on Join Date: Sep 2006
Location: anywhere and everywhere
Posts: 22,797
|
Quote:
but with the AFM, just drop the hammer and activate all 8!
__________________
Never race anything you can't afford to light on fire and push off a cliff
A group as a whole tends to be smarter than the smartest person in that group until one jackass convinces everyone otherwise. Quote:
Quote:
|
|||
09-23-2007, 08:29 PM | #22 |
I used to be Dragoneye...
|
Right...everything will be effected with only half your cyllinders running. And at the strict parameters that are set for deactivation, I don't think you'll find an exaust note welcome at those times, anyways. I.E. Highway cruising, rolling down a hill, cruising through a city street (no gas).
And if you do want the note...pop it into a higher gear, and hammer it. You'll get all eight back up (That'd be considered a high-load) AFM is definitely a win/win |
09-26-2007, 08:07 AM | #23 |
Drives: 03 Dodge Dakota Join Date: Jul 2007
Location: New York
Posts: 627
|
Just think of the fun you could have. Everyone knows horses don't like loud noises, you go from very quiet (4 cylinders) coasting through town to a growl (8) and scare the little mustangs into a stamped, when ever your around.
|
09-27-2007, 10:14 PM | #24 |
Drives: 2000 honda accord v6 Join Date: Sep 2007
Location: South Dakota
Posts: 214
|
the only thing im not sure about is...how reliable is "AFM" or "DoD"? i mean is it likely that it will eventually stop shutting down cylinders (which i guess isnt a bad thing, hearing that beast all the time ;-) ) or go out like a tranny?
on a side note, i want a camaro. |
09-27-2007, 11:26 PM | #25 |
I used to be Dragoneye...
|
I shouldn't think so...
there aren't any "moving parts" so-to-speak...it's mostly fluid working it's hydrolic magic. |
09-27-2007, 11:29 PM | #26 |
Drives: 2000 honda accord v6 Join Date: Sep 2007
Location: South Dakota
Posts: 214
|
oh really? yeah i didnt really know how it worked haha. i guess thats good then, awesome!
|
09-27-2007, 11:32 PM | #27 |
I used to be Dragoneye...
|
there are moving parts...I mean, there's a little cyllinder in between the cams and pushrods - from what I understand, and fluid compresses something inside the cyllinders to "connect" the pushrods to the cam...and releases when AFM activates...
The rest: fuel, spark, and valve deactivation signal - are all computer controlled. |
09-27-2007, 11:57 PM | #28 |
Drives: 2000 honda accord v6 Join Date: Sep 2007
Location: South Dakota
Posts: 214
|
i figured it was something like that, but wasnt sure. thanks for clearin it up
|
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
LSX owners: AFR Cylinder Head Owners | FTI-EDC | General Automotive + Other Cars Discussion | 0 | 11-10-2006 05:54 PM |