Quote:
Originally Posted by beetle6986
Wow. What was wrong with the motors. A new motor in 10k miles on a stock car is insane!
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Now that I have some first hand experience AND done some more research, I can tell you, there are multiple causes.
1. Oil pump: The new LT motors and by extension, any modern Chevy V8 that uses variable, on-demand oil pumps can suffer from a quick death when the pump goes. There's a small "tab" inside the pump that changes the ratio on the fly that has a tendency to sheer on high loads. When that happens the engine lose all oil pressure. It's just a poor design with no redundancy built in, when the variable gear fails the pump should default to using the engine RPM for pressure instead of dropping to zero.
2. Poor choice of oil for bearing clearance: Does this ring a bell? Due to higher and higher MPG demands, GM chooses to put a 5W-30 as the default fill for LTx engines prior to the switch to 5W-40 in 2019. Way too thin of an oil for a high performance engine. In fact, they recommend you switch to a 10W-50 for any sort of performance application. Why not just fill with a 10W-50 to start with?
3. Cylinder deactivation on demand: The valves that closes the intake valve when the cylinder(s) are deactivated for cruising in V4 mode is a great concept, but poorly designed in a pushrod. There are a significant number of engines that failed when the hydraulic valve fails, leading to a lot of people looking to install what they called a "range" device that attaches to the ODB2 port to permanently disable "V4" cylinder deactivation in an effort to stave off the inevitable engine failure when the valve fails.
The recent LT engine is a clear case of trying to put too much technology into an archaic design that isn't really meant for high performance applications. While the old Chevy V8 is a bullet-proof design, most of the recent problems stems from cylinder deactivation, variable load oil pump, and frankly, running way too thin of an oil for GM's DEXOS generation 2 long term fills.