A recent interview with Chris Meagher, GM's assistant chief engineer for small-block truck V-8 engines, turned up some fascinating info on the new L92 V-8. This 6.2-liter, 376-inch engine will debut in early 2006 in the Cadillac Escalade and Chevy Tahoe, and will be rated at 400 hp and 415 pounds of torque. The aluminum L92 possesses forged rods, variable valve timing (a first for mass-produced, OHV V-8s), crankcase windows for improved bay-to-bay breathing, and a powerful, 32-bit E38 ECM.
But even more intriguing is that this powerful new Gen IV's cylinder heads got a heaping portion of technology transfer from the 7.0L LS7 heads.
"We knew we wanted to increase the output of the 6.0 and 6.2 liter engines, and the best way to accomplish that was to increase the airflow," Meagher explains.
As GM Powertrain had huge amounts of data from the LS7's cylinder head development, they simply applied much of it to this new head.
"There was a lot of useful information obtained during the LS7 head's development. We knew we needed to provide more flow area--we weren't as concerned with the specifics of the port design as we had the LS7 design to work with. Through modeling, the progression along the flow path from intake to exhaust stayed flat and disturbance-free. We put quite a bit of dyno work on these heads."
The 6.2 head didn't get the LS7's radical 12-degree valve angle (it's 15 degrees like the LS1/LS2) or its 1.8-ratio rockers (they're 1.7), but a similar offset rocker-arm setup was utilized. And as far as the intake valves go, they're massive: 2.16-inches (55mm), with 1.59 (40.4mm) exhaust valves.
"As it's a [shared] head assembly, used for both the 6.0L and the 6.2L engines, we are limited from a valve size standpoint with the 6-liter's 101.6mm bore," Meagher divulges. "With the 6.2's 103.25 bore, we could maybe go another half-millimeter larger on the intake, but that's it." He stated that there's no real need to increase the exhaust valve size.
There have been several reports of cylinder head shops flowing these heads already--and the results are stupefying. One report has modified 6.2s flowing 350 cfm at .600, with an insane 280 cfm at .400! And here's the kicker: although these heads won't work on the LS1's 99mm bore, we're told that they should bolt right up to an LS2! With production scheduled to ramp up in January 2006, it shouldn't be long before these bad boys show up in the GMPP catalog. And considering the typical porting costs to get those kinds of numbers out of an LS6 head, we'll bet that the sticker price is downright affordable. Ain't technology wonderful?