Gokhan
Thread starter
Let's express the displacement, torque, and BMEP in metric units as they are expressed for all modern engines because it's getting confusing here.
The 1,991 cc Mercedes-Benz M139 has two variants -- 480 Nâ‹…m and 500 Nâ‹…m.
BMEP (bar) = 40π × torque (N⋅m) / displacement (cc) = 125.664 × torque (N⋅m) / displacement (cc)
These engines have BMEP = 30.3 bar and 31.6 bar, respectively, which are way higher than any existing production engine as A_Harman said. The review article was saying that it's very difficult to go beyond 27.0 bar because of conventional knock as well as LSPI-induced super knock but these engines are going well beyond that.
Certainly the highest-octane gasoline is a must here but that will do nothing to prevent LSPI and super knock. Oil is the crucial factor in preventing LSPI because that's what seems to be causing LSPI and super knock in high-BMEP engines. Regardless of the official oil recommendation, I would avoid any oil that's not tested for LSPI. Unfortunately the LSPI test in API SN PLUS is not very strict and the more strict dexos1 Gen 2 spec does not have oils with HTHSV ⥠3.5 cP.
Nevertheless, ACEA 2018 is expected to be released in mid-2020 or later and new A6/B5 and G6 categories for TGDI engines that include LSPI protection and timing-chain-wear protection are expected. I bet M139 will spec A6/B5 or G6 and there will be probably a new Mercedes-Benz OEM oil spec that has LSPI and timing-chain-wear tests.
https://www.lubrizoladditives360.com/introducing-acea-2018-light-duty-oil-sequences/
The 1,991 cc Mercedes-Benz M139 has two variants -- 480 Nâ‹…m and 500 Nâ‹…m.
BMEP (bar) = 40π × torque (N⋅m) / displacement (cc) = 125.664 × torque (N⋅m) / displacement (cc)
These engines have BMEP = 30.3 bar and 31.6 bar, respectively, which are way higher than any existing production engine as A_Harman said. The review article was saying that it's very difficult to go beyond 27.0 bar because of conventional knock as well as LSPI-induced super knock but these engines are going well beyond that.
Certainly the highest-octane gasoline is a must here but that will do nothing to prevent LSPI and super knock. Oil is the crucial factor in preventing LSPI because that's what seems to be causing LSPI and super knock in high-BMEP engines. Regardless of the official oil recommendation, I would avoid any oil that's not tested for LSPI. Unfortunately the LSPI test in API SN PLUS is not very strict and the more strict dexos1 Gen 2 spec does not have oils with HTHSV ⥠3.5 cP.
Nevertheless, ACEA 2018 is expected to be released in mid-2020 or later and new A6/B5 and G6 categories for TGDI engines that include LSPI protection and timing-chain-wear protection are expected. I bet M139 will spec A6/B5 or G6 and there will be probably a new Mercedes-Benz OEM oil spec that has LSPI and timing-chain-wear tests.
https://www.lubrizoladditives360.com/introducing-acea-2018-light-duty-oil-sequences/