ByByBMW

Has GM used the LT1 version of AFM in any of their other engines? Recently? My basic question is: Is this a brand new design or has it been field tested/used elsewhere in the GM line?

BlueOx

I think if you search you will find tons on this very topic here.

CitationZ06@yahoo

Yes it is in the auto Camaro, Tahoe, Truck line. They have the bugs worked out, and I like it in my Tahoe. Do a search on the Camaro Forums and you will hear guys bitch about it, but they just put in new lifters with a big cam and tune it out if they don't like it. If you are a guy that mods your motor you will get rid of it. If you drive it around town/out to dinner you will like the added mpg. I think it is a win win.

Jinx

This isn't the first pushrod AFM that GM's done, but it is the first pushrod direct injection.

It might also be the first manual transmission AFM....

jimmyb

I think it was announced that AFM will not be on the manuals, but I can't remember where I saw it. Maybe someone can chime in with a link.

Jimmy

JerriVette

The LT1 is the first GM engine to be designed from the beginning with afm in mind.

The various items such as reversed intake and exhaust valves. The 2 degree angle. The new throttle body. The new box manifold. The direct injection. The new EGR design.

This truly is a new engine design with AFM as an integral part of the design.

Previous v8 and even v6 designs of AFM were nowhere near as integrated or as complete.

Strong rumors that automatic transmission equipped vehicles better absorb power pulse differentiation (sp) so the manual version might not receive afm.

The one kicker will be aftermarket exhausts so popular will be more challenging with AFM to achieve pleasant sounds in both modes.

I look forward to the eventual efforts by aftermarket companies. I believe thecamaro automatic with AFM s were an initial challenge.

Of course the L99 was no where near as advanced as the new LT1 nor were any previous v6.

mksz51

Great comments - thanks.

235265283...

Is there an elegant (i.e., non-kludge) way to "get rid of it"? Certainly you are left with those four risers cast into the block that no longer have any purpose. If you just replace the lifters, do you leave all the solenoids, valves, etc., under the valley cover there so the ECM continues to signal the solenoids to activate and turn lifter oil flow on and off, which doesn't affect the new non-AFM lifters? Or do you reprogram the ECM and hope for no unintended consequences?

And then of course there is the voided warrenty issue.

My bet: Manual transmission C7s will have AFM.

MikeyTX

One of the very first topics discussed once the new engine was announced.

ByByBMW

Some good responses but maybe my concern wasn't stated well in the OP. Since the LT1 is a new design, as pointed out, maybe AFM won't work well, or has some unknown wrinkle that we haven't seen yet that will make the engine ultimately a time bomb. Kind of like what is happening with the LS7 valve scenario?

And yes, AFM has been discussed but my searches didn't result in any kind of discussion that addressed what I am asking.

SCM_Crash

I have a few thoughts here:

1) If this is still an issue, then this would stand to reason why a DCT would not happen along side AFM.

2) I would imagine that this isn't an issue anymore. From the videos I've seen, there's no pulse at all anymore. The change between modes is seamless.

That being said, since GM has been working on DCT technology, I would imagine that they have this AFM thing down to a science now. They won't be able to introduce a DCT without it. And since this motor is built from the ground up with AFM in mind, it would make sense to me that the AFM kicks on and off gradually, faster or slower, depending on the driver's request for speed changes (up and down).

BlueOx

Well, ultimately you are asking a question that nobody here knows the answer to yet. This version of the AFM on a brand new generation of engine is going to be a mystery unless KEEKS or someone else in the know at GM knows something specific they can reveal.

ByByBMW

Thanks BlueOx. Duh on me. You are right of course, we will just have to wait. I guess I was hoping for some kind of insight which doesn't really exist yet.

I am vette less at the moment and trying to decide if I should wait for the new C7, buy a used C6, or buy a used C6 once the C7 is out and folks start trading in.

JerriVette

Have faith in GM as their testing was rigorous and I can assure you this is not a time bomb.

You will see a forced induction system in Later iterations and the engine will again come with GM s flawless execution and 100 thousand mile warranty.

I can't say how the engine will react to early adopters to aftermarket mods though...ie cam/heads/headers or superchargers..

Might be better to buy the factory higher performance versions early on if you are after greater performance levels.

As time marches on I am confident aftermarket tuners will find reliable ways to increase hp of base models etc....

By with confidence

CitationZ06@yahoo

I started a big write up but I don't know enough about the C7. It will take time to get parts to the after market, and time to hack the PCM. Just drive the thing for a year or two and have fun, then when it feels slow drop in a big cam. This is a cut and paste form HotRod.com I hope I am not busting any rules via my cut and paste.

AFM problems (450 hp, 0.500-inch-lift cams, or high rpm): Half the lifters and their corresponding cam lobes are unique. Comp and LPE offer AFM-style cams, but they're limited to 0.500-lift because the special lifters don't work with a reduced base circle. If you raise the rev limiter beyond the L99's 6,200-rpm limit and then run up against it, Jannetty Racing says the AFM lifters will fail. Best option: Reprogram the ECU to delete AFM, then install a conventional cam and lifters.

VCT phaser woes: Valve-to-piston contact can occur with bigger cams from too much advance. Comp Cams has a phaser limit kit that allows aggressive cam profiles with up to 220 degrees duration at 0.050. Above this, either: increase intake centerline 2 degrees for every 4-degree duration increase, change pistons, or delete VCT; the latter requires installing a LS3 front cover and a conventional timing set.

Valve float: L99s don't have the LS3's hollow-stem intake valves. When switching to high-lift cams, LPE recommends installing lighter LS3 intake valves.


Read more: http://www.hotrod.com/techarticles/g...#ixzz2CcCzFVwN

Bill Dearborn

The first time I saw AFM or Displacement on Demand was at the 2002 Detroit Autoshow. GM had an LS truck engine on an engine dyno and was demonstrating how they used the dyno to test various aspects of the engine operation including shutting off some of the cylinders and turning them back on while the engine was operating. That thing ran for a lot of hours every day of the couple week long show, saw it again at the next show I went to in 04 and then in 05. They got enough test hours just running that thing through several years of shows. They would troop 20 or 30 people at a time into the booth run the engine for 5 minutes or so and then troop in another 20 or 30 people and do it all over again.

Bill

ByByBMW

Now THAT is good to hear. Thanks Bill.

GordyRay

If you go back to the post on SEMA, (just two weeks ago), two different people shared that Corvette Reps stated that the new C7 would not have AFM on the manual tranny. Do a search and read the post. Obviously that doesn't mean that this is accurate however.

Keeks, what say you dude????

SDPC

All of those other aspects of the engine are new, but the AFM design they are using is not. It's essentially the same stuff they've been using since 2007ish. The AFM design as a whole is a carryover with the risers in the block, the solenoid setup, the lifters, etc. Whileas the direct injection, reversed valves, etc are great changes that take the engine in a positive direction, they are not directly related to the AFM setup.

Those risers have been cast in the blocks since the LS2, they are no big deal. On the current models you can not leave the solenoids when you delete the AFM or else you end up with no oil pressure. You replace the valley cover with a non AFM cover that has orings on the bottom that seal off those pedestals, like an LS2 or LS3 valley cover. Hopefully the new LT1 has a non DOD version that will provide the cheap valley cover needed to delete the system like we do currently by using an LS3 or LS3 valley cover on the L99 in the Camaro and also the truck AFM applications, but even if it doesn't aftermarket valley covers will be easy to come by.

With the main parts and the system design being carried over from the tried and true systems already in use, likely the only real issue with deleting the AFM on the new engine will be tuning to eliminate it from the PCM. On the current setups it's a simple enable/disable dropdown, let's hope for the same.

rmarks

http://papers.sae.org/2007-01-1292/