New prototype GM small block, the XV8.

Thirdgen89GTA

Aka "That Focus RS Guy"
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Sep 19, 2010
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Bill
Wonder if this is the LSx series of engines replacement.

Some pretty awesome stuff in there.

Two Cams In-Block with Variable Inlet Valve Timing and Cam Phasing
The use of a camshaft "phaser" separates the timing functions of the intake and exhaust valves. This is accomplished in the XV8 engine by having two in-block camshafts, one for inlet operation and one for exhaust. The camshafts are located in a vertical plane above the crankshaft and parallel to its centre of rotation. The intake camshaft is the lower camshaft and is approximately in the centre of the block. The exhaust cam is positioned above the intake. Because the intake camshaft rather than the exhaust is "phased," the XV8's camshaft drive provides the ability to better modify and enhance full-load engine torque characteristics. In the stratified combustion mode of operation, it can be used to increase the charge dilution by advancing the intake cam timing. The set-up reduces friction and fuel consumption, particularly at idle and part-load, and also contributes to the engine's outstanding low-end torque.

"With the cams in the block," Indra said, "the valve timing precision is better than with a DOHC configuration. The different heat levels with long belts and chains in a DOHC set-up always changes the valve timing."

Having two camshafts in the engine block with the ability to "phase" one of the cams is unique to GM.

XV8camInBlock715.jpg


Narrow 75-degree Bank Angle
The XV8's narrow 75-degree bank angle and very small cylinder heads result in an overall engine compactness that is revolutionary. "The 75-degree V8 is a packaging solution that's typical of race cars," said Hayman.
Active Inlet Manifold
The air-assist direct injection system requires port geometries that generate a minimum of "in-cylinder" motion when the system is operating in stratified mode. During homogeneous operating conditions, in-cylinder motion is required in similar fashion to port fuel injected engines. The inlet manifold design supports these design objectives to achieve maximum fuel economy. The resulting design also allows the engine to deliver a broad torque band suited to spirited driving styles, supports the peak power objectives, and fully accommodates the Displacement on Demand system.

Twin Oil Pumps/Balance Shaft Assembly
The XV8 is unique not only in that it has two oil pumps, but also in that the engine's balance shaft doubles as the oil pump drive shaft. The former allows for such functions as cam phasing and Displacement on Demand at idle and the latter contributes to the engine's compact packaging.

Because the XV8 requires extensive hydraulic function, two oil pumps were used in a serial fashion. If the lubrication system was designed with the typical single oil pump, its displacement would have to be substantially increased to provide minimum pressure to the entire engine. The primary pump supplies low pressure filtered oil to the bearings, valve lifters and secondary pump inlet. The secondary pump acts to intensify the pressure for supply to the cam phaser and Displacement on Demand systems. In doing this, parasitic power consumption to the oil pump is minimized.

Because of packaging constraints, the oil pump drive was combined with the balance shaft assembly. To get the necessary 1:1 counter-rotation of the balance shaft, it is driven by a helical gear pressed on the rear of the crankshaft.

"The drive for the pumps is the balance shaft, which has to go opposite engine rotation at engine speed because of our narrow bank angle," Hayman said. "So we get the balance shaft basically for free and this is all packaged in the sump that bolts to the bottom of the block. That is unique. Also, placing the oil pumps at each end of the balance shaft helps to damp vibrations."

Integrated Air Compressor
The XV8's air compressor (used in the direct injection) is integrated into the engine assembly.

"That's another unique aspect of the engine," Hayman said. "The air compressor is part of the engine assembly itself, not just a component bolted onto the accessory drive somewhere as a standalone pump. It's integrated to the back of the cylinder head and all of the fluids are transferred through this interface. This avoids the requirement for the myriad of hoses that would have traditionally been required including the avoidance of having to run a separate air-assist rail."

Conclusion
"Starting with a clean sheet of paper allows engineers to see the whole picture for the first time - not just power or high revolutions or any one specific goal," said Indra. "They really see the requirements of the future and designed the engine around those requirements. It gets excellent fuel economy and has clean emissions, but above all, it satisfies the main requirement anyone has of an engine: It will perform."
 

Wrencher

Regular
Sep 11, 2011
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The motor went into a lot actually.
The innovations in this engine are implemented in many makes & modes of engines today.
GDI, variable cam timing, intake runner swirl port control/air assisted charge just to name a few.
Funny they build this stuff but never utilize it.
 

CrunkMaro

DurkaDurkaTerrorist
Jun 17, 2010
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the technology is being used. thats what matters.

the tooling was probably too expensive.

thats what sucks about engineers working for a business...

the engineers go all out with their ideas
but the business managers scale them back on a budget.
its a fight that never ends.
 
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