Modifying the L99

[Evilangel]

I know headpunter had mentioned previously that if you deactivate the AFM and do a tune the L99 pretty much equals a LS3. What I'm wondering is this - will GM and the aftermarket create performance parts like headers, heads, and cams specific to the L99 so that way you don't HAVE to deactivate the AFM? Also another question - does AFM hurt the performance aspect of the car?

[Mr. Wyndham]

AFM-equipped engines aren't that difficult to modify lightly...see: G8 GT...things like headers, FI, intake, exhaust, etc shouldn't be an issue.

...then again, internally they will probably cause you trouble as far as modifications...good question.

[Evilangel]

Originally Posted by Dragoneye

AFM-equipped engines aren't that difficult to modify lightly...see: G8 GT...things like headers, FI, intake, exhaust, etc shouldn't be an issue.

...then again, internally they will probably cause you trouble as far as modifications...good question.

I would imagine that cams would be considered an internal mod....

[Mr. Wyndham]

That's why I said "good question".

The lifters in AFM systems are designed to be collapsible, so they can shut down the valvetrain when AFM activates. Due to these special lifters, the cam profile is less aggressive (I read somewhere they can't take a lot of lift)...it would be interesting if GM could offer aftermarket parts to get around that.......

[headpunter]

Originally Posted by Evilangel

I know headpunter had mentioned previously that if you deactivate the AFM and do a tune the L99 pretty much equals a LS3. What I'm wondering is this - will GM and the aftermarket create performance parts like headers, heads, and cams specific to the L99 so that way you don't HAVE to deactivate the AFM? Also another question - does AFM hurt the performance aspect of the car?

as pertaining to the AFM thing.

no it wont hurt the performance of your car. it only kicks in at times of low stress on the motor. so if you have your foot in it you arent going to be gimped by it. when i drive our new tahoe with afm, i cant even tell the difference. It shifts modes so seamlessly that i can only tell by the little gauge in the DIC.

[Supermans]

Originally Posted by headpunter

as pertaining to the AFM thing.

no it wont hurt the performance of your car. it only kicks in at times of low stress on the motor. so if you have your foot in it you arent going to be gimped by it. when i drive our new tahoe with afm, i cant even tell the difference. It shifts modes so seamlessly that i can only tell by the little gauge in the DIC.

Headpunter,

I'm curious as to how different the exhaust note sounds once AFM kicks in in your tahoe since I want to get an idea what to expect if I order the A6 Camaro SS.

[headpunter]

while inside you cant tell the difference, the other thing to consider is that it doesnt enable AFM while you are idling at stops or in park. so you dont really have to worry about other people listening, it only does it at like 25-30+ mph

[Hesh]

I figure there will be plenty of goodies offered for both the l99 and the ls3. Tuners, headers, exhaust and other bolt ons. The internals may be a different story.

[CamaroSpike23]

bolt-ons, it will be like any other motor, no need to tune (you can if you want to get every little bit out of it).

heads, i imagine you can still do and not have a problem as its mainly the lifters that are doing the big part with AFM. but that limits you on the size of a cam you can do as stated before.

when doing heads, you will almost certainly need a tune as the pcm might not be able to realize that you are putting ported heads that allow for more flow that might offset the AFM functions.


but keep in mind that the L92 heads that are coming on this motor are some of the baddest heads out there.