6.6L or 6.7L ?

Zane · March 26

The rumor mill is pretty wild these days. We've heard from reliable sources that 6.6L was mentioned during the dealer update conference, however today Chevrolet released the 6.7L LS6 for 2027. It will land in the Corvette Grand Sport and also be the standard engine for the Corvette.
Leaks from Dealer Meeting: https://www.gm-trucks.com/2027-chevy-silverado-leaks-5-7l-v8-1000-mile-range/
Grand Sport and LS6 Info: https://www.gm-trucks.com/2027-corvette-grand-sport-6-7l-ls6-v8-reveal/

Since the top level Silverado/Sierra engine has traditionally been the same as the base Corvette engine- does that mean the 2027 Silverado/Sierra will get a 6.7L V8? Or are they bucking the trend and splitting up the displacements? 6.6L for trucks and 6.7L for Corvette?

newdude · March 26

I'm gonna lean to a split. I could be completely wrong though.

5.7 (350 ci) and 6.6 (400 ci) for the trucks and those will be Tonawanda is my guess.

LS6 6.7 we know for sure is Flint per the press release for the 2027 Grand Sport.

The details of the gen 6 engines is what I REALLY want. We know AFM is in the LS6 now. We also know that these have dual fuel injection (port and DI).

Badbird2000 · March 26

Just give me a 409 in a truck...

I hope they use the 6.7 liter myself... for both

Epsilon Plus · March 31

I'm already hearing the dreaded "350" nomenclature returning which took years of hearing boomers constantly mis-sizing the LS1 as one. Let's wait until confirmation before throwing that ol trope around.

As far as the current L8T.... 400 or 401? Do the CI math with published inch bore/stroke and you have a 400. Do it with the punished mm bore/stroke and it's a 401. Just happens to have 401hp too which GM has occasionally, historically, matched to inch displacement.

With GM being metric everything from the 90s on, I'd wager the MM 401ci is real truth.

All this to say, nobody really knows the displacement until after confirmation, and well, even then it's foggy.

newdude · March 31

4 hours ago, Epsilon Plus said:

I'm already hearing the dreaded "350" nomenclature returning which took years of hearing boomers constantly mis-sizing the LS1 as one. Let's wait until confirmation before throwing that ol trope around.

As far as the current L8T.... 400 or 401? Do the CI math with published inch bore/stroke and you have a 400. Do it with the punished mm bore/stroke and it's a 401. Just happens to have 401hp too which GM has occasionally, historically, matched to inch displacement.

With GM being metric everything from the 90s on, I'd wager the MM 401ci is real truth.

All this to say, nobody really knows the displacement until after confirmation, and well, even then it's foggy.

Coyote 5.0 is 4,951 cubic centimeters/302.1 cubic inches. Just like the old 5.0 was 4,942 cc/301.6 cubic inches.

4.9 liters doesn't sell...5.0 and 302 sell. Just like Vortec 5.3, 6.0 and 6.2 sold. Nobody walked into the dealer for an HD pickup asking for a 2500HD with the 364 engine.

smit303 · April 3

I bet they asked for a 409 in a C10 back in the 60's though.

newdude · April 13

On 4/3/2026 at 9:08 AM, smit303 said:

I bet they asked for a 409 in a C10 back in the 60's though.

Impossible as the 409 was never offered in the C/K pickups

They'd have asked for a 283 or 327 small block in a 1st gen C/K (60-66), a 396 big block or a 400 big block (which was really a 402ci) in a 2nd gen C/K (67-72) or a 400 or 454 big block in a 3rd gen (73-87).

shift_grind · April 19

On 3/31/2026 at 3:33 PM, newdude said:

Coyote 5.0 is 4,951 cubic centimeters/302.1 cubic inches. Just like the old 5.0 was 4,942 cc/301.6 cubic inches.

4.9 liters doesn't sell...5.0 and 302 sell. Just like Vortec 5.3, 6.0 and 6.2 sold. Nobody walked into the dealer for an HD pickup asking for a 2500HD with the 364 engine.

Everyone says they're 302s but since 2018 they're 307s. Any bigger and they'd be a 5.1

But it's like a Ls1, where everyone says they're "350s"