Two weeks ago we broke word on a new trick two-stage turbo patent application from General Motors--today we have another one for you that may point to a new turbocharged V8 from GM.

In a patent application published last August, GM is proposing a system where the high pressure turbo would be linked with the exhaust passages from the full-time active cylinders; with a low-pressure turbo fed from the exhaust of cylinders marked for deactivation.

A control valve will modulate the flow from the exhaust passages: when open, exhaust from the full-time active cylinders is allowed to merge with exhaust from the deactivated cylinders and pass through the low-pressure turbo. When closed the valve will direct gasses from the full-time active cylinders exclusively through the high-pressure turbo.

Currently, Active Fuel Management isn't possible in conjunction with single turbos. An engine with deactivated cylinders equipped with a lone turbo is compromised by the single compressor's flow and boost capabilities. GM says it's possible to optimize the single turbo for deactivated operation, however that would compromise the engine's performance at higher engine speeds.

Because this application is 9 months older, it doesn't contain the same nuanced detailing as the May 19, 2016 filing. However if you take the August 2015 application and combine it with the newer spindle actuated valve concept from May 2016, the idea becomes much more viable.

ttv8 fig1

Figure 1 shows the basic architecture of such a system.

ttv8 fig2

Figure 2 depicts the system in operation with cylinders deactivated under light load, feeding the high-pressure turbine.

ttv8 fig3

Figure 3 is a schematic view of an engine with all cylinders in operation, routing exhaust through the low pressure turbo.

ttv8 fig4

Figure 4 depicts an engine with AFM and a two-stage turbo with the exhaust manifold being an integral part of the cylinder head.

Granted none of this explicitly outlines plans for a turbocharged V8 engine, but it certainly points in the right direction. GM's current AFM technology operates through a solenoid deactivating the lifters on select cylinders of a pushrod V-engine.

With AFM being a staple of Ecotec3, small block, Gen V engines it's reasonable to expect it to either show up in conjunction with the 4.3L V6 or 5.3 and 6.3L V8s.

Of course there is also the potential for new configurations based on the Gen V small block. The recent mid-engine something sighting has produced rumors of a twin-turbo V6 capable of some 700 hp.

Elsewhere in the GM universe, JDN has promised us the Cadillac CT6 complete with a twin turbo 4.2L, although he did go on record that it will not share common architecture with the 6.2L Supercharged LT4.

Now the only question is when?