L92/L76 AFM/FlexFuel

[Cougar281]

I'm still dreaming of that 98+ Firebird and trying to put together what I want to do with it when I get one . What I want is AFM and Flexfuel both working. I know people don't like AFM because it sounds bad, but IMO, if I could get into the 30's (Just guessing; if you can get 20's out of it in a brick of a tahoe, than I'd have to think an aerodynamic car like a firebird would be able to get quite a bit better) AND put 400 ponies down, it would be worth it. I've been looking over the info on the 6.0L L76 and the 6.2L L92 engines. In the specs I found on one of GM's media sites, the L76 has Variable Valve Timing and AFM, and the L92 has Variable Valve timing. Since the L92 has VVT, if it was enabled in the ECM, the L92 would support AFM?

Flex Fuel support isn't really anything special on the engine, other than larger injectors and maybe the Alcohol sensor in the fuel line, right?

I'd also like to put either a 6L80E or 6L90E behind it, but that's another post for another time .

[ScarabEpic22]

AFM/DOD engines have a LOT of different hardware to allow the cylinders to shut off, so no you can just take a L92 and make it have AFM. The new L99 will have AFM but will not have VVT.


I like your dream, very similar to one of mine! Im thinking mid 90s Impala, maybe use an LS1, LS2, or LS3, 6L90E, you know, the usual stuff!

[GMPX]

See my sig, I am looking for an L76 with a 4Lxxx trans for the old tank (Not one of those stripped out 07 Holden one's either!!).
The E85 I am not too fussed about because it's as rare as rocking horse s*** out here, but the variable cam and AFM sounds good.

L76's are just a little more expensive than a LY6, but I'd rather pay the bit extra and get AFM.

Cheers,
Ross

[Cougar281]

AFM/DOD engines have a LOT of different hardware to allow the cylinders to shut off, so no you can just take a L92 and make it have AFM. The new L99 will have AFM but will not have VVT.


I like your dream, very similar to one of mine! Im thinking mid 90s Impala, maybe use an LS1, LS2, or LS3, 6L90E, you know, the usual stuff!

In looking, the L92 and L76 appear to be VERY similar (appear to share the same intake manifold, for one); any ideas where the L92 gets that extra .2L? Is it in the heads, different bore or pistons?

[GMPX]

http://en.wikipedia.org/wiki/GM_Vortec_engine

[ScarabEpic22]

In looking, the L92 and L76 appear to be VERY similar (appear to share the same intake manifold, for one); any ideas where the L92 gets that extra .2L? Is it in the heads, different bore or pistons?

Heads, think the L92 has intake and exhaust VVT, not sure what else. I do know that the L92 is supposed to be the biggest and baddest truck/SUV engine for the time being. There must be something else because the Escalade and GMC Denalis got it exclusively for a year which has usually meant GM saves the best for one MY then lets the other lines get it.

Someone else who knows more, please enlighten me! Now this question is burning my brain!!

[gmh308]

In looking, the L92 and L76 appear to be VERY similar (appear to share the same intake manifold, for one); any ideas where the L92 gets that extra .2L? Is it in the heads, different bore or pistons?

L92 gets another 0.2L (actually 0.15L) from larger bore and pistons.

It (now) uses an LS3 block.

The bores are 4.065" dia vs 4.0" for the L76.

The L92 and the L76's use the same heads. (originally these heads were developed for the LS7, then GM raised the bar for the HP output, and they went with specific LS7 heads a little more radical.)

L92 having VVT has different pistons to LS3 with exhaust valve reliefs. Would guess L76 VVT has these too.

Cheers.

[Cougar281]

Thanks for the info; from that, it sounds like it might be possile to get a L76 w/AFM and bore it .065 over, and effectively have the 6.2L w AFM. Hmmm....

L92 gets another 0.2L (actually 0.15L) from larger bore and pistons.

It (now) uses an LS3 block.

The bores are 4.065" dia vs 4.0" for the L76.

The L92 and the L76's use the same heads. (originally these heads were developed for the LS7, then GM raised the bar for the HP output, and they went with specific LS7 heads a little more radical.)

L92 having VVT has different pistons to LS3 with exhaust valve reliefs. Would guess L76 VVT has these too.

Cheers.

[GMPX]

I wouldn't bother, for the expense, an L76 will make plenty of power as is. Only issue is you can't really rev them too high because of the AFM system, so if you want an 8,000RPM screamer, forget AFM and go with an LS3.

Cheers,
Ross

[gmh308]

I wouldn't bother, for the expense, an L76 will make plenty of power as is. Only issue is you can't really rev them too high because of the AFM system, so if you want an 8,000RPM screamer, forget AFM and go with an LS3.

Cheers,
Ross

^^^ What Ross said!

Plus the L76 (LS2) block would unlikely tolerate a safe 0.065 overbore.

Also, AFM has lift limitations and valvetrain stability challenges beyond stock config.