To reduce frictional drag energy loss and increase fuel efficiency, gasoline direct injection (GDI) engines are now using thinner and lighter ‘low tension’ piston rings.
Piston ring spring force in older port fuel injection (PFI) engines used to be as high as 30 psi. New PFI and GDI engines can have more than a 60 percent reduction in sealing pressure on the cylinder walls.
At the same time, new PFI and GDI engine compression ratios have increased from 9:1 to as high as 14:1. These higher compression ratios dramatically increase overall pressure for fuel ignition.
This huge increase in pressure creates more force on the low tension rings. Piston rings are supposed to prevent fuel and combustion gases from “blowing down” between the piston and cylinder wall and oil from moving up into the cylinder. But, low tension piston rings have a greater tendency to allow blow-by.
Crankcase contamination compromises lubrication and promotes oil degradation, making oil more susceptible to oxidation, which can cause oil thickening. The thickening then further increases resistance against the low tension piston rings. As oxidation progresses, sludge formation can occur.
The combination is sludgy, contaminated oil lubricating the rings and low tension piston rings less capable of pushing back against deposits. Eventually deposits will impede the rings’ outward expansion to seal the cylinder wall, which will allow even more fuel and combustion gases to enter the crankcase. Or stuck rings can promote oil consumption and intake deposit formation due to engine oil moving up into the cylinder and into the intake.
So, while new PFI and GDI engines are known for efficiency, the constant struggle between low tension piston rings and high operating pressures will eventually erode fuel efficiency and diminish horsepower say BG Products.
BG EPR® Engine Performance Restoration can keep low-tension piston rings free of deposits say BG, which will keep them from sticking in place. Immobilised rings cause loss of power, diminished fuel economy and premature aging of engine oil. By keeping the rings clean, the compression is maximised.
If the fuel does blow down into the crankcase, BG MOA®, product code 110, will fortify the oil to help it withstand fuel contamination and maintain its essential lubrication qualities longer under the high pressures in today’s PFI and GDI engines.
BG Products say using BG EPR® and BG MOA® at every oil change to help prevent problems caused by low tension piston rings under extreme pressure.
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